Development and identification of wheat–Psathyrostachys huashanica 7NsS small segment translocation lines with early heading date gene Ehd-7Ns

Psathyrostachys huashanica Keng ex P. C. Kuo (2n = 2x = 14, NsNs), a wild relative of wheat, represents a valuable germplasm resource for genetic improvement of wheat. We previously confirmed that a chromosome 7Ns from P. huashanica carries genes that accelerate heading and maturity in wheat. Here, we developed three small segment translocation lines (T7NsS-2BL·2BS, T7NsS-1AS·1AL#1, and T7NsS-1AS·1AL#2) along with one additional small segment translocation line (T7NsS-7BS·7BL) through ⁶⁰Co-γ irradiation, identified using genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and liquid chip array analyses. Our findings demonstrated that chromosome 7NsS contained a major early heading date gene, tentatively designated Ehd-7Ns, which was mapped to an approximate 31.45 Mb region, corresponding to the short arm of wheat chromosome 7A (IWGSC RefSeq v1.0). The T7NsS-1AS·1AL#2 line exhibited no significant yield penalty and possessed superior agronomic traits relative to the other translocation lines in the field, making it a promising pre-breeding donor for breeding early maturing wheat. Furthermore, 21 specific Kompetitive Allele Specific PCR (KASP) markers were developed based on transcriptome data, enabling effective tracing of alien chromosomal segments carrying this source of Ehd-7Ns in marker-assisted breeding. Collectively, these newly developed translocation lines and specific KASP markers will facilitate the transfer and utilization of favorable genes from P. huashanica chromosome 7Ns in future wheat breeding programs.