Bridging classical and molecular genetics of sorghum disease resistance

Abstract

With rare exceptions, sorghum breeders have been highly successful in producing disease-resistant sorghums. Classical breeding techniques, including identification of resistant cultivars from large and readily available germplasm collections, crosses to elite but susceptible varieties, followed by backcrosses, selfing, and selection, have been used to develop disease-resistant breeding and commercial lines. However, for almost every disease, the breeding efforts must be continuous as new forms of the pathogens rapidly evolve to overcome resistance. Molecular tools that allow rapid and accurate tagging and identification of resistance genes permit, at the very least, the ability to use marker-assisted selection to combine different genes and to test the theory that stacking different genes for resistance will provide stable resistance. Knowledge of the nature and molecular functions of resistance genes promises much more: the ability to manipulate, alter, and enhance the signal transduction pathways that actually trigger host plant resistance.