First published online February 24, 2009; 10.1105/tpc.108.061549
The Plant Cell 21:386-402 (2009)
© 2009 American Society of Plant Biologists
OPEN ACCESS ARTICLE
Epigenetic Regulation, Somatic Homologous Recombination, and Abscisic Acid Signaling Are Influenced by DNA Polymerase Mutation in Arabidopsis[W],[OA]
Haibo Yina,
Xia Zhanga,b,
Jun Liua,
Youqun Wanga,
Junna Hea,
Tao Yanga,
Xuhui Honga,
Qing Yanga and
Zhizhong Gonga,c,d,1
a State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
b Biotechnology Center of Shandong Academy of Science, Jinan, 250014, China
c China Agricultural University-University of California-Riverside Center for Biological Sciences and Biotechnology, Beijing, 100193, China
d National Center for Plant Gene Research, Beijing, 100193, China
1 Address correspondence to gongzz{at}cau.edu.cn.
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 . 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) 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.
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