UDP-glucosyltransferase UGT84B1 regulates the levels of indole-3-acetic acid and phenylacetic acid in Arabidopsis

• Published in: Biochemical and biophysical research communications 2020-11, Vol.532 (2), p.244-250
• Main Authors: Aoi, Yuki, Hira, Hayao, Hayakawa, Yuya, Liu, Hongquan, Fukui, Kosuke, Dai, Xinhua, Tanaka, Keita, Hayashi, Ken-ichiro, Zhao, Yunde, Kasahara, Hiroyuki
• Format: Article
• Language: English
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Auxin; CRISPR-Cas Systems; Escherichia coli - genetics; Escherichia coli - metabolism; Gene Expression Regulation, Plant; Glucosyltransferases - genetics; Glucosyltransferases - metabolism; Indole-3-acetic acid; Indoleacetic Acids - metabolism; Metabolism; Mutation; Phenylacetates - metabolism; Phenylacetic acid; Plants, Genetically Modified; UDP-Glucosyltransferase
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2020.08.026

Auxin is a key plant growth regulator for diverse developmental processes in plants. Indole-3-acetic acid (IAA) is a primary plant auxin that regulates the formation of various organs. Plants also produce phenylacetic acid (PAA), another natural auxin, which occurs more abundantly than IAA in various plant species. Although it has been demonstrated that the two auxins have distinct transport characteristics, the metabolic pathways and physiological roles of PAA in plants remain unsolved. In this study, we investigated the role of Arabidopsis UDP-glucosyltransferase UGT84B1 in IAA and PAA metabolism. We demonstrated that UGT84B1, which converts IAA to IAA-glucoside (IAA-Glc), can also catalyze the conversion of PAA to PAA-glucoside (PAA-Glc), with a higher catalytic activity in vitro. Furthermore, we showed a significant increase in both the IAA and PAA levels in the ugt84b1 null mutants. However, no obvious developmental phenotypes were observed in the ugt84b1 mutants under laboratory growth conditions. Moreover, the overexpression of UGT84B1 resulted in auxin-deficient root phenotypes and changes in the IAA and PAA levels. Our results indicate that UGT84B1 plays an important role in IAA and PAA homeostasis in Arabidopsis. •Arabidopsis UGT84B1 proteins catalyzed the glucosylation of both IAA and PAA in vitro.•Both the IAA and PAA levels increased in the ugt84b1 knockout mutants.•The ugt84b1 null mutants still produced IAA-glucoside.•UGT84B1 overexpression altered both the IAA and PAA levels in Arabidopsis.•UGT84B1 homologs may also contribute to IAA and PAA homeostasis.