GENETICS OF THE RESISTANCE TO STEM RUST IN GENOTYPES OF DURUM WHEAT

The genetics of the resistance was determined in four durum wheat genotypes (Triticum durum L.) released for sowing in northwest Mexico. Genotypes Atil C2000, Samayoa C2004, Cirno C2008 and Movas C2009 are resistant to RTR stem rust caused by Puccinia graminis f. sp. tritici; however, the genes that confer the resistance is unknown. Genetics of the resistance was determined by analyzing the progeny derived from crosses between these resistant genotypes and the susceptible variety Noio. Segregation in the F-3 generation of Cirno C2008 and Atil C2000 showed a phenotypic relationship of 57:7, which corresponds to three dominant genes, two complementary and one independent. For Noio x Samayoa C2004, the phenotypic ratio in the F-3 generation was 1:2:1 for resistant, segregant and susceptible families and indicates the presence of a dominant gene. The progeny of the cross Noio x Movas C2009 segregated with the frequencies 67:176:13, respectively for resistant, segregant and susceptible families; this indicates that Movas 02009 has four complementary dominant genes. The absence of susceptible families among the progenies derived from the crosses with resistant varieties indicated the existence of at least one resistance gene in common.