Qualitative changes in cucumber gibberellins following cucumber mosaic virus infection

Abstract

Extracts from cucumber seedlings infected with cucumber mosaic virus, assayed biologically when virus-induced stunt was perceptible, exhibited reduced gibberellin-like activity when compared with extracts of healthy seedlings. No differences could be detected when comparisons were made prior to symptom appearance. Different spots appeared when extracts from healthy and infected plants were compared by thin layer chromatography for gibberellin-like substances, both before and after stunting could be detected. When 3 H-GA 3 was applied to shoots, different peaks, representing different breakdown products of the original 3 H-GA 3 , appeared on radiochromatograms of extracts from healthy seedlings as compared with those from virus-infected seedlings which were found to be less active biologically. These results might indicate that cucumber mosaic virus-infected cucumber plants have different metabolic pathways for their gibberellins, converting them to less or non-active forms. This may explain the reduced response of infected plants to exogenous gibberellin treatments, sustaining the possibility that gibberellin turnover might be involved with virus-induced stunt.