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Fadón E, Herrera S, Gheban TI, Rodrigo J. Chilling Requirements of Apricot ( Prunus armeniaca L.) Cultivars Using Male Meiosis as a Dormancy Biomarker. PLANTS (BASEL, SWITZERLAND) 2023; 12:3025. [PMID: 37687272 PMCID: PMC10489937 DOI: 10.3390/plants12173025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/11/2023] [Accepted: 08/18/2023] [Indexed: 09/10/2023]
Abstract
Apricot has undergone an important cultivar renewal during the last years in response to productive and commercial changes in the crop. The impact of the sharka disease (plum pox virus) prompted the release of cultivars resistant/tolerant to this virus, leading to a major cultivar renewal worldwide. This has caused high variability in chilling requirements on new releases that remain unknown in many cases. In many apricot-growing areas, the lack of winter chilling is becoming a limiting factor in recent years. To deal with this situation, growers must choose cultivars well adapted to their areas. However, the information available on the agroclimatic requirements of the cultivars is very limited. To fill this gap, in this work, we have characterized the chilling requirements of 13 new apricot cultivars from Europe (France, Greece and Spain) and North America (USA) in two experimental collections in Aragón (Spain). We established the chilling period using male meiosis as a biomarker for endodormancy release over two years. Chilling requirements ranged from 51.9 Chill Portions (CP) to 70.9 CP. Knowing the chilling requirements of cultivars will help growers to select suitable cultivars adapted to the chill availability of their region.
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Affiliation(s)
- Erica Fadón
- Departamento de Ciencia Vegetal, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Gobierno de Aragón, Avda. Montañana 930, 50059 Zaragoza, Spain (T.I.G.)
- Instituto Agroalimentario de Aragón—IA2, CITA-Universidad de Zaragoza, Calle Miguel Servet 177, 50013 Zaragoza, Spain
| | - Sara Herrera
- Departamento de Ciencia Vegetal, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Gobierno de Aragón, Avda. Montañana 930, 50059 Zaragoza, Spain (T.I.G.)
- Instituto Agroalimentario de Aragón—IA2, CITA-Universidad de Zaragoza, Calle Miguel Servet 177, 50013 Zaragoza, Spain
| | - Tudor I. Gheban
- Departamento de Ciencia Vegetal, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Gobierno de Aragón, Avda. Montañana 930, 50059 Zaragoza, Spain (T.I.G.)
| | - Javier Rodrigo
- Departamento de Ciencia Vegetal, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Gobierno de Aragón, Avda. Montañana 930, 50059 Zaragoza, Spain (T.I.G.)
- Instituto Agroalimentario de Aragón—IA2, CITA-Universidad de Zaragoza, Calle Miguel Servet 177, 50013 Zaragoza, Spain
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Cruzan MB, Streisfeld MA, Schwoch JA. Fitness effects of somatic mutations accumulating during vegetative growth. Evol Ecol 2022. [DOI: 10.1007/s10682-022-10188-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AbstractThe unique life form of plants promotes the accumulation of somatic mutations that can be passed to offspring in the next generation, because the same meristem cells responsible for vegetative growth also generate gametes for sexual reproduction. However, little is known about the consequences of somatic mutation accumulation for offspring fitness. We evaluate the fitness effects of somatic mutations in Mimulus guttatus by comparing progeny from self-pollinations made within the same flower (autogamy) to progeny from self-pollinations made between stems on the same plant (geitonogamy). The effects of somatic mutations are evident from this comparison, as autogamy leads to homozygosity of a proportion of somatic mutations, but progeny from geitonogamy remain heterozygous for mutations unique to each stem. In two different experiments, we find consistent fitness effects of somatic mutations from individual stems. Surprisingly, several progeny groups from autogamous crosses displayed increases in fitness compared to progeny from geitonogamy crosses, likely indicating that beneficial somatic mutations occurred in some stems. These results support the hypothesis that somatic mutations accumulate during vegetative growth, but they are filtered by different forms of selection that occur throughout development, resulting in the culling of expressed deleterious mutations and the retention of beneficial mutations.
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Herrera S, Lora J, Fadón E, Hedhly A, Alonso JM, Hormaza JI, Rodrigo J. Male Meiosis as a Biomarker for Endo- to Ecodormancy Transition in Apricot. FRONTIERS IN PLANT SCIENCE 2022; 13:842333. [PMID: 35463418 PMCID: PMC9021868 DOI: 10.3389/fpls.2022.842333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Dormancy is an adaptive strategy in plants to survive under unfavorable climatic conditions during winter. In temperate regions, most fruit trees need exposure to a certain period of low temperatures to overcome endodormancy. After endodormancy release, exposure to warm temperatures is needed to flower (ecodormancy). Chilling and heat requirements are genetically determined and, therefore, are specific for each species and cultivar. The lack of sufficient winter chilling can cause failures in flowering and fruiting, thereby compromising yield. Thus, the knowledge of the chilling and heat requirements is essential to optimize cultivar selection for different edaphoclimatic conditions. However, the lack of phenological or biological markers linked to the dormant and forcing periods makes it difficult to establish the end of endodormancy. This has led to indirect estimates that are usually not valid in different agroclimatic conditions. The increasing number of milder winters caused by climatic change and the continuous release of new cultivars emphasize the necessity of a proper biological marker linked to the endo- to ecodormancy transition for an accurate estimation of the agroclimatic requirements (AR) of each cultivar. In this work, male meiosis is evaluated as a biomarker to determine endodormancy release and to estimate both chilling and heat requirements in apricot. For this purpose, pollen development was characterized histochemically in 20 cultivars over 8 years, and the developmental stages were related to dormancy. Results were compared to three approaches that indirectly estimate the breaking of dormancy: an experimental methodology by evaluating bud growth in shoots collected periodically throughout the winter months and transferred to forcing chambers over 3 years, and two statistical approaches that relate seasonal temperatures and blooming dates in a series of 11-20 years by correlation and partial least square regression. The results disclose that male meiosis is a possible biomarker to determine the end of endodormancy and estimate AR in apricot.
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Affiliation(s)
- Sara Herrera
- Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Departamento de Ciencia Vegetal, Zaragoza, Spain
- Instituto Agroalimentario de Aragón-IA2 (CITA-Universidad de Zaragoza), Zaragoza, Spain
| | - Jorge Lora
- Subtropical Fruit Crops Department, Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM La Mayora-CSIC-UMA), Málaga, Spain
| | - Erica Fadón
- Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Departamento de Ciencia Vegetal, Zaragoza, Spain
- Instituto Agroalimentario de Aragón-IA2 (CITA-Universidad de Zaragoza), Zaragoza, Spain
| | - Afif Hedhly
- Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Departamento de Ciencia Vegetal, Zaragoza, Spain
| | - José Manuel Alonso
- Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Departamento de Ciencia Vegetal, Zaragoza, Spain
| | - José I. Hormaza
- Subtropical Fruit Crops Department, Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM La Mayora-CSIC-UMA), Málaga, Spain
| | - Javier Rodrigo
- Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Departamento de Ciencia Vegetal, Zaragoza, Spain
- Instituto Agroalimentario de Aragón-IA2 (CITA-Universidad de Zaragoza), Zaragoza, Spain
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Fadón E, Herrera S, Herrero M, Rodrigo J. Male meiosis in sweet cherry is constrained by the chilling and forcing phases of dormancy. TREE PHYSIOLOGY 2021; 41:619-630. [PMID: 32453409 DOI: 10.1093/treephys/tpaa063] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 03/23/2020] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
Male meiosis in temperate fruit trees occurs in the anthers once a year, synchronized with the seasons. The alternation of dormant and growth cycles determines the optimum moment for the male gametophyte formation, a process sensitive to both cold and warm temperatures. This ensures pollen viability and subsequent reproduction success that guarantee fruit production. In this work, we explore how male meiosis is framed by seasonality in sweet cherry. For this purpose, the dormant phases, male meiosis and blooming dates were established in four cultivars with different flowering dates and chilling requirements over 7 years. The chilling and heat requirements for each cultivar were empirically estimated, and chilling and heat temperatures were quantified according to the Dynamic and Growing Degree Hours (GDH) models, respectively. Endodormancy was overcome approximately a fortnight earlier during the colder winters than during the milder winters. Against our initial hypothesis, these differences were not clearly reflected in the time of male meiosis. The period between chilling fulfillment and meiosis lasted several weeks, during which a high amount of GDH accumulated. Results showed that male meiosis is conditioned by endodormancy but especially by warm temperatures, during the forcing period. This differs from what has been described in other related species and creates a framework for further studies to understand the strategies of synchronizing dormancy with seasons.
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Affiliation(s)
- Erica Fadón
- INRES - Gartenbauwissenschaft, Universität Bonn, Bonn, Germany
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Zaragoza, Spain
- Departamento de Pomología, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD - CSIC), Zaragoza, Spain
| | - Sara Herrera
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Zaragoza, Spain
| | - María Herrero
- Departamento de Pomología, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD - CSIC), Zaragoza, Spain
| | - Javier Rodrigo
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Zaragoza, Spain
- Instituto Agroalimentario de Aragón - IA2 (CITA - Universidad de Zaragoza), Zaragoza, Spain
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Williams JH, Oliveira PE. For things to stay the same, things must change: polyploidy and pollen tube growth rates. ANNALS OF BOTANY 2020; 125:925-935. [PMID: 31957784 PMCID: PMC7218811 DOI: 10.1093/aob/mcaa007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 01/17/2020] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Pollen tube growth rate (PTGR) is an important single-cell performance trait that may evolve rapidly under haploid selection. Angiosperms have experienced repeated cycles of polyploidy (whole genome duplication), and polyploidy has cell-level phenotypic consequences arising from increased bulk DNA amount and numbers of genes and their interactions. We sought to understand potential effects of polyploidy on several underlying determinants of PTGR - pollen tube dimensions and construction rates - by comparing diploid-polyploid near-relatives in Betula (Betulaceae) and Handroanthus (Bignoniaceae). METHODS We performed intraspecific, outcrossed hand-pollinations on pairs of flowers. In one flower, PTGR was calculated from the longest pollen tube per time of tube elongation. In the other, styles were embedded in glycol methacrylate, serial-sectioned in transverse orientation, stained and viewed at 1000× to measure tube wall thicknesses (W) and circumferences (C). Volumetric growth rate (VGR) and wall production rate (WPR) were then calculated for each tube by multiplying cross-sectional tube area (πr2) or wall area (W × C), by the mean PTGR of each maternal replicate respectively. KEY RESULTS In Betula and Handroanthus, the hexaploid species had significantly wider pollen tubes (13 and 25 %, respectively) and significantly higher WPRs (22 and 18 %, respectively) than their diploid congeners. PTGRs were not significantly different in both pairs, even though wider polyploid tubes were predicted to decrease PTGRs by 16 and 20 %, respectively. CONCLUSIONS The larger tube sizes of polyploids imposed a substantial materials cost on PTGR, but polyploids also exhibited higher VGRs and WPRs, probably reflecting the evolution of increased metabolic activity. Recurrent cycles of polyploidy followed by genome reorganization may have been important for the evolution of fast PTGRs in angiosperms, involving a complex interplay between correlated changes in ploidy level, genome size, cell size and pollen tube energetics.
