The Lazy Mutation in Rice Affects a Step between Statoliths and Gravity-Induced Lateral Auxin Transport

Abstract

Compared to wild type, the lazy mutant in Oryza sativa L. shows a reduced gravitropic response. In order to locate the lesion in the stimulus-response chain, coleoptile segments of lazy rice were investigated with respect to auxin transport. Gravity-induced lateral movement of radiolabelled indoleacetic acid (IAA) was strongly inhibited by the lazy mutation compared to wild type while uptake and longitudinal transport of IAA, as well as amyloplast sedimentation, were not significantly affected. These findings suggest that LAZY controls a step in the signalling chain between statoliths and auxin secretion.

Key words

Auxin lateral transport - gravitropism - lazy mutation - Oryza