Brassinosteroid signaling mutant bpg2

Abstract

We tried to screen new brassinosteroid signaling mutants from Arabidopsis activation tag lines and isolated two mutants.
In the light, Brz treated plant showed dark green leaves as compared to non-treated leaves. bpg2 was screened as pale green phenotype with Brz in the light. A T-DNA insertion site of bpg2 mutant was identified in an ORF of novel GTPase homologous gene that were conserved in many organisms. Expression of BPG2 gene was induced by light and Brz, and was highest in greening organs. BPG2-GFP fusion protein analysis revealed that BPG2 located in chloroplasts. In bpg2 mutant, abnormal chloroplast rRNA processing and protein accumulation were observed. These results might suggest that BPG2 plays an important role of posttranscriptional and/or translational regulation for chloroplast genome on brassinosteroid signaling.