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Affiliation(s)
- Joseph H Williams
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
| | - Paulo E Oliveira
- Instituto de Biologia, Universidade Federal de Uberlândia, Campus Umuarama, Uberlândia, Minas Gerais 38405-320 Brazil
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Irisarri P, Zhebentyayeva T, Errea P, Pina A. Inheritance of self- and graft-incompatibility traits in an F1 apricot progeny. PLoS One 2019; 14:e0216371. [PMID: 31071130 PMCID: PMC6508642 DOI: 10.1371/journal.pone.0216371] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/18/2019] [Indexed: 11/19/2022] Open
Abstract
Floral self-incompatibility affecting yearly yield in a weather-dependent manner and graft incompatibility affecting longevity of mature trees are two important traits for apricot production. However, genetic control of graft compatibility and relationship between these traits are unknown. Here, we analyzed its inheritance in an F1 apricot progeny from a cross between self- and graft- incompatible and self- and graft-compatible cultivars. Hybrid individuals were genotyped for establishing self-incompatibility status and grafted on the plum rootstock ‘Marianna 2624’. Phenotyping of graft incompatibility was done at two time points, one month and one year after grafting. Anatomical (necrotic layer, bark and wood discontinuity for two consecutive years) and cytomorphological (cell proliferation, cell arrangement and cell shape one month after grafting) characteristics related to graft compatibility displayed continuous variation within the progeny, suggesting a polygenic inheritance. Using the Pearson correlation test, strong and significant correlations were detected between anatomical and cytomorphological traits that may reduce the number of characters for screening genotypes or progenies for graft compatibility in segregating crosses. Furthermore, no correlation existed between self- and graft incompatibility traits suggesting that they are independent inheritance traits. Hence, screening an extended hybrid population is required for pyramiding these traits in breeding programs.
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Affiliation(s)
- Patricia Irisarri
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Instituto Agroalimentario de Aragón—IA2 (CITA-Universidad de Zaragoza), Zaragoza, Spain
| | - Tatyana Zhebentyayeva
- The Schatz Center for Tree Molecular Genetics, Department of Ecosystem Sciences and Management, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Pilar Errea
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Instituto Agroalimentario de Aragón—IA2 (CITA-Universidad de Zaragoza), Zaragoza, Spain
| | - Ana Pina
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Instituto Agroalimentario de Aragón—IA2 (CITA-Universidad de Zaragoza), Zaragoza, Spain
- * E-mail:
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Castillo DM, Moyle LC. Conspecific sperm precedence is reinforced, but postcopulatory sexual selection weakened, in sympatric populations of Drosophila. Proc Biol Sci 2019; 286:20182535. [PMID: 30900533 PMCID: PMC6452082 DOI: 10.1098/rspb.2018.2535] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/06/2019] [Indexed: 12/21/2022] Open
Abstract
Sexual selection can accelerate speciation by driving the evolution of reproductive isolation, but forces driving speciation could also reciprocally feedback on sexual selection. This might be particularly important in the context of 'reinforcement', where selection acts directly to increase prezygotic barriers to reduce the cost of heterospecific matings. Using assays of sperm competition within and between two sister species, we show a signature of reinforcement where these species interact: populations of Drosophila pseudoobscura that co-occur with sister species D. persimilis have an elevated ability to outcompete heterospecific sperm, consistent with selection for increased postcopulatory isolation. We also find these D. pseudoobscura populations have decreased sperm competitive ability against conspecifics, reducing the opportunity for sexual selection within these populations. Our findings demonstrate that direct selection to increase reproductive isolation against other species can compromise the efficacy of sexual selection within species, a collateral effect of reproductive traits responding to heterospecific interactions.
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Affiliation(s)
- Dean M. Castillo
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
- Department of Molecular Biology and Genetics, Cornell University, 526 Campus Road, Ithaca, NY 14853, USA
| | - Leonie C. Moyle
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
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Identification of Self-Incompatibility Alleles by Specific PCR Analysis and S-RNase Sequencing in Apricot. Int J Mol Sci 2018; 19:ijms19113612. [PMID: 30445779 PMCID: PMC6274852 DOI: 10.3390/ijms19113612] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/08/2018] [Accepted: 11/13/2018] [Indexed: 01/08/2023] Open
Abstract
Self-incompatibility (SI) is one of the most efficient mechanisms to promote out-crossing in plants. However, SI could be a problem for fruit production. An example is apricot (Prunus armeniaca), in which, as in other species of the Rosaceae, SI is determined by an S-RNase-based-Gametophytic Self-Incompatibility (GSI) system. Incompatibility relationships between cultivars can be established by an S-allele genotyping PCR strategy. Until recently, most of the traditional European apricot cultivars were self-compatible but several breeding programs have introduced an increasing number of new cultivars whose pollination requirements are unknown. To fill this gap, we have identified the S-allele of 44 apricot genotypes, of which 43 are reported here for the first time. The identification of Sc in 15 genotypes suggests that those cultivars are self-compatible. In five genotypes, self-(in)compatibility was established by the observation of pollen tube growth in self-pollinated flowers, since PCR analysis could not allowed distinguishing between the Sc and S8 alleles. Self-incompatible genotypes were assigned to their corresponding self-incompatibility groups. The knowledge of incompatibility relationships between apricot cultivars can be a highly valuable tool for the development of future breeding programs by selecting the appropriate parents and for efficient orchard design by planting self-compatible and inter-compatible cultivars.
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Herrera S, Lora J, Hormaza JI, Herrero M, Rodrigo J. Optimizing Production in the New Generation of Apricot Cultivars: Self-incompatibility, S-RNase Allele Identification, and Incompatibility Group Assignment. FRONTIERS IN PLANT SCIENCE 2018; 9:527. [PMID: 29755489 PMCID: PMC5935046 DOI: 10.3389/fpls.2018.00527] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 04/04/2018] [Indexed: 05/27/2023]
Abstract
Apricot (Prunus armeniaca L.) is a species of the Rosaceae that was originated in Central Asia, from where it entered Europe through Armenia. The release of an increasing number of new cultivars from different breeding programs is resulting in an important renewal of plant material worldwide. Although most traditional apricot cultivars in Europe are self-compatible, the use of self-incompatible cultivars as parental genotypes for breeding purposes is leading to the introduction of a number of new cultivars that behave as self-incompatible. As a consequence, there is an increasing need to interplant those new cultivars with cross-compatible cultivars to ensure fruit set in commercial orchards. However, the pollination requirements of many of these new cultivars are unknown. In this work, we analyze the pollination requirements of a group of 92 apricot cultivars, including traditional and newly-released cultivars from different breeding programs and countries. Self-compatibility was established by the observation of pollen tube behavior in self-pollinated flowers under the microscope. Incompatibility relationships between cultivars were established by the identification of S-alleles by PCR analysis. The self-(in)compatibility of 68 cultivars and the S-RNase genotype of 74 cultivars are reported herein for the first time. Approximately half of the cultivars (47) behaved as self-compatible and the other 45 as self-incompatible. Identification of S-alleles in self-incompatible cultivars allowed allocating them in 11 incompatibility groups, six of them reported here for the first time. The determination of pollination requirements and the incompatibility relationships between cultivars is highly valuable for the appropriate selection of apricot cultivars in commercial orchards and of parental genotypes in breeding programs. The approach described can be transferred to other woody perennial crops with similar problems.
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Affiliation(s)
- Sara Herrera
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Instituto Agroalimentario de Aragón, IA2, CITA, Universidad de Zaragoza, Zaragoza, Spain
| | - Jorge Lora
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (UMA-CSIC), Málaga, Spain
| | - José I. Hormaza
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (UMA-CSIC), Málaga, Spain
| | - Maria Herrero
- Pomology Department, Estación Experimental Aula Dei-CSIC, Zaragoza, Spain
| | - Javier Rodrigo
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Instituto Agroalimentario de Aragón, IA2, CITA, Universidad de Zaragoza, Zaragoza, Spain
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Fadón E, Herrero M, Rodrigo J. Dormant Flower Buds Actively Accumulate Starch over Winter in Sweet Cherry. FRONTIERS IN PLANT SCIENCE 2018; 9:171. [PMID: 29497434 PMCID: PMC5818465 DOI: 10.3389/fpls.2018.00171] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 01/30/2018] [Indexed: 05/12/2023]
Abstract
Temperate woody perennials survive to low temperatures in winter entering a dormant stage. Dormancy is not just a survival strategy, since chilling accumulation is required for proper flowering and arbitrates species adaptation to different latitudes. In spite of the fact that chilling requirements have been known for two centuries, the biological basis behind remain elusive. Since chilling accumulation is required for the normal growth of flower buds, it is tempting to hypothesize that something might be going on at this particular stage during winter dormancy. Here, we characterized flower bud development in relation to dormancy, quantifying changes in starch in the flower primordia in two sweet cherry cultivars over a cold and a mild year. Results show that, along the winter, flower buds remain at the same phenological stage with flower primordia at the very same developmental stage. But, surprisingly, important variation in the starch content of the ovary primordia cells occurs. Starch accumulated following the same pattern than chilling accumulation and reaching a maximum at chilling fulfillment. This starch subsequently vanished during ecodormancy concomitantly with ovary development before budbreak. These results showed that, along the apparent inactivity during endodormancy, flower primordia were physiologically active accumulating starch, providing a biological basis to understand chilling requirements.
