The promotive effect of auxin on shoot cell expansion provided the bioassay used to isolate this central plant hormone nearly a century ago. While the mechanisms underlying auxin perception and signaling to regulate transcription have largely been elucidated, how auxin controls cell expansion is only now attaining molecular-level definition. The good news is that the decades-old acid growth theory invoking plasma membrane Hbsup+esup-ATPase activation is still useful. The better news is that a mechanistic framework has emerged, wherein Small Auxin Up RNA (SAUR) proteins regulate protein phosphatases to control Hbsup+esup-ATPase activity. In this review, we focus on rapid auxin effects, their relationship to Hbsup+esup-ATPase activation and other transporters, and dependence on TIR1/AFB signaling. We also discuss how some observations, such as near-instantaneous effects on ion transport and root growth, do not fit into a single, comprehensive explanation of how auxin controls cell expansion, and where more research is warranted.
|Original language||English (US)|
|Number of pages||24|
|Journal||Annual Review of Plant Biology|
|State||Published - Apr 29 2020|
Bibliographical noteFunding Information:
Research in the authors’ lab is supported by grants from the National Institutes of Health (GM067203 to W.M.G.) and the National Science Foundation (MCB-1613809 to W.M.G. and IOS-1360751 to E.P.S.). The authors wish to thank Dr. Lihao Lin for assistance with figure preparation and members of the Gray lab for helpful comments.
- PM H+-ATPase
- acid growth
- cell expansion