Influence of fusaric acid on circadian leaf movements of the cotton plant, Gossypium hirsutum.

The cotton plant, Gossypium hirsutum L. (cv. Lakshmi) exhibits circadian leaf movements. Fusaric acid (5-n butyl pyridine 2-carboxylic acid), an in vivo toxin shown to be produced during the pathogenesis of the wilt disease in cotton, causes phase shifts of the leaf movement rhythm that varied in degree and magnitude as a function of the treated phases. The data support the hypothesis that membranes play a vital role as a pacemaker in circadian rhythms.