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Affiliation(s)
- Erica Fadón
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Instituto Agroalimentario de Aragón (IA2), Universidad de Zaragoza, Zaragoza, Spain
- Department of Pomology, Estación Experimental de Aula Dei (CSIC), Zaragoza, Spain
| | - María Herrero
- Department of Pomology, Estación Experimental de Aula Dei (CSIC), Zaragoza, Spain
| | - Javier Rodrigo
- Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Instituto Agroalimentario de Aragón (IA2), Universidad de Zaragoza, Zaragoza, Spain
- *Correspondence: Javier Rodrigo,
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Cannon CH, Scher CL. Exploring the potential of gametic reconstruction of parental genotypes by F 1 hybrids as a bridge for rapid introgression. Genome 2017; 60:713-719. [PMID: 28732173 DOI: 10.1139/gen-2016-0181] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Interspecific hybridization and genetic introgression are commonly observed in natural populations of many species, especially trees. Among oaks, gene flow between closely related species has been well documented. And yet, hybridization does not lead to a "melting pot", i.e., the homogenization of phenotypic traits. Here, we explore how the combination of several common reproductive and genomic traits could create an avenue for interspecific gene flow that partially explains this apparent paradox. During meiosis, F1 hybrids will produce approximately (½)n "reconstructed" parental gametes, where n equals the number of chromosomes. Crossing over would introduce a small amount of introgressive material. The resulting parental-type gametophytes would probably possess a similar fertilization advantage as conspecific pollen. The resulting "backcross" would actually be the genetic equivalent of a conspecific out-cross, with a small amount of heterospecific DNA captured through crossing over. Even with detailed genomic analysis, the resulting offspring would not appear to be a backcross. This avenue for rapid introgression between species through the F1 hybrid will be viable for organisms that meet certain conditions: low base chromosome number, conserved genomic structure and size, production of billions of gametes/gametophytes during each reproductive event, and conspecific fertilization advantage.
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Affiliation(s)
- Charles H Cannon
- The Center for Tree Science, The Morton Arboretum, Lisle, IL 60532, USA.,The Center for Tree Science, The Morton Arboretum, Lisle, IL 60532, USA
| | - C Lane Scher
- The Center for Tree Science, The Morton Arboretum, Lisle, IL 60532, USA.,The Center for Tree Science, The Morton Arboretum, Lisle, IL 60532, USA
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12
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Evolutionary Dynamics of Unreduced Gametes. Trends Genet 2017; 33:583-593. [PMID: 28732599 DOI: 10.1016/j.tig.2017.06.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/23/2017] [Accepted: 06/27/2017] [Indexed: 11/20/2022]
Abstract
Unreduced gametes, which have the somatic (2n) chromosome number, are an important precursor to polyploid formation and apomixis. The product of irregularities in meiosis, 2n gametes are expected to be rare and deleterious in most natural populations, contrary to their wide taxonomic distribution and the prevalence of polyploidy. To better understand this discrepancy, we review contemporary evidence related to four aspects of 2n gamete dynamics in natural populations: (i) estimates of their frequency; (ii) their environmental and genetic determinants; (iii) adaptive and nonadaptive processes regulating their evolution; and (iv) factors regulating their union and production of polyploids in diploid populations. Aided by high-throughput methods of detection, these foci will advance our understanding of variation in 2n gametes within and among species, and their role in polyploid evolution.
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Lyu N, Du W, Wang XF. Unique growth paths of heterospecific pollen tubes result in late entry into ovules in the gynoecium of Sagittaria (Alismataceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2017; 19:108-114. [PMID: 27687794 DOI: 10.1111/plb.12508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 09/24/2016] [Indexed: 06/06/2023]
Abstract
Pollen-pistil interactions are a fundamental process in the reproductive biology of angiosperms and play a particularly important role in maintaining incipient species that exist in sympatry. However, the majority of previous studies have focused on species with syncarpous gynoecia (fused carpels) and not those with apocarpous gynoecia (unfused carpels). In the present study, we investigated the growth of conspecific pollen tubes compared to heterospecific pollen tubes in Sagittaria species, which have apocarpous gynoecia. We conducted controlled pollinations between S. pygmaea and S. trifolia and observed the growth of conspecific and heterospecific pollen tubes under a fluorescence microscope. Heterospecific and conspecific pollen tubes arrived at locules within the ovaries near simultaneously. However, conspecific pollen tubes entered into the ovules directly, whereas heterospecific tubes passed through the carpel base and adjacent receptacle tissue, to ultimately fertilize other unfertilized ovules. This longer route taken by heterospecific pollen tubes therefore caused a delay in the time required to enter into the ovules. Furthermore, heterospecific pollen tubes displayed similar growth patterns at early and peak pollination. The growth pattern of heterospecific pollen tubes at late pollination was similar to that of conspecific pollen tubes at peak pollination. Heterospecific and conspecific pollen tubes took different routes to fertilize ovules. A delayed entry of heterospecific pollen into ovules may be a novel mechanism of conspecific pollen advantage (CPA) for apocarpous species.
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Affiliation(s)
- N Lyu
- College of Life Sciences, Wuhan University, Wuhan, China
| | - W Du
- College of Life Sciences, Wuhan University, Wuhan, China
| | - X-F Wang
- College of Life Sciences, Wuhan University, Wuhan, China
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Williams JH, Edwards JA, Ramsey AJ. Economy, efficiency, and the evolution of pollen tube growth rates. AMERICAN JOURNAL OF BOTANY 2016; 103:471-483. [PMID: 26936897 DOI: 10.3732/ajb.1500264] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 10/08/2015] [Indexed: 06/05/2023]
Abstract
PREMISE Pollen tube growth rate (PTGR) is an important aspect of male gametophyte performance because of its central role in the fertilization process. Theory suggests that under intense competition, PTGRs should evolve to be faster, especially if PTGR accurately reflects gametophyte quality. Oddly, we know remarkably little about how effectively the work of tube construction is translated to elongation (growth and growth rate). Here we test the prediction that pollen tubes grow equally efficiently by comparing the scaling of wall production rate (WPR) to PTGR in three water lilies that flower concurrently: Nymphaea odorata, Nuphar advena and Brasenia schreberi. METHODS Single-donor pollinations on flower or carpel pairs were fixed just after pollen germination (time A) and 45 min later (time B). Mean PTGR was calculated as the average increase in tube length over that growth period. Tube circumferences (C) and wall thicknesses (W) were measured at time B. For each donor, WPR = mean (C × W) × mean PTGR. KEY RESULTS Within species, pollen tubes maintained a constant WPR to PTGR ratio, but species had significantly different ratios. N. odorata and N. advena had similar PTGRs, but for any given PTGR, they had the lowest and highest WPRs, respectively. CONCLUSIONS We showed that growth rate efficiencies evolved by changes in the volume of wall material used for growth and in how that material was partitioned between lateral and length dimensions. The economics of pollen tube growth are determined by tube design, which is consequent on trade-offs between efficient growth and other pollen tube functions.
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Affiliation(s)
- Joseph H Williams
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996 USA
| | - Jacob A Edwards
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996 USA
| | - Adam J Ramsey
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996 USA
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Swanson RJ, Hammond AT, Carlson AL, Gong H, Donovan TK. Pollen performance traits reveal prezygotic nonrandom mating and interference competition in Arabidopsis thaliana. AMERICAN JOURNAL OF BOTANY 2016; 103:498-513. [PMID: 26928008 DOI: 10.3732/ajb.1500172] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 10/01/2015] [Indexed: 06/05/2023]
Abstract
PREMISE The lack of ability to measure pollen performance traits in mixed pollinations has been a major hurdle in understanding the mechanisms of differential success of compatible pollen donors. In previous work, we demonstrated that nonrandom mating between two accessions of Arabidopsis thaliana, Columbia (Col) and Landsberg (Ler), is mediated by the male genotype. Despite these genetic insights, it was unclear at what stage of reproduction these genes were acting. Here, we used an experimental strategy that allowed us to differentiate different pollen populations in mixed pollinations to ask: (1) What pollen performance traits differed between Col and Ler accessions that direct nonrandom mating? (2) Is there evidence of interference competition? METHODS We used genetically marked pollen that can be visualized colorimetrically to quantify pollen performance of single populations of pollen in mixed pollinations. We used this and other assays to measure pollen viability, germination, tube growth, patterns of fertilization, and seed abortion. Finally, we assessed interference competition. RESULTS In mixed pollinations on Col pistils, Col pollen sired significantly more seeds than Ler pollen. Col pollen displayed higher pollen viability, faster and greater pollen germination, and faster pollen tube growth. We saw no evidence of nonrandom seed abortion. Finally, we found interference competition occurs in mixed pollinations. CONCLUSION The lack of differences in postzygotic processes coupled with direct observation of pollen performance traits indicates that nonrandom mating in Arabidopsis thaliana is prezygotic, due mostly to differential pollen germination and pollen tube growth rates. Finally, this study unambiguously demonstrates the existence of interference competition.
