title: SLOW WALKER2, a NOC1/MAK21 homologue, is essential for coordinated cell cycle progression during female gametophyte development in Arabidopsis.
abstract: Morphogenesis requires the coordination of cell growth, division, and cell differentiation. Female gametogenesis in flowering plants, where a single haploid spore undergoes continuous growth and nuclear division without cytokinesis to form an eight-nucleate coenocytic embryo sac before cellularization, provides a good system to study the genetic control of such processes in multicellular organisms. Here, we report the characterization of an Arabidopsis (Arabidopsis thaliana) female gametophyte mutant, slow walker2 (swa2), in which the progression of the mitotic cycles and the synchrony of female gametophyte development were impaired, causing an arrest of female gametophytes at the two-, four-, or eight-nucleate stage. Delayed pollination test showed that a portion of the mutant ovules were able to develop into functional embryo sacs and could be fertilized. SWA2 encodes a nucleolar protein homologous to yeast NUCLEOLAR COMPLEX ASSOCIATED PROTEIN1 (NOC1)/MAINTENANCE OF KILLER21 that, together with NOC2, is involved in preribosome export from the nucleus to the cytoplasm. Similarly, SWA2 can physically interact with a putative Arabidopsis NOC2 homologue. SWA2 is expressed ubiquitously throughout the plant, at high levels in actively dividing tissues and gametophytes. Therefore, we conclude that SWA2 most likely plays a role in ribosome biogenesis that is essential for the coordinated mitotic progression of the female gametophyte.
authors.affiliation: Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.forename: Naiyou
authors.initials: N
authors.lastname: Liu
authors.forename: Dongqiao
authors.initials: D
authors.lastname: Shi
authors.forename: Xinran
authors.initials: X
authors.lastname: Li
authors.forename: Zuoshun
authors.initials: Z
authors.lastname: Tang
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Venkatesan
authors.initials: V
authors.lastname: Sundaresan
authors.forename: Wei-Cai
authors.initials: WC
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics*; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics; D005718:Gametogenesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000235:genetics; D007381:Intermediate Filament Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D056771:Ovule / Q000254:growth & development*; D018749:RNA, Plant / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D007381:Intermediate Filament Proteins; C115485:MAK21 protein, S cerevisiae; D018749:RNA, Plant; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C114142:tip1 protein, S pombe