Identification and validation of a novel tiller inhibition locus (tin7) on chromosome 2BL in wheat

Tiller number is a key determinant of the number of spikes per plant, significantly influencing yield. Here, we identify and characterize a novel tiller inhibition line, N2496. Using an F₂ segregating population derived from crossing N2496 and CN16, we mapped this locus. The F₁ line demonstrated a high number of tillers, while the F₂ population exhibited segregated ratios of 3:1 in tiller number. BSR-Seq analysis indicated that only one locus controls tiller number, located on chromosome 2B (Chr. 2B). This genetic analysis confirmed the presence of a single recessive locus controlling the tiller inhibition trait within this population. Subsequently, we constructed a genetic map on Chr. 2B using a wheat 55 K single nucleotide polymorphism array. By combining recombinant analysis with the genotype and phenotype of the F_2-3 family, we identified and named a major and novel locus, tiller inhibition gene (tin7), mapped within a 2.43 cM interval. The influence of tin7 was verified across six different background populations all sharing N2496 as a common parent. Using new recombinant lines from these six populations, we further narrowed down the interval of tin7 to a genetic interval of 2.08 cM. Analysis of thousand grain weight and grain-related traits suggests that by regulating tiller number, tin7 holds the potential to increase yield in wheat. Our research provides access to a novel tiller number locus and available markers for regulating tiller number, which could be used in developing new cultivars with an optimal number of tillers.

The online version contains supplementary material available at 10.1007/s11032-025-01567-z.