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Affiliation(s)
- Robert J Swanson
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 USA
| | - Adam T Hammond
- Biophysical Sciences, The University of Chicago, Chicago, Illinois 60637 USA
| | - Ann L Carlson
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 USA
| | - Hui Gong
- Department of Mathematics and Computer Science, Valparaiso University, Valparaiso, Indiana 46383 USA
| | - Thad K Donovan
- Smith Donovan Marketing & Communications, Chesterton, Indiana 46304 USA
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16
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Husband BC. Effect of inbreeding on pollen tube growth in diploid and tetraploid Chamerion angustifolium: Do polyploids mask mutational load in pollen? AMERICAN JOURNAL OF BOTANY 2016; 103:532-40. [PMID: 26944354 DOI: 10.3732/ajb.1500243] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 10/21/2015] [Indexed: 05/16/2023]
Abstract
PREMISE OF THE STUDY Deleterious recessive mutations are an important determinant of fitness (mutational load) in the sporophytic phase of plants and a major cause of inbreeding depression; however, their role in gametophyte function is less well documented but may account for variation in pollen tube growth and siring ability, especially between diploid and polyploid plants, which can mask the load. METHODS We investigated the role of mutational load in pollen performance using the perennial polyploid Chamerion angustifolium by comparing tube growth of pollen, in styles and in growth medium, from inbred (selfed) and outbred diploids to that of inbred and outbred tetraploids. Pollen from tetraploids is expected to mask deleterious mutations more effectively in the outbred condition but reveal them after inbreeding. In contrast, gametophytes from diploids should express the same genetic load in inbred or outbred plants. KEY RESULTS Pollen tube growth measured in growth medium was highest in outbred tetraploids and generally lower in inbred than outbred plants. The effect of selfing was significant in pollen from tetraploids but not diploids. The differential effect of selfing was also evident in the proportion of pollen reaching the base of styles, but the ploidy × pollination interaction was not significant. Selfing also had a negative effect on sporophyte fitness but was greater in diploids than tetraploids. CONCLUSIONS Pollen performance is influenced by the expression of mutational load, which is masked in polyploids. This effect may partly explain strong siring success of tetraploids in this species.
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Affiliation(s)
- Brian C Husband
- Department of Integrative Biology, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1 Canada
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17
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Hedhly A, Wünsch A, Kartal Ö, Herrero M, Hormaza JI. Paternal-specific S-allele transmission in sweet cherry (Prunus avium L.): the potential for sexual selection. J Evol Biol 2016; 29:490-501. [PMID: 26559165 DOI: 10.1111/jeb.12790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/30/2015] [Accepted: 11/03/2015] [Indexed: 11/27/2022]
Abstract
Homomorphic self-incompatibility is a well-studied example of a physiological process that is thought to increase population diversity and reduce the expression of inbreeding depression. Whereas theoretical models predict the presence of a large number of S-haplotypes with equal frequencies at equilibrium, unequal allele frequencies have been repeatedly reported and attributed to sampling effects, population structure, demographic perturbation, sheltered deleterious mutations or selection pressure on linked genes. However, it is unclear to what extent unequal segregations are the results of gametophytic or sexual selection. Although these two forces are difficult to disentangle, testing S-alleles in the offspring of controlled crosses provides an opportunity to separate these two phenomena. In this work, segregation and transmission of S-alleles have been characterized in progenies of mixed donors and fully compatible pollinations under field conditions in Prunus avium. Seed set patterns and pollen performance have also been characterized. The results reveal paternal-specific distorted transmission of S-alleles in most of the crosses. Interestingly, S-allele segregation within any given paternal or maternal S-locus was random. Observations on pollen germination, pollen tube growth rate, pollen tube cohort size, seed set dynamics and transmission patterns strongly suggest post-pollination, prezygotic sexual selection, with male-male competition as the most likely mechanism. According to these results, post-pollination sexual selection takes precedence over frequency-dependent selection in explaining unequal S-haplotype frequencies.
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Affiliation(s)
- A Hedhly
- Institute of Plant Biology, University of Zurich, Zurich, Switzerland
| | - A Wünsch
- Centro de Investigación y Tecnología Agroalimentaria (CITA), Instituto Agroalimentario de Aragón - IA2 (CITA-Universidad de Zaragoza), Zaragoza, Spain
| | - Ö Kartal
- Institute of Plant Biology, University of Zurich, Zurich, Switzerland
| | - M Herrero
- Estación Experimental de Aula Dei, CSIC, Zaragoza, Spain
| | - J I Hormaza
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM La Mayora - CSIC - UMA), Algarrobo-Costa, Málaga, Spain
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18
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Cannon CH, Lerdau M. Variable mating behaviors and the maintenance of tropical biodiversity. Front Genet 2015; 6:183. [PMID: 26042148 PMCID: PMC4437050 DOI: 10.3389/fgene.2015.00183] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 04/30/2015] [Indexed: 12/25/2022] Open
Abstract
Current theoretical studies on mechanisms promoting species co-existence in diverse communities assume that species are fixed in their mating behavior. Each species is a discrete evolutionary unit, even though most empirical evidence indicates that inter-specific gene flow occurs in plant and animal groups. Here, in a data-driven meta-community model of species co-existence, we allow mating behavior to respond to local species composition and abundance. While individuals primarily out-cross, species maintain a diminished capacity for selfing and hybridization. Mate choice is treated as a variable behavior, which responds to intrinsic traits determining mate choice and the density and availability of sympatric inter-fertile individuals. When mate choice is strongly limited, even low survivorship of selfed offspring can prevent extinction of rare species. With increasing mate choice, low hybridization success rates maintain community level diversity for extended periods of time. In high diversity tropical tree communities, competition among sympatric congeneric species is negligible, because direct spatial proximity with close relatives is infrequent. Therefore, the genomic donorship presents little cost. By incorporating variable mating behavior into evolutionary models of diversification, we also discuss how participation in a syngameon may be selectively advantageous. We view this behavior as a genomic mutualism, where maintenance of genomic structure and diminished inter-fertility, allows each species in the syngameon to benefit from a greater effective population size during episodes of selective disadvantage. Rare species would play a particularly important role in these syngameons as they are more likely to produce heterospecific crosses and transgressive phenotypes. We propose that inter-specific gene flow can play a critical role by allowing genomic mutualists to avoid extinction and gain local adaptations.
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Affiliation(s)
- Charles H. Cannon
- Key Lab in Tropical Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, China
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Manuel Lerdau
- Key Lab in Tropical Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, China
- Departments of Environmental Sciences and Biology, University of Virginia, Charlottesville, VA, USA
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Liu J, Zhang H, Cheng Y, Kafkas S, Güney M. Pistillate flower development and pollen tube growth mode during the delayed fertilization stage in Corylus heterophylla Fisch. PLANT REPRODUCTION 2014; 27:145-52. [PMID: 25073757 DOI: 10.1007/s00497-014-0248-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 07/16/2014] [Indexed: 05/04/2023]
Abstract
Unlike most angiosperms, in which fertilization occurs within several days after pollination, fertilization in hazel (Corylus Spp.) is delayed by two to three and a half months. However, the female inflorescences or young fruits are too hard or lignified to be dissected according to regular paraffin sectioning technique. So, what the nature of development during the extended progamic phases of hazel remains unknown. The female inflorescence development and pollen tube growth mode during the delayed fertilization stage in hazel were investigated by improved paraffin sectioning and aniline blue staining of pollen tubes. The results showed ovaries and ovules of hazel were invisible at the time of blooming. Early ovary and ovule primordium began to form from 15 to 20 days after blooming, respectively. Integument and mature embryo sacs differentiated from the nucellus on 40th and 55th day after blooming, respectively. Pollen tubes were retarded in the bottom of the style or the pollen tube cavity (PTC, a specifical lignified cavity structure at the bottom of style for pollen tube to rest during progamic phase) for about 26 days. Then, the pollen tubes were observed to leave the PTC and began to enter the ovary. After that, a single pollen tube passed through the vicinity of the micropyle. Finally, pollen tubes turned a corner and penetrated the embryo sac through the tissue of the chalaza instead of micropyle on 52 and 55 days after blooming, respectively. The results of more in-depth information will be beneficial to better understanding of the delayed fertilization process in hazel.
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Affiliation(s)
- Jianfeng Liu
- College of Life Sciences, Jilin Normal University, Siping, 136000, Jilin Province, China,
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20
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Ferradás Y, López M, Rey M, González MV. Programmed cell death in kiwifruit stigmatic arms and its relationship to the effective pollination period and the progamic phase. ANNALS OF BOTANY 2014; 114:35-45. [PMID: 24782437 PMCID: PMC4071096 DOI: 10.1093/aob/mcu073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
BACKGROUND AND AIMS Kiwifruit is a crop with a highly successful reproductive performance, which is impaired by the short effective pollination period of female flowers. This study investigates whether the degenerative processes observed in both pollinated and non-pollinated flowers after anthesis may be considered to be programmed cell death (PCD). METHODS Features of PCD in kiwifruit, Actinidia chinensis var. deliciosa, were studied in both non-pollinated and pollinated stigmatic arms using transmission electron microscopy, DAPI (4',6-diamidino-2-phenylindole) staining, TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling) assays, DNA gel electrophoresis and caspase-like activity assays. KEY RESULTS In the secretory tissues of the stigmatic arms, cell organelles disintegrated sequentially while progressive vacuolization was detected. At the same time, chromatin condensation, nuclear deformation, and DNA fragmentation and degradation were observed. These features were detected in both non-pollinated and pollinated stigmatic arms; they were evident in the stigmas of pollinated flowers by the second day after anthesis but only by 4 d after anthesis in non-pollinated flowers. In addition, in pollinated stigmatic arms, these features were first initiated in the stigma and gradually progressed through the style, consistent with pollen tube growth. This timing of events was also observed in both non-pollinated and pollinated stigmatic arms for caspase-3-like activity. CONCLUSIONS The data provide evidence to support the hypothesis that PCD processes occurring in the secretory tissue of non-pollinated kiwifruit stigmatic arms could be the origin for the observed short effective pollination period. The results obtained in the secretory tissue of pollinated kiwifruit stigmatic arms upon pollination support the idea that PCD might be accelerated by pollination, pointing to the involvement of PCD during the progamic phase.
