Photosynthetic changes inFusarium-infected cotton

摘要

Resistant and susceptible cotton cultivars when infected withFusarium vasinfectumshowed a reduced rate of photosynthesis as determined by O2evolution and14CO2fixation by their leaf tissues. The infected leaves exhibited a lower starch content and a slight, but consistent, reduction in total chlorophyll and chlorophyllb. There was no direct correlation between loss of chlorophyll and the low rate of photosynthesis. Chlorophyllase activity was enhanced in the infected leaves. Fusaric acid reduced the rate of photosynthesis of cotton cultivars slightly, whereas crude and dialysed culture filtrates brought about marked reduction in photosynthetic rates. The possible role of a hitherto unidentified toxin in wilt pathogenesis is suggested.