Molecular and Cytogenetic Identification of Stem Rust Resistant Wheat- Thinopyrum intermedium Introgression Lines.

Thinopyrum intermedium (JJJ s J s StSt, 2 n = 6 x = 42), a wild relative of common wheat, possesses many desirable agronomic genes for wheat improvement. The production of wheat- Thinopyrum intermedium introgression lines is a key step for transferring these beneficial genes into wheat. In this study, we characterized three wheat- Thinopyrum intermedium introgression lines TA3681, TA5566, and TA5567 using non-denaturing fluorescence in situ hybridization, genomic in situ hybridization, PCR-based landmark unique gene, and intron targeting markers. Our results showed that TA3681 is a wheat- Thinopyrum intermedium 1St disomic addition line, TA5566 is a wheat- Thinopyrum intermedium non-Robertsonian translocation line carrying two pairs of 3A-7J s translocation chromosomes, and that TA5567 is a wheat- Thinopyrum intermedium non-Robertsonian translocation line carrying a pair of 3A-7J s translocation chromosomes. We developed 13, 36, and 15 Thinopyrum intermedium chromosome-specific markers for detecting the introgressed Thinopyrum chromosomes in TA3681, TA5566, and TA5567, respectively. Stem rust assessment revealed that TA3681 exhibited a high level of seedling resistance to Chinese-prevalent Puccinia graminis f. sp. tritici pathotypes, and both TA5566 and TA5567 were highly resistant to Australian P . graminis f. sp. tritici pathotypes, indicating that Thinopyrum intermedium chromosomes 1St and 7J s might carry new stem rust resistance genes. Therefore, the new identified introgression lines may be useful for improving wheat stem rust resistance.