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Affiliation(s)
- Yolanda Ferradás
- Departamento de Fisiología Vegetal, Facultad de Farmacia, Universidad de Santiago, Campus Sur, 15872 Santiago de Compostela, Spain
| | - Marián López
- Departamento de Fisiología Vegetal, Facultad de Farmacia, Universidad de Santiago, Campus Sur, 15872 Santiago de Compostela, Spain
| | - Manuel Rey
- Departamento de Biología Vegetal y Ciencia del Suelo, Facultad de Biología, Universidad de Vigo, 36310 Vigo, Spain
| | - Ma Victoria González
- Departamento de Fisiología Vegetal, Facultad de Farmacia, Universidad de Santiago, Campus Sur, 15872 Santiago de Compostela, Spain
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Fitz Gerald JN, Carlson AL, Smith E, Maloof JN, Weigel D, Chory J, Borevitz JO, Swanson RJ. New Arabidopsis advanced intercross recombinant inbred lines reveal female control of nonrandom mating. PLANT PHYSIOLOGY 2014; 165:175-85. [PMID: 24623850 PMCID: PMC4012578 DOI: 10.1104/pp.113.233213] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 02/28/2014] [Indexed: 05/23/2023]
Abstract
Female control of nonrandom mating has never been genetically established, despite being linked to inbreeding depression and sexual selection. In order to map the loci that control female-mediated nonrandom mating, we constructed a new advanced intercross recombinant inbred line (RIL) population derived from a cross between Arabidopsis (Arabidopsis thaliana) accessions Vancouver (Van-0) and Columbia (Col-0) and mapped quantitative trait loci (QTLs) responsible for nonrandom mating and seed yield traits. We genotyped a population of 490 RILs. A subset of these lines was used to construct an expanded map of 1,061.4 centimorgans with an average interval of 6.7±5.3 centimorgans between markers. QTLs were then mapped for female- and male-mediated nonrandom mating and seed yield traits. To map the genetic loci responsible for female-mediated nonrandom mating and seed yield, we performed mixed pollinations with genetically marked Col-0 pollen and Van-0 pollen on RIL pistils. To map the loci responsible for male-mediated nonrandom mating and seed yield, we performed mixed pollinations with genetically marked Col-0 and RIL pollen on Van-0 pistils. Composite interval mapping of these data identified four QTLs that control female-mediated nonrandom mating and five QTLs that control female-mediated seed yield. We also identified four QTLs that control male-mediated nonrandom mating and three QTLs that control male-mediated seed yield. Epistasis analysis indicates that several of these loci interact. To our knowledge, the results of these experiments represent the first time female-mediated nonrandom mating has been genetically defined.
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Affiliation(s)
- Jonathan Nesbit Fitz Gerald
- Department of Biology, Rhodes College, Memphis, Tennessee 38112 (J.N.F.G.)
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 (A.L.C., R.J.S.)
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637 (E.S., J.O.B.)
- Department of Plant Biology, Salk Institute, San Diego, California 92037 (J.N.M., D.W., J.C., J.O.B.)
- Department of Plant Biology, University of California, Davis, California 95616 (J.N.M.)
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (D.W.); and
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (J.O.B.)
| | - Ann Louise Carlson
- Department of Biology, Rhodes College, Memphis, Tennessee 38112 (J.N.F.G.)
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 (A.L.C., R.J.S.)
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637 (E.S., J.O.B.)
- Department of Plant Biology, Salk Institute, San Diego, California 92037 (J.N.M., D.W., J.C., J.O.B.)
- Department of Plant Biology, University of California, Davis, California 95616 (J.N.M.)
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (D.W.); and
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (J.O.B.)
| | - Evadne Smith
- Department of Biology, Rhodes College, Memphis, Tennessee 38112 (J.N.F.G.)
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 (A.L.C., R.J.S.)
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637 (E.S., J.O.B.)
- Department of Plant Biology, Salk Institute, San Diego, California 92037 (J.N.M., D.W., J.C., J.O.B.)
- Department of Plant Biology, University of California, Davis, California 95616 (J.N.M.)
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (D.W.); and
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (J.O.B.)
| | - Julin N. Maloof
- Department of Biology, Rhodes College, Memphis, Tennessee 38112 (J.N.F.G.)
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 (A.L.C., R.J.S.)
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637 (E.S., J.O.B.)
- Department of Plant Biology, Salk Institute, San Diego, California 92037 (J.N.M., D.W., J.C., J.O.B.)
- Department of Plant Biology, University of California, Davis, California 95616 (J.N.M.)
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (D.W.); and
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (J.O.B.)
| | - Detlef Weigel
- Department of Biology, Rhodes College, Memphis, Tennessee 38112 (J.N.F.G.)
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 (A.L.C., R.J.S.)
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637 (E.S., J.O.B.)
- Department of Plant Biology, Salk Institute, San Diego, California 92037 (J.N.M., D.W., J.C., J.O.B.)
- Department of Plant Biology, University of California, Davis, California 95616 (J.N.M.)
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (D.W.); and
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (J.O.B.)
| | - Joanne Chory
- Department of Biology, Rhodes College, Memphis, Tennessee 38112 (J.N.F.G.)
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 (A.L.C., R.J.S.)
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637 (E.S., J.O.B.)
- Department of Plant Biology, Salk Institute, San Diego, California 92037 (J.N.M., D.W., J.C., J.O.B.)
- Department of Plant Biology, University of California, Davis, California 95616 (J.N.M.)
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (D.W.); and
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (J.O.B.)
| | - Justin O. Borevitz
- Department of Biology, Rhodes College, Memphis, Tennessee 38112 (J.N.F.G.)
- Department of Biology, Valparaiso University, Valparaiso, Indiana 46383 (A.L.C., R.J.S.)
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637 (E.S., J.O.B.)
- Department of Plant Biology, Salk Institute, San Diego, California 92037 (J.N.M., D.W., J.C., J.O.B.)
- Department of Plant Biology, University of California, Davis, California 95616 (J.N.M.)
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany (D.W.); and
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (J.O.B.)
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Losada JM, Herrero M. Glycoprotein composition along the pistil of Malus x domestica and the modulation of pollen tube growth. BMC PLANT BIOLOGY 2014; 14:1. [PMID: 25316555 PMCID: PMC3890559 DOI: 10.1186/1471-2229-14-1] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 12/20/2013] [Indexed: 05/17/2023]
Abstract
BACKGROUND The characteristics of pollen tube growth are not constant, but display distinct patterns of growth within the different tissues of the pistil. In the stigma, the growth rate is slow and autotrophic, whereas in the style, it is rapid and heterotrophic. Very little is known about the interactions between these distinct maternal tissues and the traversing pollen tube and the role of this interaction on the observed metabolism. In this work we characterise pollen tube growth in the apple flower and look for differences in glycoprotein epitope localization between two different maternal tissues, the stigma and the style. RESULTS While immunocytochemically-detected arabinogalactan proteins were present at high levels in the stigma, they were not detected in the transmitting tissue of the style, where extensins were abundant. Whereas extensins remained at high levels in unpollinated pistils, they were no longer present in the style following pollen tube passage. Similarily, while abundant in unpollinated styles, insoluble polysaccharides such as β-glucans, were depleted in pollinated pistils. CONCLUSIONS The switch from autotropic to heterotrophic pollen tube growth correlates spatially with a change of glycoprotein epitopes between the stigma and the style. The depletion of extensins and polysaccharides following pollen tube passage in the style suggest a possible contribution to the acceleration of heterotrophic pollen tube growth, which would imply an active contribution of female tissues on prezygotic male-female crosstalk.
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Affiliation(s)
- Juan M Losada
- Pomology Department, Aula Dei Experimental Station CSIC, Apdo 13034, 50080 Zaragoza, Spain
- Present address: Arnold Arboretum of Harvard University, 1300 Centre Street, 02131 Boston, MA, USA
| | - Maria Herrero
- Pomology Department, Aula Dei Experimental Station CSIC, Apdo 13034, 50080 Zaragoza, Spain
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Carlson AL, Gong H, Toomajian C, Swanson RJ. Parental genetic distance and patterns in nonrandom mating and seed yield in predominately selfing Arabidopsis thaliana. PLANT REPRODUCTION 2013; 26:317-28. [PMID: 23843176 PMCID: PMC3825607 DOI: 10.1007/s00497-013-0228-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/03/2013] [Indexed: 05/09/2023]
Abstract
In this study, we ask two questions: (1) Is reproductive success independent of parental genetic distance in predominately selfing plants? (2) In the absence of early inbreeding depression, is there substantial maternal and/or paternal variation in reproductive success in natural populations? Seed yield in single pollinations and proportion of seeds sired in mixed pollinations were studied in genetically defined accessions of the predominately selfing plant Arabidopsis thaliana by conducting two diallel crosses. The first diallel was a standard, single pollination design that we used to examine variance in seed yield. The second diallel was a mixed pollination design that utilized a standard pollen competitor to examine variance in proportion of seeds sired. We found no correlation between reproductive success and parental genetic distance, and self-pollen does not systematically differ in reproductive success compared to outcross pollen, suggesting that Arabidopsis populations do not experience embryo lethality due to early-acting inbreeding or outbreeding depression. We used these data to partition the contributions to total phenotypic variation from six sources, including maternal contributions, paternal contributions and parental interactions. For seed yield in single pollinations, maternal effects accounted for the most significant source of variance (16.6 %). For proportion of seeds sired in mixed pollinations, the most significant source of variance was paternal effects (17.9 %). Thus, we show that population-level genetic similarities, including selfing, do not correlate with reproductive success, yet there is still significant paternal variance under competition. This suggests two things. First, since these differences are unlikely due to early-acting inbreeding depression or differential pollen viability, this implicates natural variation in pollen germination and tube growth dynamics. Second, this strongly supports a model of fixation of pollen performance genes in populations, offering a focus for future genetic studies in differential reproductive success.
