Pyramiding strategy for durable resistance to wheat leaf rust pathogen

Abstract

Leaf rust caused by Puccinia recondita Rob. ex Desm. F. sp. tritici Eriks. & Henn is one of the most important diseases in wheat worldwide. The cultivation of resistant wheat is the most economical and environmental by sound method to reduce the yield losses. More than 40 genes for resistance against wheat leaf rust (Lr genes) have been described. The method to achieve a more durable resistance is to use different Lr genes in combination. In our breeding program we applied pyramiding strategy using several strong resistance genes to get durable resistance to wheat leaf rust pathogen. After several years of testing International Wheat Rust Nurseries, eight genetically different sources of resistance were selected and crossed with recurrent parents Princ and Starke. Hybrid combinations of the first backcross have been tested with three international pathogen cultures and inheritance of resistance has shown in the hybrids the presence of one, two, or three resistant genes. Eight of the best hybrid lines have been selected and crossed again with only effective isogenic lines containing the resistant genes Lr9, Lr19 and Lr24. Twenty crossing combinations have been tested with three pathotypes of Puccinia recondita tritici. Segregation ratios demonstrated accumulation of the used resistant genes.