LEAF RUST RESISTANCE ANALYSIS IN RAINFED BREAD WHEAT

Abstract

In order to know the resistance genes present in both seedling and adult plant stages in 50 genotypes of the second rainfed bread wheat (Triticum aestivum L.) several tests were performed. Greenhouse seedlings were challenged with 12 leaf rust races of P. triticina E. Race MCJ/SP was used in the field to determine the type of resistance in adult plants. Among the 50 known leaf rust genes identified, in this research Twelve were identified to be present, either alone or in different combinations. Identified genes were: Lr1, 2a, 3, 3bg, 10, 13, 16, 17, 23, 26, 27+31 and others not yet identified. Among these genes, Lr1 was the most common in seedlings. Race MCJ/SP enabled genotypes classification into two groups: susceptible in seedling stage and either resistant or susceptible in adult stage; and resistant in seedling stage and either susceptible or resistant in adult plants. Among the 50 genotypes, 50% showed a good level of resistance in the field and agronomically accepted; whereas 30% combined seedling with adult plant resistance. In the nursery 20 % of the genotypes showed slow rusting or partial resistance that might be durable and more stable across environments. Cultivars Romoga, Juchi and Tlaxcala showed this type of resistance.