Abstract
To determine essential nuclear-genes for chloroplast development, we systematically analyzed albino or pale green Arabidopsis thaliana mutants by using a two-component transposon system based on the Ac/Ds element of maize as mutagen.
In this meeting, we present phenotypes of the apg4 mutant, and discuss functions of the APG4 gene in chloroplast development. The apg4 mutant has white cotyledons and yellow or green variegated true leaves, fertility. We showed that apg4 has Ds inserted in promoter region of ribosome binding factor (RBFA) homologue. The mRNA expression of RBFA was not detected in apg4 by RT-PCR analysis. 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. Moreover, we found that the APG4 is involved in the processing of the pre-rRNA to form the mature 23S and 4.5S rRNAs.
