title: Epigenetic regulation, somatic homologous recombination, and abscisic acid signaling are influenced by DNA polymerase epsilon mutation in Arabidopsis.
abstract: Based on abscisic acid (ABA) inhibition of seed germination and seedling growth assays, we isolated an ABA overly sensitive mutant (abo4-1) caused by a mutation in the Arabidopsis thaliana POL2a/TILTED1(TIL1) gene encoding a catalytic subunit of DNA polymerase epsilon. The dominant, ABA-insensitive abi1-1 or abi2-1 mutations suppressed the ABA hypersensitivity of the abo4-1 mutant. The abo4/til1 mutation reactivated the expression of the silenced Athila retrotransposon transcriptional silent information (TSI) and the silenced 35S-NPTII in the ros1 mutant and increased the frequency of somatic homologous recombination (HR) approximately 60-fold. ABA upregulated the expression of TSI and increased HR in both the wild type and abo4-1. MEIOTIC RECOMBINATION11 and GAMMA RESPONSE1, both of which are required for HR and double-strand DNA break repair, are expressed at higher levels in abo4-1 and are enhanced by ABA, while KU70 was suppressed by ABA. abo4-1 mutant plants are sensitive to UV-B and methyl methanesulfonate and show constitutive expression of the G2/M-specific cyclin CycB1;1 in meristems. The abo4-1 plants were early flowering with lower expression of FLOWER LOCUS C and higher expression of FLOWER LOCUS T and changed histone modifications in the two loci. Our results suggest that ABO4/POL2a/TIL1 is involved in maintaining epigenetic states, HR, and ABA signaling in Arabidopsis.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Yin
authors.forename: Xia
authors.initials: X
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Youqun
authors.initials: Y
authors.lastname: Wang
authors.forename: Junna
authors.initials: J
authors.lastname: He
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Xuhui
authors.initials: X
authors.lastname: Hong
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Gong
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D002453:Cell Cycle / Q000235:genetics; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D019175:DNA Methylation; D004257:DNA Polymerase II / Q000235:genetics* / Q000502:physiology; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006657:Histones / Q000378:metabolism; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D009154:Mutation; D021122:Protein Subunits / Q000235:genetics / Q000502:physiology; D011995:Recombination, Genetic; D015398:Signal Transduction / Q000502:physiology*; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D006657:Histones; D021122:Protein Subunits; D000040:Abscisic Acid; D008741:Methyl Methanesulfonate; C507136:POL2a protein, Arabidopsis; D004257:DNA Polymerase II