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Gago J, Grima-Pettenati J, Gallego PP. Vascular-specific expression of GUS and GFP reporter genes in transgenic grapevine (Vitis vinifera L. cv. Albariño) conferred by the EgCCR promoter of Eucalyptus gunnii. Plant Physiol Biochem 2011; 49:413-9. [PMID: 21393008 DOI: 10.1016/j.plaphy.2011.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 02/07/2011] [Indexed: 05/24/2023]
Abstract
In the view of the economic importance of grapevine and the increasing threaten represented by vascular diseases, transgenic grapevine with enhanced tolerance could represent an attractive opportunity. Hitherto, constitutive promoters have been used generally to study the effects of transgene expression in grapevine. Given the fact that constitutive gene expression may be harmful to the host plant, affecting plant growth and development, the use of tissue -specific promoters restricting gene expression to tissues of interest and at given developmental stages could be more appropriate. For this purpose, we decided to study in grapevine the activity of the Eucalyptus gunnii CCR promoter that was previously reported to be vascular-preferential. We transformed grapevine with the "Sonication assisted Agrobacterium-mediated transformation" (SAAT) method and a construct where both GUS and GFP (green fluorescent protein) marker genes were under control of the EgCCR promoter. High GUS and GFP activities were found to be associated with the newly formed vascular tissues in stems, leaves and petioles of transformed grapevine, suggesting a preferential activity of the EgCCR promoter in the vascular tissues of grapevine. These results suggest the tissue-specificity of this promoter from eucalyptus is conserved in grapevine and that it could be used to drive expression of defense genes in order to enhance resistance against vascular pathogens.
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Affiliation(s)
- Jorge Gago
- Applied Plant and Soil Biology, Faculty of Biology, University of Vigo, Vigo, Spain
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202
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Navarro M, Ayax C, Martinez Y, Laur J, El Kayal W, Marque C, Teulières C. Two EguCBF1 genes overexpressed in Eucalyptus display a different impact on stress tolerance and plant development. Plant Biotechnol J 2011; 9:50-63. [PMID: 20492548 DOI: 10.1111/j.1467-7652.2010.00530.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Two C-repeat binding factor genes (EguCBF1a/b), isolated from E. gunnii and differentially cold-regulated, were constitutively overexpressed in a cold-sensitive Eucalyptus hybrid. In addition to the expected improvement on freezing tolerance, some resulting transgenic lines (EguCBF1a-OE and EguCBF1b-OE) exhibited a decrease in stomata density and an over-accumulation of anthocyanins also observed to a lesser extent in a cold-acclimated control plant. Given that the induction of five putative CBF target genes was observed in CBF-overexpressing lines as well as in the cold-acclimated control line, these phenotypes might be related to cold acclimation. In comparison with the control plant, the most altered transgenic line (EguCBF1a-OE A1 line), exhibited reduced growth and better water retention capacity. This modified phenotype includes reduced leaf area and thickness associated with a decrease in cell size, as well as a higher oil gland density and a wax deposition on the cuticle. Surprisingly, the EguCBF1b-OE B9 line, with a level of transgene expression equivalent to the A1 line, showed a less marked phenotype, suggesting a difference in transactivation efficiency between EguCBF1A and B factors. The features of these transgenic lines provide the first signs of adaptive mechanisms controlled by CBF transcription factors in an evergreen broad-leaved tree. These data also open new prospects towards genetic improvement on Eucalyptus for freezing tolerance.
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Affiliation(s)
- Marie Navarro
- Université de Toulouse (UT3): ERT 1045, Pôle de Biotechnologie Végétale, Castanet-Tolosan, France
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203
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Legay S, Sivadon P, Blervacq AS, Pavy N, Baghdady A, Tremblay L, Levasseur C, Ladouce N, Lapierre C, Séguin A, Hawkins S, Mackay J, Grima-Pettenati J. EgMYB1, an R2R3 MYB transcription factor from eucalyptus negatively regulates secondary cell wall formation in Arabidopsis and poplar. New Phytol 2010; 188:774-86. [PMID: 20955415 DOI: 10.1111/j.1469-8137.2010.03432.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
• The eucalyptus R2R3 transcription factor, EgMYB1 contains an active repressor motif in the regulatory domain of the predicted protein. It is preferentially expressed in differentiating xylem and is capable of repressing the transcription of two key lignin genes in vivo. • In order to investigate in planta the role of this putative transcriptional repressor of the lignin biosynthetic pathway, we overexpressed the EgMYB1 gene in Arabidopsis and poplar. • Expression of EgMYB1 produced similar phenotypes in both species, with stronger effects in transgenic Arabidopsis plants than in poplar. Vascular development was altered in overexpressors showing fewer lignified fibres (in phloem and interfascicular zones in poplar and Arabidopsis, respectively) and reduced secondary wall thickening. Klason lignin content was moderately but significantly reduced in both species. Decreased transcript accumulation was observed for genes involved in the biosynthesis of lignins, cellulose and xylan, the three main polymers of secondary cell walls. Transcriptomic profiles of transgenic poplars were reminiscent of those reported when lignin biosynthetic genes are disrupted. • Together, these results strongly suggest that EgMYB1 is a repressor of secondary wall formation and provide new opportunities to dissect the transcriptional regulation of secondary wall biosynthesis.
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Affiliation(s)
- Sylvain Legay
- UMR 5546, CNRS-UPS Surfaces Cellulaires et Signalisation chez les Végétaux, Castanet-Tolosan, France
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204
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Rahantamalala A, Rech P, Martinez Y, Chaubet-Gigot N, Grima-Pettenati J, Pacquit V. Coordinated transcriptional regulation of two key genes in the lignin branch pathway--CAD and CCR--is mediated through MYB- binding sites. BMC Plant Biol 2010; 10:130. [PMID: 20584286 PMCID: PMC3017776 DOI: 10.1186/1471-2229-10-130] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 06/28/2010] [Indexed: 05/02/2023]
Abstract
BACKGROUND Cinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) catalyze the final steps in the biosynthesis of monolignols, the monomeric units of the phenolic lignin polymers which confer rigidity, imperviousness and resistance to biodegradation to cell walls. We have previously shown that the Eucalyptus gunnii CCR and CAD2 promoters direct similar expression patterns in vascular tissues suggesting that monolignol production is controlled, at least in part, by the coordinated transcriptional regulation of these two genes. Although consensus motifs for MYB transcription factors occur in most gene promoters of the whole phenylpropanoid pathway, functional evidence for their contribution to promoter activity has only been demonstrated for a few of them. Here, in the lignin-specific branch, we studied the functional role of MYB elements as well as other cis-elements identified in the regulatory regions of EgCAD2 and EgCCR promoters, in the transcriptional activity of these gene promoters. RESULTS By using promoter deletion analysis and in vivo footprinting, we identified an 80 bp regulatory region in the Eucalyptus gunnii EgCAD2 promoter that contains two MYB elements, each arranged in a distinct module with newly identified cis-elements. A directed mutagenesis approach was used to introduce block mutations in all putative cis-elements of the EgCAD2 promoter and in those of the 50 bp regulatory region previously delineated in the EgCCR promoter. We showed that the conserved MYB elements in EgCAD2 and EgCCR promoters are crucial both for the formation of DNA-protein complexes in EMSA experiments and for the transcriptional activation of EgCAD2 and EgCCR promoters in vascular tissues in planta. In addition, a new regulatory cis-element that modulates the balance between two DNA-protein complexes in vitro was found to be important for EgCAD2 expression in the cambial zone. CONCLUSIONS Our assignment of functional roles to the identified cis-elements clearly demonstrates the importance of MYB cis-elements in the transcriptional regulation of two genes of the lignin-specific pathway and support the hypothesis that MYB elements serve as a common means for the coordinated regulation of genes in the entire lignin biosynthetic pathway.
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Affiliation(s)
- Anjanirina Rahantamalala
- Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France
- CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France
| | - Philippe Rech
- Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France
- CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France
- Université Pierre et Marie Curie Paris 6, EAC7180 CNRS, UR5, Mécanismes de la Régénération des Plantes, F-75252 Paris cedex 05, France
| | - Yves Martinez
- Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France
- CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France
| | - Nicole Chaubet-Gigot
- Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France
- CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France
| | - Jacqueline Grima-Pettenati
- Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France
- CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France
| | - Valérie Pacquit
- Université de Toulouse; UPS; UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux; BP 42617, F-31326, Castanet-Tolosan, France
- CNRS; UMR 5546; BP 42617, F-31326, Castanet-Tolosan, France
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205
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MacMillan CP, Mansfield SD, Stachurski ZH, Evans R, Southerton SG. Fasciclin-like arabinogalactan proteins: specialization for stem biomechanics and cell wall architecture in Arabidopsis and Eucalyptus. Plant J 2010. [PMID: 20202165 DOI: 10.1111/tpj.2010.62.issue-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The ancient cell adhesion fasciclin (FAS) domain is found in bacteria, fungi, algae, insects and animals, and occurs in a large family of fasciclin-like arabinogalactan proteins (FLAs) in higher plants. Functional roles for FAS-containing proteins have been determined for insects, algae and vertebrates; however, the biological functions of the various higher-plant FLAs are not clear. Expression of some FLAs has been correlated with the onset of secondary-wall cellulose synthesis in Arabidopsis stems, and also with wood formation in the stems and branches of trees, suggesting a biological role in plant stems. We examined whether FLAs contribute to plant stem biomechanics. Using phylogenetic, transcript abundance and promoter-GUS fusion analyses, we identified a conserved subset of single FAS domain FLAs (group A FLAs) in Eucalyptus and Arabidopsis that have specific and high transcript abundance in stems, particularly in stem cells undergoing secondary-wall deposition, and that the phylogenetic conservation appears to extend to other dicots and monocots. Gene-function analyses revealed that Arabidopsis T-DNA knockout double mutant stems had altered stem biomechanics with reduced tensile strength and a reduced tensile modulus of elasticity, as well as altered cell-wall architecture and composition, with increased cellulose microfibril angle and reduced arabinose, galactose and cellulose content. Using materials engineering concepts, we relate the effects of these FLAs on cell-wall composition with stem biomechanics. Our results suggest that a subset of single FAS domain FLAs contributes to plant stem strength by affecting cellulose deposition, and to the stem modulus of elasticity by affecting the integrity of the cell-wall matrix.
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206
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MacMillan CP, Mansfield SD, Stachurski ZH, Evans R, Southerton SG. Fasciclin-like arabinogalactan proteins: specialization for stem biomechanics and cell wall architecture in Arabidopsis and Eucalyptus. Plant J 2010; 62:689-703. [PMID: 20202165 DOI: 10.1111/j.1365-313x.2010.04181.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The ancient cell adhesion fasciclin (FAS) domain is found in bacteria, fungi, algae, insects and animals, and occurs in a large family of fasciclin-like arabinogalactan proteins (FLAs) in higher plants. Functional roles for FAS-containing proteins have been determined for insects, algae and vertebrates; however, the biological functions of the various higher-plant FLAs are not clear. Expression of some FLAs has been correlated with the onset of secondary-wall cellulose synthesis in Arabidopsis stems, and also with wood formation in the stems and branches of trees, suggesting a biological role in plant stems. We examined whether FLAs contribute to plant stem biomechanics. Using phylogenetic, transcript abundance and promoter-GUS fusion analyses, we identified a conserved subset of single FAS domain FLAs (group A FLAs) in Eucalyptus and Arabidopsis that have specific and high transcript abundance in stems, particularly in stem cells undergoing secondary-wall deposition, and that the phylogenetic conservation appears to extend to other dicots and monocots. Gene-function analyses revealed that Arabidopsis T-DNA knockout double mutant stems had altered stem biomechanics with reduced tensile strength and a reduced tensile modulus of elasticity, as well as altered cell-wall architecture and composition, with increased cellulose microfibril angle and reduced arabinose, galactose and cellulose content. Using materials engineering concepts, we relate the effects of these FLAs on cell-wall composition with stem biomechanics. Our results suggest that a subset of single FAS domain FLAs contributes to plant stem strength by affecting cellulose deposition, and to the stem modulus of elasticity by affecting the integrity of the cell-wall matrix.
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207
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Andrew RL, Wallis IR, Harwood CE, Foley WJ. Genetic and environmental contributions to variation and population divergence in a broad-spectrum foliar defence of Eucalyptus tricarpa. Ann Bot 2010; 105:707-17. [PMID: 20228089 PMCID: PMC2859910 DOI: 10.1093/aob/mcq034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS Both environmental and genetic effects contribute to phenotypic variation within and among populations. Genetic differentiation of quantitative traits among populations has been shown in many species, yet it can also be accompanied by other genetic changes, such as divergence in phenotypic plasticity and in genetic variance. Sideroxylonal (a formylated phloroglucinol compound or FPC) is an important chemical defence in eucalypts. The effect of environmental variation on its production is a critical gap in our understanding of its genetics and evolution. METHODS The stability of genetic variation in sideroxylonal was assessed within and among populations of Eucalyptus tricarpa in three replicated provenance/progeny trials. The covariance structure of the data was also modelled to test whether genetic variances were consistent among populations and Fain's test was applied for major gene effects. KEY RESULTS A significant genotype x environment interaction occurred at the level of population, and was related to temperature range and seasonality in source populations. Within-population genetic variation was not affected by genotype x environment effects or different sampling years. However, within-population genetic variance for sideroxylonal concentration differed significantly among source populations. Regression of family variance on family mean suggested that this trait is subject to major gene effects, which could explain the observed differences in genetic variances among populations. CONCLUSIONS These results highlight the importance of replicated common-garden experiments for understanding the genetic basis of population differences. Genotype x environment interactions are unlikely to impede evolution or responses to artificial selection on sideroxylonal, but the lack of genetic variation in some populations may be a constraint. The results are broadly consistent with localized selection on foliar defence and illustrate that differentiation in population means, whether due to selection or to drift, can be accompanied by changes in other characteristics, such as plasticity and genetic variance.
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Affiliation(s)
- Rose L Andrew
- School of Botany and Zoology, The Australian National University, Canberra, ACT 0200, Australia.
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208
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Affiliation(s)
- X Z Liu
- Southwest Forestry College, White Dragon Temple, Kunming, Yunnan Province 650224, People's Republic of China
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209
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Tsuchihira A, Hanba YT, Kato N, Doi T, Kawazu T, Maeshima M. Effect of overexpression of radish plasma membrane aquaporins on water-use efficiency, photosynthesis and growth of Eucalyptus trees. Tree Physiol 2010; 30:417-30. [PMID: 20124554 DOI: 10.1093/treephys/tpp127] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Eucalyptus is a diverse genus of flowering trees with more than 700 genotypic species which are mostly native to Australia. We selected 19 wild provenances of Eucalyptus camaldulensis grown in Australia, compared their growth rate and drought tolerance and determined the protein levels of plasma membrane aquaporins (PIPs). There was a positive relationship between the drought tolerance and PIP content. PIPs are divided into two subgroups, PIP1 and PIP2. Most members of the PIP2 subgroup, but not PIP1 subgroup, exhibit water channel activity. We introduced two radish (Raphanus sativus L.) PIPs, RsPIP1;1 and RsPIP2;1, into a hybrid clone of Eucalyptus grandis and Eucalyptus urophylla to examine the effect of their overexpression. Expression of these genes was confirmed by real-time polymerase chain reaction (PCR) and the protein accumulation of RsPIP2;1 by immunoblotting. Drought tolerance was not enhanced in transgenic lines of either gene. However, one transgenic line expressing RsPIP2;1 showed high photosynthesis activity and growth rate under normal growth conditions. For RsPIP1;1-transformed lines, the RsPIP1;1 protein did not accumulate, and the abundance of endogenous PIP1 and PIP2 was decreased. The endogenous PIP1 and PIP2 genes were suppressed in these lines. Therefore, the decreased levels of PIP1 and PIP2 protein may be due to co-suppression of the PIP genes and/or high turnover of PIP proteins. RsPIP1;1-expressing lines gave low values of photosynthesis and growth compared with the control. These results suggest that down-regulation of PIP1 and PIP2 causes serious damage and that up-regulation of PIP2 improves the photosynthetic activity and growth of Eucalyptus trees.
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Affiliation(s)
- Ayako Tsuchihira
- Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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210
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Jaya ESKD, Clemens J, Song J, Zhang H, Jameson PE. Quantitative expression analysis of meristem identity genes in Eucalyptus occidentalis: AP1 is an expression marker for flowering. Tree Physiol 2010; 30:304-12. [PMID: 20038505 DOI: 10.1093/treephys/tpp117] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A number of Eucalyptus species exhibit precocious flowering, flowering within a year of germination and often while still exhibiting juvenile foliage. To understand the nature of precocious flowering in Eucalyptus occidentalis, partial homologues of the inflorescence meristem identity gene TERMINAL FLOWER1 and of the floral meristem identity genes LEAFY and APETALA1 (EOTFL1, EOLFY and EOAP1, respectively) were isolated and characterized. The expression patterns of these meristem identity genes during the development of branched and single-stem plants were analysed by quantitative reverse transcriptase PCR. All E. occidentalis plants commenced flowering within 40 weeks of germination. However, the branched plants reached maximum flowering some 5-6 weeks earlier than did single-stem plants. Levels of EOTFL1 and EOLFY expression varied little during the study period irrespective of architecture treatment, whereas expression of EOAP1 reached a peak coincident with peak flowering in both branched and single-stem plants. AP1 is clearly an expression marker for flowering in this species.
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Affiliation(s)
- Elizabeth S K D Jaya
- Institute of Molecular Biosciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand
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211
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Silva JO, Oliveira KN, Santos KJ, Espírito-Santo MM, Neves FS, Faria ML. [Effects of landscape structure and Eucalyptus genotype on the abundance and biological control of Glycaspis brimblecombei Moore (Hemiptera: Psyllidae)]. Neotrop Entomol 2010; 39:91-96. [PMID: 20305903 DOI: 10.1590/s1519-566x2010000100012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Accepted: 10/16/2009] [Indexed: 05/29/2023]
Abstract
Glycaspis brimblecombei Moore is an Australian native pest of Eucalyptus detected in Brazil in 2003. Since then, it has spread fast and colonized plantations in several states of the country. This study aimed to investigate the influence of cerrado remnants on the abundance and biological control of G. brimblecombei. We placed yellow sticky card traps to capture insects in four plantations of hybrid clones of Eucalyptus urophylla x Eucalyptus grandis ('Urograndis') and four plantations of E. urophylla x Eucalyptus camaldulensis ('Urocam'). Traps were placed in three areas of these plantations: center, border with cerrado and border without cerrado. We also collected leaves from the same clones to estimate psyllid egg and lerp abundance. The abundance of G. brimblecombei was lower in the plantation-cerrado border, and the inverse pattern was observed for microhymenopterans. The leaf abaxial surface showed a higher abundance of eggs and nymphs, probably as a consequence of a lower parasitism rate and mechanical removal by wind and rain. Egg number was higher on Urograndis than in Urocam clones, but the number of psyllid lerps was higher in the latter. Thus, the establishment of first instars is probably a critical event to psyllid infestation, and these differences may be caused by morphological, anatomical and biochemical leaf features of distinct clones. Our results suggest that the maintenance of native vegetation around plantations is a promising management practice to promote the natural biological control of G.brimblecombei, a strategy that would also enhance the preservation of cerrado remnants.
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Affiliation(s)
- Jhonathan O Silva
- Depto de Biologia Geral, Lab de Ecologia Evolutiva, Centro de Ciências Biológicas e da Saúde, Univ Estadual de Montes Claros, Montes Claros, MG, Brasil 39401-089
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212
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Ohara K, Matsunaga E, Nanto K, Yamamoto K, Sasaki K, Ebinuma H, Yazaki K. Monoterpene engineering in a woody plant Eucalyptus camaldulensis using a limonene synthase cDNA. Plant Biotechnol J 2010; 8:28-37. [PMID: 20055958 DOI: 10.1111/j.1467-7652.2009.00461.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Metabolic engineering aimed at monoterpene production has become an intensive research topic in recent years, although most studies have been limited to herbal plants including model plants such as Arabidopsis. The genus Eucalyptus includes commercially important woody plants in terms of essential oil production and the pulp industry. This study attempted to modify the production of monoterpenes, which are major components of Eucalyptus essential oil, by introducing two expression constructs containing Perilla frutescens limonene synthase (PFLS) cDNA, whose gene products were designed to be localized in either the plastid or cytosol, into Eucalyptus camaldulensis. The expression of the plastid-type and cytosol-type PFLS cDNA in transgenic E. camaldulensis was confirmed by real-time polymerase chain reaction (PCR). Gas chromatography with a flame ionization detector analyses of leaf extracts revealed that the plastidic and cytosolic expression of PFLS yielded 2.6- and 4.5-times more limonene than that accumulated in wild-type E. camaldulensis, respectively, while the ectopic expression of PFLS had only a small effect on the emission of limonene from the leaves of E. camaldulensis. Surprisingly, the high level of PFLS in Eucalyptus was accompanied by a synergistic increase in the production of 1,8-cineole and alpha-pinene, two major components of Eucalyptus monoterpenes. This genetic engineering of monoterpenes demonstrated a new potential for molecular breeding in woody plants.
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Affiliation(s)
- Kazuaki Ohara
- Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto, Japan
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213
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Abstract
Lignin is the second most abundant plant biopolymer mainly present in the secondary walls of tracheary elements and fibers in wood. Understanding how lignin is biosynthesized has long been an interest to plant biologists and will have a significant impact on tree biotechnology. Lignin is polymerized from monolignols that are synthesized through the lignin biosynthetic pathway. To make lignin, all the genes in the lignin biosynthetic pathway need to be coordinately turned on. It has been shown that a common cis-element, namely the AC element, is present in the majority of the lignin biosynthetic genes and required for their expression in lignifying cells. Important progress has been made in the identification of transcription factors that bind to the AC elements and are potentially involved in the coordinated regulation of lignin biosynthesis. The Arabidopsis MYB58 and MYB63 as well as their poplar ortholog PtrMYB28 are transcriptional activators of the lignin biosynthetic pathway, whereas the eucalyptus EgMYB2 and pine PtMYB4 transcription factors are likely Arabidopsis MYB46 orthologs involved in the regulation of the entire secondary wall biosynthetic program. It was found that the transcriptional regulation of lignin biosynthesis is under the control of the same transcriptional network regulating the biosynthesis of other secondary wall components, including cellulose and xylan. The identification of transcription factors directly activating lignin biosynthetic genes provides unprecedented tools to potentially manipulate the amount of lignin in wood and other plant products based on our needs.
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Affiliation(s)
- Ruiqin Zhong
- Department of Plant Biology, University of Georgia, Athens, GA, USA
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214
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Goodger JQD, Cao B, Jayadi I, Williams SJ, Woodrow IE. Non-volatile components of the essential oil secretory cavities of Eucalyptus leaves: discovery of two glucose monoterpene esters, cuniloside B and froggattiside A. Phytochemistry 2009; 70:1187-1194. [PMID: 19604527 DOI: 10.1016/j.phytochem.2009.06.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 06/01/2009] [Accepted: 06/02/2009] [Indexed: 05/06/2023]
Abstract
The essential oils extracted from the embedded foliar secretory cavities of many Eucalyptus species are of economic value as pharmaceuticals and fragrance additives. Recent studies have indicated that Eucalyptus secretory cavities may not be exclusively involved in the biosynthesis and storage of essential oils. Therefore, we selected three species upon which to perform an examination of the contents of foliar secretory cavities: Eucalyptus froggattii, E. polybractea and E. globulus. This paper describes the isolation and structural characterization of two non-volatile glucose monoterpene esters, which we have named cuniloside B and froggattiside A, from within the secretory cavities of these species, and shows the presence of these compounds in solvent extracts of the leaves from two other species of Eucalyptus. Both compounds were found in high proportions relative to the essential oils extracted from the leaves. We propose that many other carbohydrate monoterpene esters previously isolated from bulk leaf extracts of various Eucalyptus species may also be localized within the non-volatile fraction of foliar secretory cavities.
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Affiliation(s)
- Jason Q D Goodger
- School of Botany, The University of Melbourne, Victoria 3010, Australia.
| | - Benjamin Cao
- Bio21 Molecular Science and Biotechnology Institute and School of Chemistry, The University of Melbourne, Victoria 3010, Australia
| | - Inneke Jayadi
- School of Botany, The University of Melbourne, Victoria 3010, Australia
| | - Spencer J Williams
- Bio21 Molecular Science and Biotechnology Institute and School of Chemistry, The University of Melbourne, Victoria 3010, Australia.
| | - Ian E Woodrow
- School of Botany, The University of Melbourne, Victoria 3010, Australia
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Barros E, van Staden CA, Lezar S. A microarray-based method for the parallel analysis of genotypes and expression profiles of wood-forming tissues in Eucalyptus grandis. BMC Biotechnol 2009; 9:51. [PMID: 19473481 PMCID: PMC2698882 DOI: 10.1186/1472-6750-9-51] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Accepted: 05/27/2009] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Fast-growing Eucalyptus grandis trees are one of the most efficient producers of wood in South Africa. The most serious problem affecting the quality and yield of solid wood products is the occurrence of end splitting in logs. Selection of E. grandis planting stock that exhibit preferred wood qualities is thus a priority of the South African forestry industry. We used microarray-based DNA-amplified fragment length polymorphism (AFLP) analysis in combination with expression profiling to develop fingerprints and profile gene expression of wood-forming tissue of seven different E. grandis trees. RESULTS A 1578-probe cDNA microarray was constructed by arraying 768 cDNA-AFLP clones and 810 cDNA library clones from seven individual E. grandis trees onto silanised slides. The results revealed that 32% of the spotted fragments showed distinct expression patterns (with a fold change of at least 1.4 or -1.4 and a p value of 0.01) could be grouped into clusters representing co-expressed genes. Evaluation of the binary distribution of cDNA-AFLP fragments on the array showed that the individual genotypes could be discriminated. CONCLUSION A simple, yet general method was developed for genotyping and expression profiling of wood-forming tissue of E. grandis trees differing in their splitting characteristics and in their lignin contents. Evaluation of gene expression profiles and the binary distribution of cDNA-AFLP fragments on the chip suggest that the prototype chip developed could be useful for transcript profiling and for the identification of Eucalyptus trees with preferred wood quality traits in commercial breeding programmes.
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Affiliation(s)
- Eugenia Barros
- CSIR – Biosciences, Meiring Naude Road, Brummeria, Pretoria, 0001, South Africa
| | | | - Sabine Lezar
- CSIR – Biosciences, Meiring Naude Road, Brummeria, Pretoria, 0001, South Africa
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216
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Rengel D, Clemente HS, Servant F, Ladouce N, Paux E, Wincker P, Couloux A, Sivadon P, Grima-Pettenati J. A new genomic resource dedicated to wood formation in Eucalyptus. BMC Plant Biol 2009; 9:36. [PMID: 19327132 PMCID: PMC2670833 DOI: 10.1186/1471-2229-9-36] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 03/27/2009] [Indexed: 05/17/2023]
Abstract
BACKGROUND Renowned for their fast growth, valuable wood properties and wide adaptability, Eucalyptus species are amongst the most planted hardwoods in the world, yet they are still at the early stages of domestication because conventional breeding is slow and costly. Thus, there is huge potential for marker-assisted breeding programs to improve traits such as wood properties. To this end, the sequencing, analysis and annotation of a large collection of expressed sequences tags (ESTs) from genes involved in wood formation in Eucalyptus would provide a valuable resource. RESULTS We report here the normalization and sequencing of a cDNA library from developing Eucalyptus secondary xylem, as well as the construction and sequencing of two subtractive libraries (juvenile versus mature wood and vice versa). A total of 9,222 high quality sequences were collected from about 10,000 cDNA clones. The EST assembly generated a set of 3,857 wood-related unigenes including 2,461 contigs (Cg) and 1,396 singletons (Sg) that we named 'EUCAWOOD'. About 65% of the EUCAWOOD sequences produced matches with poplar, grapevine, Arabidopsis and rice protein sequence databases. BlastX searches of the Uniref100 protein database allowed us to allocate gene ontology (GO) and protein family terms to the EUCAWOOD unigenes. This annotation of the EUCAWOOD set revealed key functional categories involved in xylogenesis. For instance, 422 sequences matched various gene families involved in biosynthesis and assembly of primary and secondary cell walls. Interestingly, 141 sequences were annotated as transcription factors, some of them being orthologs of regulators known to be involved in xylogenesis. The EUCAWOOD dataset was also mined for genomic simple sequence repeat markers, yielding a total of 639 putative microsatellites. Finally, a publicly accessible database was created, supporting multiple queries on the EUCAWOOD dataset. CONCLUSION In this work, we have identified a large set of wood-related Eucalyptus unigenes called EUCAWOOD, thus creating a valuable resource for functional genomics studies of wood formation and molecular breeding in this economically important genus. This set of publicly available annotated sequences will be instrumental for candidate gene approaches, custom array development and marker-assisted selection programs aimed at improving and modulating wood properties.
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Affiliation(s)
- David Rengel
- UMR CNRS/Université Toulouse III 5546, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP42617 Auzeville, 31326 Castanet Tolosan, France
| | - Hélène San Clemente
- UMR CNRS/Université Toulouse III 5546, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP42617 Auzeville, 31326 Castanet Tolosan, France
| | - Florence Servant
- UMR CNRS/Université Toulouse III 5546, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP42617 Auzeville, 31326 Castanet Tolosan, France
- Current address : Syngenta Seeds SAS, BP27, 31790 Saint Sauveur, France
| | - Nathalie Ladouce
- UMR CNRS/Université Toulouse III 5546, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP42617 Auzeville, 31326 Castanet Tolosan, France
| | - Etienne Paux
- UMR CNRS/Université Toulouse III 5546, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP42617 Auzeville, 31326 Castanet Tolosan, France
- Current address : INRA-UBP, UMR 1095, INRA Site de Crouël, 234 avenue du Brézet, 63100 Clermont-Ferrand, France
| | - Patrick Wincker
- Génoscope, CNRS, UMR 8030 and Université d'Evry, 91057 Evry, France
| | - Arnaud Couloux
- Génoscope, CNRS, UMR 8030 and Université d'Evry, 91057 Evry, France
| | - Pierre Sivadon
- UMR CNRS/Université Toulouse III 5546, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP42617 Auzeville, 31326 Castanet Tolosan, France
- Current address : Université de Pau et des Pays de l'Adour, UMR CNRS 5254 IPREM, IBEAS – BP1155, 64013 Pau Cedex, France
| | - Jacqueline Grima-Pettenati
- UMR CNRS/Université Toulouse III 5546, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP42617 Auzeville, 31326 Castanet Tolosan, France
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217
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Tuffi Santos LD, Sant'Anna-Santos BF, Meira RMSA, Ferreira FA, Tiburcio RAS, Machado AFL. Leaf anatomy and morphometry in three eucalypt clones treated with glyphosate. BRAZ J BIOL 2009; 69:129-36. [PMID: 19347155 DOI: 10.1590/s1519-69842009000100016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Accepted: 06/15/2007] [Indexed: 11/22/2022] Open
Abstract
This work aimed to evaluate the effects of simulated drift of glyphosate on the morphoanatomy of three eucalypt clones and to correlate the intoxication symptoms on a microscopic scale with those observed in this visual analysis. The effects of glyphosate drift were proportional to the five doses tested, with Eucalyptus urophylla being more tolerant to the herbicide than E. grandis and urograndis hybrid. The symptoms of intoxication which were similar for the different clones at 7 and 15 days after application were characterized by leaf wilting, chlorosis and curling and, at the highest rates, by necrosis, leaf senescence and death. Anatomically glyphosate doses higher than 86.4 g.ha-1 caused cellular plasmolysis, hypertrophy and hyperplasia, formation of the cicatrization tissue and dead cells on the adaxial epidermis. The spongy parenchyma had a decrease, and the palisade parenchyma and leaf blade thickness had an increase. The increased thickness in leaf blade and palisade parenchyma may be related to the plant response to glyphosate action, as a form of recovering the photosynthetically active area reduced by necroses and leaf senescence caused by the herbicide.
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Affiliation(s)
- L D Tuffi Santos
- Instituto de Ciências Agrárias, Universidade Federal de Minas Gerais, Montes Claros, MG, Brazil
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218
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Foucart C, Jauneau A, Gion JM, Amelot N, Martinez Y, Panegos P, Grima-Pettenati J, Sivadon P. Overexpression of EgROP1, a Eucalyptus vascular-expressed Rac-like small GTPase, affects secondary xylem formation in Arabidopsis thaliana. New Phytol 2009; 183:1014-1029. [PMID: 19549133 DOI: 10.1111/j.1469-8137.2009.02910.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
To better understand the genetic control of secondary xylem formation in trees we analysed genes expressed during Eucalyptus xylem development. Using eucalyptus xylem cDNA libraries, we identified EgROP1, a member of the plant ROP family of Rho-like GTPases. These signalling proteins are central regulators of many important processes in plants, but information on their role in xylogenesis is scarce. Quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) confirmed that EgROP1 was preferentially expressed in the cambial zone and differentiating xylem in eucalyptus. Genetic mapping performed in a eucalyptus breeding population established a link between EgROP1 sequence polymorphisms and quantitative trait loci (QTLs) related to lignin profiles and fibre morphology. Overexpression of various forms of EgROP1 in Arabidopsis thaliana altered anisotropic cell growth in transgenic leaves, but most importantly affected vessel element and fibre growth in secondary xylem. Patches of fibre-like cells in the secondary xylem of transgenic plants showed changes in secondary cell wall thickness, lignin and xylan composition. These results suggest a role for EgROP1 in fibre cell morphology and secondary cell wall formation making it a good candidate gene for marker-based selection of eucalyptus trees.
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Affiliation(s)
- Camille Foucart
- UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet Tolosan, France
| | - Alain Jauneau
- IFR 40, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet Tolosan, France
| | - Jean-Marc Gion
- UPR39 Génétique Forestière, Cirad-BIOS, Campus de Baillarguet TA 10C, F-34398 Montpellier Cedex 5, France
| | - Nicolas Amelot
- UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet Tolosan, France
| | - Yves Martinez
- IFR 40, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet Tolosan, France
| | - Patricia Panegos
- UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet Tolosan, France
| | - Jacqueline Grima-Pettenati
- UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet Tolosan, France
| | - Pierre Sivadon
- UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet Tolosan, France
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219
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Costa E Silva F, Shvaleva A, Broetto F, Ortuño MF, Rodrigues ML, Almeida MH, Chaves MM, Pereira JS. Acclimation to short-term low temperatures in two Eucalyptus globulus clones with contrasting drought resistance. Tree Physiol 2009; 29:77-86. [PMID: 19203934 DOI: 10.1093/treephys/tpn002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We tested the hypothesis that Eucalyptus globulus Labill. genotypes that are more resistant to dry environments might also exhibit higher cold tolerances than drought-sensitive plants. The effect of low temperatures was evaluated in acclimated and unacclimated ramets of a drought-resistant clone (CN5) and a drought-sensitive clone (ST51) of E. globulus. We studied the plants' response via leaf gas exchanges, leaf water and osmotic potentials, concentrations of soluble sugars, several antioxidant enzymes and leaf electrolyte leakage. Progressively lowering air temperatures (from 24/16 to 10/-2 degrees C, day/night) led to acclimation of both clones. Acclimated ramets exhibited higher photosynthetic rates, stomatal conductances and lower membrane relative injuries when compared to unacclimated ramets. Moreover, low temperatures led to significant increases of soluble sugars and antioxidant enzymes activity (glutathione reductase, ascorbate peroxidase and superoxide dismutases) of both clones in comparison to plants grown at control temperature (24/16 degrees C). On the other hand, none of the clones, either acclimated or not, exhibited signs of photoinhibition under low temperatures and moderate light. The main differences in the responses to low temperatures between the two clones resulted mainly from differences in carbon metabolism, including a higher accumulation of soluble sugars in the drought-resistant clone CN5 as well as a higher capacity for osmotic regulation, as compared to the drought-sensitive clone ST51. Although membrane injury data suggested that both clones had the same inherent freezing tolerance before and after cold acclimation, the results also support the hypothesis that the drought-resistant clone had a greater cold tolerance at intermediate levels of acclimation than the drought-sensitive clone. A higher capacity to acclimate in a short period can allow a clone to maintain an undamaged leaf surface area along sudden frost events, increasing growth capacity. Moreover, it can enhance survival chances in frost-prone sites expanding the plantation range with more adaptive clones.
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Affiliation(s)
- F Costa E Silva
- Instituto Superior de Agronomia, Tapada da Ajuda 1349-017, Lisbon, Portugal.
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220
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Navarro M, Marque G, Ayax C, Keller G, Borges JP, Marque C, Teulières C. Complementary regulation of four Eucalyptus CBF genes under various cold conditions. J Exp Bot 2009; 60:2713-24. [PMID: 19457981 PMCID: PMC2692017 DOI: 10.1093/jxb/erp129] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 03/16/2009] [Accepted: 03/26/2009] [Indexed: 05/17/2023]
Abstract
CBF transcription factors play central roles in the control of freezing tolerance in plants. The isolation of two additional CBF genes, EguCBF1c and EguCBF1d, from E. gunnii, one of the cold-hardiest Eucalyptus species, is described. While the EguCBF1D protein sequence is very similar to the previously characterized EguCBF1A and EguCBF1B sequences, EguCBF1C is more distinctive, in particular in the AP2-DBD (AP2-DNA binding domain). The expression analysis of the four genes by RT-qPCR reveals that none of them is specific to one stress but they are all preferentially induced by cold, except for the EguCBF1c gene which is more responsive to salt. The calculation of the transcript copy number enables the quantification of constitutive CBF gene expression. This basal level, significant for the four genes, greatly influences the final EguCBF1 transcript level in the cold. A cold shock at 4 degrees C, as well as a progressive freezing which mimics a natural frost episode, trigger a fast and strong response of the EguCBF1 genes, while growth at acclimating temperatures results in a lower but more durable induction. The differential expression of the four EguCBF1 genes under these cold regimes suggests that there is a complementary regulation. The high accumulation of the CBF transcript, observed in response to the different types of cold conditions, might be a key for the winter survival of this evergreen broad-leaved tree.
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Affiliation(s)
| | | | | | | | | | | | - C. Teulières
- To whom correspondence should be addressed. E-mail:
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221
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Toloza AC, Lucia A, Zerba E, Masuh H, Picollo MI. Interspecific hybridization of Eucalyptus as a potential tool to improve the bioactivity of essential oils against permethrin-resistant head lice from Argentina. Bioresour Technol 2008; 99:7341-7. [PMID: 18261899 DOI: 10.1016/j.biortech.2007.12.067] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 12/03/2007] [Accepted: 12/03/2007] [Indexed: 05/13/2023]
Abstract
The essential oils extracted from Eucalyptus grandis, Eucalyptus camaldulensis, Eucalyptus tereticornis, and the hybrids E. grandisxE. camaldulensis, and E. grandisxE. tereticornis were analyzed by GC-MS, and evaluated for their fumigant and repellent effects on permethrin-resistant head lice. Fumigant activity of both hybrids was higher than that for pure species. E. grandisxE. tereticornis and E. grandisxE. camaldulensis showed KT50 values of 12.99 and 13.63min, respectively. E. grandis, E. camaldulensis, and E. tereticornis showed KT50 values of 25.57, 35.01, and 31.31, respectively. A simple regression analysis revealed a significant correlation between KT50 data and % of 1,8-cineole in these essential oils. Repellency varied from 47.80+/-16% to 80.69+/-6% for the five Eucalyptus essential oils tested. Interspecific hybridization improves the pediculicidal activity of Eucalyptus essential oils.
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Affiliation(s)
- Ariel Ceferino Toloza
- Centro de Investigaciones de Plagas e Insecticidas (CITEFA-CONICET), Juan Bautista de La Salle 4397 (B1603ALO), Villa Martelli, Buenos Aires, Argentina.
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222
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Marsden C, Nouvellon Y, Epron D. Relating coarse root respiration to root diameter in clonal Eucalyptus stands in the Republic of the Congo. Tree Physiol 2008; 28:1245-54. [PMID: 18519255 DOI: 10.1093/treephys/28.8.1245] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Root respiration is an important component of the carbon balance of a forest ecosystem. We measured CO2 efflux of excised fine roots and intact coarse roots in 3-, 4- and 13-year-old Eucalyptus stands in the region of Pointe-Noire, Republic of the Congo. A transportable and adaptable closed chamber gas exchange system directly measured CO2 efflux of roots from 0.5 to 32 mm in diameter. Fluxes were corrected for measurement system leaks and normalized to a reference temperature of 30 degrees C. Mean fine root respiration rates at the reference temperature varied between 8.5 and 10.8 micromol CO2 kg(-1) s(-1) depending on the stand. Coarse root respiration was strongly negatively correlated to root diameter. We propose a model based on a radial gradient of respiratory activity within the root to simulate the exponential decrease in respiration with diameter. Although many sources of uncertainty in the measurements remain, as discussed in this paper, these results provide a basis for scaling up organ-level root respiration measurements to the tree and stand levels.
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Affiliation(s)
- Claire Marsden
- CIRAD, UPR-80, Campus de Baillarguet TA 10/C, 34398 Montpellier cedex 5, France.
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223
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Callister AN, Arndt SK, Ades PK, Merchant A, Rowell D, Adams MA. Leaf osmotic potential of Eucalyptus hybrids responds differently to freezing and drought, with little clonal variation. Tree Physiol 2008; 28:1297-1304. [PMID: 18519261 DOI: 10.1093/treephys/28.8.1297] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Concentrations of solutes, and thus leaf osmotic potential (Psi pi), often increase when plants are subject to drought or sub-zero (frost) temperatures. We measured Psi pi and concentrations of individual solutes in leaves of 3-year-old Eucalyptus camaldulensis Dehn., E. globulus Labill., E. grandis W. Hill ex Maid. and 29 hybrid clones on a site subjected to both summer drought and winter frost. We sought to characterize seasonal and genetic variations in Psi pi and to determine whether Psi pi or leaf turgor is related to bole volume increment. Leaf osmotic potential at full turgor (Psi pi(100)) was 0.7 MPa more negative in winter than in late summer, and this trend was uniform across genotypes. Soluble carbohydrates were confirmed as key contributors to Psi pi, accounting for 40-44% of total osmolality. The seasonal trend in Psi pi(100) was facilitated by changes in leaf morphology, such as reduced turgid mass:dry mass ratio and increased apoplastic water fraction in winter. Cell wall elasticity increased significantly from winter to summer. Our results suggest that elastic adjustment may be more important than osmotic adjustment in leaves exposed to drought. Although Psi pi(100) was a reasonable predictor of in situ osmotic potential and turgor, we found no relationship between any physiological trait and bole volume increment. Clone-within-family variation in Psi pi(100) was small in both summer and winter and was unrelated to bole volume increment. We conclude that, for the study species, tree improvement under water-limited conditions should concentrate on direct selection for growth rather than on indirect selection based on osmotic potential.
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Affiliation(s)
- Andrew N Callister
- School of Forest and Ecosystem Science, University of Melbourne, Water Street, Creswick, VIC, Australia.
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224
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Pinto G, Park YS, Neves L, Araújo C, Santos C. Genetic control of somatic embryogenesis induction in Eucalyptus globulus Labill. Plant Cell Rep 2008; 27:1093-1101. [PMID: 18317772 DOI: 10.1007/s00299-008-0532-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 02/15/2008] [Accepted: 02/20/2008] [Indexed: 05/26/2023]
Abstract
A reproducible protocol for somatic embryogenesis (SE) induction in Eucalyptus globulus from mature zygotic embryos is available since 2002. However, for the use of SE in tree breeding programs, the frequency of SE initiation needs to be improved and controlled, and this was investigated in 13 open-pollinated (OP) families over three consecutive years. A diallel mating design with five parent trees was used to study genetic control of SE induction. Results showed that SE induction varies across E. globulus families and over the years of seed production tested. Somatic embryogenesis was initiated on explants from 84% of the OP families tested in 2002 and 100% of the families tested in 2003 and 2004. The year 2003 gave best results for percentage of induction and total number of somatic embryos produced. Results concerning genetic control showed that SE induction is under the control of additive genetic effects, as 22.0% of variation in SE initiation was due to general combining ability (GCA) effect, whereas 6.4% was due to maternal effects. Neither specific combining ability (SCA) nor reciprocal effects were significant.
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Affiliation(s)
- G Pinto
- Laboratory of Biotechnology and Cytomics, CESAM and Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal.
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225
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Gallo de Carvalho MCDC, Caldas DGG, Carneiro RT, Moon DH, Salvatierra GR, Franceschini LM, de Andrade A, Celedon PAF, Oda S, Labate CA. SAGE transcript profiling of the juvenile cambial region of Eucalyptus grandis. Tree Physiol 2008; 28:905-19. [PMID: 18381271 DOI: 10.1093/treephys/28.6.905] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Despite the importance of Eucalyptus spp. in the pulp and paper industry, functional genomic approaches have only recently been applied to understand wood formation in this genus. We attempted to establish a global view of gene expression in the juvenile cambial region of Eucalyptus grandis Hill ex Maiden. The expression profile was obtained from serial analysis of gene expression (SAGE) library data produced from 3- and 6-year-old trees. Fourteen-base expressed sequence tags (ESTs) were searched against public Eucalyptus ESTs and annotated with GenBank. Altogether 43,304 tags were generated producing 3066 unigenes with three or more copies each, 445 with a putative identity, 215 with unknown function and 2406 without an EST match. The expression profile of the juvenile cambial region revealed the presence of highly frequent transcripts related to general metabolism and energy metabolism, cellular processes, transport, structural components and information pathways. We made a quantitative analysis of a large number of genes involved in the biosynthesis of cellulose, pectin, hemicellulose and lignin. Our findings provide insight into the expression of functionally related genes involved in juvenile wood formation in young fast-growing E. grandis trees.
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Affiliation(s)
- Mayra Costa da Cruz Gallo de Carvalho
- Laboratório Max Feffer de Genética de Plantas, Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba-SP, Brazil
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226
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Gleadow RM, Haburjak J, Dunn JE, Conn ME, Conn EE. Frequency and distribution of cyanogenic glycosides in Eucalyptus L'Hérit. Phytochemistry 2008; 69:1870-1874. [PMID: 18474385 DOI: 10.1016/j.phytochem.2008.03.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 03/02/2008] [Accepted: 03/25/2008] [Indexed: 05/26/2023]
Abstract
In this study approximately 420 of the described species of Eucalyptus were examined for cyanogenesis. Our work has identified an additional 18 cyanogenic species, 12 from living tissues and a further six from herbarium samples. This brings the total of known cyanogenic species to 23, representing approximately 4% of the genus. The taxonomic distribution of the species within the genus is restricted to the subgenus Symphyomyrtus, with only two exceptions. Within Symphyomyrtus, the species are in three closely related sections. The cyanogenic glycoside was found to be predominantly prunasin (1) in the 11 species where this was examined. We conclude that cyanogenesis is plesiomorphic in Symphyomyrtus (i.e. a common basal trait) but has probably arisen independently in the other two subgenera, consistent with recent phylogenetic treatments of the genus. The results of this study have important implications for the selection of trees for plantations to support wildlife, and to preserve genetic diversity.
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Affiliation(s)
- Roslyn M Gleadow
- School of Biological Sciences, Monash University, Victoria 3800, Australia.
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227
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Freeman JS, O'Reilly-Wapstra JM, Vaillancourt RE, Wiggins N, Potts BM. Quantitative trait loci for key defensive compounds affecting herbivory of eucalypts in Australia. New Phytol 2008; 178:846-851. [PMID: 18373517 DOI: 10.1111/j.1469-8137.2008.02417.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
* Formylated phloroglucinols (FPCs) are key defensive compounds that influence herbivory by mammals and arthropods in eucalypts. However, the genetic architecture underlying variation in their levels remains poorly understood. * Quantitative trait loci (QTL) analysis for the concentrations of two major FPCs, sideroxylonal A and macrocarpal G, was conducted using juvenile leaves from 112 clonally duplicated progenies from an outcross F2 of Eucalyptus globulus. * Two unlinked QTL were located for macrocarpal, while another unlinked QTL was located for sideroxylonal. The sideroxylonal QTL collocated with one for total sideroxylonal previously reported using adult Eucalyptus nitens foliage, providing independent validation in a different evolutionary lineage and a different ontogenetic stage. * Given the potential widespread occurrence of these QTL, their ontogenetic stability, and their impact on a range of dependent herbivores, it is possible that they have extended phenotypic effects in the Australian forest landscape.
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Affiliation(s)
- J S Freeman
- School of Plant Science and CRC for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania, Australia 7001
| | - J M O'Reilly-Wapstra
- School of Plant Science and CRC for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania, Australia 7001
| | - R E Vaillancourt
- School of Plant Science and CRC for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania, Australia 7001
| | - N Wiggins
- School of Plant Science and CRC for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania, Australia 7001
| | - B M Potts
- School of Plant Science and CRC for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania, Australia 7001
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228
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Lu S, Li L, Yi X, Joshi CP, Chiang VL. Differential expression of three eucalyptus secondary cell wall-related cellulose synthase genes in response to tension stress. J Exp Bot 2008; 59:681-695. [PMID: 18281718 DOI: 10.1093/jxb/erm350] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Trees constitute the majority of lignocellulosic biomass existing on our planet. Trees also serve as important feedstock materials for various industrial products. However, little is known about the regulatory mechanisms of cellulose synthase (CesA) genes of trees. Here, the cloning and characterization of three CesA genes (EgraCesA1, EgraCesA2, and EgraCesA3) from an economically important tree species, Eucalyptus grandis, are reported. All three genes were specifically expressed in xylem cells of eucalyptus undergoing secondary cell wall biosynthesis. The GUS gene, expressed under the control of the EgraCesA2 or EgraCesA3 promoter, was also localized in the secondary xylem in transgenic tobacco stems. However, the EgraCesA1 promoter alone or along with its 5'-UTR introns was insufficient to direct appropriate GUS expression. EgraCesA2 and EgraCesA3 gene expression was up-regulated in tension-stressed eucalyptus xylem cells. Accordingly, GUS expression directed by the EgraCesA2 or EgraCesA3 promoter was also up-regulated. EgraCesA1 had no such response. Thus, it is most unlikely that EgraCesA1 is a subunit of the EgraCesA2-EgraCesA3 complex. The presence of at least two types of cellulose biosynthesis machinery in wood formation is an important clue in deciphering the underpinnings of the perennial growth of trees in various environmental conditions. By analysing GUS gene expression directed by the EgraCesA3 promoter or its deletions, several negative and positive regulatory regions controlling gene expression in xylem or phloem were identified. Also a region which is likely to contain mechanical stress-responsive elements was deduced. These results will guide further studies on identifying cis-regulatory elements directing CesA gene transcription and wood formation regulatory networks.
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Affiliation(s)
- Shanfa Lu
- Forest Biotechnology Group, Department of Forestry and Environmental Resources, College of Natural Resources, North Carolina State University, Raleigh, NC 27695, USA.
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229
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Qiu D, Wilson IW, Gan S, Washusen R, Moran GF, Southerton SG. Gene expression in Eucalyptus branch wood with marked variation in cellulose microfibril orientation and lacking G-layers. New Phytol 2008; 179:94-103. [PMID: 18422902 DOI: 10.1111/j.1469-8137.2008.02439.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In response to gravitational stresses, angiosperm trees form tension wood in the upper sides of branches and leaning stems in which cellulose content is higher, microfibrils are typically aligned closely with the fibre axis and the fibres often have a thick inner gelatinous cell wall layer (G-layer). Gene expression was studied in Eucalyptus nitens branches oriented at 45 degrees using microarrays containing 4900 xylem cDNAs, and wood fibre characteristics revealed by X-ray diffraction, chemical and histochemical methods. Xylem fibres in tension wood (upper branch) had a low microfibril angle, contained few fibres with G-layers and had higher cellulose and decreased Klason lignin compared with lower branch wood. Expression of two closely related fasciclin-like arabinogalactan proteins and a beta-tubulin was inversely correlated with microfibril angle in upper and lower xylem from branches. Structural and chemical modifications throughout the secondary cell walls of fibres sufficient to resist tension forces in branches can occur in the absence of G-layer enriched fibres and some important genes involved in responses to gravitational stress in eucalypt xylem are identified.
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Affiliation(s)
- Deyou Qiu
- CSIRO Forest Biosciences, PO Box E4008, Kingston ACT 2604, Australia
| | - Iain W Wilson
- CSIRO Plant Industry, PO Box 1600, Canberra ACT 2001, Australia
| | - Siming Gan
- CSIRO Forest Biosciences, PO Box E4008, Kingston ACT 2604, Australia
| | - Russell Washusen
- CSIRO Forest Biosciences, Private Bag 10, Clayton South VIC 3168, Australia
| | - Gavin F Moran
- CSIRO Forest Biosciences, PO Box E4008, Kingston ACT 2604, Australia
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230
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Abstract
Eucalyptus is the most widely planted hardwood crop in the tropical and subtropical world because of its superior growth, broad adaptability and multipurpose wood properties. Plantation forestry of Eucalyptus supplies high-quality woody biomass for several industrial applications while reducing the pressure on tropical forests and associated biodiversity. This review links current eucalypt breeding practices with existing and emerging genomic tools. A brief discussion provides a background to modern eucalypt breeding together with some current applications of molecular markers in support of operational breeding. Quantitative trait locus (QTL) mapping and genetical genomics are reviewed and an in-depth perspective is provided on the power of association genetics to dissect quantitative variation in this highly diverse organism. Finally, some challenges and opportunities to integrate genomic information into directional selective breeding are discussed in light of the upcoming draft of the Eucalyptus grandis genome. Given the extraordinary genetic variation that exists in the genus Eucalyptus, the ingenuity of most breeders, and the powerful genomic tools that have become available, the prospects of applied genomics in Eucalyptus forest production are encouraging.
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Affiliation(s)
- Dario Grattapaglia
- Plant Genetics Laboratory, Embrapa - Genetic Resources and Biotechnology, Parque Estação Biológica, Brasília 70770-970 DF, Brazil
- Graduate Program in Genomic Sciences and Biotechnology, Universidade Católica de Brasília - SGAN 916 módulo B, Brasília 70790-160 DF, Brazil
| | - Matias Kirst
- School of Forest Resources and Conservation, Graduate Program in Plant Molecular and Cellular Biology, and University of Florida Genetics Institute, University of Florida, PO Box 110410, Gainesville, FL 32611, USA
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231
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Creux NM, Ranik M, Berger DK, Myburg AA. Comparative analysis of orthologous cellulose synthase promoters from Arabidopsis, Populus and Eucalyptus: evidence of conserved regulatory elements in angiosperms. New Phytol 2008; 179:722-737. [PMID: 18547376 DOI: 10.1111/j.1469-8137.2008.02517.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
* The cellulose synthase (CesA) gene family encodes the catalytic subunits of a large protein complex responsible for the deposition of cellulose into plant cell walls. Early in vascular plant evolution, the gene family diverged into distinct members with conserved structures and functions (e.g. primary or secondary cell wall biosynthesis). Although the functions and expression domains of CesA genes have been extensively studied in plants, little is known about transcriptional regulation and promoter evolution in this gene family. * Here, comparative sequence analysis of orthologous CesA promoters from three angiosperm genera, Arabidopsis, Populus and Eucalyptus, was performed to identify putative cis-regulatory sequences. The promoter sequences of groups of Arabidopsis genes that are co-expressed with the primary or secondary cell wall-related CesA genes were also analyzed. * Reporter gene analysis of newly isolated promoter regions of six E. grandis CesA genes in Arabidopsis revealed the conserved functionality of the promoter sequences. Comparative sequence analysis identified 71 conserved sequence motifs, of which 66 were significantly over-represented in either primary or secondary wall-associated promoters. * The presence of conserved cis-regulatory elements in the evolutionary distant CesA promoters of Arabidopsis, Populus and Eucalyptus suggests an ancient transcriptional network regulating cellulose biosynthesis in vascular plants.
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Affiliation(s)
| | | | - David Kenneth Berger
- Department of Plant Science, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, 0002, South Africa
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232
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Freeman JS, Potts BM, Vaillancourt RE. Few Mendelian genes underlie the quantitative response of a forest tree, Eucalyptus globulus, to a natural fungal epidemic. Genetics 2008; 178:563-71. [PMID: 18202395 PMCID: PMC2206102 DOI: 10.1534/genetics.107.081414] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 11/07/2007] [Indexed: 11/18/2022] Open
Abstract
Foliar fungal pathogens from the genus Mycosphaerella affect eucalyptus in natural forests and plantations worldwide. QTL analysis was conducted to dissect the genetic control of resistance in Eucalyptus globulus to a natural infection by Mycosphaerella leaf disease, using a clonally replicated outbred F2 family (112 genotypes) planted in a field trial. Two major QTL, with high LOD support (20.2 and 10.9) and high genomewide significance, explained a large proportion (52%) of the phenotypic variance in the severity of damage by Mycosphaerella cryptica, which may be indicative of oligogenic control. Both QTL were validated in a second F2 family and one was validated in a third F2 family. The mean values of different genotype classes at both major QTL argue for Mendelian inheritance with resistance dominant over susceptibility. There were strong correlations between the levels of Mycosphaerella damage in related genetic material planted in three widely separated locations in Tasmania. These findings together provide evidence that the genes controlling resistance to Mycosphaerella damage are stable in different genetic backgrounds and across different environments.
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Affiliation(s)
- Jules S Freeman
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Hobart, Tasmania 7001, Australia.
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233
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O'Reilly-Wapstra JM, Humphreys JR, Potts BM. Stability of genetic-based defensive chemistry across life stages in a Eucalyptus species. J Chem Ecol 2007; 33:1876-84. [PMID: 17924167 DOI: 10.1007/s10886-007-9366-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Accepted: 09/10/2007] [Indexed: 11/26/2022]
Abstract
Defensive chemistry is a key plant fitness trait, and the investigation of the expression of plant secondary metabolites across life stages is important in understanding the lifetime evolutionary selection pressures on a plant. The expression of genetic-based differences in foliar defensive chemistry, known to influence mammalian herbivore preferences, was studied across two contrasting life phases of the heteroblastic tree, Eucalyptus globulus. With plants from different subraces of E. globulus growing in a field trial, we compared the levels of seven chemical constituents in adult and juvenile foliage from related coppiced plants. Defensive chemistry was generally higher in more vulnerable coppice foliage than adult foliage. Significant, genetic-based differences among subraces were detected for two key defensive chemicals, a sideroxylonal and a macrocarpal, and these differences were stable across life phases. In contrast, significant differences among subraces in adult leaf condensed tannins were not evident in the coppice because of the absence of this group of tannins in this foliage. These findings lend support to hypotheses that suggest condensed tannins may have evolved for reasons other than mammalian herbivore defense.
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Affiliation(s)
- Julianne M O'Reilly-Wapstra
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.
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234
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Abstract
Exploring the spatial distribution of variation in plant secondary metabolites is critical for understanding the evolutionary ecology of biochemical diversity in wild organisms. In the present study, concentrations of foliar sideroxylonal, an important and highly heritable defense chemical of Eucalyptus melliodora, displayed strong, fine-scale spatial autocorrelation. The spatial patterns observed could promote associational effects on herbivore foraging decisions, which may influence the selection pressures exerted on sideroxylonal content. Multiple chemical traits have roles in certain eucalypt-herbivore interactions, and the spatial characteristics of the herbivore foraging environment are therefore determined by these different factors. We used a model of E. melliodora intake by common brushtail possums (Trichosurus vulpecula), based on the combined effects of two chemical traits, to explore this idea and found that the spatial patterns were different to those of sideroxylonal alone. Spatial genetic autocorrelation, examined using microsatellites, was strong and occurred at a fine scale, implying that restricted gene flow might allow genetic patches to respond to selection relatively independently. Local two-dimensional genetic autocorrelation, explored using a new heuristic method, was highly congruent with the pattern of local phenotypic variation observed for sideroxylonal, suggesting that the genetic variance underlying the sideroxylonal variation is similarly structured. Our results suggest that the spatial distribution of genetic and phenotypic variation could influence both the selective pressure imposed by herbivores on eucalypt defenses and the potential of populations to respond to natural selection. Spatial context should be considered in future studies of plant-herbivore interactions.
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Affiliation(s)
- Rose L Andrew
- School of Botany and Zoology, The Australian National University, Canberra, ACT 0200, Australia.
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235
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Ochieng JW, Henry RJ, Baverstock PR, Steane DA, Shepherd M. Nuclear ribosomal pseudogenes resolve a corroborated monophyly of the eucalypt genus Corymbia despite misleading hypotheses at functional ITS paralogs. Mol Phylogenet Evol 2007; 44:752-64. [PMID: 17570687 DOI: 10.1016/j.ympev.2007.04.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2006] [Revised: 03/26/2007] [Accepted: 04/15/2007] [Indexed: 01/08/2023]
Abstract
Divergent paralogs can create both obstacles and opportunities for phylogenetic reconstruction. Phylogenetic relationships among eucalypt genera have been incongruent among datasets in previous studies, where morphological characters supported monophyly of the genus Corymbia, while intergenic spacers of the nuclear ribosomes (ITS) and chloroplast loci (trnL, trnH, psbA) showed Corymbia as either equivocal or paraphyletic. Ribosomal DNA occurs in multiple copies in a genome. We cloned and sequenced the nrITS to investigate if gene duplication was the cause of incongruence among trees in the eucalypts. Three ITS riboforms, two of them widespread, were recovered within some genomes. One of the ITS riboforms recovered a robust phylogeny showing Corymbia as a monophyletic genus, corroborating the evidence from morphology, fossil data, a recent ITS/ETS dataset and microsatellites (SSRs). Compelling evidence suggested that this divergent riboform is a pseudogene, i.e., non-functional paralog: comparatively lower GC content suggesting lower structural stability, deamination-like mutations at potential methylation sites, lack of conserved helices and hairpins and conspicuously lower thermodynamic stability in secondary structures. Phylogenies from the apparently functional riboform retained Corymbia as paraphyletic. We show here that pseudogenes can recover a well-corroborated phylogeny whereas their functional paralogs show misleading hypotheses. We explain that phylogenetic signals may be obscured when functional constraints in ITS necessitate compensatory mutations in the secondary structure helices involved in RNA transcription, whereas pseudogenes mutate under neutrality.
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Affiliation(s)
- Joel W Ochieng
- Centre for Plant Conservation Genetics, Southern Cross University, Military Road, P.O. Box 157, Lismore, NSW 2480, Australia.
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236
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Spokevicius AV, Southerton SG, MacMillan CP, Qiu D, Gan S, Tibbits JFG, Moran GF, Bossinger G. beta-tubulin affects cellulose microfibril orientation in plant secondary fibre cell walls. Plant J 2007; 51:717-26. [PMID: 17605757 DOI: 10.1111/j.1365-313x.2007.03176.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Cellulose microfibrils are the major structural component of plant secondary cell walls. Their arrangement in plant primary cell walls, and its consequent influence on cell expansion and cellular morphology, is directed by cortical microtubules; cylindrical protein filaments composed of heterodimers of alpha- and beta-tubulin. In secondary cell walls of woody plant stems the orientation of cellulose microfibrils influences the strength and flexibility of wood, providing the physical support that has been instrumental in vascular plant colonization of the troposphere. Here we show that a Eucalyptus grandisbeta-tubulin gene (EgrTUB1) is involved in determining the orientation of cellulose microfibrils in plant secondary fibre cell walls. This finding is based on RNA expression studies in mature trees, where we identified and isolated EgrTUB1 as a candidate for association with wood-fibre formation, and on the analysis of somatically derived transgenic wood sectors in Eucalyptus. We show that cellulose microfibril angle (MFA) is correlated with EgrTUB1 expression, and that MFA was significantly altered as a consequence of stable transformation with EgrTUB1. Our findings present an important step towards the production of fibres with altered tensile strength, stiffness and elastic properties, and shed light on one of the molecular mechanisms that has enabled trees to dominate terrestrial ecosystems.
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Affiliation(s)
- Antanas V Spokevicius
- The University of Melbourne, School of Forest and Ecosystem Science, Water Street, Creswick, Victoria 3363, Australia
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237
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Andrew RL, Wallis IR, Harwood CE, Henson M, Foley WJ. Heritable variation in the foliar secondary metabolite sideroxylonal in Eucalyptus confers cross-resistance to herbivores. Oecologia 2007; 153:891-901. [PMID: 17593399 DOI: 10.1007/s00442-007-0784-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 05/24/2007] [Indexed: 10/23/2022]
Abstract
Plants encounter a broad range of natural enemies and defend themselves in diverse ways. The cost of defense can be reduced if a plant secondary metabolite confers resistance to multiple herbivores. However, there are few examples of positively correlated defenses in plants against herbivores of different types. We present evidence that a genetically variable chemical trait that acts as a strong antifeedant to mammalian herbivores of Eucalyptus also deters insect herbivores, suggesting a possible mechanism for cross-resistance. We provide field confirmation that sideroxylonal, an important antifeedant for mammalian herbivores, also determines patterns of damage by Christmas beetles, a specialist insect herbivore of Eucalyptus. In a genetic progeny trial of Eucalyptus tricarpa, we found significant heritabilities of sideroxylonal concentration (0.60), overall insect damage (0.34), and growth traits (0.30-0.53). Population of origin also had a strong effect on each trait. Negative phenotypic correlations were observed between sideroxylonal and damage, and between damage and growth. No relationship was observed between sideroxylonal concentration and any growth trait. Our results suggest that potential for evolution by natural selection of sideroxylonal concentrations is not strongly constrained by growth costs and that both growth and defense traits can be successfully incorporated into breeding programs for plantation trees.
