SMAP1 is a positive regulator for 2,4-Dichlorophenoxyacetic acid mediated actin degradation and acts independent of known auxin signaling pathway

Takahashi, Maho*; Ono, Yutaka; Rahman, A.*

Traditionally, it is believed that plant hormone IAA and 2,4-D share a common signaling pathway. However, recent studies have challenged this idea both at physiological and genetic level. To provide a molecular explanation of 2,4-D specific action in Arabidopsis, we characterized the functionally unknown protein SMAP1. The molecular and cell biological analyses revealed that, (1) SMAP1 acts as a positive regulator for 2,4-D induced degradation of actin, cell division and cell elongation processes, and (2) the double mutant of and , a component of E3 ubuquitin ligaes, in root growth assay, shows complete insensitivity to 2,4-D at the concentration that inhibits eighty percent root growth in respective single mutants. Our results identify a novel 2,4-D specific biologically significant pathway in plants.