THE INHERITANCE OF RESISTANCE TO PUCCINIA RECONDITA IN HEXAPLOID TRITICALE

Abstract

Rob. ex. Desm. f. sp. tritici, was studied in the hexaploid triticale cultivars 6A-190, Rosner, Armadillo, Bronco, and Toluca 160.Resistance in the triticales studied was monogenically inherited and each cultivar carried a single dominant gene. The genes conditioned resistance to races 15 and 30, and were designated genes A (6A-190), B (Rosner) C (Armadillo), D (Bronco), and E (Toluca 160). Gene A was linked in repulsion with gene C with a crossover value of 44.75 ± 1.44% and segregated independently from the other genes. Genes B and C were also independently inherited. Gene B was not linked with genes C, D, and E but observed distorted ratios with genes D and E suggested the presence of a modifying gene or genes. A similar distorted ratio was observed between genes C and D. Gene C assorted independently from gene E. No recombinants were recovered from the cross between Bronco × Toluca 160 suggesting that genes D and E were allelic or closely linked. The parental triticale cultivars Bronco and Toluca 160 carrying the genes D and E, respectively, appeared to carry modifying genes which inhibited the expression of resistance in certain crosses.The result obtained indicated that the genes governing resistance were derived from the tetraploid wheat parental species and that resistance to wheat leaf rust carried by the rye parent was not expressed in the triticale amphiploid. It was also found that genes conditioning resistance to wheat leaf rust were equally effective in conditioning resistance to rye leaf rust.