Molecular cytogenetic identification of a wheat - Thinopyrum ponticum substitution line with stripe rust resistance

Thinopyrum ponticum (Th. ponticum) (2n = 10x = 70) is an important breeding material with excellent resistance and stress tolerance. In this study, we characterized the derivative line CH1113-B13-1-1-2-1 (CH1113-B13) through cytological, morphological, genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), expressed sequence tag (EST), and PCR-based landmark unique gene (PLUG) marker analysis. The GISH analysis revealed that CH1113-B13 contained 20 pairs of common wheat chromosomes and one pair of J^St genomic chromosomes. Linkage analysis of Th. ponticum using seven EST and seven PLUG markers indicated that the pair of alien chromosomes belonged to the seventh homeologous group. Nulli-tetrasomic and FISH analysis revealed that wheat 7B chromosomes were absent in CH1113-B13; thus, CH1113-B13 was identified as a 7J^St (7B) substitution line. Finally, adult-stage CH1113-B13 exhibited immunity to wheat stripe rust. This substitution line is therefore a promising germplasm resource for wheat breeding.