A DEAD-Box Protein, AtRH36, is Essential for Female Gametophyte Development and is Involved in rRNA Biogenesis in Arabidopsis

Abstract

DEAD-box RNA helicases are involved in RNA metabolism, including pre-mRNA splicing, ribosome biogenesis, RNA decay and gene expression. In this study, we identified 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 fluorescent 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.

Ribosomal Protein RPL27a Promotes Female Gametophyte Development in a Dose-Dependent Manner

“…By comparison, ribosome biogenesis mutants swa1, swa2, swa3/atrh36, and nof1 that are female gametophyte lethal initiate megagametogenesis but do not complete mitotic cell divisions (Shi et al, 2005;Li et al, 2009;Harscoët et al, 2010;Huang et al, 2010;Liu et al, 2010). In swa1, defective embryo sacs are asynchronous with development arrested at the functional megaspore stage or at two, four, or eight nuclei stages of development.…”

“…SLOW WALKER1 (SWA1), SWA3/Arabidopsis thaliana RNA HELICASE36 (AtRH36), and NUCLEOLAR FACTOR1 (NOF1) encode nucleolar-localized proteins required for processing 18S pre-rRNA (Shi et al, 2005;Harscoët et al, 2010;Huang et al, 2010;Liu et al, 2010). Mutations in other genes encoding proteins predicted to be involved in pre-rRNA processing and ribosome maturation or in export of preribosomes from the nucleus to the cytoplasm also reduce female fertility (Li et al, 2009(Li et al, , 2010Chantha et al, 2010;Wang et al, 2012;Missbach et al, 2013).…”

Nuclear Ribosome Biogenesis Mediated by the DIM1A rRNA Dimethylase Is Required for Organized Root Growth and Epidermal Patterning in Arabidopsis

“…sites (Shi et al, 2005;Huang et al, 2010) (Figure 4A). The results show that similar levels of unprocessed 59 external transcribed spacer (ETS) are detected from wild-type and dim1A seedling tissue ( Figure 4B), suggesting that the dim1A mutation affects 18S rRNA dimethylation, but not pre-rRNA processing.…”

Spatial and Temporal Expression of Cold-responsive DEAD-box RNA Helicases Reveals their Functional Roles During Embryogenesis in Arabidopsis thaliana

“…upf1 mutants contain high levels of aberrant mRNAs and exhibit abnormalities in seed development (Yoine et al 2006). AtRH36 has been shown to be essential for mitotic division during female gametogenesis and is important in 18S rRNA processing in A. thaliana (Huang et al 2010). The knockout allele cannot be transmitted to progeny seed through the female parent, indicating a female gametophyte lethal phenotype.…”