Abstract only

Leaf rust (LR) (caused by Puccinia triticina) poses a major threat to durum wheat (DW) (Triticum turgidum ssp. durum) production in developing countries. The most effective way to control LR is through the deployment of resistant cultivars. Even though new sources of resistance have been identified in CIMMYT germplasm, several genes have lost their effectiveness due to the appearance of new virulent races in Mexico. The CIMMYT DW line ?Quetru? is moderately resistant to LR in the field displaying severities of 15MR-50MR depending on the environment. An F5 population was developed from the cross of Quetru with highly susceptible ?Atil*2/Local Red? for investigating the genetic basis of resistance. A total of 113 F5 lines were evaluated under high disease pressure in Obregon in 2009-10 and in El Batan in 2010 . At least two genes that interact in an additive manner governed resistance in the field. One of the resistance genes in Quetru seemed to be a race-specific kind since Quetru displayed IT ?X? on adult plants based on greenhouse tests, but susceptible infection type on seedlings. The second gene in Quetru was found to be Lr46 based on molecular analysis using the associated marker developed by CSIRO, Australia. Phenotypic reductions of 50-58% in Obregon for lines in the population carrying the Lr46 positive marker allele, and of 14-29% in El Batan were observed. This is the first report of Lr46 in DW. This gene plays an important role in enhancing resistance in gene combinations and further studies are needed to investigate its frequency in DW.

Global Wheat Program

English

Lucia Segura

INT2833|INT0610