Chlorophyllase is transcriptionally regulated by CsMYB308/ CsDOF3 in young leaves of tea plant

Chlorophyll contributes to tea coloration, which is an important factor in tea quality. Chlorophyll metabolism is induced by light, but the transcriptional regulation responsible for light-induced chlorophyll metabolism is largely unknown in tea leaves. Here, we characterized a chlorophyllase1 gene CsCLH1 from young tea leaves and showed it is essential for chlorophyll metabolism, using transient overexpression and silencing in tea leaves and ectopic overexpression in Arabidopsis. CsCLH1 was significantly induced by high light. The DOF protein CsDOF3, an upstream direct regulator of CsCLH1, was also identified. Acting as a nuclear-localized transcriptional factor, CsDOF3 responded for light and repressed CsCLH1 transcription and increased chlorophyll content by directly binding to the AAAG cis-element in the CsCLH1 promoter. CsDOF3 was able to physically interact with the R2R3-MYB transcription factor CsMYB308 and interfere with transcriptional activity of CsCLH1. In addition, CsMYB308 binds to the CsCLH1 promoter to enhance CsCLH1 expression and decrease chlorophyll content. CsMYB308 and CsDOF3 act as an antagonistic complex to regulate CsCLH1 transcription and chlorophyll in young leaves. Collectively, the study adds to the understanding of the transcriptional regulation of chlorophyll in tea leaves in response to light and provides a basis for improving the appearance of tea.

Automated summary

This study identified the key chlorophyll metabolism gene CsCLH1 in tea leaves and elucidated its regulatory mechanism. The DOF protein CsDOF3 was found to be an upstream direct regulator of CsCLH1, and the two proteins interacted to regulate chlorophyll synthesis in tea leaves.