GENETICS OF LEAF RUST REACTION IN THREE INTRODUCTIONS OF COMMON WHEAT

Abstract

The genetics of seedling resistance to leaf rust (Puccinia recondita Rob. ex. Desm.) was investigated in wheat (Triticum aestivum L.) introductions PI 268454, PI 58548 and PI 268316, originally collected in Afghanistan, China and Iran, respectively. PI 268454 was heterogeneous for resistance. A selection (PI 268454a) has a gene that confers a 1+ reaction while a 2nd selection (PI 268454b) probably has resistance gene Lr2b. PI 58548 has 2 genes for resistance, one giving a 1+ reaction reaction and the 2nd a 2+. These 2 genes interact to produce a;1 reaction. PI 268316 has 3 interacting genes, one giving a 1+ reaction, the 2nd a 2+ and a 3rd resistance gene similar to LrB. The gene giving the 1+ reaction was common to all 3 introductions. PI 58548 and PI 268316 carry different genes for infection type 2+. Backcross lines of the single genes were produced. Implications to breeding for disease resistance of genes interacting to produce different phenotype are discussed.