Genetic dissection of an extremely early heading mutant in Aegilops tauschii

The heading date is an important trait that affects crop adaptability and significantly affects crop yield. The discovery and functional understanding of genes related to heading are crucial for wheat breeding in various environments. Aegilops tauschii, the D-genome donor of wheat, serves as an important model for exploring genetic regulatory mechanisms in common wheat. In this study, extremely early heading mutants were identified after treatment with 0.4% ethyl methanesulfonate (EMS) and compared with the wild type. Genetic analysis revealed that a single recessive gene was responsible for early heading, and gene mapping revealed a mutation in a 10.3-Mb region on the short arm of chromosome 6D. Bulked segregant exon capture sequencing revealed a missense mutation within the highly conserved nucleotide-binding domain of AET6Gv20469900, which encodes a protein phosphatase 2C (PP2C). This gene was in the mapping interval and associated with early heading. Transcriptomic profiling and quantitative validation analyses suggest that PP2C likely modulates vernalization pathways, thereby affecting heading date. This work provides a novel genetic resource for breeding early heading wheat cultivars.