Title
The main oxidative inactivation pathway of the plant hormone auxin
Author
Ken-ichiro Hayashi, Kazushi Arai, Yuki Aoi, Yuka Tanaka, Hayao Hira, Ruipan Guo, Yun Hu, Chennan Ge, Yunde Zhao, Hiroyuki Kasahara & Kosuke Fukui
Year
2021
Journal
Nature Communications
Abstract
Inactivation of the phytohormone auxin plays important roles in plant development, and several enzymes have been implicated in auxin inactivation. In this study, we show that the predominant natural auxin, indole-3-acetic acid (IAA), is mainly inactivated via the GH3-ILR1-DAO pathway. IAA is first converted to IAA-amino acid conjugates by GH3 IAA-amidosynthetases. The IAA-amino acid conjugates IAA-aspartate (IAA-Asp) and IAA-glutamate (IAA-Glu) are storage forms of IAA and can be converted back to IAA by ILR1/ILL amidohydrolases. We further show that DAO1 dioxygenase irreversibly oxidizes IAA-Asp and IAA-Glu into 2-oxindole-3-acetic acid-aspartate (oxIAA-Asp) and oxIAA-Glu, which are subsequently hydrolyzed by ILR1 to release inactive oxIAA. This work established a complete pathway for the oxidative inactivation of auxin and defines the roles played by auxin homeostasis in plant development.
Full Article
Instrument
LC-4000
Keywords
auxin, plant, homeostasis,