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Affiliation(s)
- Rose L Andrew
- School of Botany and Zoology, The Australian National University, Canberra, ACT 0200, Australia.
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238
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Abstract
Using Eucalyptus camaldulensis as a model system, we describe here a basic Agrobacterium-mediated genetic transformation protocol through organogenesis for the production of transgenic plants. Hypocotyl segments or cotyledon pieces from in vitro seedlings are used as starting materials. The explants are inoculated and cocultivated with a disarmed, binary strain of A. tumefaciens CIB542 harboring a mini Ti plasmid, pBI121. A modified Gamborg's B5 medium is used as the basal culture medium throughout stages of co-cultivation, callus induction and shoot regeneration. The incorporation of neomycin phosphotransferase II (nptII) and beta-glucuronidase (gus) genes into the plant nuclear genome are primarily verified by histochemical analysis and polymerase chain reaction (PCR). Modifications of this protocol to use in mature tissues derived from elite trees and other Eucalyptus species are also described.
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Affiliation(s)
- Zenn-Zong Chen
- Division of Silviculture, Taiwan Forestry Research Institute, Taipei 100, Taiwan
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239
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Gamboa MC, Rasmussen-Poblete S, Valenzuela PDT, Krauskopf E. Isolation and characterization of a cDNA encoding a CBF transcription factor from E. globulus. Plant Physiol Biochem 2007; 45:1-5. [PMID: 17303430 DOI: 10.1016/j.plaphy.2006.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Accepted: 12/21/2006] [Indexed: 05/14/2023]
Abstract
The transcription factors CBF/DREB play an important role during low temperature, drought and high-salt stress in higher plants. In this work, we isolated one full-length CBF cDNA clone from the angiosperm Eucalyptus globulus. The derived peptide sequence reveals that it encodes a transcriptional activator that has all the characteristic motifs present in CBF proteins previously described in Arabidopsis and tomato. RT-PCR analysis shows that EgCBF1 is transiently induced in E. globulus seedlings that had been exposed to low temperature within the first 15 min. These results suggest that the isolated CBF gene participates in the cold responsive pathway of E. globulus.
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Affiliation(s)
- Maria C Gamboa
- Instituto Milenio MIFAB - Fundación Ciencia para la Vida, Zañartu 1482, Nuñoa, Santiago, Chile
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240
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Abstract
Three small populations of a dwarf ecotype of the forest tree Eucalyptus globulus are found on exposed granite headlands in south-eastern Australia. These populations are separated by at least 100 km. Here, we used 12 nuclear microsatellites and a chloroplast DNA marker to investigate the genetic affinities of the dwarf populations to one another and to their nearest populations of tall E. globulus. Cape Tourville was studied in greater detail to assess the processes enabling the maintenance of distinct ecotypes in close geographical proximity. The three dwarf populations were not related to one another and were more closely related to adjacent tall trees than to one another. At Cape Tourville the dwarf and tall ecotypes were significantly differentiated in microsatellites and in chloroplast DNA. The dwarf and tall populations differed in flowering time and no evidence of pollen dispersal from the more extensive tall to the dwarf population was found. The three dwarf populations have evolved in parallel from the local tall ecotypes. This study shows that small marginal populations of eucalypts are capable of developing reproductive isolation from nearby larger populations through differences in flowering time and/or minor spatial separation, making parapatric speciation possible.
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Affiliation(s)
- Susan A Foster
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Gay E McKinnon
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Dorothy A Steane
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Brad M Potts
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - René E Vaillancourt
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
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241
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Henery ML, Moran GF, Wallis IR, Foley WJ. Identification of quantitative trait loci influencing foliar concentrations of terpenes and formylated phloroglucinol compounds in Eucalyptus nitens. New Phytol 2007; 176:82-95. [PMID: 17696979 DOI: 10.1111/j.1469-8137.2007.02159.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Leaves of eucalypt species contain a variety of plant secondary metabolites, including terpenoids and formylated phloroglucinol compounds (FPCs). Both terpene and FPC concentrations are quantitative traits that can show large variation within a population and have been shown to be heritable. The molecular genetic basis of this variation is currently unknown. Progeny from a field trial of a three-generation mapping pedigree of Eucalyptus nitens were assayed for terpenes and FPCs. Quantitative trait loci (QTL) analyses were conducted using a map constructed from 296 markers to locate regions of the genome influencing foliar concentrations of these plant secondary compounds. A large number of significant QTL for 14 traits were located across nine linkage groups, with significant clustering of QTL on linkage groups 7, 8 and 9. As expected, QTL for biosynthetically related compounds commonly colocated, but QTL for unrelated monterpenes and FPCs also mapped closely together. Colocation of these QTL with mapped candidate genes from the various biosynthetic pathways, and subsequent use of these genes in association mapping, will assist in determining the causes of variation in plant secondary metabolites in eucalypts.
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Affiliation(s)
- Martin L Henery
- School of Botany and Zoology, Australian National University, Canberra ACT 0200, Australia
| | - Gavin F Moran
- School of Botany and Zoology, Australian National University, Canberra ACT 0200, Australia
| | - Ian R Wallis
- School of Botany and Zoology, Australian National University, Canberra ACT 0200, Australia
| | - William J Foley
- School of Botany and Zoology, Australian National University, Canberra ACT 0200, Australia
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242
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Abstract
Visualizing the pattern of variation using microsatellites within a Eucalyptus globulus forest on the island of Tasmania provided surprising insights into the complex nature of the fine-scale spatial genetic structure that resides in these forests. We used spatial autocorrelation and principal coordinate analysis to compare fine-scale genetic structure between juvenile and mature cohorts in a study area, 140 m in diameter, located within a typical, continuous E. globulus forest. In total, 115 juvenile and 168 mature individuals were genotyped with eight highly polymorphic microsatellite loci. There was no significant difference in the level of genetic diversity between cohorts. However, there were differences in the spatial distribution of the genetic variation. Autocorrelation analysis provided clear evidence for significant spatial genetic structure in the mature cohort and significant, but weaker, structure in the juvenile cohort. The spatial interpolation of principal coordinate axes, derived from ordination of the genetic distance matrix between individuals, revealed a spatially coherent family group which was evident in both cohorts. Direct comparison of the genetic structure within each cohort allowed visualization of a shift in the spatial distribution of genetic variation within the population of approximately 10 m. As the shift coincided with the direction of prevailing winds, it is hypothesized that this phenomenon is due to downwind dispersal of seeds and is indicative of the important role of prevailing winds in forcing eastward gene flow in these high-latitude forests.
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Affiliation(s)
- Tim H Jones
- School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Australia.
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Baghdady A, Blervacq AS, Jouanin L, Grima-Pettenati J, Sivadon P, Hawkins S. Eucalyptus gunnii CCR and CAD2 promoters are active in lignifying cells during primary and secondary xylem formation in Arabidopsis thaliana. Plant Physiol Biochem 2006; 44:674-83. [PMID: 17107813 DOI: 10.1016/j.plaphy.2006.10.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Accepted: 10/10/2006] [Indexed: 05/02/2023]
Abstract
Cell-specific expression patterns of the Eucalyptus gunnii cinnamoyl coenzymeA reductase (EgCCR) and cinnamyl alcohol dehydrogenase (EgCAD2) promoters were analyzed by promoter-GUS histochemistry in the primary and secondary xylem tissues from floral stems and roots of Arabidopsis thaliana. Expression patterns indicated that the EgCCR and EgCAD2 genes were expressed in a coordinated manner in primary and secondary xylem tissues of the Arabidopsis floral stem and root. Both genes were expressed in all lignifying cells (vessel elements, xylem fibers and paratracheal parenchyma cells) of xylem tissues. The capacity for long-term monolignol production appeared to be related to the cell-specific developmental processes and biological roles of different cell types. Our results suggested that lignification of short-lived vessel elements was achieved by a two-step process involving (i) monolignol production by vessel elements prior to vessel programmed cell death and (ii) subsequent monolignol production by vessel-associated living paratracheal parenchyma cells following vessel element cell death. EgCCR and EgCAD2 gene expression patterns suggested that the process of xylem cell lignification was similar in both primary and secondary xylem tissues in Arabidopsis floral stems and roots.
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Affiliation(s)
- A Baghdady
- Stress abiotiques et différenciation des végétaux cultivés, UMR USTL-INRA 1281, université des sciences et technologies de Lille, bâtiment SN2, cité scientifique, 59655 Villeneuve-d'Ascq cedex, France
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244
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Brondani RPV, Williams ER, Brondani C, Grattapaglia D. A microsatellite-based consensus linkage map for species of Eucalyptus and a novel set of 230 microsatellite markers for the genus. BMC Plant Biol 2006; 6:20. [PMID: 16995939 PMCID: PMC1599733 DOI: 10.1186/1471-2229-6-20] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Accepted: 09/22/2006] [Indexed: 05/11/2023]
Abstract
BACKGROUND Eucalypts are the most widely planted hardwood trees in the world occupying globally more than 18 million hectares as an important source of carbon neutral renewable energy and raw material for pulp, paper and solid wood. Quantitative Trait Loci (QTLs) in Eucalyptus have been localized on pedigree-specific RAPD or AFLP maps seriously limiting the value of such QTL mapping efforts for molecular breeding. The availability of a genus-wide genetic map with transferable microsatellite markers has become a must for the effective advancement of genomic undertakings. This report describes the development of a novel set of 230 EMBRA microsatellites, the construction of the first comprehensive microsatellite-based consensus linkage map for Eucalyptus and the consolidation of existing linkage information for other microsatellites and candidate genes mapped in other species of the genus. RESULTS The consensus map covers approximately 90% of the recombining genome of Eucalyptus, involves 234 mapped EMBRA loci on 11 linkage groups, an observed length of 1,568 cM and a mean distance between markers of 8.4 cM. A compilation of all microsatellite linkage information published in Eucalyptus allowed us to establish the homology among linkage groups between this consensus map and other maps published for E. globulus. Comparative mapping analyses also resulted in the linkage group assignment of other 41 microsatellites derived from other Eucalyptus species as well as candidate genes and QTLs for wood and flowering traits published in the literature. This report significantly increases the availability of microsatellite markers and mapping information for species of Eucalyptus and corroborates the high conservation of microsatellite flanking sequences and locus ordering between species of the genus. CONCLUSION This work represents an important step forward for Eucalyptus comparative genomics, opening stimulating perspectives for evolutionary studies and molecular breeding applications. The generalized use of an increasingly larger set of interspecific transferable markers and consensus mapping information, will allow faster and more detailed investigations of QTL synteny among species, validation of expression-QTL across variable genetic backgrounds and positioning of a growing number of candidate genes co-localized with QTLs, to be tested in association mapping experiments.
