Characterization of mutants; A Small acidic protein 1 (SMAP1) that mediates responses of the arabidopsis root to the synthetic auxin 2,4-dichlorophenoxyacetic acid

Ono, Yutaka; Rahman, A.*; Biswas, K. K.*; Chhun, T.*; Tsurumi, Seiji*; Narumi, Issei

The mechanism of plant hormoneauxin action has been revealed by identification of several auxin-related mutants. However, the detailed regulatory system of signaling pathway and whether known auxin receptors TIR1/AFBs accounts for all auxin response largely remains unclear. It is may be possible that other uncharacterized proteins are involved in TIR1/AFBs dependent or independent auxin signaling pathway. To investigate novel factors involved in auxin signaling, we screened new mutants that exhibits a long primary root in presence of antiauxin PCIB. The mutants were classified at least 5 independent loci including two known auxin-related loci and . Furthermore, physiological and molecular characterization of a novel auxin-related mutants, suggested that small acidic protein 1 is a regulatory component that mediates 2,4-D-induced auxin response and mode of action of 2,4-D is distinct from that of IAA at least in part.