Effects of DNA Mismatch Repair Genes on Homeologous Recombination in Tomato

In plant breeding, the ability to manipulate genetic (meiotic) recombination would be beneficial for facilitating gene transfer from wild relatives of crop plants. The DNA mismatch repair (MMR) system helps maintain genetic integrity by correcting base mismatches that arise via DNA synthesis or damage, and antagonizes recombination between homeologous (divergent) DNA sequences. Previous studies have established that the genomes of cultivated tomato (Solanum lycopersicum) and the wild relative S. lycopersicoides are substantially diverged (homeologous) such that recombination between their chromosomes is strongly reduced. Here, we report the effects on homeologous recombination of suppressing endogenous MMR genes in S. lycopersicum via co-suppression, RNAi-induced silencing of SlMSH2, and SlMSH7 or overexpressing dominant negatives of Arabidopsis MSH2 (AtMSH2-DN) in alien substitution/introgression lines (SL-8, SL-10 and SL7-F) of S. lycopersicoides in tomato.