title: Abscisic acid uridine diphosphate glucosyltransferases play a crucial role in abscisic acid homeostasis in Arabidopsis.
abstract: The phytohormone abscisic acid (ABA) is crucial for plant growth and adaptive responses to various stress conditions. Plants continuously adjust the ABA level to meet physiological needs, but how ABA homeostasis occurs is not fully understood. This study provides evidence that UGT71B6, an ABA uridine diphosphate glucosyltransferase (UGT), and its two closely related homologs, UGT71B7 and UGT71B8, play crucial roles in ABA homeostasis and in adaptation to dehydration, osmotic stress, and high-salinity stresses in Arabidopsis (Arabidopsis thaliana). UGT RNA interference plants that had low levels of these three UGT transcripts displayed hypersensitivity to exogenous ABA and high-salt conditions during germination and exhibited a defect in plant growth. However, the ectopic expression of UGT71B6 in the atbg1 (for β-glucosidase) mutant background aggravated the ABA-deficient phenotype of atbg1 mutant plants. In addition, modulation of the expression of the three UGTs affects the expression of CYP707A1 to CYP707A4, which encode ABA 8'-hydroxylases; four CYP707As were expressed at higher levels in the UGT RNA interference plants but at lower levels in the UGT71B6:GFP-overexpressing plants. Based on these data, this study proposes that UGT71B6 and its two homologs play a critical role in ABA homeostasis by converting active ABA to an inactive form (abscisic acid-glucose ester) depending on intrinsic cellular and environmental conditions in plants.
authors.affiliation: Division of Integrative Biosciences and Biotechnology , Pohang University of Science and Technology, Pohang, 790-784 Korea.
authors.forename: Ting
authors.initials: T
authors.lastname: Dong
authors.forename: Zheng-Yi
authors.initials: ZY
authors.lastname: Xu
authors.forename: Youngmin
authors.initials: Y
authors.lastname: Park
authors.forename: Dae Heon
authors.initials: DH
authors.lastname: Kim
authors.forename: Yongjik
authors.initials: Y
authors.lastname: Lee
authors.forename: Inhwan
authors.initials: I
authors.lastname: Hwang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination / Q000187:drug effects; D005964:Glucosyltransferases / Q000378:metabolism*; D016695:Glycosyltransferases / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects; D006900:Hydroxylation / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D009995:Osmosis / Q000187:drug effects; D010641:Phenotype; D021381:Protein Transport / Q000187:drug effects; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D012995:Solubility; D013312:Stress, Physiological / Q000187:drug effects; D014530:Uridine Diphosphate / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D011993:Recombinant Fusion Proteins; C000593853:UGT71B8 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride; D014530:Uridine Diphosphate; D000040:Abscisic Acid; D016695:Glycosyltransferases; C503922:UGT71B6 protein, Arabidopsis; D005964:Glucosyltransferases; C000593852:UGT71B7 protein, Arabidopsis