In vivo Phenotypic Mixing between Two Strains of Tobacco Mosaic Virus

Infective particles have been reconstituted in vitro from the disaggregated protein and RNA of several plant viruses and virus strains. The protein and nucleic acid need not be from the same virus strain, or indeed not even from serologically related viruses (Hiebert, Bancroft & Bracker, 1968; Lebeurier, Wurtz & Hirth, 1969; Breck & Gordon, 1970). Thus the RNA from brome mosaic, broad-bean mottle or cowpea chlorotic mottle viruses has been combined with the protein of any of the three viruses and the RNA of potato virus X with protein of tobacco mosaic virus (TMV). With strains of TMV, the more differences there are in amino acid composition or the more distant the serological relationship, the smaller is the yield of infective particles and the less stable they are (Fraenkel-Conrat & Singer, 1957; Holoubek, 1962).