title: Mutation in the catalytic subunit of DNA polymerase alpha influences transcriptional gene silencing and homologous recombination in Arabidopsis.
abstract: REPRESSOR OF SILENCING 1 (ROS1) encodes a DNA demethylase that actively removes DNA methylation. Mutation in ROS1 leads to transcriptional gene silencing of a T-DNA locus that contains two genes, RD29A-LUC and 35S-NPTII, originally expressed in the C24 wild type. These units have different silencing regulation mechanisms: the former mechanism is dependent on small interfering RNA (siRNA)-directed DNA methylation, but the latter is not. We studied the latter gene silencing mechanism by screening the suppressors of the ros1 mutant using the silenced 35S-NPTII as a selection marker gene. The polalpha/incurvata2 (icu2) gene was isolated as one ros1 suppressor because its mutation leads to the reactivation of the silenced 35S-NPTII gene. POLalpha/ICU2 encodes a catalytic subunit of DNA polymerase alpha. Mutation of POLalpha/ICU2 did not affect DNA methylation, but reduced histone H3 Lys9 dimethylation (H3K9me2) modification in the 35S promoter. The polalpha mutation also influences the development of the shoot apical meristem, and delays the G2/M phase with high expression of a G2/M marker gene CycB1;1:GUS. Furthermore, the frequency of homologous recombination is greater in the polalpha/icu2 mutant than in the C24 wild type. Our results suggest that DNA polymerase alpha is involved in mediating epigenetic states and in DNA homologous recombination in Arabidopsis.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Xiaozhi
authors.initials: X
authors.lastname: Ren
authors.forename: Haibo
authors.initials: H
authors.lastname: Yin
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Ran
authors.initials: R
authors.lastname: Xia
authors.forename: Youqun
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Gong
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D004256:DNA Polymerase I / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011995:Recombination, Genetic / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; C471271:ROS1 protein, Arabidopsis; C525567:INCURVATA2 protein, Arabidopsis; D004256:DNA Polymerase I