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Vascular transport and soybean nodule function. III: Implications of a continual phloem supply of carbon and water
Author(s) -
WALSH K. B.
Publication year - 1990
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1990.tb01979.x
Subject(s) - phloem , photosynthesis , apoplast , nodule (geology) , symplast , biology , metabolism , botany , biophysics , agronomy , biochemistry , cell wall , paleontology
. In soybean, stores of carbon within the leaf have been demonstrated to support nodule metabolism under both photosynthetic and non‐photosynthetic conditions. Indeed, a net depletion of nodule starch is observed only under conditions of suboptimal rates of nodule metabolism. Therefore, maximal rates of nodule metabolism are associated with a continual supply of phloem sap to the nodule, delivering water, carbon and other solutes. A restriction of phloem supply to the nodule may result in changes in turgor between the apoplast of the export pathway and the symplast of the nodule. This change may cause the observed decrease in the permeability to gases and to the rate of product export from nodules deprived of a phloem supply. It is suggested that nodule metabolism is homeostatically regulated in terms of internal O 2 levels by the delivery of phloem water and solutes.