Effects of plant hormones on white clover mosaic potexvirus double-stranded RNA

The double-stranded RNAs (dsRNA) produced during the replication of white clover mosaic potexvirus (WClMV) in the primary leaves of Phaseolus vulgaris during the 10 days following inoculation were investigated. Replication of a large dsRNA fragment (dsRNA 1) occurred within 24 h of inoculation and probably represents the replicative form of the genomic RNA. A second dsRNA fragment (dsRNA 5) appeared at day 3, and four other dsRNAs were detected from day 5; the putative functions of these are unknown, however their appearance coincided with a rapid increase in virus titre. Hormone treatments that inhibited virus replication altered the production of these dsRNAs. Dihydrozeatin, jasmonic acid and salicylic acid inhibited production of all dsRNAs except dsRNA 1, while 1-amino-1-cyclopropane carboxylic acid reduced the levels of dsRNAs produced but did not alter the pattern of expression.