Abstract

Photosynthesis sustains the majority of life on Earth and in plants it is performed in organelles known as chloroplasts. Chloroplast biogenesis is controlled by nucleus-encoded transcription factors. Despite decades of research aimed at understanding the underlying genetic network, our knowledge about chloroplast biogenesis remains very limited. With the exception of Golden2-like (GLK) and the GATA families of transcription factors no other regulators are known. Although GLK is considered a master regulator of chloroplast biogenesis and photosynthesis, the presence of chlorophyll in glk mutants indicates that an additional pathway is likely to control chloroplast biogenesis.

We used the bryophyte Marchantia polymorpha, which , has a streamlined genome, as a platform to identify novel regulators of chloroplast biogenesis. We successfully identified RR-MYBs as a new class of transcription factors for the control of chloroplast biogenesis and photosynthesis. Importantly, we discovered that this role is conserved in the angiosperm Arabidopsis thaliana, implying that its function might be ancestral.