MutS Homolog 1 (MSH1)

The plant growth phenotype of recA3-1 msh1-1 double mutants suggests that these two genes control different aspects of homology surveillance. The ectopic recombination events seen in the single mutants are distinct, and the double mutants seem to suffer both sets of ectopic recombination. This suggests that while mitochondrial genes may exist in a few different linkage relationships on different molecules in the single mutants, they apparently exist in a large number of linkage relationships, topologies, and stoichiometries in the double mutants. This genomic complexity could interfere with replication efficiency, perhaps accounting for the observed reduction in mitotic index and plant growth rate. The biochemical details of RECA3 and MSH1 functions that lead to prevention of homeologous recombination are important future questions.