Molecular cytogenetic and disease resistance characterization of the wheat- Psathyrostachys huashanica disomic substitution line 16DH25-7

<italic>Psathyrostachys huashanica</italic> Keng (2<italic>n</italic> = 2<italic>x</italic> = 14, NsNs), a valuable germplasm resource in the tertiary gene pool of wheat, exhibits remarkable resistance to biotic stresses such as powdery mildew and stripe rust, making it highly valuable for wheat genetic improvement. In this study, a derivative line, 16DH25-7, exhibiting resistance to both powdery mildew and stripe rust, was selected from the progeny of the wheat-<italic>P. huashanica</italic> heptaploid H8911 and durum wheat D4286. To elucidate the genetic background of this material, cytogenetic analysis, fluorescence <italic>in situ</italic> hybridization (FISH), liquid-phase chip technology, and molecular marker analysis were used to characterize its chromosomal composition. Cytogenetic analysis revealed that 16DH25-7 had a chromosome number of 2<italic>n</italic> = 42. FISH analysis showed that it carried two <italic>P. huashanica</italic> Ns chromosomes and simultaneously lacked both wheat 5D chromosomes. Combined analysis using molecular markers and SNP chip data confirmed that the missing 5D chromosomes were replaced by <italic>P. huashanica</italic> 5Ns chromosomes, indicating that 16DH25-7 is a wheat-<italic>P. huashanica</italic> 5Ns (5D) disomic substitution line. Agronomic evaluation demonstrated that 16DH25-7 possesses desirable traits such as reduced plant height and increased tiller number. Disease resistance assessments confirmed its high resistance to both stripe rust and powdery mildew. In conclusion, 16DH25-7 represents an elite disease-resistant germplasm that holds great potential for wheat resistance breeding and genetic improvement.