POSTULATION AND IDENTIFICATION OF STEM RUST RESISTANCE GENES IN WHEAT VARIETIES

Abstract

The identification of stem rust (caused by Puccinia graminis f. sp. tritici) resistance genes present in cultivated wheat (Triticum aestivum L.) varieties allows to know those that remain effective against the disease. The most effective method from both, economic and environmental perspectives, to protect the crop is the use of varieties with genetic resistance. Therefore, the postulation of genes is a valuable tool to identify the most appropriate type of genetic resistance for the specific conditions of a given growing region. In order to postulate and identify stem rust resistance genes present in 75 Mexican wheat varieties released between 1948 and 2007, ten different stem rust strains were used. At the seedling stage, the stem rust resistance genes Sr7a, Sr8a, Sr11 and Sr31 were identified, while using molecular techniques the genes Sr2, Sr12, Sr31, Sr55, Sr57 and Sr58 were identified in combinations of two and up to six genes. This study allowed to find association between molecular markers and the resistance genes Sr2, Sr55, Sr57 and Sr58 that confer resistance in adult plants and are of non-specific race. The germplasm studied has a broad and effective genetic base, which can be used in breeding programs to generate varieties with durable resistance, and can be considered a cornerstone of resistance to wheat stem rust in Mexico.