The N-terminal 12 amino acids of tomato aspermy virus 2b protein function in infection and recombination

Abstract

The roles for various regions of the 2b protein in infection, hypervirulence and recombination were examined by introducing stop codons in a chimeric virus containing RNA 1 from the cucumber mosaic virus (CMV strain Q), RNA 3 from the tomato aspermy virus (TAV) and RNA 2 of CMV with a 2b gene from TAV. Chimeric virus expressing the intact 2b protein induced severe symptoms in inoculated Nicotiana clevelandii and Nicotiana glutinosa and facilitated CMV–TAV recombination, while chimeric viruses not expressing 2b protein did not infect plants systemically. Chimeric viruses expressing either the N-terminal 43 or 12 aa of the 2b protein infected both plant species systemically and facilitated CMV–TAV recombination, but induced mild symptoms and no symptoms in the infected plants, respectively. These data suggest that oligopeptides can have important functions in the biology of viruses and prompt a re-examination of existing small ORFs in sequenced virus genomes.