title: CHR11, a chromatin-remodeling factor essential for nuclear proliferation during female gametogenesis in Arabidopsis thaliana.
abstract: Chromatin-remodeling factors regulate the establishment of transcriptional programs during plant development. Although 42 genes encoding members of the SWI2/SNF2 family have been identified in Arabidopsis thaliana, <10 have been assigned a precise function on the basis of a mutant phenotype, and none have been shown to play a specific role during the gametophytic phase of the plant life cycle. A. thaliana chromatin-remodeling protein 11 (CHR11) encodes an imitation of switch (ISWI)-like chromatin-remodeling protein abundantly expressed during female gametogenesis and embryogenesis in Arabidopsis. To determine the function of CHR11 in wild-type plants, we introduced a hairpin construct leading to the production of double-stranded RNA, which specifically degraded the endogenous CHR11 mRNA by RNA interference (RNAi). Transcription of the RNAi-inducing hairpin RNA was driven by either a constitutive cauliflower mosaic virus 35S promoter (CaMV35S) acting at most stages of the sporophytic phase or a newly identified specific promoter acting at the onset of the female gametophytic phase (pFM1). All adult transformants that constitutively lacked sporophytic CHR11 activity showed reduced plant height and small cotyledonary embryos with limited cell expansion. In contrast, RNAi lines in which CHR11 was specifically silenced at the onset of female gametogenesis (megagametogenesis) had normal height and embryo size but had defective female gametophytes arrested before the completion of the mitotic haploid nuclear divisions. These results show that CHR11 is essential for haploid nuclear proliferation during megagametogenesis and cell expansion during the sporophytic phase, demonstrating the functional versatility of SWI2/SNF2 chromatin-remodeling factors during both generations of the plant life cycle.
authors.affiliation: Laboratory of Reproductive Development and Apomixis, Department of Genetic Engineering, Centro de Investigación y de Estudios Avanzados-Unidad Irapuato, Apartado Postal 629, CP 36500, Irapuato, Guanajuato, Mexico.
authors.forename: Wilson
authors.initials: W
authors.lastname: Huanca-Mamani
authors.forename: Marcelina
authors.initials: M
authors.lastname: Garcia-Aguilar
authors.forename: Gloria
authors.initials: G
authors.lastname: León-Martínez
authors.forename: Ueli
authors.initials: U
authors.lastname: Grossniklaus
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Vielle-Calzada
mesh_terms: D000251:Adenosine Triphosphatases; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D048750:Cell Nucleus Division / Q000235:genetics / Q000502:physiology*; D048429:Cell Size; D042002:Chromatin Assembly and Disassembly / Q000235:genetics / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000502:physiology; D005718:Gametogenesis / Q000235:genetics / Q000502:physiology*; D006238:Haploidy; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D013170:Spores / Q000166:cytology / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae