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Experimental Evidence for Seed Metabolic Allometry in Barrel Medic (Medicago truncatula Gaertn.). Int J Mol Sci 2022; 23:ijms23158484. [PMID: 35955618 PMCID: PMC9369157 DOI: 10.3390/ijms23158484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/22/2022] [Accepted: 07/28/2022] [Indexed: 12/10/2022] Open
Abstract
Seed size is often considered to be an important trait for seed quality, i.e., vigour and germination performance. It is believed that seed size reflects the quantity of reserve material and thus the C and N sources available for post-germinative processes. However, mechanisms linking seed size and quality are poorly documented. In particular, specific metabolic changes when seed size varies are not well-known. To gain insight into this aspect, we examined seed size and composition across different accessions of barrel medic (Medicago truncatula Gaertn.) from the genetic core collection. We conducted multi-elemental analyses and isotope measurements, as well as exact mass GC–MS metabolomics. There was a systematic increase in N content (+0.17% N mg−1) and a decrease in H content (–0.14% H mg−1) with seed size, reflecting lower lipid and higher S-poor protein quantity. There was also a decrease in 2H natural abundance (δ2H), due to the lower prevalence of 2H-enriched lipid hydrogen atoms that underwent isotopic exchange with water during seed development. Metabolomics showed that seed size correlates with free amino acid and hexoses content, and anticorrelates with amino acid degradation products, disaccharides, malic acid and free fatty acids. All accessions followed the same trend, with insignificant differences in metabolic properties between them. Our results show that there is no general, proportional increase in metabolite pools with seed size. Seed size appears to be determined by metabolic balance (between sugar and amino acid degradation vs. utilisation for storage), which is in turn likely determined by phloem source metabolite delivery during seed development.
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Booth NJ, Smith PMC, Ramesh SA, Day DA. Malate Transport and Metabolism in Nitrogen-Fixing Legume Nodules. Molecules 2021; 26:6876. [PMID: 34833968 PMCID: PMC8618214 DOI: 10.3390/molecules26226876] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 11/22/2022] Open
Abstract
Legumes form a symbiosis with rhizobia, a soil bacterium that allows them to access atmospheric nitrogen and deliver it to the plant for growth. Biological nitrogen fixation occurs in specialized organs, termed nodules, that develop on the legume root system and house nitrogen-fixing rhizobial bacteroids in organelle-like structures termed symbiosomes. The process is highly energetic and there is a large demand for carbon by the bacteroids. This carbon is supplied to the nodule as sucrose, which is broken down in nodule cells to organic acids, principally malate, that can then be assimilated by bacteroids. Sucrose may move through apoplastic and/or symplastic routes to the uninfected cells of the nodule or be directly metabolised at the site of import within the vascular parenchyma cells. Malate must be transported to the infected cells and then across the symbiosome membrane, where it is taken up by bacteroids through a well-characterized dct system. The dicarboxylate transporters on the infected cell and symbiosome membranes have been functionally characterized but remain unidentified. Proteomic and transcriptomic studies have revealed numerous candidates, but more work is required to characterize their function and localise the proteins in planta. GABA, which is present at high concentrations in nodules, may play a regulatory role, but this remains to be explored.
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Affiliation(s)
- Nicholas J. Booth
- College of Science & Engineering, Flinders University, GPO Box 5100, Adelaide, SA 5001, Australia; (N.J.B.); (S.A.R.)
| | | | - Sunita A. Ramesh
- College of Science & Engineering, Flinders University, GPO Box 5100, Adelaide, SA 5001, Australia; (N.J.B.); (S.A.R.)
| | - David A. Day
- College of Science & Engineering, Flinders University, GPO Box 5100, Adelaide, SA 5001, Australia; (N.J.B.); (S.A.R.)
