LAUSR

Hypoxia induced by flooding or submergence is a serious abiotic stress affecting crop productivity worldwide. During evolution, plants have developed different metabolism mechanisms to cope with the energy crisis caused by hypoxia stress. Among those, the metabolism of γ-aminobutyric acid (GABA), a non-protein amino acid, is recognized as a crucial component for low-oxygen stress responses because of its link both in carbon and nitrogen metabolism. However, it is largely unknown how to control GABA homeostasis. In this study, we identified a novel glycosyltransferase encoding gene, UGT79B7, which was significantly downregulated by low-oxygen treatment in Arabidopsis. ugt79b7 knockout mutants showed increased resistance to hypoxia, while the overexpression lines showed increased sensitivity. We demonstrated that glycosyltransferase UGT79B7 could catalyze GABA to form GABA glucose conjugate (GABA-Glc) in vitro. The in vivo biochemical function of UGT79B7 in controlling GABA glycosylation was also verified. Moreover, we also demonstrated that UGT79B7 could negatively modulate the accumulation of GABA under hypoxia stress. Our data suggest that the glycosylation of GABA plays an important role in GABA homeostasis and reveal a new way for the regulation of plant hypoxia response through a dynamic balance of GABA and its glycosylation products, GABA-Glc.