AtUGT76C2, an Arabidopsis cytokinin glycosyltransferase is involved in drought stress adaptation

The Arabidopsis uridine diphosphate (UDP)-glycosyltransferase 76C2 (UGT76C2), a member of family 1 UGTs, is described as a cytokinin glycosyltransferase. In this study, we demonstrate a novel role of UGT76C2 in response to water deficit. QRT-PCR assay identified that the expression of this gene was downregulated by drought, osmotic stress and abscisic acid (ABA). Compared with wild type (WT) plants, transgenic lines ectopically expressing UGT76C2 exhibited reduced tolerance to ABA and osmotic stress during postgermination growth, while enhanced adaptation to drought stress at mature stage. Consistently, the ugt76c2 mutant plants showed opposite responses to these conditions. To explore the possible mechanisms of UGT76C2 contributing to drought stress adaptation, six stress inducible genes including DREB2A, RD22, RD29B, LEA, COR47 and KIN1 were detected, which showed significant upregulation in UGT76C2 overexpression plants under drought stress. Besides, five cytokinin marker genes AHK2, AHK3, AHK4, ARR1 and ARR2 were also evaluated, which showed less induced in UGT76C2 overexpression plants in response to drought stress. Our results reveal that UGT76C2, as a cytokinin glycosyltransferase, is involved in the plant response to drought stress and might represent novel cues in abiotic stress adaptation.