MYB-related transcription factors control chloroplast biogenesis
Eftychios Frangedakis, Nataliya E. Yelina, Kumari Billakurthi, Lei Hua, Tina B. Schreier, Patrick Dickinson, Marta Tomaselli, Jim Haseloff, Julian M. Hibberd
Abstract
Chloroplast biogenesis is dependent on master regulators from the GOLDEN2-LIKE (GLK) family of transcription factors. However, glk mutants contain residual chlorophyll, indicating that other proteins must be involved. Here, we identify MYB-related transcription factors as regulators of chloroplast biogenesis in the liverwort Marchantia polymorpha and angiosperm Arabidopsis thaliana . In both species, double-mutant alleles in MYB -related genes show very limited chloroplast development, and photosynthesis gene expression is perturbed to a greater extent than in GLK mutants. Genes encoding enzymes of chlorophyll biosynthesis are controlled by MYB-related and GLK proteins, whereas those allowing CO 2 fixation, photorespiration, and photosystem assembly and repair require MYB-related proteins. Regulation between the MYB-related and GLK transcription factors appears more extensive in A. thaliana than in M. polymorpha . Thus, MYB -related and GLK genes have overlapping as well as distinct targets. We conclude that MYB-related and GLK transcription factors orchestrate chloroplast development in land plants.