Influence of plant hormones on virus replication and pathogenesis-related proteins in Phaseolus vulgaris L. infected with white clover mosaic potexvirus

The influence of plant hormones on the replication of while clover mosaic potexvirus (WClMV) in Phaseolus vulgaris L. cv. Top Crop was examined. Plants were wick-fed hormones and the influence on virus replication was assessed using ELISA to measure virus titre. Abscisic acid, indole-3-acetic acid and gibberellic acid did not affect virus replication, while dihydrozeatin, 1-aminocyclopropane-1-carboxylic acid (ACC), salicylic acid and jasmonic acid all inhibited virus replication. Hormone treatment did not prevent systemic spread of the virus but virus titre in the systemic leaves was reduced by dihydrozeatin, ACC, salicylic acid and jasmonic acid. Pathogenesis-related (PR) proteins From groups 2 and 3 were detected in hormone treated plants bur only following virus challenge. PR-proteins are unlikely to act directly upon viruses, and the expression of PR-proteins may be the result of viral-induced hormone imbalance. The absence of both induced PR-1 proteins and a hypersensitive response indicated that resistance to WClMV was independent of systemic acquired resistance. (C) 1998 Academic Press.