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Affiliation(s)
- Ann L. Carlson
- Department of Biology, Valparaiso University, Valparaiso, IN 46383 USA
| | - Hui Gong
- Department of Mathematics and Computer Science, Valparaiso University, Valparaiso, IN 46383 USA
| | | | - Robert J. Swanson
- Department of Biology, Valparaiso University, Valparaiso, IN 46383 USA
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Sonnleitner M, Weis B, Flatscher R, García PE, Suda J, Krejčíková J, Schneeweiss GM, Winkler M, Schönswetter P, Hülber K. Parental ploidy strongly affects offspring fitness in heteroploid crosses among three cytotypes of autopolyploid Jacobaea carniolica (Asteraceae). PLoS One 2013; 8:e78959. [PMID: 24265735 PMCID: PMC3827125 DOI: 10.1371/journal.pone.0078959] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 09/17/2013] [Indexed: 11/25/2022] Open
Abstract
Reproductive interactions among cytotypes in their contact zones determine whether these cytotypes can co-exist and form stable contact zones or not. In autopolyploids, heteroploid cross-compatibilities might depend on parental ploidy, but tests of this hypothesis in autopolyploid systems with more than two ploidies are lacking. Here, we study Jacobaea carniolica, which comprises diploid, tetraploid, and hexaploid individuals regularly forming contact zones. Seeds obtained from in situ cross-pollinations within and among cytotypes were subjected to DNA flow cytometry and greenhouse germination experiments. Hybrid fitness and parental effects on hybrid fitness were tested with regression models comparing fitness parameters of early life stages. Irrespective of the direction of crosses, seed viability and seedling survival in diploid-polyploid crosses were substantially lower than in tetraploid-hexaploid crosses. In contrast, seedling growth traits indicated neither transgressive character expression nor any selection against hybrid offspring. Congruent with a model of genome dosage effects, these traits differed between reciprocal crosses, especially of diploids and tetraploids, where trait values resembled those of the maternal parent. The strong effect of parental ploidy on offspring fitness in heteroploid crosses may cause contact zones involving exclusively polyploid cytotypes to be less stable over longer terms than those involving diploids and polyploids.
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Affiliation(s)
- Michaela Sonnleitner
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria
- Department of Conservation Biology, Vegetation Ecology and Landscape Ecology, University of Vienna, Vienna, Austria
| | - Birgit Weis
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria
| | - Ruth Flatscher
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria
- Institute of Botany, University of Innsbruck, Innsbruck, Austria
| | - Pedro Escobar García
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria
| | - Jan Suda
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic
- Institute of Botany, Academy of Sciences of the Czech Republic, Průhonice, Czech Republic
| | - Jana Krejčíková
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic
- Institute of Botany, Academy of Sciences of the Czech Republic, Průhonice, Czech Republic
| | - Gerald M. Schneeweiss
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria
| | - Manuela Winkler
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria
| | | | - Karl Hülber
- Department of Conservation Biology, Vegetation Ecology and Landscape Ecology, University of Vienna, Vienna, Austria
- Vienna Institute for Nature Conservation & Analyses, Vienna, Austria
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25
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Abadie P, Roussel G, Dencausse B, Bonnet C, Bertocchi E, Louvet JM, Kremer A, Garnier-Géré P. Strength, diversity and plasticity of postmating reproductive barriers between two hybridizing oak species (Quercus robur L. and Quercus petraea (Matt) Liebl.). J Evol Biol 2011; 25:157-73. [PMID: 22092648 DOI: 10.1111/j.1420-9101.2011.02414.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Very little is known about the nature and strength of reproductive isolation (RI) in Quercus species, despite extensive research on the estimation and evolutionary significance of hybridization rates. We characterized postmating pre- and postzygotic RI between two hybridizing oak species, Quercus robur and Quercus petraea, using a large set of controlled crosses between different genotypes. Various traits potentially associated with reproductive barriers were quantified at several life history stages, from pollen-pistil interactions to seed set and progeny fitness-related traits. Results indicate strong intrinsic postmating prezygotic barriers, with significant barriers also at the postzygotic level, but relatively weaker extrinsic barriers on early hybrid fitness measures assessed in controlled conditions. Using general linear modelling of common garden data with clonal replicates, we showed that most traits exhibited important genotypic differences, as well as different levels of sensitivity to micro-environmental heterogeneity. These new findings suggest a large potential genetic diversity and plasticity of reproductive barriers and are confronted with hybridization evidence in these oak species.
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Affiliation(s)
- P Abadie
- INRA, UMR 1202 BIOGECO, 69 route d'Arcachon, F-33612 Cestas, France
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Pons E, Navarro A, Ollitrault P, Peña L. Pollen competition as a reproductive isolation barrier represses transgene flow between compatible and co-flowering citrus genotypes. PLoS One 2011; 6:e25810. [PMID: 21991359 PMCID: PMC3185051 DOI: 10.1371/journal.pone.0025810] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 09/11/2011] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND/OBJECTIVE Despite potential benefits granted by genetically modified (GM) fruit trees, their release and commercialization raises concerns about their potential environmental impact, and the transfer via pollen of transgenes to cross-compatible cultivars is deemed to be the greatest source for environmental exposure. Information compiled from field trials on GM trees is essential to propose measures to minimize the transgene dispersal. We have conducted a field trial of seven consecutive years to investigate the maximum frequency of pollen-mediated crop-to-crop transgene flow in a citrus orchard, and its relation to the genetic, phenological and environmental factors involved. METHODOLOGY/PRINCIPAL FINDINGS Three different citrus genotypes carrying the uidA (GUS) tracer marker gene (pollen donors) and a non-GM self-incompatible contiguous citrus genotype (recipient) were used in conditions allowing natural entomophilous pollination to occur. The examination of 603 to 2990 seeds per year showed unexpectedly low frequencies (0.17-2.86%) of transgene flow. Paternity analyses of the progeny of subsets of recipient plants using 10 microsatellite (SSR) loci demonstrated a higher mating competence of trees from another non-GM pollen source population that greatly limited the mating chance of the contiguous cross-compatible and flowering-synchronized transgenic pollen source. This mating superiority could be explained by a much higher pollen competition capacity of the non-GM genotypes, as was confirmed through mixed-hand pollinations. CONCLUSIONS/SIGNIFICANCE Pollen competition strongly contributed to transgene confinement. Based on this finding, suitable isolation measures are proposed for the first time to prevent transgene outflow between contiguous plantings of citrus types that may be extendible to other entomophilous transgenic fruit tree species.
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Affiliation(s)
- Elsa Pons
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, Valencia, Spain
| | - Antonio Navarro
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, Valencia, Spain
| | - Patrick Ollitrault
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, Valencia, Spain
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), UPR Amélioration Génétique des Espèces à Multiplication Végétative, Montpellier, France
| | - Leandro Peña
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, Valencia, Spain
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Julian C, Rodrigo J, Herrero M. Stamen development and winter dormancy in apricot (Prunus armeniaca). ANNALS OF BOTANY 2011; 108:617-25. [PMID: 21474504 PMCID: PMC3170150 DOI: 10.1093/aob/mcr056] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 02/01/2011] [Indexed: 05/19/2023]
Abstract
BACKGROUND AND AIMS In temperate woody perennials, flower bud development is halted during the winter, when the buds enter dormancy. This dormant period is a prerequisite for adequate flowering, is genetically regulated, and plays a clear role in possibly adapting species and cultivars to climatic areas. However, information on the biological events underpinning dormancy is lacking. Stamen development, with clear differentiated stages, appears as a good framework to put dormancy in a developmental context. Here, stamen developmental changes are characterized in apricot (Prunus armeniaca) and are related to dormancy. METHODS Stamen development was characterized cytochemically from the end of August to March, over 4 years. Developmental changes were related to dormancy, using the existing empirical information on chilling requirements. KEY RESULTS Stamen development continued during the autumn, and the flower buds entered dormancy with a fully developed sporogenous tissue. Although no anatomical changes were observed during dormancy, breaking of dormancy occurred following a clear sequence of events. Starch accumulated in particular places, pre-empting further development in those areas. Vascular bundles developed and pollen mother cells underwent meiosis followed by microspore development. CONCLUSIONS Dormancy appears to mark a boundary between the development of the sporogenous tissue and the occurrence of meiosis for further microspore development. Breaking of dormancy occurs following a clear sequence of events, providing a developmental context in which to study winter dormancy and to evaluate differences in chilling requirements among genotypes.
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Affiliation(s)
- C. Julian
- Unidad de Fruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Av. Montañana 930, 50059 Zaragoza, Spain
- Departamento de Pomología, EEAD-CSIC, Av. Montañana 1005, 50059 Zaragoza, Spain
| | - J. Rodrigo
- Unidad de Fruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Av. Montañana 930, 50059 Zaragoza, Spain
| | - M. Herrero
- Departamento de Pomología, EEAD-CSIC, Av. Montañana 1005, 50059 Zaragoza, Spain
- For correspondence. E-mail
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Baldwin SJ, Husband BC. Genome duplication and the evolution of conspecific pollen precedence. Proc Biol Sci 2011; 278:2011-7. [PMID: 21123263 PMCID: PMC3107648 DOI: 10.1098/rspb.2010.2208] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 11/08/2010] [Indexed: 11/12/2022] Open
Abstract
Conspecific pollen precedence can be a strong reproductive barrier between polyploid and diploid species, but the role of genome multiplication in the evolution of this barrier has not been investigated. Here, we examine the direct effect of genome duplication on the evolution of pollen siring success in tetraploid Chamerion angustifolium. To separate the effects of genome duplication from selection after duplication, we compared pollen siring success of synthesized tetraploids (neotetraploids) with that of naturally occurring tetraploids by applying 2x, 4x (neo or established) or 2x + 4x pollen to diploid and tetraploid flowers. Seed set increased in diploids and decreased in both types of tetraploids as the proportion of pollen from diploid plants increased. Based on offspring ploidy from mixed-ploidy pollinations, pollen of the maternal ploidy always sired the majority of offspring but was strongest in established tetraploids and weakest in neotetraploids. Pollen from established tetraploids had significantly higher siring rates than neotetraploids when deposited on diploid (4x(est) = 47.2%, 4x(neo) = 27.1%) and on tetraploid recipients (4x(est) = 91.9%, 4x(neo) = 56.0%). Siring success of established tetraploids exceeded that of neotetraploids despite having similar pollen production per anther and pollen diameter. Our results suggest that, while pollen precedence can arise in association with the duplication event, the strength of polyploid siring success evolves after the duplication event.
