Identification and mapping of PmSE5785, a new recessive powdery mildew resistance locus, in synthetic hexaploid wheat

Abstract

Powdery mildew of wheat (Triticum aestivum L.) caused by Blumeria graminis f. sp. tritici, is a major fungal disease in many areas of the world. Synthetic hexaploids, created from durum wheat and Aegilops tauschii are important sources of beneficial genes for wheat improvement. Synthetic wheat ‘SE5785’ was found resistant to powdery mildew at the seedling and adult stages. Genetic analyses of the F2 population and F2:3 families developed from a cross of ‘SE5785’ with the susceptible common wheat, ‘Xiaoyan 22’, revealed that resistance in ‘SE5785’ was controlled by a single recessive gene. Bulked segregant analysis was used to map the powdery mildew resistance locus. The resulting genetic map comprised of markers Xcfd62, Xbarc59, PmSE5785, Xgwm539, and Xwmc817 spanned 16.3 cM. Markers Xbarc59 and Xgwm539 were tightly linked to the resistance locus at genetic distances of 3.6 and 4.0 cM, respectively. ‘Chinese Spring’ and its nulli-tetrasomic lines confirmed that PmSE5785 was located on chromosome 2D. Because no gene for powdery mildew resistance had ever been located on this chromosome in the genus Triticum, this must be a new locus, therefore, designated PmSE5785. N07228-1 and N07228-2 with large seeds and powdery mildew resistance were selected from the progeny of the cross ‘SE5785’/‘Xiaoyan 22’. These new lines can serve as sources of resistance to powdery mildew in wheat breeding.