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van Bel AJE. The plant axis as the command centre for (re)distribution of sucrose and amino acids. JOURNAL OF PLANT PHYSIOLOGY 2021; 265:153488. [PMID: 34416599 DOI: 10.1016/j.jplph.2021.153488] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 07/13/2021] [Accepted: 08/01/2021] [Indexed: 06/13/2023]
Abstract
Along with the increase in size required for optimal colonization of terrestrial niches, channels for bidirectional bulk transport of materials in land plants evolved during a period of about 100 million years. These transport systems are essentially still in operation - though perfected over the following 400 million years - and make use of hydrostatic differentials. Substances are accumulated or released at the loading and unloading ends, respectively, of the transport channels. The intermediate stretch between the channel termini is bifunctional and executes orchestrated release and retrieval of solutes. Analyses of anatomical and physiological data demonstrate that the release/retrieval zone extends deeper into sources and sinks than is commonly thought and covers usually much more than 99% of the translocation stretch. This review sketches the significance of events in the intermediate stretch for distribution of organic materials over the plant body. Net leakage from the channels does not only serve maintenance and growth of tissues along the pathway, but also diurnal, short-term or seasonal storage of reserve materials, and balanced distribution of organic C- and N-compounds over axial and terminal sinks. Release and retrieval are controlled by plasma-membrane transporters at the vessel/parenchyma interface in the contact pits along xylem vessels and by plasma-membrane transporters at the interface between companion cells and phloem parenchyma along sieve tubes. The xylem-to-phloem pathway vice versa is a bifacial, radially oriented system comprising a symplasmic pathway, of which entrance and exit are controlled at specific membrane checkpoints, and a parallel apoplasmic pathway. A broad range of specific sucrose and amino-acid transporters are deployed at the checkpoint plasma membranes. SUCs, SUTs, STPs, SWEETs, and AAPs, LTHs, CATs are localized to the plasma membranes in question, both in monocots and eudicots. Presence of Umamits in monocots is uncertain. There is some evidence for endo- and exocytosis at the vessel/parenchyma interface supplementary to the transporter-mediated uptake and release. Actions of transporters at the checkpoints are equally decisive for storage and distribution of amino acids and sucrose in monocots and eudicots, but storage and distribution patterns may differ between both taxa. While the majority of reserves is sequestered in vascular parenchyma cells in dicots, lack of space in monocot vasculature urges "outsourcing" of storage in ground parenchyma around the translocation path. In perennial dicots, specialized radial pathways (rays) include the sites for seasonal alternation of storage and mobilization. In dicots, apoplasmic phloem loading and a correlated low rate of release along the path would favour supply with photoassimilates of terminal sinks, while symplasmic phloem loading and a correlated higher rate of release along the path favours supply of axial sinks and transfer to the xylem. The balance between the resource acquisition by terminal and axial sinks is an important determinant of relative growth rate and, hence, for the fitness of plants in various habitats. Body enlargement as the evolutionary drive for emergence of vascular systems and mass transport propelled by hydrostatic differentials.
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Affiliation(s)
- Aart J E van Bel
- Institute of Phythopathology, Centre for BioSystems, Land Use and Nutrition, Justus-Liebig University, Heinrich-Buff-Ring 26-32, D-35392, Giessen, Germany.
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Halder NK, Fuentes D, Possell M, Bradshaw B, Ingram L, Merchant A. Phloem sap metabolites vary according to the interactive effects of nutrient supply and seasonal conditions in Eucalyptus globulus (Labill). TREE PHYSIOLOGY 2021; 41:1439-1449. [PMID: 33517450 DOI: 10.1093/treephys/tpab009] [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: 05/21/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
Improving the efficiency of fertilizer application is paramount to both the sustainability and profitability of forest plantations. Therefore, developing reliable, cost-effective tools to assess tree nutritional status is of great interest. This investigation sought to assess the use of phloem sap-derived metabolites as an indicator of nutritional status on a background of seasonal water availability of Eucalyptus globulus (Labill) trees grown under field conditions. Phloem is a central conduit for long-distance transport and signaling in plants and offers great promise in reflecting plant-scale resource limitations. Changes in the abundance of solutes and isotopes in phloem sap are sensitive to environmental cues. With a focus on both water and nutrient availability, we characterize patterns in phloem sugars, amino acids and the abundance of carbon isotopes in phloem sap obtained from E. globulus among different seasons and fertilizer treatments. Phloem-derived total amino acid concentration was found to increase with an increasing nitrogen (N) supply; however, this response was lost with the concurrent addition of phosphorus and at the highest level of N supply. Significant seasonal variation in all measured parameters was also detected, highlighting the need for caution in making quantitative relationships with growth. Broader implications of the interactive effects of both water supply and multi-nutrient additions and relationships with growth are discussed.
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Affiliation(s)
- Nirmol Kumar Halder
- Faculty of Science, Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW 2570, Australia
- Ministry of Planning. Government of the People Republic of Bangladesh, Dhakar, Dhakar District, 1207 Bangladesh
| | - David Fuentes
- Sydney Mass Spectrometry, Charles Perkins Centre, University of Sydney, NSW 2006, Australia
| | - Malcolm Possell
- Faculty of Science, Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW 2570, Australia
| | - Ben Bradshaw
- Australian Blue Gum Plantations, 3/191 Chesterpass Road, Albany, WA 6330, Australia
| | - Lachlan Ingram
- Faculty of Science, Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW 2570, Australia
| | - Andrew Merchant
- Faculty of Science, Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW 2570, Australia
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Smith MR, Merchant A. Limitations to using phloem sap to assess tree water and nutrient status. TREE PHYSIOLOGY 2019; 39:332-339. [PMID: 30551158 DOI: 10.1093/treephys/tpy132] [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: 05/31/2018] [Revised: 11/05/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
Rapid, reliable tools are needed to infer physiological and nutritional health for managing forest systems. Understanding the processes governing tree health is central to the development of these tools. Non-foliar approaches such as the collection of phloem sap reflect processes governing both the use and acquisition of plant water and nutrients at a wide range of temporal (diurnal to seasonal) and spatial (canopy) scales. Despite this, phloem sap is not commonly employed due to an incomplete understanding of transport and post-photosynthetic processes and their effects on chemical concentrations and carbon isotope discrimination. We highlight the need to characterize the influences of storage, remobilization and transport on the concentrations of metabolites to address the time and spatial decoupling of phloem contents to that of environmental stimuli. A conceptual framework is suggested to focus research on key phenomena regarding metabolite transport and highlight significant advantages, misconceptions and limitations to its application.