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Affiliation(s)
- Sarah J Baldwin
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
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Lora J, Herrero M, Hormaza JI. Stigmatic receptivity in a dichogamous early-divergent angiosperm species, Annona cherimola (Annonaceae): influence of temperature and humidity. AMERICAN JOURNAL OF BOTANY 2011; 98:265-74. [PMID: 21613115 DOI: 10.3732/ajb.1000185] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
PREMISE OF THE STUDY A variety of mechanisms to prevent inbreeding have arisen in different angiosperm taxa during plant evolution. In early-divergent angiosperms, a widespread system is dichogamy, in which female and male structures do not mature simultaneously, thus encouraging cross pollination. While this system is common in early-divergent angiosperms, it is less widespread in more recently evolved clades. An evaluation of the consequences of this system on outbreeding may provide clues on this change, but this subject has been little explored. METHODS In this work, we characterized the cycle and anatomy of the flower and studied the influence of temperature and humidity on stigmatic receptivity in Annona cherimola, a member of an early-divergent angiosperm clade with protogynous dichogamy. KEY RESULTS Paternity analysis reveals a high proportion of seeds resulting from self-fertilization, indicating that self-pollination can occur in spite of the dichogamous system. Stigmatic receptivity is environmentally modulated--shortened by high temperatures and prolonged by high humidity. CONCLUSIONS Although spatial and temporal sexual separation in this system seems to effectively decrease selfing, the system is modulated by environmental conditions and may allow high levels of selfing that can guarantee reproductive assurance.
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Affiliation(s)
- Jorge Lora
- Department of Subtropical Pomology, Instituto de Hortofruticultura Subtropical y Mediterránea la Mayora (IHSM la Mayora-CSIC), 29750 Algarrobo-Costa, Málaga, Spain
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Lora J, Hormaza JI, Herrero M. The progamic phase of an early-divergent angiosperm, Annona cherimola (Annonaceae). ANNALS OF BOTANY 2010; 105:221-31. [PMID: 19939980 PMCID: PMC2814751 DOI: 10.1093/aob/mcp276] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 08/05/2009] [Accepted: 10/12/2009] [Indexed: 05/21/2023]
Abstract
BACKGROUND AND AIMS Recent studies of reproductive biology in ancient angiosperm lineages are beginning to shed light on the early evolution of flowering plants, but comparative studies are restricted by fragmented and meagre species representation in these angiosperm clades. In the present study, the progamic phase, from pollination to fertilization, is characterized in Annona cherimola, which is a member of the Annonaceae, the largest extant family among early-divergent angiosperms. Beside interest due to its phylogenetic position, this species is also an ancient crop with a clear niche for expansion in subtropical climates. METHODS The kinetics of the reproductive process was established following controlled pollinations and sequential fixation. Gynoecium anatomy, pollen tube pathway, embryo sac and early post-fertilization events were characterized histochemically. KEY RESULTS A plesiomorphic gynoecium with a semi-open carpel shows a continuous secretory papillar surface along the carpel margins, which run from the stigma down to the obturator in the ovary. The pollen grains germinate in the stigma and compete in the stigma-style interface to reach the narrow secretory area that lines the margins of the semi-open stylar canal and is able to host just one to three pollen tubes. The embryo sac has eight nuclei and is well provisioned with large starch grains that are used during early cellular endosperm development. CONCLUSIONS A plesiomorphic simple gynoecium hosts a simple pollen-pistil interaction, based on a support-control system of pollen tube growth. Support is provided through basipetal secretory activity in the cells that line the pollen tube pathway. Spatial constraints, favouring pollen tube competition, are mediated by a dramatic reduction in the secretory surface available for pollen tube growth at the stigma-style interface. This extramural pollen tube competition contrasts with the intrastylar competition predominant in more recently derived lineages of angiosperms.
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Affiliation(s)
- J. Lora
- Department of Subtropical Pomology, Estación Experimental “La Mayora” – CSIC, 29760 Algarrobo-Costa, Málaga, Spain
| | - J. I. Hormaza
- Department of Subtropical Pomology, Estación Experimental “La Mayora” – CSIC, 29760 Algarrobo-Costa, Málaga, Spain
| | - M. Herrero
- Department of Pomology, Estación Experimental “Aula Dei” – CSIC, Apdo. 202, 50080 Zaragoza, Spain
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Lora J, Testillano PS, Risueño MC, Hormaza JI, Herrero M. Pollen development in Annona cherimola Mill. (Annonaceae). Implications for the evolution of aggregated pollen. BMC PLANT BIOLOGY 2009; 9:129. [PMID: 19874617 PMCID: PMC2774696 DOI: 10.1186/1471-2229-9-129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 10/29/2009] [Indexed: 05/07/2023]
Abstract
BACKGROUND In most flowering plants, pollen is dispersed as monads. However, aggregated pollen shedding in groups of four or more pollen grains has arisen independently several times during angiosperm evolution. The reasons behind this phenomenon are largely unknown. In this study, we followed pollen development in Annona cherimola, a basal angiosperm species that releases pollen in groups of four, to investigate how pollen ontogeny may explain the rise and establishment of this character. We followed pollen development using immunolocalization and cytochemical characterization of changes occurring from anther differentiation to pollen dehiscence. RESULTS Our results show that, following tetrad formation, a delay in the dissolution of the pollen mother cell wall and tapetal chamber is a key event that holds the four microspores together in a confined tapetal chamber, allowing them to rotate and then bind through the aperture sites through small pectin bridges, followed by joint sporopollenin deposition. CONCLUSION Pollen grouping could be the result of relatively minor ontogenetic changes beneficial for pollen transfer or/and protection from desiccation. Comparison of these events with those recorded in the recent pollen developmental mutants in Arabidopsis indicates that several failures during tetrad dissolution may convert to a common recurring phenotype that has evolved independently several times, whenever this grouping conferred advantages for pollen transfer.
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Affiliation(s)
- Jorge Lora
- Estación Experimental "La Mayora", CSIC, 29760 Algarrobo-Costa, Málaga, Spain
| | - Pilar S Testillano
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Maria C Risueño
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Jose I Hormaza
- Estación Experimental "La Mayora", CSIC, 29760 Algarrobo-Costa, Málaga, Spain
| | - Maria Herrero
- Dep. Pomología, Estación Experimental "Aula Dei", CSIC, Apdo. 202/50080 Zaragoza, Spain
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Lora J, Herrero M, Hormaza JI. The coexistence of bicellular and tricellular pollen in Annona cherimola (Annonaceae): Implications for pollen evolution. AMERICAN JOURNAL OF BOTANY 2009; 96:802-808. [PMID: 21628235 DOI: 10.3732/ajb.0800167] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Most angiosperms release bicellular pollen. However, in about one-third of extant angiosperms, the second pollen mitosis occurs before anthesis such that pollen is tricellular upon release. The shift from bicellular to tricellular development has occurred several times independently, but its causes are largely unknown. In this work, we observed the coexistence of both kinds of pollen at anther dehiscence in Annona cherimola, a species that belongs to the basal angiosperm family Annonaceae. Examination of pollen cell number during anther development showed that this coexistence was due to a late mitosis starting shortly before pollen shedding. Both types of pollen germinated equally well over the course of development. Because variable proportions of bicellular and tricellular pollen were observed at different sampling times, we tested the role of temperature by performing field and growth chamber experiments, which showed that higher temperatures near anthesis advanced the time of pollen mitosis II. The results show that selection could favor the production of tricellular pollen under certain environmental circumstances that prime rapid pollen germination and provide evidence of a system in which developmental variation persists, but that can be modified by external factors such as temperature.
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Affiliation(s)
- Jorge Lora
- Estación Experimental "La Mayora", CSIC 29760 Algarrobo-Costa, Málaga, Spain
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Hedhly A, Hormaza JI, Herrero M. Global warming and sexual plant reproduction. TRENDS IN PLANT SCIENCE 2009; 14:30-6. [PMID: 19062328 DOI: 10.1016/j.tplants.2008.11.001] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 10/30/2008] [Accepted: 11/06/2008] [Indexed: 05/19/2023]
Abstract
The sexual reproductive phase in plants might be particularly vulnerable to the effects of global warming. The direct effect of temperature changes on the reproductive process has been documented previously, and recent data from other physiological processes that are affected by rising temperatures seem to reinforce the susceptibility of the reproductive process to a changing climate. But the reproductive phase also provides the plant with an opportunity to adapt to environmental changes. Understanding phenotypic plasticity and gametophyte selection for prevailing temperatures, along with possible epigenetic changes during this process, could provide new insights into plant evolution under a global-warming scenario.
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Affiliation(s)
- Afif Hedhly
- Departamento de Pomología, Estación Experimental de Aula Dei, CSIC, Zaragoza, 50059, Spain; Estación Experimental la Mayora, CSIC, Málaga, 29760, Spain.
