An RNase R Family Functions in Ribosomal RNA Processing in Chloroplasts of Arabidopsis

Abstract

Gene expression of chloroplast is dependent on a large numbers of nuclear-encoded factors. To determine such nuclear-encoded factors for chloroplast gene expression, we isolated high chlorophyll fluorescence mutants of Arabidopsis. Among 59 mutants, a 2627-2 had a T-DNA insertion in a gene encoding an RNase R family member with a putative targeting signal to chloroplasts. Our RNA blot analysis showed that mutant 2627-2 had an impaired processing of ribosomal, and the significant reduction in ribosomal RNA in chloroplasts, suggesting the RNase functions in the maturation of chloroplast ribosomal RNA. The levels of some chloroplasts RNA were higher in 2627-2 than in the wild type, which is possibly due to the transcription rate regulated by nuclear-encoded RNA polymerase as secondary effects of the reduced rRNA levels.