ABSTRACT Rice is an economically important crop and a staple food for a large proportion of the world's population. Although rice is generally adapted to flooded soils, cultivars may differ in their responses to reduced oxygen availability. Here, we evaluated growth, physiological performance and organ‐specific metabolic profiles of two rice cultivars under a fine gradient of hypoxia (severe, moderate and slight). São Francisco (SF) and BRS Esmeralda (ES) were exposed to controlled oxygen restriction and severe hypoxia reduced growth, particularly root development, together with decreases in photosynthetic pigments, CO 2 assimilation, stomatal conductance, transpiration, instantaneous carboxylation efficiency, electron transport rate and PSII performance. Ion accumulation (Na + , Cl − and K + ) also varied with hypoxia level and cultivar. Considering the full set of physiological and biochemical variables, multivariate analysis captured clear differences among hypoxia treatments. Metabolomic profiling indicated that hypoxia‐driven adjustment was more pronounced in roots than in leaves: 39 metabolites in leaves and 40 in roots were differentially modulated by hypoxia level and/or cultivar, with a clearer separation of treatments in root profiles. Under severe hypoxia, SF exhibited a root‐centred metabolic reprogramming, with modulation of metabolites associated with glycolysis and the tricarboxylic acid cycle, consistent with mechanisms that may help mitigate oxygen restriction in flooded environments.
Viana et al. (Fri,) studied this question.