A DEAD-box protein, AtRH36, is essential for female gametophyte development and is involved in rRNA biogenesis in Arabidopsis

DEAD-box RNA helicases are involved in RNA metabolism, including pre-mRNA splicing, ribosome biogenesis, RNA decay and gene expression. In this study, we identifi ed a homolog of the RH36 gene, AtRH36 , which encodes a DEAD-box protein in Arabidopsis thaliana . The gene was expressed ubiquitously throughout the plant. The AtRH36 fused to green fl uorescent protein was localized in the nucleus. Homozygosity for the Arabidopsis atrh36 mutants, atrh36-1 and atrh36-2 , could not be obtained. Progeny of selfed Arabidopsis atrh36 heterozygote plants were obtained at a heterozygote to wild-type ratio of 1 : 1, which suggested that the AtRH36 gene was involved in gametogenesis. Therefore, we performed a reciprocal cross to determine whether AtRH36 was involved in female gametophyte development. Female gametogenesis was delayed in atrh36-1 , and asynchronous development of the female gametophytes was found within a single pistil. Knock-down of AtRH36 gave a pleiotropic phenotype and led to the accumulation of unprocessed 18S pre-rRNA. These results suggest that AtRH36 is essential for mitotic division during female gametogenesis and plays an important role in rRNA biogenesis in Arabidopsis.