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Affiliation(s)
- Millicent R Smith
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney NSW, Australia
| | - A Merchant
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney NSW, Australia
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Dean JM, Mescher MC, De Moraes CM. Plant dependence on rhizobia for nitrogen influences induced plant defenses and herbivore performance. Int J Mol Sci 2014; 15:1466-80. [PMID: 24451132 PMCID: PMC3907880 DOI: 10.3390/ijms15011466] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/15/2014] [Accepted: 01/15/2014] [Indexed: 11/17/2022] Open
Abstract
Symbiotic rhizobia induce many changes in legumes that could affect aboveground interactions with herbivores. We explored how changing the intensity of Bradyrhizobium japonicum, as modulated by soil nitrogen (N) levels, influenced the interaction between soybean (Glycine max) and herbivores of different feeding guilds. When we employed a range of fertilizer applications to manipulate soil N, plants primarily dependent on rhizobia for N exhibited increased root nodulation and higher levels of foliar ureides than plants given N fertilizer; yet all treatments maintained similar total N levels. Soybean podworm (Helicoverpa zea) larvae grew best on plants with the highest levels of rhizobia but, somewhat surprisingly, preferred to feed on high-N-fertilized plants when given a choice. Induction of the defense signaling compound jasmonic acid (JA) by H. zea feeding damage was highest in plants primarily dependent on rhizobia. Differences in rhizobial dependency on soybean did not appear to affect interactions with the phloem-feeding soybean aphid (Aphis glycines). Overall, our results suggest that rhizobia association can affect plant nutritional quality and the induction of defense signaling pathways and that these effects may influence herbivore feeding preferences and performance-though such effects may vary considerably for different classes of herbivores.
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Affiliation(s)
- Jennifer M Dean
- Center for Chemical Ecology, Department of Entomology, Pennsylvania State University, 501 Agricultural and Life Sciences Building, University Park, PA 16802, USA.
| | - Mark C Mescher
- Center for Chemical Ecology, Department of Entomology, Pennsylvania State University, 501 Agricultural and Life Sciences Building, University Park, PA 16802, USA.
| | - Consuelo M De Moraes
- Center for Chemical Ecology, Department of Entomology, Pennsylvania State University, 501 Agricultural and Life Sciences Building, University Park, PA 16802, USA.
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Kovalskaya N, Owens R, Baker CJ, Deahl K, Hammond RW. Application of a modified EDTA-mediated exudation technique and guttation fluid analysis for Potato spindle tuber viroid RNA detection in tomato plants (Solanum lycopersicum). J Virol Methods 2013; 198:75-81. [PMID: 24388932 DOI: 10.1016/j.jviromet.2013.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 11/26/2013] [Accepted: 12/17/2013] [Indexed: 11/29/2022]
Abstract
Potato spindle tuber viroid (PSTVd) is a small plant pathogenic circular RNA that does not encode proteins, replicates autonomously, and traffics systemically in infected plants. Long-distance transport occurs by way of the phloem; however, one report in the literature describes the presence of viroid RNA in the xylem ring of potato tubers. In this study, a modified method based on an EDTA-mediated phloem exudation technique was applied for detection of PSTVd in the phloem of infected tomato plants. RT-PCR, nucleic acid sequencing, and Southern blot analyses of RT-PCR products verified the presence of viroid RNA in phloem exudates. In addition, the guttation fluid collected from the leaves of PSTVd-infected tomato plants was analyzed revealing the absence of viroid RNA in the xylem sap. To our knowledge, this is the first report of PSTVd RNA detection in phloem exudates obtained by the EDTA-mediated exudation technique.
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Affiliation(s)
- Natalia Kovalskaya
- Molecular Plant Pathology Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA; Institute of Ecological Soil Science of MV Lomonosov Moscow State University, Moscow 119991, Russia
| | - Robert Owens
- Molecular Plant Pathology Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA
| | - C Jacyn Baker
- Molecular Plant Pathology Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA
| | - Kenneth Deahl
- Genetic Improvement of Fruits and Vegetables Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA
| | - Rosemarie W Hammond
- Molecular Plant Pathology Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA.
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Merritt SZ. Within-plant variation in concentrations of amino acids, sugar, and sinigrin in phloem sap of black mustard,Brassica nigra (L.) Koch (Cruciferae). J Chem Ecol 2013; 22:1133-45. [PMID: 24225933 DOI: 10.1007/bf02027950] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/1994] [Accepted: 01/30/1996] [Indexed: 11/24/2022]
Abstract
Although within-plant variation in the nutrient and allelochemical composition of phloem sap has been invoked to explain patterns of host use by phloem-feeding insects, little is known about within-plant variation in phloem chemistry. Here I describe a new technique in which I use the green peach aphid,Myzus persicae Sulz., to investigate within-plant variation in the concentrations of chemicals in the phloem sap of black mustard,Brassica nigra (L.) Koch (Cruciferae). Relationships between the concentrations of chemicals in aphid diets and honeydew were established using honeydew from aphids fed on artificial diets with known concentrations of amino acids, sucrose, and sinigrin. These relationships were applied to honeydew from aphids fed on different aged leaves of black mustard to estimate the concentrations of the chemicals in phloem sap. Sinigrin concentration was estimated to be high (>10 mM) in phloem sap in young leaves, calling into question the prevailing opinion that phloem sap contains only low concentrations of allelochemicals. High concentrations may function as defenses against sap-feeding herbivores. Within-plant variation in phloem sap composition was high: (1) young leaves had high concentrations of nutrients (216 mM amino acids, 26% sugar) and sinigrin (>10 mM); (2) mature and presenescent leaves had lower concentrations of nutrients (77-83 mM amino acids, 19-20% sugar) and low concentrations of sinigrin (1-2 mM); and (3) senescing leaves had high concentrations of nutrients (199 mM amino acids, 25% sugar) and low concentrations of sinigrin (3 mM).
