Abstract
Terfestatin A (TrfA) is isolated as a novel auxin signaling inhibitor from Streptomyces sp. F-40. TrfA inhibits the early auxin-responsive gene expression, such as Aux/IAAs, in competition with auxin. Auxin affects the hypocotyl elongation, lateral root and root hair promotion, and gravitropic response in intact plant. TrfA also antagonize these auxin actions in Arabidopsis seedling. In consistent with activities on intact plant, TrfA inhibited auxin-driven cell division of tobacco BY2 cell culture and the cyclin B1 gene expression. TrfA alone diminished gravitropic response of root. The agravitropic response of aux 1-7, auxin influx carrier mutant, is restored by membrane-permeable NAA. TrfA also inhibited NAA-restored gravitropic response of aux 1-7 same as wild type, suggesting auxin influx carrier would not be TrfA target. To address TrfA, we screened 40000 Arabidopsis EMS-mutated M2 seed to isolate TrfA insensitive mutant. As the results, 52B3 line is isolated as TrfA insensitive mutant.
