The bRPS6-Family Protein RFC3 Prevents Interference by the Splicing Factor CFM3b during Plastid rRNA Biogenesis in .

Plastid ribosome biogenesis is important for plant growth and development. REGULATOR OF FATTY ACID COMPOSITION3 (RFC3) is a member of the bacterial ribosomal protein S6 family and is important for lateral root development. dramatically reduces the plastid rRNA level and produces lateral roots that lack stem cells. In this study, we isolated a () mutant that enabled recovery of most mutant phenotypes, including abnormal primary and lateral root development and reduced plastid rRNA level. Northern blotting showed that immature and mature plastid rRNA levels were reduced, with the exception of an early 23S rRNA intermediate, in mutants. These changes were recovered in mutants, but a second defect in the processing of 16S rRNA appeared in this line. The results suggest that mutants may be defective in at least two steps of plastid rRNA processing, one of which is specifically affected by the mutation. mutants had a mutation in (), which encodes a plastid-localized splicing factor. A bimolecular fluorescence complementation (BiFC) assay suggested that RFC3 and SPRT2/CFM3b interact with each other in plastids. These results suggest that RFC3 suppresses the nonspecific action of SPRT2/CFM3b and improves the accuracy of plastid rRNA processing.