Molecular cytogenetic characterization of a new wheat-Thinopyrum intermedium partial amphiploid resistant to powdery mildew and stripe rust.

A partial amphiploid, TE253, derived from crosses between the common wheat (Triticum aestivum L.) cultivar Yannong 15 and Thinopyrum intermedium (Host) Barkworth & D.R. Dewey was characterized by cytogenetic observations, disease resistance tests and genomic in situ hybridization (GISH). Mitotic observations showed that most plants of TE253 had 56 chromosomes, but a few had 54 or 55 chromosomes. The chromosomes in most pollen mother cells of plants with 2n = 56 formed 28 bivalents. Univalents (0.89 per cell) and tetravalents (0.087 per cell) occasionally occurred at meiotic metaphase I, showing a high degree of cytogenetic stability. After inoculation with the powdery mildew and stripe rust pathogens, Yannong 15 was highly susceptible, whereas TE253 and Th. intermedium were immune to both diseases. This indicated that the resistance of TE253 to powdery mildew and stripe rust was derived from Th. intermedium. GISH analysis using St-genomic DNA from Pseudoroegneria strigosa (M. Bieb) A. Löve as a probe and ABD-genomic DNA from Chinese Spring wheat as a blocker demonstrated that TE253 consisted of 2 St-genome chromosomes, 8 J(S)-genome chromosomes, 2 SAT J chromosomes and 2 J-St translocated chromosomes. Line TE253 is a new partial amphiploid with resistance to both powdery mildew and stripe rust and can be used as a source of resistance genes in wheat improvement.