title: AUXIN RESPONSE FACTOR17 is essential for pollen wall pattern formation in Arabidopsis.
abstract: In angiosperms, pollen wall pattern formation is determined by primexine deposition on the microspores. Here, we show that AUXIN RESPONSE FACTOR17 (ARF17) is essential for primexine formation and pollen development in Arabidopsis (Arabidopsis thaliana). The arf17 mutant exhibited a male-sterile phenotype with normal vegetative growth. ARF17 was expressed in microsporocytes and microgametophytes from meiosis to the bicellular microspore stage. Transmission electron microscopy analysis showed that primexine was absent in the arf17 mutant, which leads to pollen wall-patterning defects and pollen degradation. Callose deposition was also significantly reduced in the arf17 mutant, and the expression of CALLOSE SYNTHASE5 (CalS5), the major gene for callose biosynthesis, was approximately 10% that of the wild type. Chromatin immunoprecipitation and electrophoretic mobility shift assays showed that ARF17 can directly bind to the CalS5 promoter. As indicated by the expression of DR5-driven green fluorescent protein, which is an synthetic auxin response reporter, auxin signaling appeared to be specifically impaired in arf17 anthers. Taken together, our results suggest that ARF17 is essential for pollen wall patterning in Arabidopsis by modulating primexine formation at least partially through direct regulation of CalS5 gene expression.
authors.affiliation: College of Tourism, Shanghai Normal University, Shanghai 200234, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Tian
authors.forename: Ming-Xi
authors.initials: MX
authors.lastname: Sun
authors.forename: Xue-Yong
authors.initials: XY
authors.lastname: Huang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: Yue-Feng
authors.initials: YF
authors.lastname: Guan
authors.forename: Qi-Shi
authors.initials: QS
authors.lastname: Jia
authors.forename: Zhong-Nan
authors.initials: ZN
authors.lastname: Yang
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D017930:Genes, Reporter; D005936:Glucans / Q000235:genetics / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D008540:Meiosis; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D051479:Plant Infertility / Q000235:genetics; D030821:Plants, Genetically Modified; D011058:Pollen / Q000254:growth & development / Q000502:physiology*; D053205:Pollen Tube / Q000235:genetics / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: C506720:ARF17 protein, Arabidopsis; D029681:Arabidopsis Proteins; D005936:Glucans; D007210:Indoleacetic Acids; D014157:Transcription Factors; C048306:callose; C585562:CalS5 protein, Arabidopsis; D005964:Glucosyltransferases