Genes for Low Reaction to Puccinia graminis tritici in Aegilops and Triticum¹

Bulk and single‐plant accessions of Aegilops longissima Schweinf. and Muschl. and Ae. sharonensis Eig from Israel were tested for reaction to Puccinia graminis Pers. f. sp. tritici Erikss. and E. Henn. Forty‐four lines from these accessions and 23 wheat ( Triticum sp.) lines monogenie for different Sr genes were inoculated with 20 cultures of P. graminis tritici . Data were recorded as infection types (IT) and by the low‐high (L‐H) system of interorganismal genetics. The data were processed by internal, external, and boxing computer programs as well as visual analysis. Internal correlations placed the 44 Aegilops lines in 18 groups with different L‐H patterns, indicating a minimum of five different genes for low reaction (LR). Eight different genes for LR were postulated by the boxing program. Visual analysis differentiated five additional LR genes. External correlation demonstrated that four Aegilops lines carried genes for LR which were not present in any of the monogene wheat lines. Analysis of the comparisons between IT's on the Aegilops and monogene wheat lines suggested the presence of several more LR genes in the Aegilops lines that are different from those in the monogene wheat lines as well as some that are the same. It was concluded that there are available in Aegilops sp. many genes for low reaction to P. graminis tritici that could be used effectively in wheat breeding programs.