title: Enzyme activities of Arabidopsis inositol polyphosphate kinases AtIPK2α and AtIPK2β are involved in pollen development, pollen tube guidance and embryogenesis.
abstract: Inositol polyphosphate kinase (IPK2) is a key component of inositol polyphosphate signaling. There are two highly homologous inositol polyphosphate kinases (AtIPK2α and AtIPK2β) in Arabidopsis. Previous studies that overexpressed or reduced the expression of AtIPK2α and AtIPK2β revealed their roles in auxiliary shoot branching, abiotic stress responses and root growth. Here, we report that AtIPK2α and AtIPK2β act redundantly during pollen development, pollen tube guidance and embryogenesis. Single knock-out mutants of atipk2α and atipk2β were indistinguishable from the wild type, whereas the atipk2α atipk2β double mutant could not be obtained. Detailed genetic and cytological investigations showed that the mutation of AtIPK2α and AtIPK2β resulted in severely reduced transmission of male gametophyte as a result of abnormal pollen development and defective pollen tube guidance. In addition, the early embryo development of the atipk2α atipk2β double mutant was also aborted. Expressing either catalytically inactive or substrate specificity-altered variants of AtIPK2β could not rescue the male gametophyte and embryogenesis defects of the atipk2α atipk2β double mutant, implying that the kinase activity of AtIPK2 is required for pollen development, pollen tube guidance and embryogenesis. Taken together, our results provide genetic evidence for the requirement of inositol polyphosphate signaling in plant sexual reproduction.
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072, China.
authors.forename: Huadong
authors.initials: H
authors.lastname: Zhan
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072, China.
authors.forename: Yujiao
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: College of Life and Environment Sciences, Shanghai Normal University, Shanghai, 200234, China.
authors.forename: Zhongnan
authors.initials: Z
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, Hubei, 430072, China.
authors.forename: Huijun
authors.initials: H
authors.lastname: Xia
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D053205:Pollen Tube / Q000378:metabolism* / Q000502:physiology; D012639:Seeds / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C000607351:IPK2 alpha protein, Arabidopsis; C523083:IPK2beta protein, Arabidopsis; D017853:Phosphotransferases (Alcohol Group Acceptor)
keywords: Arabidopsis thaliana; AtIPK2α and AtIPK2β; embryogenesis; inositol polyphosphate kinase; kinase activity; pollen development; pollen tube guidance