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Affiliation(s)
- S Z Merritt
- Department of Biology, University of Michigan, 48109-1048, Ann Arbor, Michigan
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9
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Sulieman S, Tran LSP. Asparagine: an amide of particular distinction in the regulation of symbiotic nitrogen fixation of legumes. Crit Rev Biotechnol 2012; 33:309-27. [DOI: 10.3109/07388551.2012.695770] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Atkins CA, Smith PMC, Rodriguez-Medina C. Macromolecules in phloem exudates--a review. PROTOPLASMA 2011; 248:165-72. [PMID: 21057827 DOI: 10.1007/s00709-010-0236-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 10/26/2010] [Indexed: 05/02/2023]
Abstract
Proteomic and transcriptomic analyses using the growing resources of genomic information have been applied to identification of macromolecules in exudates collected from phloem. Most of the analyses rely on collection of exudate following incisions made to the vasculature, but some limited data are available for exudates collected from excised aphid stylets. Species examined, to date, include a number of cereals (rice, barley, and wheat), a number of cucurbits, castor bean, members of the genus Lupinus, brassicas, and Arabidopsis. As many as 1,100 proteins, some hundreds of transcripts, and a growing number of small ribonucleic acids (RNAs), including micro-RNAs, have been identified across the species with a high degree of commonality. Questions relating to the nature and extent of contamination of sieve element contents with those of surrounding companion cells and nonvascular cells are addressed together with likely functions of identified macromolecules. The review considers likely translocation and systemic signaling functions among the macromolecular inventory of phloem exudates.
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Affiliation(s)
- Craig A Atkins
- School of Plant Biology, University of Western Australia, Crawley, WA, 6009, Australia.
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Sulieman S, Schulze J. Phloem-derived γ-aminobutyric acid (GABA) is involved in upregulating nodule N2 fixation efficiency in the model legume Medicago truncatula. PLANT, CELL & ENVIRONMENT 2010; 33:2162-2172. [PMID: 20716066 DOI: 10.1111/j.1365-3040.2010.02214.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Nitrogen fixation in legumes is downregulated through a whole plant N feedback mechanism, for example, when under stress. This mechanism is probably triggered by the impact of shoot-borne, phloem-delivered compounds. However, little is known about any whole-plant mechanism that might upregulate nitrogen fixation, for example, under N deficiency. We induced emerging N-deficiency through partial excision of nodules from Medicago truncatula plants. Subsequently, the activity and composition of the remaining nodules and shifts in concentration of free amides/amino acids in the phloem were monitored. Furthermore, we mimicked these shifts through artificial feeding of γ-aminobutyric acid (GABA) into the phloem of undisturbed plants. As a result of increased specific activity of nodules, N(2) fixation per plant recovered almost completely 4-5 d after excision. The concentration of amino acids, sugars and organic acids increased strongly in the upregulated nodules. A concomitant analysis of the phloem revealed a significant increase in GABA concentration. Comparable with the effect of nodule excision, artificial GABA feeding into the phloem resulted in an increased activity and higher concentration of amino acids and organic acids in nodules. It is concluded that GABA might be involved in upregulating nodule activity, possibly because of its constituting part of a putative amino acid cycle between bacteroids and the cytosol.
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Affiliation(s)
- Saad Sulieman
- Department of Crop Sciences, Plant Nutrition, Georg-August-University of Göttingen, Göttingen, Germany
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Merchant A, Peuke AD, Keitel C, Macfarlane C, Warren CR, Adams MA. Phloem sap and leaf delta13C, carbohydrates, and amino acid concentrations in Eucalyptus globulus change systematically according to flooding and water deficit treatment. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:1785-93. [PMID: 20211969 PMCID: PMC2852667 DOI: 10.1093/jxb/erq045] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 01/28/2010] [Accepted: 02/12/2010] [Indexed: 05/18/2023]
Abstract
Phloem is a central conduit for the distribution of photoassimilate, nutrients, and signals among plant organs. A revised technique was used to collect phloem sap from small woody plants in order to assess changes in composition induced by water deficit and flooding. Bled phloem sap delta(13)C and sugar concentrations were compared to delta(13)C of bulk material, soluble carbon extracts, and the neutral sugar fraction from leaves. Amino acid composition and inorganic ions of the phloem sap was also analysed. Quantitative, systematic changes were detected in phloem sap composition and delta(13)C in response to altered water availability. Phloem sap delta(13)C was more sensitive to changes of water availability than the delta(13)C of bulk leaf, the soluble carbon fraction, and the neutral soluble fraction of leaves. Changes in water availability also resulted in significant changes in phloem sugar (sucrose and raffinose), inorganic nutrient (potassium), and amino acid (phenylalanine) concentrations with important implications for the maintenance of phloem function and biomass partitioning. The differences in carbohydrate and amino acid composition as well as the delta(13)C in the phloem, along with a new model system for phloem research, offer an improved understanding of the phloem-mediated signal, nutrient, and photoassimilate transduction in relation to water availability.
