Presentation SMALL ACIDIC PROTEIN 1 (SMAP1) and SCFTIR1 ubiquitin proteasome pathway act in concert to regulate 2,4-dichlorophenoxyacetic acid-mediated alteration of actin in Arabidopsis root

Takahashi, Maho  ,  Umetsu, Kana  ,  Higaki, Takumi  ,  大野, 豊  ,  B. Blancaflor, Elison

2,4-dichlorophanoxyacetic acid (2,4-D), a functional analogue of auxin, is used as an exogenous source of auxin as it evokes physiological responses like the endogenous auxin, indole-3-acetic acid (IAA).Using genetic and cellular approaches, here we demonstrate that the distinct effects of 2,4-D and IAA on actin filament organization partly dictate the differential responses of roots to these two auxin analogues. 2,4-D but not IAA altered the actin structure in long term and short term assays. Analysis of the 2,4-D specific mutant aar1-1 revealed that Small Acidic Protein 1 (SMAP1) acts as a positive regulator for the 2,4-D-induced alterations of actin. The ubiquitin proteasome mutants, tir1-1 and axr1-12, which show enhanced resistance to 2,4-D compared with IAA for root growth inhibition, were also found to have less disrupted actin filament networks after 2,4-D exposure. Collectively, these results suggest that the effects of 2,4-D on actin filament organization and root growth is mediated through synergistic interactions between SMAP1 and SCFTIR1 ubiquitin proteasome components.
22nd International Plant Growth Substances Association (IPGSA) conference

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