The genetics of resistance in Vicia faba to two races of Uromyces viciae-fabae from Manitoba.
Inheritance of resistance to races 1 and 3 of U. viciae-fabae was investigated in 11 faba bean inbred lines. The F1 and F2 generations from a series of reciprocal crosses were studied. The 5 genes conditioning resistance to race 1 or 3 or to both were identified in lines 1 to 4. Additional genes for resistance were found in lines 5 to 8. The resistance in line 1 was shown to be controlled by 3 genes; one gene controlled resistance to race 1, a second gene to race 3 and a third to both. The resistance in lines 3 and 4 to the 2 rust races was controlled by a single gene identical to one of the resistance genes in line 1. However the reversal of resistance to race 1 in line 3 from dominant when crossed to line 10 to recessive when crossed to line 11 suggested that the genes for resistance in lines 3 and 4 may be different. Reversal of reaction from dominant to recessive also occurred when lines 5 and 6 were crossed to line 11. The resistance in line 2 appeared to be governed by 2 genes effective against both races and these were shown to be different from the resistance genes identified in lines 1, 3 and 4. The expression of the gene controlling resistance to race 3 was influenced by the genetic background of the inbred lines, 1, 3 and 4.