POSTULATION OF LEAF RUST RESISTANCE GENES IN BREAD WHEAT PROGENITORS OF THE INIFAP-CEVAMEX PROGRAM

Abstract

Rusts have been one of the major probles of wheat (Triticum spp.) worldwide, of which the leaf rust, caused by the fungus Puccinia triticina, is the most common and the most widely distributed. The use of resistant varieties is the most effective and ecologically sustainable method for its control. The objective of this study was to postulate the genes for resistance to leaf rust in seedlings of elite genotypes and their response to the disease in adult plants. Thirty-eight genotypes of the group of parents of the INIFAP-CEVAMEX Wheat Program were evaluated, including varieties and experimental lines. Sixteen different races of leaf rust were inoculated under greenhouse conditions to be evaluated at the seedling stage, and the MBJ/SP race was inoculated to evaluate their response in adult plant in field and greenhouse conditions. Based on the infection types expressed by the genotypes at seedling stage, the presence of 14 genes was postulated: Lr1, 2a, 2c, 3, 9, 10, 13, 14b, 16, 17, 23, 24 and 27+31, alone or in combinations of up to eight, having a total of 31 different combinations; likewise, there was variation in the response in adult plants. Genotypes that combine resistance genes at the seedling and adult plant stages were identified, with newly formed genotypes presenting greater resistance in adult plant, reflecting advances in improvement through the accumulation of genes for the genetic control of leaf rust.