Evolutionary and functional diversification of the DOG gene family in wheat (Triticum aestivum L.) and their roles in seed dormancy

Seed germination is a critical developmental process in plants, regulated by numerous genetic factors. The delay of germination 1 (DOG) gene family plays a pivotal role in controlling seed dormancy and germination in various species. However, as a heterohexaploid (AABBDD), the genome structure of wheat (Triticum aestivum L.) is complex, and the evolutionary process, functional differentiation and association mechanism of the DOG gene family with pre-harvest sprouting (PHS) have not been clarified, which urgently needs to be systematically analyzed. In this study, we conducted a comprehensive genome-wide analysis of the DOG gene family in wheat, identifying 53 DOG family members (designated TaDOG1 ~ TaDOG53). Phylogenetic analysis grouped wheat, Arabidopsis, rice, and maize DOG proteins into three clades, with wheat genes showing closer relationships to monocots (rice/maize) than to Arabidopsis. Structural diversity, including motif composition and exon-intron organization, suggested functional specialization: Group Ⅰ genes (8 ~ 12 exons) harbored more regulatory motifs, while Group Ⅲ (1 ~ 2 exons) had minimal structures. Promoter analysis revealed abundant ABA (22.52%) and MeJA responsive (36.56%) cis-elements, consistent with hormone-treated expression dynamics: Synteny analysis indicated segmental duplications drove wheat DOG expansion, with 124 intra-genomic events and strong synteny with rice/maize. RT-PCR showed distinct temporal patterns under ABA/MeJA, with early (1 ~ 4 h) and delayed (12 h) responders mediating phased signaling. RNA-seq shows TaDOG genes have diverse expressions in 8 wheat tissues, clustered into 4 groups with distinct expression and roles, with grain-specific genes (TaDOG3) highlighting potential roles in seed dormancy. It was found that there is a negative correlation between TaDOG3 expression and PHS rate, and TaDOG3 can be used as a marker gene to detect the degree of spike germination. This study systematically analyzed the evolutionary history and functional differentiation of the wheat TaDOG gene family, confirming that the TaDOG genes play a multi-level role in seed dormancy regulation through differentiated hormone response patterns and tissue expression characteristics. Among them, TaDOG3, as a potential molecular marker of PHS resistance, provides a theoretical basis and practical target for wheat anti-spike germination breeding.