Integration of Marker Assisted Selection in ICARDA's Wheat Breeding Program.

In Central and West Asia and North Africa (CWANA) wheat is grown in diverse agro-ecological zones and it is the most important stable crop; however, its productivity is limited by many abiotic and biotic constraints. Main biotic constraints include stem, leaf and yellow rust, Septoria tritici, Sunn pest, Hessian fly, Russian wheat aphid and wheat stem sawfly. To enhance productivity wheat breeders aim at developing new varieties with higher yield potential, enhanced resistances to biotic and abiotic stresses, and improved adaptation to diverse environmental conditions. The development, assemblage, characterization and use of relevant germplasm including elite lines in crossing blocks are essential to meeting the challenge of recombining the desired attributes. Molecular markers linked to various traits of agronomic importance are amongst the tools used to achieve this objective. Recent efforts in genomics have generated large amounts of sequence information which are continually being used to develop molecular markers. These provide great opportunities to advance and implement genetic marker technologies and trait discovery in ICARDA’s wheat breeding program. In this study seventy eight elite wheat lines with reputed multiple disease resistance commonly used in crossing block are being characterized using linked and diagnostic markers for stem, leaf and yellow rusts, Hessian fly and Russian wheat aphid. The reliability and diagnostic capabilities of several molecular markers are being evaluated and validated. The results from the analysis of these key germplasm would enable the wheat program to understand and clarify the relationship between the lines with multiple disease resistance, to more efficiently pyramid genes into adapted germplasm and maximize utilization of existing genes in marker-assisted selection (MAS) to eventually improve breeding for durable resistance for stem rust with other effective resistance genes. Ultimately, it would enable wheat breeding program to develop strategies for routine and efficient MAS implementation.