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Affiliation(s)
- Andrew Merchant
- School of Biological, Earth and Environmental Science University of New South Wales, Sydney NSW, Australia 2052.
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Waters BM, Grusak MA. Whole-plant mineral partitioning throughout the life cycle in Arabidopsis thaliana ecotypes Columbia, Landsberg erecta, Cape Verde Islands, and the mutant line ysl1ysl3. THE NEW PHYTOLOGIST 2008; 177:389-405. [PMID: 18042200 DOI: 10.1111/j.1469-8137.2007.02288.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Minimal information exists on whole-plant dynamics of mineral flow through Arabidopsis thaliana or on the source tissues responsible for mineral export to developing seeds. Understanding these phenomena in a model plant could help in the development of nutritionally enhanced crop cultivars. A whole-plant partitioning study, using sequential harvests, was conducted to characterize growth and mineral concentrations and contents of rosettes, cauline leaves, stems, immature fruit, mature fruit hulls, and seeds of three WT lines (Col-0, Ler, and Cvi) and one mutant line (Col-0::ysl1ysl3). Shoot mineral content increased throughout the life cycle for all minerals, although tissue-specific mineral partitioning differed between genotypes. In particular, iron (Fe), zinc (Zn), and copper (Cu) were aberrantly distributed in ysl1ysl3. Remobilization was observed for several minerals from various tissues, including cauline leaves and silique hulls, but the amounts were generally far below the total mineral accretion observed in seeds. When YSL1 and YSL3 are nonfunctional, Cu, Fe, and Zn are not effectively remobilized from, or do not effectively pass through, leaf and maternal fruit tissues. With respect to seed mineral accretion in Arabidopsis, continued uptake and translocation of minerals to source tissues during seed fill are as important, if not more important, than remobilization of previously stored minerals.
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Affiliation(s)
- Brian M Waters
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA
| | - Michael A Grusak
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA
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Atkins CA, Smith PMC. Translocation in legumes: assimilates, nutrients, and signaling molecules. PLANT PHYSIOLOGY 2007; 144:550-61. [PMID: 17556518 PMCID: PMC1914204 DOI: 10.1104/pp.107.098046] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Accepted: 04/03/2007] [Indexed: 05/15/2023]
Affiliation(s)
- Craig Anthony Atkins
- School of Plant Biology M090, University of Western Australia, Crawley, Western Australia 6009, Australia.
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Pélissier HC, Tegeder M. PvUPS1 plays a role in source-sink transport of allantoin in French bean (Phaseolus vulgaris). FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:282-291. [PMID: 32689354 DOI: 10.1071/fp06277] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Accepted: 12/06/2006] [Indexed: 05/03/2023]
Abstract
Nodulated tropical legumes such as French bean (Phaseolus vulgaris L.) receive their nitrogen via N-fixing rhizobia. The principal products of fixed nitrogen are the ureides allantoin and allantoic acid that are synthesised in root nodules and then translocated to the mature leaves of the shoot via the xylem. By feeding [14C]allantoin to mature leaves and roots of French bean plants we showed that this ureide is transported over long distances by xylem and then phloem to developing organs such as pods, root tips and growing leaves. For analysis of allantoin partitioning within the plant, concentrations of allantoin in French bean organs and xylem sap were determined. The amounts of allantoin varied between organs, with the highest levels being detected in the stems. Differences in levels of allantoin were found between nodulated and non-nodulated plants, with generally higher allantoin concentrations in tissues and xylem sap of nodulated plants. RNA and protein expression of the recently identified French bean allantoin permease PvUPS1 (AY461734) was detected in all plant organs indicating a function in allantoin transport throughout the plant. The levels of PvUPS1 expression were consistent with the allantoin concentrations in the different organs. In situ RNA hybridisation studies were carried out and showed that PvUPS1 is expressed in the phloem throughout the plant. Together, our results indicate that in French bean allantoin is transported from source to sink and that PvUPS1 plays a role in phloem loading and in allantoin transport to developing sinks.
