Regulation of chloroplast development by RPGE-GLK pairs

Abstract

Proper chloroplast formation is a very important development process for plants. The glk1/2 mutant which removed GLKs, major chloroplast development transcription factors, has a pale green leaf phenotype in Arabidopsis due to the lesion on chloroplasts. Our previous study showed that the overexpression of PIFs-induced RPGE have a pale green leaf phenotype. This study confirmed high level of negative correlation between RPGE and GLK. We confirmed the phenotypic similarities and strong correlations between RPGE-OX and glk1/2. It was found that RPGE binds to GLK-GCT region, where GLK forms homodimer or interacts with many other proteins. Also, RPGE inhibits the transcriptional activity of GLK, and disrupts the DNA binding of GLK. In addition, RPGE decreases the homodimer formation of GLK. The RPGE-GLK regulatory pair, which plays an important role in the chloroplast development, has been conserved from charophytes to land plants, and acts interspecipically between species. In particular, we identified that the RPGE-GLK regulatory pair plays a major role in certain light conditions, such as shade, in which PIFs are activated, using transcriptome analysis and ChIP assay.