Derivation of a New Strain of Cowpea Chlorotic Mottle Virus from Resistant Cowpeas

Summary A new strain (R) of cowpea chlorotic mottle virus (CCMV) was isolated from plants of the resistant cowpea plant introduction 186465 which were inoculated with the type strain (T). Strain R was serologically different from five naturally occurring CCMV strains. Furthermore, it was able to replicate in and systemically invade cowpea plants which were resistant to strain T. Pseudorecombinant studies with the RNAs of strains T and R established that RNA 1 controlled systemic invasion of the resistant cowpea cultivar. Both RNA 1 and RNA 3 influenced replication in resistant cowpeas. RNA 3 also controlled the composition of the coat protein, while RNA 1 influenced symptoms in susceptible cowpeas.