Umeå University's logo

Conifers pose challenges for breeding programs due to their extended vegetative phases. Despite the critical role of APETALA2 (AP2) in regulating phase transitions, the AP2/ERF superfamily remains largely unexplored in gymnosperms. Here, the first genome-wide analysis of the AP2/ERF superfamily in a conifer, Larix kaempferi (Japanese larch) is presented, and 374 members were identified. Among all eight paralogs, four euAP2 lineage genes, TARGET OF EATs (TOEs), exhibit age-decreased expression patterns. Functional characterization of LkTOE1-2 demonstrates its involvement in somatic embryogenesis and seed germination. Importantly, the RUBY reporter system confirmed an enhanced promoter activity in somatic embryo maturation. Over-expression of LkTOE1-2 in Arabidopsis accelerates seed germination by 23.77%, bolting by 6.93%, and flowering by 5.92%. This study provides not only an expanded genomic resource for gymnosperms but also a candidate gene (LkTOE1-2) to shorten the juvenile phase of larch via molecular breeding.