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Affiliation(s)
- Hélène C Pélissier
- School of Biological Sciences, Center for Integrated Biotechnology, Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
| | - Mechthild Tegeder
- School of Biological Sciences, Center for Integrated Biotechnology, Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
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Bromilow RH, Chamberlain K, Patil SG. A rapid method usingRicinus communisfor the estimation of phloem translocation of xenobiotics. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/ps.2780300102] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bromilow RH, Rigitano RLO, Briggs GG, Chamberlain K. Phloem translocation of non-ionised chemicals inRicinus communis. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/ps.2780190202] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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18
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Patrick JW, Offler CE. Compartmentation of transport and transfer events in developing seeds. JOURNAL OF EXPERIMENTAL BOTANY 2001; 52:551-564. [PMID: 11373304 DOI: 10.1093/jexbot/52.356.551] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Developing seeds are net importers of organic and inorganic nutrients. Nutrients enter seeds through the maternal vascular system at relatively high concentrations in the phloem. They exit importing sieve elements via interconnecting plasmodesmata and, during subsequent symplasmic passage, are sequestered into labile storage pools (vacuoles; starch). Transporters function to retrieve nutrients leaked to the seed apoplasm during symplasmic passage. Maternal cells responsible for nutrient release to the seed apoplasm are characteristically located at the maternal/filial interface. Their plasma membranes are enriched in transport proteins and, in some species, these cells are modified to a transfer cell morphology. Apoplasmic volumes of seeds are relatively small, but contain high concentrations of sugars, potassium and a range of amino acids. Sucrose and amino acids are taken up from the seed apoplasm by one to two cell layers of filial tissues that juxtapose the maternal tissues. The plasma membranes of the uptake cells are enriched in sucrose and amino acid/H(+) transporters which co-localize with H(+)-ATPASES: In some species, these cells are modified to a transfer cell morphology. High densities of plasmodesmata support symplasmic delivery of accumulated nutrients to underlying storage cells where polymer formation (starch, protein) takes place. Hexoses, resulting from sucrose hydrolysis and leakage to the seed apoplasm, are retrieved by hexose/H(+) symporters.
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Affiliation(s)
- J W Patrick
- School of Biological and Chemical Sciences, The University of Newcastle, NSW 2308, Australia.
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Stable Isotope Techniques using Enriched 15N and 13C for Studies of Soil Organic Matter Accumulation and Decomposition in Agricultural Systems. ACTA ACUST UNITED AC 2001. [DOI: 10.1007/978-94-015-9841-5_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Polacco JC, Holland MA. Roles of Urease in Plant Cells. INTERNATIONAL REVIEW OF CYTOLOGY VOLUME 145 1993. [DOI: 10.1016/s0074-7696(08)60425-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Shelp BJ, Da Silva MC. Distribution and metabolism of xylem-borne ureido and amino compounds in developing soybean shoots. PLANT PHYSIOLOGY 1990; 94:1505-11. [PMID: 16667883 PMCID: PMC1077413 DOI: 10.1104/pp.94.4.1505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Pulse-chase feeding (30-120 minutes) of (14)C-labeled nitrogenous compounds to cut transpiring shoots was used to investigate the early fate of the major xylem-borne solutes in N(2)-fixing soybean (Glycine max) plants at the V(4) growth stage. By comparison with the foliar distribution of [(14)C]inulin (a xylem marker), it was determined that the phloem supply of allantoin, allantoic acid, asparagine, glutamine, aspartate, and arginine, respectively, provided about 20, 10, three, two, five, and 20 times the (14)C delivered to the developing trifoliolate in the xylem stream. Recovery of unmetabolized asparagine, aspartate, and arginine in this indicator trifoliolate, and significant declines in the percentage of (14)C from allantoic acid and allantoin recovered in the first trifoliolate, provided some support for the direct xylem-to-phloem transfer of these compounds, but did not preclude the involvement of indirect transfer. Data on stem retention and foliar distribution, expressed as a function of the relative xylem sap composition, indicated that ureides provide the major sources of nitrogen to all plant parts. There was no consistent distinction in distribution patterns between pairs of similar anionic and neutral compounds. The extent of xylem-to-phloem transfer among the ureido or the amino compounds was inversely related to its prominence in xylem sap.
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Affiliation(s)
- B J Shelp
- Department of Horticultural Science, University of Guelph, Guelph, Ontario Canada N1G 2W1
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23
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Atkins CA, Storer PJ, Pate JS. Pathways of Nitrogen Assimilation in Cowpea Nodules Studied using N(2) and Allopurinol. PLANT PHYSIOLOGY 1988; 86:204-7. [PMID: 16665867 PMCID: PMC1054455 DOI: 10.1104/pp.86.1.204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
In the presence of 0.5 millimolar allopurinol (4-hydroxypyrazolo [3,4-d]pyrimidine), an inhibitor of NAD:xanthine oxidoreductase (EC 1.2.3.2), intact attached nodules of cowpea (Vigna unguiculata L. Walp. cv Vita 3) formed [(15)N]xanthine from (15)N(2) at rates equivalent to those of ureide synthesis, confirming the direct assimilation of fixed nitrogen into purines. Xanthine accumulated in nodules and was exported in increasing amounts in xylem of allopurinol-treated plants. Other intermediates of purine oxidation, de novo purine synthesis, and ammonia assimilation did not increase and, over the time course of experiments (4 hours), allopurinol had no effect on nitrogenase (EC 1.7.99.2) activity. Negligible (15)N-labeling of asparagine from (15)N(2) was observed, suggesting that the significant pool (up to 14 micromoles per gram of nodule fresh weight) of this amide in cowpea nodules was not formed directly from fixation but may have accumulated as a consequence of phloem delivery.
