Transport of organic solutes in Phloem and xylem of a nodulated legume.
TLDR
Collections of xylem exudate of root stumps or detached nodules, and of phloem bleeding sap from stems, petioles, and fruits were made from variously aged plants of Lupinus albus L. relying on nodules for their N supply.Abstract:
Collections of xylem exudate of root stumps or detached nodules, and of phloem bleeding sap from stems, petioles, and fruits were made from variously aged plants of Lupinus albus L. relying on nodules for their N supply. Sucrose was the major organic solute of phloem, asparagine, glutamine, serine, aspartic acid, valine, lysine, isoleucine, and leucine, the principal N solutes of both xylem and phloem. Xylem sap exhibited higher relative proportions of asparagine, glutamine and aspartic acid than phloem sap, but lower proportions of other amino acids. Phloem sap of petioles was less concentrated in asparagine and glutamine but richer in sucrose than was phloem sap of stem and fruit, suggesting that sucrose was unloaded from phloem and amides added to phloem as translocate passed through stems to sinks of the plant. Evidence was obtained of loading of histidine, lysine, threonine, serine, leucine and valine onto phloem of stems but the amounts involved were small compared with amides. Analyses of petiole phloem sap from different age groups of leaves indicated ontogenetic changes and effects of position on a shoot on relative rates of export of sucrose and N solutes. Diurnal fluctuations were demonstrated in relative rates of loading of sucrose and N solutes onto phloem of leaves. Daily variations in the ability of stem tissue to load N onto phloem streams were of lesser amplitude than, or out of phase with fluctuations in translocation of N from leaves. Data were related to recent information on C and N transport in the species.read more
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References
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Journal ArticleDOI
Ultrastructure and functioning of the transport system of the leguminous root nodule.
TL;DR: The structure of the vascular tissues of nitrogen-fixing nodules of 27 genera of legumes and some non-legumes has been investigated by light microscopy and a pathway for symplastic lateral transfer of assimilates exists, from the sieve elements through the pericycle, endodermis and cortex, is described.
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Modeling the Transport and Utilization of Carbon and Nitrogen in a Nodulated Legume
TL;DR: An empirical modeling technique was developed for depicting quantitatively the transport and partitioning of photosynthetically fixed C and symbiotically fixed N during 10-day intervals of a 40-day period in the growth of nodulated plants of white lupin.
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Xylem to phloem transfer of solutes in fruiting shoots of legumes, studied by a phloem bleeding technique
TL;DR: Increased nitrate supply to roots led to increased amino acid levels in xylem and phloem but did not alter markedly the balance between individual amino acids.
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Phloem bleeding from legume fruits-A technique for study of fruit nutrition.
TL;DR: Bleeding from phloem of cut distal tips of attached fruits was demonstrated in the genera Spartium, Genista, Lupinus and Jacksonia and highly specific source-sink relationships between foliar organs and fruits of the primary inflorescence were revealed.