Fine mapping and verification of a tiller inhibition gene in synthetic hexaploid wheat derivative

Tiller number is a pivotal agronomic trait governing wheat yield potential, yet its underlying genetic regulation remains insufficiently elucidated. Here, we report the map-based cloning of tin7, a major gene controlling tiller number in wheat. Using near-isogenic lines (NIL-H, high-tillering; NIL-L, low-tillering), we fine-mapped tin7. Eleven polymorphic markers genotyped 10,753 F₂ individuals, tin7 was mapped to a 400.61 kb physical interval in Chinese Spring genome, which contained 16 high-confidence genes in Chinese Spring (17 high-confidence genes in emmer wheat). Sequence and expression analyses identified TraesCS2B01G619900 (ortholog of emmer wheat TRIDC2BG090810) as the candidate for tin7, with NIL-L harboring a premature stop codon. Functional validation via EMS-induced and CRISPR/Cas9-mediated mutants confirmed its role: EMS mutants showed 67.90-80.25% tiller reduction, while CRISPR/Cas9 mutants in KN199 exhibited a significant reduction (37.31-62.88%). These findings confirm TraesCS2B01G619900 is tin7, regulating wheat tillering and providing a valuable genetic resource for yield improvement via molecular breeding.

The online version contains supplementary material available at 10.1007/s11032-026-01640-1.