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Affiliation(s)
- C A Atkins
- Botany Department, University of Western Australia, Nedlands Western Australia 6009, Australia
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Gifford RM, Thorne JH. Phloem unloading in soybean seed coats: dynamics and stability of efflux into attached ;empty ovules'. PLANT PHYSIOLOGY 1986; 80:464-9. [PMID: 16664644 PMCID: PMC1075136 DOI: 10.1104/pp.80.2.464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The time-course of sucrose efflux from attached seedcoats (having their embryos surgically removed) into aqueous traps placed in the ;empty ovules' had three phases. The first phase lasted 10 minutes and probably was a period of apoplastic flushing. The second lasted 2 to 3 hours and is thought to be a phase of equilibration of seed coat symplast with the frequently refreshed liquid. The third phase of relatively steady efflux was postulated to reflect the continued import of sucrose from the plant, and hence to reflect the rate of sieve tube unloading. The average steady state efflux was equal under most conditions to the estimated rate of sucrose import. Efflux and import were unaffected by 150 millimolar osmoticum (mannitol or polyethylene glycol [molecular weight about 400]), by 0.5 millimolar CaCl(2), or by pretreatments up to 20 minutes with p-chloromercuribenzenesulfonic acid (PCMBS); they were enhanced by 40 micromolar abscisic acid, 40 micromolar indoleacetic acid, 20 micromolar fusicoccin, and 1 millimolar dithiothreitol (DTT) and were inhibited by 100 micromolar KCN, by 0.03% H(2)O(2), by 20 micromolar and 5 micromolar trifluoromethoxy (carbonyl cyamide) phenylhydrazone, by repeated 5 minutes per hour treatments with 5 millimolar PCMBS, and by 5 millimolar DTT. The ;steady state' sucrose efflux was able to account for about half the rate of dry weight growth of the embryo, but stabilization of the system with <1 millimolar DTT taken together with other considerations is likely to give good correspondence between experimental unloading rates and in vivo growth rates.
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Affiliation(s)
- R M Gifford
- CSIRO, Division of Plant Industry, GPO Box 1600, Canberra, A.C.T. 2601, Australia
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Pate JS, Peoples MB, Storer PJ, Atkins CA. The extrafloral nectaries of cowpea (Vigna unguiculata (L.) Walp.) II. Nectar composition, origin of nectar solutes, and nectary functioning. PLANTA 1985; 166:28-38. [PMID: 24241308 DOI: 10.1007/bf00397382] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/1985] [Accepted: 04/30/1985] [Indexed: 06/02/2023]
Abstract
Nectar was collected from the extrafloral nectaries of leaf stipels and inflorescence stalks, and phloem sap from cryopunctured fruits of cowpea plants. Daily sugar losses as nectar were equivalent to only 0.1-2% of the plant's current net photosynthate, and were maximal in the fourth week after anthesis. Sucrose:glucose:fructose weight ratios of nectar varied from 1.5:1:1 to 0.5:1:1, whereas over 95% of phloem-sap sugar was sucrose. [(14)C]Sucrose fed to leaves was translocated as such to nectaries, where it was partly inverted to [(14)C]glucose and [(14)C]fructose prior to or during nectar secretion. Invertase (EC 3.2.1.26) activity was demonstrated for inflorescence-stalk nectar but not stipel nectar. The nectar invertase was largely associated with secretory cells that are extruded into the nectar during nectary functioning, and was active only after osmotic disruption of these cells upon dilution of the nectar. The nectar invertase functioned optimally (phloem-sap sucrose as substrate) at pH 5.5, with a starting sucrose concentration of 15% (w/v). Stipel nectar was much lower in amino compounds relative to sugars (0.08-0.17 mg g(-1) total sugar) than inflorescence nectar (22-30 mg g(-1)) or phloem sap (81-162 mg g(-1)). The two classes of nectar and phloem sap also differed noticeably in their complements of organic acids. Xylem feeding to leaves of a range of (14)C-labelled nitrogenous solutes resulted in these substrates and their metabolic products appearing in fruit-phloem sap and adjacent inflorescence-stalk nectar. (14)C-labelled asparagine, valine and histidine transferred freely into phloem and appeared still largely as such in nectar. (14)C-labelled glycine, serine, arginine and aspartic acid showed limited direct access to phloem and nectar, although labelled metabolic products were transferred and secreted. The ureide allantoin was present in phloem, but absent from both types of nectar. Models of nectary functioning are proposed.
