Crosses between Andean and Mesoamerican common beans are usually incompatible. There are doubts about the genetic control of the trait. Singh & Gutiérrez (1984) reported that two genes are involved in the trait control and that double recessive epistasis occurs. On the other hand, Vilarinho (2004) presented results indicating that more than two genes are involved. The present study was carried out to clarify the genetic control of this trait. For this purpose, the Andean cultivar 'Jalo EEP 558' was crossed with 'Small White', which is Mesoamerican, but compatible with the former one. The Mesoamerican cultivar 'Mulatinho da Vagem Roxa' was also crossed with 'Small White'. The F1 generation of these two hybrids was crossed with each other. The resulting seeds were sown on the field and the occurrence of incompatibility was evaluated. Segregation of 3 (normal) to 1 (incompatible) plants was observed, indicating that there are two genes, DL1 and DL2, as reported by Singh & Gutiérrez (1984), and that the genotype of the cultivars involved are: 'Jalo EEP 558' dl1dl1DL2DL2 ; 'Mulatinho da Vagem Roxa' DL1DL1dl2dl2 ; 'Small White' dl1dl1dl2dl2 .
Phaseolus vulgaris L.; epistasis; genes
