INVOLVEMENT OF THE CUCUMBER NECROSIS VIRUS COAT PROTEIN IN THE SPECIFICITY OF FUNGUS TRANSMISSION BY OLPIDIUM-BORNOVANUS

Cucumber necrosis (CNV) and the cherry strain of tomato bushy stunt (T BSV-Ch) are tombusviruses which differ in transmissibility by the fung us Olpidium bornovanus (Sahtiyanci) Karling (= O. radicale Schwartz an d Cook), Zoospores acquire and transmit CNV, but not TBSV-Ch, in the i n vitro manner. To assess the role of the coat protein in the specific ity of fungus transmission, reciprocal exchanges were made between the coat protein genes of these two viruses in full-length infectious cDN A clones. Virions containing a modified TBSV-Ch genome with the CNV co at protein gene were efficiently transmitted, but those containing a m odified CNV genome with the TBSV-Ch coat protein gene were not. This i s the first direct demonstration for the role of a viral coat protein in the specificity of transmission by a fungus. (C) 1994 Academic Pres s, Inc.