Characteristics Of Resistance To Powdery Mildew And Cereal Cyst Nematode In Octoploid Trititrigia And Its Derivatives

Wheat powdery mildew (caused by Blumeria graminis f. sp. tritici, Bgt) is oneof the important wind-borne diseases in wheat (Triticum aestivum) production. Cerealcyst nematode (CCN) consists of a group of important soil-borne nematodes in wheat.The pathogenic nematodes that damage wheat production in China are Heteroderaavenae and H. filipjevi. The octoploid Tritielytrigia is a new species derived fromartificial breeding after distant hybridization between Elytrigia spp. and commonwheat, which inherits many good traits from Thinopyrum spp..In this study, resistance to powdery mildew and CCN was identified in Zhong4and13octoploid Tritielytrigia from the hybridization between Th. intermedium andthe common wheat cultivar Yannong15. Lines95079,95143,96267and96257wereresistant to10Bgt isolates tested. Line96346was immune or near immune to9isolates except E22. Lines96374,96259and Zhong4were resistant to4to6isolates.Using the greenhouse inoculation methed, the13octoploid Tritielytrigia wereinoculated with H. avenae from Xingyang, and H. filipjevi from Xuchang, Henanprovince, respectively. Lines95143,96263,96267and96257were resistant to H.avenae, and none of them showed resistance to H. filipjevi. Microscopic observationfound that the juvenile nematodes were able to penetrate the roots of all lines in earlyvaccinating period, but the number of juveniles in the roots of the resistant lines wassignificantly less than that of the susceptible controls.Results of the disease assessments showed that the three octoploid Tritielytrigialines95143,96267and96257were resistant against both powdery mildew and CCN.These lines can be used as new source of resistance to both diseases in breedingprograms.SSR primers were screened between Th. intermedium and Yannong15and thepolymorphic primers were chosen to amplify in13octoploid Tritielytrigia. A pair ofSSR primers CFD12from5D amplified Th. intermedium-specific band in theoctoploid Tritielytrigia lines with resistance to powdery mildew.The results of powdery mildew assessment were performed in F2plants from the cross between the octoploid Tritelytrigia line96346with resistance to powderymildew and common wheat cultivar Jingdong8. The molecular marker analysisindicated that the powdery mildew resistance may originate from Th. intermedium.The agronomic performance, cytogenetic observation and powdery mildew testin HBOT09035, which is the progeny derived from the cross between octoploidTritielytrigia line SNTE263and the wheat cultivar Jingdong8, were analyzed. Theresults indicated that line HBOT09035was stable in terms of morphological andcytological levels. This line can serve as a source of resistant germplasm inimprovement of resistance to wheat powdery mildew.