The inheritance of leaf and stem rust resistance in Triticum monococcum L.

Abstract

Resistance to leaf rust (Puccinia recondita f. sp. tritici Rob. ex Desm.) is common in Triticum monococcum L. For example, the 49 accessions in the University of Saskatchewan collection all gave a fleck reaction to leaf rust race CBB. To obtain some indication of whether they all carried the same gene, a set of diallel crosses was made among five of the accessions and three extra crosses were made between two additional accessions and two in the diallel set. The 13 F2 populations involving a total of seven accessions were tested with LR CBB and no segregation for susceptible seedlings occurred. Thus, the seven T. monococcum accessions all carried at least one gene in common. To determine the number of genes involved in leaf rust resistance, four crosses were made between a highly resistant accession, TM157 (IT 0;), and four moderately resistant ones (IT 2−). The F2 populations segregated for two independent dominant genes, one conditioning a fleck reaction and one a type 2 reaction. All seven highly resistant accessions must carry the first gene. Two of the T. monococcum accessions were resistant to stem rust (P. graminisf. sp. tritici Eriks. & Henn.) SR TMH. They proved to carry single genes for resistance, Sr22 in TM65 and Sr35 in TM157. Key words: Wheat, leaf rust, stem rust, inheritance