The role of viral infection in inducing variability in virus-free progeny in tomato.

The effect of virus-host interactions on subsequent generations is poorly understood. The evaluation of the effects of viral infection on inheritance of quantitative traits in the progeny of infected plants and elucidation of a possible relationship between chiasma frequency in the infected plants and variability of traits in the progeny were investigated. The current study involved genotypes of four intraspecific hybrids of tomato (Solanum lycopersicum L.), their parental forms and two additional cultivars. Used as infection were the tobacco mosaic virus (TMV) and potato virus X (PVX). The consequences of the effect of viral infection were evaluated based on chromosome pairing in diakinesis and/or by examining quantitative and qualitative traits in the progeny of the infected tomato plants. Tomato plants infected with TMV + PVX were found to differ in chiasma frequency per pollen mother cell or per bivalent. Deviations have been observed for genotypes of both F(1) hybrids and cultivars. At the same time, differences in mean values of the traits under study have only been found for progeny populations (F(2)-F(4)) derived from virus-infected F(1) hybrids, but not in the case of progeny of the infected cultivars. The rate of recombinants combining traits of both parents increased significantly (2.22-8.24 times) in progeny populations of hybrids infected with TMV + PVX. The above suggests that the observed effects could be the result of modification of recombination frequencies that can be manifested in heterozygous hybrids and make small contributions to variability in cases of 'homozygous' tomato genotypes (i.e. cultivars).