Abstract

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is one of the most serious diseases of bread (Triticum aestivum L.) and durum (Triticum durum Desf.) wheat worldwide. The discovery of new Pgt races in Africa, Ug99 and its variants, brings a new threat to global wheat production. Currently, the research of stem rust in wheat is focusing on identifying further resistance genes to control Ug99 and its derivatives. Some resistance genes, which were identified from wild relatives and chromosomal regions conferring resistance to stem rust, were also detected using QTL analysis and genome wide association studies. Additionally, development of molecular markers linked to stem rust resistance (Sr) genes is one of the focus areas of current research. These molecular markers play a key role in the genetic characterization of the new sources of resistance as well as in stacking two or more resistance genes in a single line. Pyramiding several, major and minor, stem rust resistance genes into adapted varieties as opposed to breeding varieties with a single resistance gene is considered a more effective method to combat new races. Therefore, recent progress on molecular marker development and improved donor sources are accelerating the pyramiding and deployment of cultivars with more durable resistance to stem rust.

Key words: Molecular markers, resistance, Sr genes, stem rust, Ug99.