Products of anaerobic metabolism in waterlogged roots of soybean are exported in the xylem

Author(s)

Vitor, Simone Cespedes ^[1] ; Sodek, Ladaslav ^[1]

Affiliation

^[1] Univ Campinas UNICAMP, Inst Biol, Dept Plant Biol, POB 6109, BR-13083970 Campinas, SP - Brazil

• Document type: Journal article
• Source: Plant Science; v. 284, p. 82-90, JUL 2019.
• Web of Science Citations: 0

Abstract

Waterlogging leads to hypoxia of the root system. Metabolic changes occur that enable the plant to tolerate the hypoxic stress. We investigated the export of organic acids, products of anaerobic metabolism, via xylem of waterlogged soybean (Glycine max) plants. Organic acids were quantified by GC-MS and their formation via aspartate metabolism investigated using {[}4-C-13]aspartate. Elevated levels of malate were found together with variable amounts of other organic acids, notably lactate and succinate. Addition of {[}4-C-13]aspartate to the medium led to isotopic enrichment of several organic acids in the xylem sap. Quantitatively, malate carried the highest amount of label among the organic acids. Labelling of succinate indicates its formation by reversal of the TCA-cycle from oxaloacetate. Since aspartate was a prominent amino acid of the phloem sap, it is suggested that this is an important source of malate exported in the xylem. The export of these organic acids will play the role of removing electrons from the hypoxic roots, representing an additional mechanism in the metabolic response to root hypoxia. Malate, normally considered an intermediate in succinate formation, is definitively a product of anaerobic metabolism. (AU)

• FAPESP's process: 13/03325-8 - Role of organic acids in the metabolism and recycling of N in the roots of soybean
• Grantee: Simone Cespedes Vitor
• Support Opportunities: Scholarships in Brazil - Doctorate