Figure 6.

Northern blot analysis of the accumulation of BMV recombinants generated in the newly constructed homomolecular system. The total RNA was isolated from individual lesions, separated in a 1% agarose gel, blotted onto a nylon membrane and probed with a ³²P-labeled RNA (200 nt probe complementary to the 3′-UTR shared by all BMV genomic RNAs). A mixture of the BMV RNA transcripts used for plant inoculation was applied as a molecular mass marker (lane S). (A) Non-homologous recombination. Representative data obtained for MatNH-HVR- and MatNH-X-BMV. All lesions developed on the MatNH-HVR-BMV infected plants contained one of two almost identical recombinants (lanes 1 and 2) (see Figure 5E). During infection with MatNH-X-BMV, several different recombinants were generated (lanes 3 and 4). In the 10% of lesions where a recombinant was not generated, the parental virus accumulated to a very low level (lane 5). (B) Homologous recombination. About 55% of lesions developed during MatH-HVR-BMV infection contain identical recombinants (lanes 1 and 3); the parental virus accumulated in the remaining ones (lane 2).