Fine mapping of the tiller inhibition gene TIN5 in Triticum urartu.

KEY MESSAGE: A tiller inhibition gene TIN5 was delimited to an approximate 2.1 Mb region on chromosome Tu7 that contains 24 annotated genes. Grain yield in wheat (Triticum aestivum L.) is a polygenic trait representing many developmental processes and their interactions with the environments. Among them, tillering capacity is an important agronomic trait for plant architecture and grain yield, but the genetic basis of tiller formation in wheat remains largely unknown. In this study, we identified a tiller inhibition 5 (tin5) mutant from ethyl methane sulfonate treated G1812 (Triticum urartu Thumanjan ex Gandilyan). A mapping population was constructed with tin5/G3146. Based on the sequence differences between G1812 and G3146, large insertions and deletions (≥ 5 bp) were selected and verified, and a skeleton physical map was constructed with genome-wide 168 polymorphic InDel markers. Genetic analysis revealed that the low-tiller phenotype was controlled by a single recessive locus, which we named TIN5. This locus was mapped to a 2.1-Mb region that contained 24 annotated genes on chromosome Tu7. Among these annotated genes, only TuG1812G0700004539 showed a non-synonymous polymorphism between tin5 and the wild type. Our finding will facilitate its map-based cloning and pave the way for an in-depth analysis of the underlying genetic basis of tiller formation and regulation patterns.