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Hypoxia-driven changes in glycolytic and tricarboxylic acid cycle metabolites of two nodulated soybean genotypes

Borella, Junior, Oliveira, Halley Caixeta, de Oliveira, Denise dos Santos Colares, Braga, Eugenia Jacira Bolacel, de Oliveira, Ana Claudia Barneche, Sodek, Ladaslav, do Amarante, Luciano
Environmental and experimental botany 2017 v.133 pp. 118-127
Glycine max, alanine transaminase, amino acid composition, amino acids, carbon, fermentation, gas chromatography-mass spectrometry, gene expression, genotype, glycolysis, high performance liquid chromatography, hydroponics, hypoxia, lactic acid, metabolites, nitrogen, nitrogen metabolism, normoxia, pyruvic acid, root systems, roots, soybeans, succinic acid, tissues, tricarboxylic acid cycle, vermiculite
Oxygen deprivation triggers changes at different levels of carbon and nitrogen metabolism, which may differ between plant-genotypes. The aim of this study was to evaluate the hypoxia-induced alterations of carbon and nitrogen metabolites in relation to alanine aminotransferase (AlaAT; EC activity in two genotypes of nodulated soybean (Glycine max). Nodulated soybean plants (Fundacep 53 RR and BRS Macota) were grown in vermiculite and transferred to a hydroponic system at the early reproductive stage. The root system was subjected to hypoxia by continuously flushing the solution with N2 gas for 24 or 72h. For recovery, after 72h in hypoxia, plants returned to normoxic conditions after transfer to vermiculite for 24 and 72h. Root and nodule organic acids and amino acids were analysed by gas chromatography-mass spectrometry and high-performance liquid chromatography, respectively. Relative expression of AlaAT and AlaAT activity were also verified in both genotypes. Plants of Fundacep and Macota genotypes responded distinctly to hypoxia. In root tissues, Fundacep presented higher pyruvate and lactate accumulation than Macota, indicating higher glycolytic and fermentation rates. Furthermore, Fundacep responded more effectively on recovery by restoring pre-hypoxic levels of the metabolites. Although the amino acid composition did not differ between the genotypes, there was a clear link between glycolysis and the Krebs-cycle via increased gene expression and activity of AlaAT allied to succinate accumulation in roots of Fundacep. This may represents a metabolic advantage for this genotype over Macota with regard to hypoxia tolerance.