Functional analysis of ribosome binding factor (RBFA) Homologue APG4(Albino or Pale Green 4) using Ac/Ds transposon system in Arabidopsis thaliana

Abstract

To determine essential nuclear-genes for chloroplast development, we systematically analyzed mutants by using a two-component transposon system based on the Ac/Ds. The apg4 mutant has white cotyledons and yellow or green variegated true leaves. White cotyledons had abnormal plastids that lacked internal membrane's structures and highly vacuolated. But their true leaves had normal plastids contained developed lamella structure and abnormal ones. We showed that the apg4 has Ds inserted in promoter region of RBFA homologue. The mRNA expression of RBFA was not detected in apg4 by RT-PCR analysis. It was previously reported that the RBFA, 30S ribosome-binding factor, is involved in the processing of the pre-rRNA to form the mature 16S rRNA in E.coli. We found that the APG4 is involved in the processing of the pre-rRNA to form the mature 23S and 4.5S rRNA and related accumulation of rrn16 transcripts.