Homogenization-resistant and -susceptible components of tobacco mosaic virus replicative form RNA

When prepared from tissue frozen with liquid nitrogen, tobacco mosaic virus replicative form RNA (TMV RF) was uniform in size but when prepared by high-speed homogenization, or when TMV RF prepared with liquid nitrogen was homogenized, 80 to 90% of the RF broke into relatively discrete pieces. The unbroken RF was not fragmented by additional homogenization. The TMV RF components susceptible and resistant to breakage, respectively, were synthesized with similar kinetics in relation to length of labelling period, but the slightly more resistant component was synthesized during the early infection period. Both components were produced by different strains of TMV but leaves infected with cowpea chlorotic mottle or southern bean mosaic viruses yielded only RF resistant to breakage. TMV replicative intermediate RNA was also broken by homogenization. The occurrence of the two RF components may be of significance in the replication of RNA viruses.