INFECTIOUS EGGPLANT MOSAIC TYMOVIRUS AND ONONIS YELLOW MOSAIC TYMOVIRUS FROM CLONED CDNA

Eggplant mosaic virus (EMV) and ononis yellow mosaic virus (OYMV) are two tymoviruses that have ssRNA genomes of about 6.2 kb and 6.3 kb, an d which infect solanaceous and leguminous hosts, respectively. Full-le ngth cDNA clones of these viruses were constructed with a T 7 promoter adjacent to the 5' terminus of the DNA copy of the viral genome, and with unique restriction endonuclease sites at the 3' terminus. This al lowed RNA to be transcribed from the DNA encoding the genome. The tran script RNA was infectious when inoculated to Nicotiana glutinosa (for EMV) and Pisum sativum (for OYMV). These clones, together with clones of turnip yellow mosaic tymovirus, which infects brassicas, have been used to construct hybrids in which the virion protein gene was exchang ed between EMV or OYMV and turnip yellow mosaic virus. These and other hybrids are being used to investigate the molecular basis for host ra nge differences in tymoviruses.