Study on the involvement of SDG7 in FLC transcriptional activation in Arabidopsis embryos

Flowering is a pivotal developmental transition in the plant life cycle. In Arabidopsis thaliana (L.) Heynh., FLOWERING LOCUS C (FLC) is a central regulator of the vernalization pathway and is transcriptionally reactivated in the next generation. SET DOMAIN GROUP 7 (SDG7) encodes a histone methyltransferase associated with H3K36me3 modification, but whether SDG7 contributes to FLC reactivation during early embryonic development remains unclear. This study investigated the role of SDG7 in embryonic FLC activation. Transcript analysis and fluorescence-based observations in siliques revealed that SDG7 was expressed in developing embryos. Loss-of-function sdg7 mutants exhibited early flowering phenotypes, accompanied by reduced FLC transcript levels in seedlings, indicating that SDG7 regulates flowering time through positive control of FLC expression. FLC promoter-driven GUS staining and expression analyses further demonstrated that SDG7 promoted FLC activation during embryogenesis. Although FLC expression, regulated by FRIGIDA (FRI), varied significantly among ecotypes, transcript-level assays confirmed that FRI did not affect SDG7 expression.