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Affiliation(s)
- Rosana PV Brondani
- EMBRAPA Recursos Genéticos e Biotecnologia, CP 02372, 70770-970 DF Brasilia, Brazil
- Department of Cell Biology, Universidade de Brasília UnB, DF, Brasília
- EMBRAPA Arroz e Feijão, CP 179, Goiânia GO 74001-970, Brazil
| | - Emlyn R Williams
- CSIRO Forestry and Forest Products, POBox E4008, Kingston ACT 2604, Australia
| | - Claudio Brondani
- EMBRAPA Recursos Genéticos e Biotecnologia, CP 02372, 70770-970 DF Brasilia, Brazil
- EMBRAPA Arroz e Feijão, CP 179, Goiânia GO 74001-970, Brazil
| | - Dario Grattapaglia
- EMBRAPA Recursos Genéticos e Biotecnologia, CP 02372, 70770-970 DF Brasilia, Brazil
- Graduate Program in Genomic Sciences and Biotechnology, Universidade Catolica de Brasília, 70790-160 DF Brasilia, Brazil
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245
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Ranik M, Myburg AA. Six new cellulose synthase genes from Eucalyptus are associated with primary and secondary cell wall biosynthesis. Tree Physiol 2006; 26:545-56. [PMID: 16452068 DOI: 10.1093/treephys/26.5.545] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Higher plants contain a family of cellulose synthase catalytic subunit (CesA) genes that encode components of an enzyme complex embedded in the cell membrane. Recent studies in several higher plant species have demonstrated that two groups of CesA genes exist, associated with either primary or secondary cell wall deposition. We cloned six full-length CesA cDNAs from Eucalyptus grandis W. Hill ex Maiden (EgCesA1 through 6) and determined their expression patterns in a variety of organs from an adult tree. The six EgCesA genes encode predicted proteins of 978 to 1097 amino acid residues, each of which contains all of the key regions and motifs characteristic of functional CESA proteins. The predicted proteins share limited amino acid identity with each other, ranging from 61 to 70%. In contrast, similar CESA proteins from higher plant species exhibit 81 to 90% identity with the six EgCESAs. Gene expression analysis using quantitative reverse-transcription polymerase chain reaction indicated that transcripts of EgCesA1 to 3 were abundant in tissues enriched with cells laying down secondary cell walls (e.g., xylem), but were weakly expressed in tissues undergoing primary growth (e.g., unfolding leaves). Expression of EgCesA4 and EgCesA5 was upregulated in tissues rich in rapidly dividing cells undergoing primary wall synthesis, whereas EgCesA6 was weakly expressed in all tissues analyzed. These results suggest that Eucalyptus, like other higher plants, expresses two contrasting groups of apparently co-regulated CesAs involved in either primary or secondary cell wall biosynthesis.
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Affiliation(s)
- Martin Ranik
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa.
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246
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Missiaggia A, Grattapaglia D. Plant microsatellite genotyping with 4-color fluorescent detection using multiple-tailed primers. Genet Mol Res 2006; 5:72-8. [PMID: 16755499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We extended the concept of fluorescent microsatellite genotyping with a single-universal tailed primer to the simultaneous use of three different tailed primers to allow multiplexed 4-color detection for medium throughput genotyping of plant species. The method was tested on Eucalyptus DNA samples using three forward primer sequences of human microsatellite markers labeled with different fluorescent dyes. The robustness of the method was tested for the simultaneous detection and genetic analysis of microsatellites in a genetic mapping experiment. This method allows reliable and cost-effective genotyping with the same level of multiplexing attained in regular microsatellite fluorescent detection assays. Besides the enhanced quality of the genotypic data provided by the fluorescent detection method when compared to colorimetric ones, the economy brought about by this method becomes greater with an increasing number of microsatellite markers. This method has been particularly useful for genotyping populations of several tropical tree species addressing community-wide population genetics and conservation questions.
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Affiliation(s)
- Alexandre Missiaggia
- Laboratório de Genética Vegetal, Embrapa-Recursos Genéticos e Biotecnologia, Parque Estação Biológica, Brasília, DF, Brazil
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247
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Abstract
Despite the availability of high-throughput transcript profiling technology, little is known about tissue-specific gene expression patterns in the wood-forming tissues of Eucalyptus plantation tree species. We used cDNA-amplified fragment length polymorphism (AFLP) analysis in combination with infrared fragment detection and semi-automated band quantification to profile gene expression in a 6-year-old, fast- growing Eucalyptus tree. The expression profiles of 6385 transcript-derived fragments (TDFs) were analyzed across four major woody tissues (mature xylem, immature xylem, phloem and cork) collected from two stem positions, to provide a global view of transcript abundance and variability in the Eucalyptus stem. About 21% of the TDFs were differentially expressed and could be grouped into clusters representing co- expressed genes. A total of 71 TDFs representing different gene clusters were isolated and characterized. These included genes implicated in cell fate, signal transduction and cell wall biosynthesis, processes closely associated with xylogenesis. Analysis of the expression levels of selected TDFs by quantitative RT-PCR corroborated the TDF quantification and confirmed that cDNA-AFLP analysis is a highly efficient and accurate tool for transcript profiling and gene discovery in wood-forming tissues of tree species.
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MESH Headings
- Cluster Analysis
- DNA, Complementary/metabolism
- DNA, Plant/metabolism
- Eucalyptus/genetics
- Eucalyptus/growth & development
- Gene Expression Profiling
- Gene Expression Regulation, Plant
- Genes, Plant
- Genome, Plant
- Polymorphism, Genetic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription, Genetic
- Trees/genetics
- Wood/genetics
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Affiliation(s)
- Martin Ranik
- Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, 0002, South Africa
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248
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Poke FS, Martin DP, Steane DA, Vaillancourt RE, Reid JB. The impact of intragenic recombination on phylogenetic reconstruction at the sectional level in Eucalyptus when using a single copy nuclear gene (cinnamoyl CoA reductase). Mol Phylogenet Evol 2006; 39:160-70. [PMID: 16403657 DOI: 10.1016/j.ympev.2005.11.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Revised: 11/09/2005] [Accepted: 11/15/2005] [Indexed: 11/27/2022]
Abstract
Low copy number nuclear genes have been found to be useful for phylogenetic reconstruction at different taxonomic levels. This study investigated the utility of a single copy gene, cinnamoyl CoA reductase (CCR), for resolving phylogenetic relationships at the sectional level within Eucalyptus. The monophyly of sections Exsertaria and Latoangulatae was explored, using section Maidenaria as an outgroup, and the impact of intragenic recombination on phylogenetic reconstruction examined. Phylogenetic analysis did not resolve monophyletic groups. Latoangulatae and Maidenaria were polyphyletic or paraphyletic. Exsertaria species formed a clade but included a single Latoangulatae species (E. major). Recombination analysis identified two intragenic recombination events that involved species from different sections, which have probably been facilitated by inter-sectional hybridisation. One of the events most likely occurred prior to speciation, with several Latoangulatae species having the recombinant allele. The other event may have occurred after speciation, since only one of two E. globulus samples possessed the recombinant allele. This is the first detailed report of intragenic recombination in both CCR and Eucalyptus, and between species of different sections of a plant genus. The occurrence of intragenic recombination may explain the anomalous positions of some species within the phylogenetic tree, and indicates that phylogenetic analysis of Eucalyptus using nuclear genes will be problematic unless recombination is taken into account.
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Affiliation(s)
- Fiona S Poke
- School of Plant Science and Cooperative Research Centre for Sustainable Production Forestry, University of Tasmania, Private Bag 55, Hobart 7001, Tasmania, Australia.
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249
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El Kayal W, Navarro M, Marque G, Keller G, Marque C, Teulieres C. Expression profile of CBF-like transcriptional factor genes from Eucalyptus in response to cold. J Exp Bot 2006; 57:2455-69. [PMID: 16816002 DOI: 10.1093/jxb/erl019] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Two CBF (CRT/DRE-binding factor) homologues isolated from Eucalyptus gunnii were designated EguCBF1a and EguCBF1b and belong to a gene family which includes at least five members. Both promoter and coding sequences were found to exhibit the main characteristics of a CBF transcription activator gene and, as expected, the corresponding protein targeted the nucleus. Gene expression was quantitatively analysed using real-time reverse transcription-polymerase chain reaction (RT-PCR) after a short exposure to different environmental conditions or along a two-step cold acclimation programme with either short or long daylengths. A very strong and fast response to cold was observed, with dark conditions and cold intensity (down to 0 degrees C) having a positive effect on the magnitude of induction. The two genes under study exhibited several similar features such as light response. However, interestingly, their regulation by cold proved differential and complementary as EguCBF1a was more transiently induced by a direct and intense exposure while EguCBF1b responded to milder treatments and exhibited a longer (i.e. which started earlier and finished later) time course. During acclimation, the short daylength positively affected the freezing tolerance in the same way as it positively affected the CBF transcript accumulation, suggesting a potential involvement of these genes in the adaptive response. Although very quick after the first signal, the up-regulation of the two EguCBF1 genes unexpectedly lasted throughout the chilling culture, and new inductions were seen during the thermoperiod transitions. Using a quantitative and highly sensitive measurement of gene expression combined with the application of a cold treatment consistent with natural environmental conditions, this study provides new information on the regulation of CBF-like genes by cold in planta.
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Affiliation(s)
- Walid El Kayal
- Université Paul Sabatier: UMR 5546, Surfaces Cellulaires et Signalisation chez les Végétaux Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, BP 42617 Auzeville, F-31326 Castanet-Tolosan, France
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250
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Foucart C, Paux E, Ladouce N, San-Clemente H, Grima-Pettenati J, Sivadon P. Transcript profiling of a xylem vs phloem cDNA subtractive library identifies new genes expressed during xylogenesis in Eucalyptus. New Phytol 2006; 170:739-52. [PMID: 16684235 DOI: 10.1111/j.1469-8137.2006.01705.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Eucalyptus is one of the world's main sources of biomass. The genus includes species representing the principle hardwood trees used for pulp and paper. Here, we aimed to identify genes specifically expressed in differentiating secondary xylem compared with phloem. We constructed a xylem vs phloem subtractive library (Xp) that generated 263 unique sequences. By transcript profiling of xylem, phloem, vascular cambium and leaves using macroarrays, we classified the 263 unigenes into distinct tissue-specific groups. Reverse transcription-polymerase chain reaction (RT-PCR) confirmed the differential expression of representative expressed sequence tags (ESTs). A total of 87 unigenes were preferentially expressed in xylem. They were involved in functional categories known to play roles in xylogenesis, such as hormone signaling and metabolism, secondary cell wall thickening and proteolysis. Some of these genes, including unknown genes, may be considered xylem-specific and they are likely to control important functions in xylogenesis. These data shed light on the cellular functions of xylem cells and, importantly, provide us with a portfolio of Eucalyptus xylem genes that may be major players in the control of wood formation and quality.
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Affiliation(s)
- Camille Foucart
- UMR 5546 CNRS/Université Paul Sabatier Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville Tolosane, 31326 Castanet Tolosan, France
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