Molecular cytogenetic identification of a wheat–Psathyrostachys huashanica Keng 5Ns disomic addition line with stripe rust resistance

We developed a new stripe rust resistant line of common wheat–Psathyrostachys huashanica Keng (2n = 2x = 14, NsNs) from a cross between wheat cv. 7182 and P. huashanica via embryo culture, and we refer to this line as 3-8-10-2. We characterized this new line by cytology, genomic in situ hybridization (GISH), EST-SSR, EST-STS, and disease resistance screening. GISH using P. huashanica genomic DNA as the probe indicated that a pair of Ns chromosomes with strong hybridization signals was introduced into 3-8-10-2. We screened 255 EST-SSR and EST-STS multiple-loci markers from seven wheat homoeologous groups in the parent lines. Of these, 90 markers were polymorphic with a polymorphism frequency of 40 %, while two EST-SSR markers and six EST-STS markers located on wheat chromosome group 5 produced specific bands in P. huashanica and 3-8-10-2, respectively. This suggested that the introduced Ns chromosome pair belonged to homoeologous group 5, which was identified using new genome-specific markers. After inoculation with stripe rust isolates, 3-8-10-2 exhibited stripe rust resistance that probably originated from its P. huashanica parent. 3-8-10-2 can be used as a donor source for introducing novel disease resistance genes into wheat during breeding programs with the assistance of molecular and cytogenetic markers. Moreover, 3-8-10-2 had improved agronomic characteristics compared with its parents. Therefore, the addition line could be exploited as an important bridge for wheat breeding and chromosome engineering.