Development and Characterization of Novel St-R Translocation Triticale from a Trigeneric Hybrid

Triticale (×Triticosecale Wittmack), a synthetic hybrid of wheat (Triticum spp.) and rye (Secale cereale), is a valuable dual-purpose crop for its high yield and stress tolerance. Introducing beneficial alien chromatin is crucial for expanding genetic diversity and improving cultivars. This study aimed to introduce Thinopyrum intermedium St genome chromatin into hexaploid triticale via trigeneric hybridization to develop novel germplasm. Six stable lines were selected from crosses between an octoploid wheat-Th. intermedium partial amphiploid line Maicao 8 and a hexaploid triticale cultivar Hashi 209. Agronomic traits were evaluated over two cropping seasons, revealing that the translocation lines exhibited superior agronomic performance compared to the parental triticales. These lines showed longer spikes, higher tiller numbers, and increased grain protein content, without compromising thousand-kernel weight. Cytogenetic analysis using sequential multicolor genomic in situ hybridization (smGISH), fluorescence in situ hybridization (FISH), and oligonucleotide probes, alongside validation with species-specific molecular markers, identified all six lines as St-R terminal translocation lines containing 14 rye chromosomes. Three lines carried a small terminal St segment on chromosome 1R, while the other three carried St segments on both 1RL and 4RS chromosomes. This work demonstrates that trigeneric hybridization is an effective strategy for inducing intergeneric recombination between Thinopyrum intermedium and rye chromosomes, leading to stable, small-segment terminal translocations. The developed St-R translocation lines represent a novel and valuable germplasm resource for enriching genetic diversity and breeding improved triticale cultivars with enhanced yield and quality traits.