Two host genes in Vicia faba for nodulation deficiency with strain specificity for Rhizobium leguminosarum

In greenhouse tests, two inbred lines of faba bean, I 40 and I 25, proved to be nodulation resistant and F₂ progenies were used to determine the genetic control of this nodulation deficiency. The defect is strain-specific for the Rhizobium strains St 48 and St 53. In inbred line I 40, the deficient nodulation character is controlled by a dominant gene which is called Sym-2, while another recessive gene sym-3 is assumed for line I 25; Sym-2 is epistatic over sym-3.