Cytogenetical Studies in Wheat. IX. Monosomic Analyses, Telocentric Mapping and Linkage Relationships of Genes Sr21, Pm4 and Mle

Gene Sr21 for resistance to Puccinia graminis tritici in five hexaploid derivatives of the diploid Triticum monococcum was located in chromosome 2A. Since only one chromosome was involved in resistance, abnormal ratios found in some diploid wheat crosses and in one hexaploid derivative were attributed to differential transmission of gametes rather than to gene duplication in the diploid wheat sources. By using 2AS and an unknown telocentric presumed to be 2AL in telocentric mapping, Sr21 was placed 2·4±0·9 recombination units from the centromere in 2AL.