Phenotyping and validation of molecular markers associated with rust resistance genes in wheat cultivars in Egypt.

BACKGROUND: Thirteen Egyptian wheat cultivars were evaluated and characterized for adult plant resistance to yellow, leaf, and stem rusts. SSR markers linked to yellow, leaf and stem rust resistance genes were validated and subsequently used to identify wheat cultivars containing more than one rust resistance gene.

RESULTS: Results of the molecular marker detection indicated that several genes, either alone or in different combinations, were present among the wheat cultivars, including Yr, Yr78 (stripe rust), Lr, Lr70 (leaf rust), Sr. Sr33, SrTA10187, Sr13, and Sr35 (stem rust), and Lr34/Yr18 and Lr49/Yr29 (leaf/stripe rust). The cultivar Sakha-95 was resistant to leaf and stem rusts, and partially resistant to stripe rust; however, this cultivar contained additional rust resistance genes (Lr, Sr and Lr/Yr). The area under the disease progress curve (AUDPC) type for the various wheat cultivars differed depending on the type of rust infection (yellow, leaf, or stem rust, indicated by Yr, Lr, and Sr). The cultivars Gem-12, Sids-14, Giza-171, and Giza-168 had AUDPC types of partial resistance and resistance. All six cultivars, however, contained additional rust resistance genes.

CONCLUSIONS: Marker-assisted selection can be applied to improve wheat cultivars with efficient gene combinations that would directly support the development of durable resistance in Egypt. Once the expression of the resistance genes targeted in this study have been confirmed by phenotypic screening, the preferable cultivars can be used as donors by Egyptian wheat breeders. The results of this study will help breeders determine the extent of resistance under field conditions when breeding for rust resistance in bread wheat.