Molecular Breeding Approaches For Improving Rust Resistance In Wheat: Marker Assisted Gene Pyramiding

Abstract

Among the diseases which affect wheat, rusts caused by fungal pathogens are prominent. The three important rusts of wheat, black or stem rust caused by PucciniagraminisPers.f.sptritici Eriks. and Henn.,brown or leaf rust caused by PucciniatriticinaEriks. (Syn: Pucciniarecondita) and yellow or stripe rust incited by PucciniastriiformisWestend. are known to cause significant losseswhen they appear in epidemic proportion.These are most destructive diseases worldwide and have the ability to destroy the entire wheat crop. They have the ability to form new races and can attack previously resistant cultivars, and have the capacity to move long distances with potential to develop rapidly under optimal environmental conditions resulting in serious yield losses. The presence of races capable of overcoming different resistance genes has been demonstrated for all three rust fungi.Growing resistant cultivars is the most economic, effective and environment-friendly approach to control the disease.Single major gene resistance in a cultivar may become ineffective soon after it is deployed because of continuous evolution of new pathotypesand slow hypersensitivity.Pyramiding two or more genes in one cultivar can enhance durability and the level of rust resistance.Molecular markers have made it possible to identify and pyramid valuable genes of agronomic importance in resistance breeding.