UDP-Glucosyltransferase71C5 a Major Glucosyltransferase Mediates Abscisic Acid Homeostasis in Arabidopsis

摘要

Abscisic acid () plays a key role in plant growth and development. The effect of in plants mainly depends on its concentration, which is determined by a balance between biosynthesis and catabolism of . In this study, we characterize a unique UDP-glucosyltransferase (UGT), UGT71C5, which plays an important role in homeostasis by glucosylating to abscisic acid>-glucose ester () in Arabidopsis (Arabidopsis thaliana). Biochemical analyses show that UGT71C5 glucosylates in vitro and in vivo. Mutation of UGT71C5 and down-expression of UGT71C5 in Arabidopsis cause delay in seed germination and enhanced drought tolerance. In contrast, overexpression of UGT71C5 accelerates seed germination and reduces drought tolerance. Determination of the content of and in Arabidopsis revealed that mutation in UGT71C5 and down-expression of UGT71C5 resulted in increased level of and reduced level of , whereas overexpression of UGT71C5 resulted in reduced level of and increased level of . Furthermore, altered levels of in plants lead to changes in transcript abundance of -responsive genes, correlating with the concentration of regulated by UGT71C5 in Arabidopsis. Our work shows that UGT71C5 plays a major role in href="#def1" rid="def1" class=" def">ABA glucosylation for href="#def1" rid="def1" class=" def">ABA homeostasis.