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Fishman L, Aagaard J, Tuthill JC. TOWARD THE EVOLUTIONARY GENOMICS OF GAMETOPHYTIC DIVERGENCE: PATTERNS OF TRANSMISSION RATIO DISTORTION IN MONKEYFLOWER (MIMULUS) HYBRIDS REVEAL A COMPLEX GENETIC BASIS FOR CONSPECIFIC POLLEN PRECEDENCE. Evolution 2008; 62:2958-70. [DOI: 10.1111/j.1558-5646.2008.00475.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Schulte F, Lingott J, Panne U, Kneipp J. Chemical Characterization and Classification of Pollen. Anal Chem 2008; 80:9551-6. [DOI: 10.1021/ac801791a] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Franziska Schulte
- Humboldt-Universität zu Berlin, Chemistry Department, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany, and BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, D-12489 Berlin, Germany
| | - Jana Lingott
- Humboldt-Universität zu Berlin, Chemistry Department, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany, and BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, D-12489 Berlin, Germany
| | - Ulrich Panne
- Humboldt-Universität zu Berlin, Chemistry Department, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany, and BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, D-12489 Berlin, Germany
| | - Janina Kneipp
- Humboldt-Universität zu Berlin, Chemistry Department, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany, and BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, D-12489 Berlin, Germany
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Benavente E, Cifuentes M, Dusautoir JC, David J. The use of cytogenetic tools for studies in the crop-to-wild gene transfer scenario. Cytogenet Genome Res 2008; 120:384-95. [PMID: 18504367 DOI: 10.1159/000121087] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2007] [Indexed: 11/19/2022] Open
Abstract
Interspecific hybridization in plants is an important evolutionary phenomenon involved in the dynamics of speciation that receives increasing interest in the context of possible gene escapes from transgenic crop varieties. Crops are able to cross-pollinate with a number of wild related species and exchange chromosome segments through homoeologous recombination. In this paper, we review a set of cytogenetic techniques that are appropriate to document the different steps required for the stable introgression of a chromosome segment from a donor species (i.e., the crop) into a recipient species (i.e., the wild). Several examples in hybrids and derivatives are given to illustrate how these approaches may be used to evaluate the potential for gene transfer between crops and wild relatives. Different techniques, from classical chromosome staining methods to recent developments in molecular cytogenetics, can be used to differentiate genomes and identify the chromosome regions eventually involved in genetic exchanges. Some clues are also given for the study of fertility restoration in the interspecific hybrid forms.
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Affiliation(s)
- E Benavente
- Departamento de Biotecnología, ETS Ingenieros Agrónomos, Universidad Politécnica de Madrid, Spain.
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Lee CB, Page LE, McClure BA, Holtsford TP. Post-pollination hybridization barriers in Nicotiana section Alatae. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s00497-008-0077-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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SOGO AKIKO, TOBE HIROSHI. Mode of pollen-tube growth in Pistils of Myrica rubra (Myricaceae): a comparison with related families. ANNALS OF BOTANY 2006; 97:71-7. [PMID: 16291781 PMCID: PMC2803377 DOI: 10.1093/aob/mcj015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS It is generally known that fertilization is delayed for more than a few weeks after pollination in Fagales. Recent studies showed that, during that period, pollen tubes grew in pistils in close association with the development of the ovule in a five-step process in Casuarina (Casuarinaceae) and a four-step process in Alnus (Betulaceae). The number of pollen tubes was reduced from many to one, a fact suggesting that delayed fertilization plays a role for gametophyte selection. Myrica (Myricaceae) also shows delayed fertilization for >2 weeks after pollination, but nothing is known of how pollen tubes grow in the pistil during that period. METHODS Pollen-tube growth and the development of the ovule in pistils was investigated by fluorescent and scanning electron microscopy and analysis of microtome sections of the pistils. KEY RESULTS Developmental study of the pollen-tube growth in the pistil of M. rubra showed that the tip of the pollen tube was branched or lay in a zigzag pattern in the upper space of the ovarian locule or near the tip of the integument, and subsequently was swollen on the nucellar surface. Such morphological changes indicate that the pollen-tube growth was temporarily arrested before fertilization. The pollen-tube growth in M. rubra can therefore be summarized as occurring in three steps: (1) from the stigma to the ovarian locule; (2) from the ovarian locule to the nucellar surface; and (3) from the nucellar surface to the embryo sac. CONCLUSION Myrica differs from other families in that the pollen tubes arrest their growth on the nucellar surface, probably digesting nutrient from nucellar cells. There is little information on five other families of Fagales. An extensive study is needed to better understand the diversity and function of the mode of pollen-tube growth within the order.
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Baack EJ. Ecological factors influencing tetraploid establishment in snow buttercups (Ranunculus adoneus , Ranunculaceae): minority cytotype exclusion and barriers to triploid formation. AMERICAN JOURNAL OF BOTANY 2005; 92:1827-35. [PMID: 21646100 DOI: 10.3732/ajb.92.11.1827] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Polyploid speciation is an ongoing, important source of angiosperm diversity. However, the barriers to polyploid speciation and mechanisms of establishment remain poorly understood for all but a few species. Several factors likely to have influenced tetraploid establishment, including barriers to triploid formation, consequences of mixed-ploidy pollen loads, and the reproductive success of the minority cytotype, were examined in snow buttercups (Ranunculus adoneus) through a series of pollination and transplant experiments. Tetraploid snow buttercups do not have stigmatic barriers to pollen from diploid plants, nor does pollen from tetraploid plants have an advantage over pollen from diploids when on tetraploid stigmas. Tetraploid plants transplanted into a diploid population produced 50% fewer seeds than tetraploid plants in a tetraploid population. Intrinsic barriers to triploid formation were relatively weak, but few triploid seeds formed when mixed-ploidy pollen was present. Fecundity of triploid plants was very low, and no tetraploid offspring resulted. These results indicate that in snow buttercups, a triploid plant will contribute 0.8% of the tetraploid seeds of a minority tetraploid plant making it a minor contributor to the demographics of tetraploid establishment. The reproductive costs facing minority cytotype plants may explain the previously observed spatial segregation in snow buttercups.
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Affiliation(s)
- Eric J Baack
- Center for Population Biology, One Shields Avenue, University of California, Davis, California 95616 USA
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Palme AE, Su Q, Palsson S, Lascoux M. Extensive sharing of chloroplast haplotypes among European birches indicates hybridization among Betula pendula, B. pubescens and B. nana. Mol Ecol 2004; 13:167-78. [PMID: 14653797 DOI: 10.1046/j.1365-294x.2003.02034.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Extensive sharing of chloroplast haplotypes among the silver birch, Betula pendula Roth., the downy birch, B. pubescens Ehrh., and the dwarf birch, B. nana L., was discovered using polymerase chain reaction-restriction fragment length polymporphism markers. The geographical component of the genetic variation was stronger than the species component: the species were not significantly different while 11% of the variation could be attributed to differentiation between the two main regions studied, Scandinavia and western Russia. All haplotypes occurring in more than 2% of the individuals were shared among the species and the introgression ratios were quite large: 0.79 between B. pubescens and B. pendula and 0.67 between B. pubescens and B. nana. The data also indicate that B. pendula individuals are more similar to sympatric B. pubescens than to B. pendula individuals from nearby forests. However, this trend is not as pronounced when B. pubescens is considered, suggesting that introgression is not symmetrical. The haplotype sharing among the three Betula species is most likely caused by hybridization and subsequent cytoplasmic introgression.
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Affiliation(s)
- A E Palme
- Department of Conservation Biology and Genetics, Evolutionary Biology Centre, Uppsala University Norbyvägen 18 D, 752 36 Uppsala, Sweden
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Husband BC, Schemske DW, Burton TL, Goodwillie C. Pollen competition as a unilateral reproductive barrier between sympatric diploid and tetraploid Chamerion angustifolium. Proc Biol Sci 2002; 269:2565-71. [PMID: 12573071 PMCID: PMC1691195 DOI: 10.1098/rspb.2002.2196] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Speciation requires the evolution of barriers to gene exchange between descendant and progenitor populations. Cryptic reproductive barriers in plants arise after pollination but before fertilization as a result of pollen competition and interactions between male gametophytes and female reproductive tissues. We tested for such gametic isolation between the polyploid Chamerion angustifolium and its diploid progenitor by conducting single (diploid or tetraploid) and mixed ploidy (1 : 1 diploid and tetraploid) pollinations on both cytotypes and inferring siring success from paternity analysis and pollen-tube counts. In mixed pollinations, polyploids sired most (79%) of their own seeds as well as those of diploids (61%) (correcting for triploid block, siring success was 70% and 83%, respectively). In single donor pollinations, pollen tubes from tetraploids were more numerous than those from diploids at four different positions in each style and for both diploid and tetraploid pollen recipients. The lack of a pollen donor x recipient interaction indicates that the tetraploid siring advantage is a result of pollen competition rather than pollen-pistil interactions. Such unilateral pollen precedence results in an asymmetrical pattern of isolation, with tetraploids experiencing less gene flow than diploids. It also enhances tetraploid establishment in sympatric populations, by maximizing tetraploid success and simultaneously diminishing that of diploids through the production of inviable triploid offspring.
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Affiliation(s)
- Brian C Husband
- Department of Botany, University of Guelph, Guelph, ON, N1G 2W1, Canada.
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Williams JH, Boecklen WJ, Howard DJ. Reproductive processes in two oak (Quercus) contact zones with different levels of hybridization. Heredity (Edinb) 2001; 87:680-90. [PMID: 11903563 DOI: 10.1046/j.1365-2540.2001.00968.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Patterns of reproductive isolation between two sympatric species of oaks, Quercus gambelii and Q. grisea, that exhibit strong ecological differentiation were examined. A full diallel cross using four trees of each species (i.e. all possible pollinations among eight trees) was performed. This design was repeated at two sites that represent different outcomes of sympatry: (1) a xeric mountain ridge where many hybrids are established (HZ); and (2) a mesic valley bottom where virtually no hybrids are established (MOCYN). By measuring fruit survival at several developmental stages, both the timing and strength of reproductive barriers within and between sites, species, cross types, and pollen dosage levels were examined. In three of four cases, heterospecific fruit set was significantly reduced compared to conspecific fruit set. This reduction occurred after the time of fertilization, but before the onset of embryo growth. Increasing the dose of pollen from an average of 9-194 grains/stigma did not affect this result. Thus, early postfertilization processes play a strong role in species fidelity in these oaks. Quercus gambelii experienced a five-fold decrease in conspecific fruit set at HZ relative to MOCYN. In contrast, heterospecific fruit set of Q. gambelii was the same at both sites. Poor Q. gambelii pollen performance is implicated as playing the major role in this result. One Q. gambelii individual at HZ was highly fecund, and had higher heterospecific than conspecific fruit set; slight introgression in this tree was detected uisng RAPD markers. The Environmental Emasculation Hypothesis that posits that environmental stress can increase the probability of hybrid formation by reducing the competitive ability of male gametes of one species is proposed.
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Affiliation(s)
- J H Williams
- Department of Biology, MSC 3AF, PO Box 30001, New Mexico State University, Las Cruces, NM 88003, USA.
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