CsMYB308 as a repressive transcription factor inhibits anthocyanin biosynthesis in tea plants

Anthocyanins in tea (Camellia sinensis) leaves enhance tea quality due to their unique health benefits. MYB transcription factors are crucial in regulating anthocyanin biosynthesis in various plant species. In this research, a typical R2R3 repressive transcription factor CsMYB308 was identified which includes an EAR motif that belongs to the SG4 subfamily and was localized in the nucleus. Antisense oligonucleotide (asODN)-mediated CsMYB308 silencing revealed that the anthocyanin synthesis of structural genes was up-regulated. Furthermore, DNA affinity purification sequencing (DAP-seq) screened downstream genes regulated by CsMYB308. Dual-luciferase reporter (DLR) results showed that CsMYB308 suppressed anthocyanin biosynthesis by regulating the transcriptional activity of CsF3'5'H, CsDFR, and CsANS and electrophoretic mobility shift assay (EMSA) proved the concrete binding sites. In addition, we elucidated the molecular mechanism of Zijuan accumulating anthocyanin at an optimal concentration by shading experiment in summer. The results could provide an agronomic strategy to enhance the utilization of fresh leaves in summer. This study also presented a new insight of the regulatory pathway involved in anthocyanin biosynthesis in tea plants.