Assessment of Resistance to Cereal Cyst Nematode, Stripe Rust, and Powdery Mildew in Wheat- Derivatives and Their Chromosome Composition.

Wide hybridization between wheat and wild relatives such as is important for broadening genetic diversity and improving disease resistance in wheat. We developed 30 wheat- derivatives. Here, we report assessments of their resistance to different pathogens including cereal cyst nematode (CCN; spp.), f. Erikss. causing stripe rust, and f. (DC.) Speer inciting powdery mildew. Under natural field infection, all the wheat- lines were resistant to at least one of the pathogens, and four lines were resistant to multiple pathogens. Twenty-nine of 30 tested lines exhibited resistance to , a dominant CCN species in wheat fields. Twenty-four lines were resistant to , an emerging threat to wheat production. Tests of phenotypic responses in the naturally infected field nurseries identified six stripe rust-resistant lines and 13 powdery mildew-resistant lines. Mitotic observation demonstrated that these newly developed wheat- derivatives included not only octoploid but also chromosome addition, substitution, and translocation lines. Chromosome compositions of the four lines resistant to multiple pathogens were analyzed by genomic in situ hybridization and fluorescence in situ hybridization. The octoploid lines Zhong 10-68 and Zhong 10-117 carried both intact chromosomes and translocated chromosomes. Line Zhong 10-149 had 42 wheat chromosomes and two wheat ditelosomes plus a pair of T3BS·J translocated chromosomes. Line Zhong 10-160 carried 41 wheat chromosomes plus one pair of the J genome chromosomes of . The multiple disease-resistant wheat- derivatives, especially lines with chromosome counts close to that of common wheat, provide valuable materials for wheat resistance breeding programs.