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Affiliation(s)
- J S Pate
- Botany Department, University of Western Australia, 6009, Nedlands, W.A., Australia
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Peoples MB, Atkins CA, Pate JS, Murray DR. Nitrogen nutrition and metabolic interconversions of nitrogenous solutes in developing cowpea fruits. PLANT PHYSIOLOGY 1985; 77:382-8. [PMID: 16664063 PMCID: PMC1064524 DOI: 10.1104/pp.77.2.382] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Budgets for import and utilization of ureide, amides, and a range of amino acids were constructed for the developing first-formed fruit of symbiotically dependent cowpea (Vigna unguiculata [L.] Walp. cv Vita 3). Data on fruit total N economy, and analyses of the xylem and phloem streams serving the fruit, were used to predict the input of various solutes while the compositions of the soluble and protein pools of pod, seed coat, and embryo were used to estimate the net consumption of compounds. Ureides and amides provided virtually all of the fruit's N requirements for net synthesis of amino compounds supplied inadequately from the parent plant. Xylem was the principal source of ureide to the pod, while phloem was the major source of amides to pod and seed. All fruit parts showed in vitro activity of urease (EC 3.5.1.5), allantoinase (EC 3.5.2.5), asparaginase (EC 3.5.11), ammonia-assimilating enzymes and aspartate and alanine aminotransferases (EC 2.61.1 and EC 2.6.1.1.2). Asparagine:pyruvate aminotransferase (EC 2.6.1.14) was recovered only from the pod. The pod was initially the major site for processing and incorporating N; later seed coats and finally embryos became predominant. Ureides were broken down mainly in the pod and seed coat. Amide metabolism occurred in all fruit organs, but principally in the embryo during much of seed growth. Seed coats released N to embryos mainly as histidine, arginine, glutamine, and asparagine, hardly at all as ureide. Amino compounds delivered in noticeably deficient amounts to the fruit were arginine, histidine, glycine, glutamate, and aspartate, while seeds received insufficient arginine, histidine, serine, glycine, and alanine. Quantitatively based schemes are proposed depicting the principal metabolic transformation accompanying N-flow between seed compartments during development.
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Affiliation(s)
- M B Peoples
- Department of Botany, University of Western Australia, Nedlands, WA 6009, Australia
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Pate JS, Peoples MB, van Bel AJ, Kuo J, Atkins CA. Diurnal water balance of the cowpea fruit. PLANT PHYSIOLOGY 1985; 77:148-56. [PMID: 16663998 PMCID: PMC1064473 DOI: 10.1104/pp.77.1.148] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The vascular network of the cowpea (Vigna unguiculata [L.] Walp.) fruit exhibits the anatomical potential for reversible xylem flow between seeds, pod, and parent plant. Feeding of cut shoots with the apoplast marker acid fuchsin showed that fruits imported regularly via xylem at night, less frequently in early morning, and only rarely in the afternoon. The dye never entered seeds or inner dorsal pod strands connecting directly to seeds. Root feeding (early morning) of intact plants with (32)PO(4) or (3)H(2)O rapidly (20 min) labeled pod walls but not seeds, consistent with uptake through xylem. Weak subsequent (4 hours) labeling of seeds suggested slow secondary exchange of label with the phloem stream to the fruit. Vein flap feeding of subtending leaves with [(14)C]sucrose, (3)H(2)O, and (32)PO(4) labeled pod and seed intensely, indicating mass flow in phloem to the fruit. Over 90% of the (14)C and (3)H of fruit cryopuncture phloem sap was as sucrose and water, respectively. Specific (3)H activities of transpired water collected from fruits and peduncles were assayed over 4 days after feeding (3)H(2)O to roots, via leaf flaps, or directly to fruits. The data indicated that fruits transpired relatively less xylem-derived (apoplastic) water than did peduncles, that fruit and peduncle relied more heavily on phloem-derived (symplastic) water for transpiration in the day than at night, and that water diffusing back from the fruit was utilized in peduncle transpiration, especially during the day. The data collectively support the hypothesis of a diurnally reversing xylem flow between developing fruit and plant.
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Affiliation(s)
- J S Pate
- Department of Botany, The University of Western Australia, Nedlands, WA 6009, Australia
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Peoples MB, Pate JS, Atkins CA, Murray DR. Economy of water, carbon, and nitrogen in the developing cowpea fruit. PLANT PHYSIOLOGY 1985; 77:142-7. [PMID: 16663997 PMCID: PMC1064472 DOI: 10.1104/pp.77.1.142] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The nutritional economy of the fruit of cowpea (Vigna unguiculata (L.) Walp cv Vita 3) was assessed quantitatively from intake and utilization of carbon, nitrogen, and water. Fruits failed to make net gains of CO(2) from the atmosphere during daytime, although pod photosynthesis did play a role in the fruit's carbon economy by refixing a proportion of the fruit's respired CO(2). Of every 100 units by weight of carbon entering the fruit, 70.4 were finally incorporated into seeds, 10.3 remained as nonmobilizable material in pod walls, and the remaining 19.3 were lost in fruit respiration. Phloem supplied 97% of the fruit's carbon and 72% of its nitrogen. The xylem contribution of nitrogen occurred mainly in early growth. Ninety-six% of the fruit's nitrogen was incorporated into seeds, approximately 10% of this mobilized from the senescing pod. The mean transpiration ratio of the fruit was very low-8 milliliters water transpired per gram dry matter accumulated. Models of carbon, nitrogen, and water flow were constructed for the two consecutive 11 day periods of fruit development, and indicated a considerably greater entry of water through xylem and phloem than could be accounted for in changes in fruit tissue water and transpiration loss. This discrepancy was greater in the second half of fruit growth and was interpreted as evidence that a significant fraction of the water entering the fruit through phloem cycled back to the parent plant via the xylem.
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Affiliation(s)
- M B Peoples
- Department of Botany, The University of Western Australia, Nedlands, WA 6009, Australia
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