Formation of merodiploid clones by cojugation in Rhizobium lupini

Off the transconjugants formed in the R. lupini conjugation 0.5 to 5% are merodiploids. When two differently pigmented parents are used in the crossing experiment the diploid transconjugants by their additive pigmentation type. The segregation patterns of these diploid clones were analyzed. The results are in agreement with the theory that the exogenotic donor DNA can be integrated at different sites of the homologous recipient chromosomal region forming a tandem sequence. Consequently the segregants of these merodiploid clones are formed by endochromosomal recombination.