title: Arabidopsis INCURVATA2 Regulates Salicylic Acid and Abscisic Acid Signaling, and Oxidative Stress Responses.
abstract: Epigenetic regulatory states can persist through mitosis and meiosis, but the connection between chromatin structure and DNA replication remains unclear. Arabidopsis INCURVATA2 (ICU2) encodes the catalytic subunit of DNA polymerase α, and null alleles of ICU2 have an embryo-lethal phenotype. Analysis of icu2-1, a hypomorphic allele of ICU2, demonstrated that ICU2 functions in chromatin-mediated cellular memory; icu2-1 strongly impairs ICU2 function in the maintenance of repressive epigenetic marks but does not seem to affect ICU2 polymerase activity. To better understand the global function of ICU2 in epigenetic regulation, here we performed a microarray analysis of icu2-1 mutant plants. We found that the genes up-regulated in the icu2-1 mutant included genes encoding transcription factors and targets of the Polycomb Repressive Complexes. The down-regulated genes included many known players in salicylic acid (SA) biosynthesis and accumulation, ABA signaling and ABA-mediated responses. In addition, we found that icu2-1 plants had reduced SA levels in normal conditions; infection by Fusarium oxysporum induced SA accumulation in the En-2 wild type but not in the icu2-1 mutant. The icu2-1 plants were also hypersensitive to salt stress and exogenous ABA in seedling establishment, post-germination growth and stomatal closure, and accumulated more ABA than the wild type in response to salt stress. The icu2-1 mutant also showed high tolerance to the oxidative stress produced by 3-amino-1,2,4-triazole (3-AT). Our results uncover a role for ICU2 in the regulation of genes involved in ABA signaling as well as in SA biosynthesis and accumulation.
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Micol-Ponce
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain.
authors.forename: Ana Belén
authors.initials: AB
authors.lastname: Sánchez-García
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Plant Industry, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Qian
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Plant Industry, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: José María
authors.initials: JM
authors.lastname: Barrero
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Micol
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain mrponce@umh.es.
authors.forename: María Rosa
authors.initials: MR
authors.lastname: Ponce
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000640:Amitrole / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004256:DNA Polymerase I / Q000378:metabolism*; D005670:Fusarium / Q000378:metabolism; D018384:Oxidative Stress; D010937:Plant Growth Regulators / Q000378:metabolism; D054046:Plant Stomata / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D014157:Transcription Factors; D000040:Abscisic Acid; C525567:INCURVATA2 protein, Arabidopsis; D004256:DNA Polymerase I; D020156:Salicylic Acid; D000640:Amitrole
keywords: ABA; Arabidopsis thaliana; DNA polymerase α catalytic subunit; Oxidative stress; SA