title: Induced Pib Expression and Resistance to Magnaporthe grisea are Compromised by Cytosine Demethylation at Critical Promoter Regions in Rice.
abstract: Pib is a well-characterized rice blast-resistance gene belonging to the nucleotide binding site (NBS) and leucine-rich repeat (LRR) superfamily. Expression of Pib was low under non-challenged conditions, but strongly induced by the blast-causing fungal pathogen Magnaporthe grisea, thereby conferring resistance to the pathogen. It is generally established that cytosine methylation of the promoter-region often plays a repressive role in modulating expression of the gene in question. We report here that two critical regions of the Pib promoter were heavily CG cytosine-methylated in both cultivars studied. Surprisingly, induced expression of Pib by M. grisea infection did not entail its promoter demethylation, and partial demethylation by 5-azacytidine-treatment actually reduced Pib expression relative to wild-type plants. Accordingly, the blast disease-resistance was compromised in the 5'-azaC-treated plants relative to wild-type. In contrast, the disease susceptibility was not affected by the 5'-azaC treatment in another two rice cultivars that did not contain the Pib gene, ruling out effects of other R genes and non-specific genotoxic effects by the drug-treatment as a cause for the compromised Pib-conditioned blast-resistance. Taken together, our results suggest that promoter DNA methylation plays a novel enhancing role in conditioning high-level of induced expression of the Pib gene in times of M. grisea infection, and its conferred resistance to the pathogen.
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Xia
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Hongping
authors.initials: H
authors.lastname: Kou
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Xiuyun
authors.initials: X
authors.lastname: Lin
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Chunming
authors.initials: C
authors.lastname: Xu
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Shaochen
authors.initials: S
authors.lastname: Xing
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and The Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, ChinaDepartment of Agronomy, Jilin Agricultural University, Changchun 130118, ChinaCenter of Agribiotechnology, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
authors.forename: Bao
authors.initials: B
authors.lastname: Liu
mesh_terms: D001374:Azacitidine / Q000494:pharmacology; D003596:Cytosine / Q000378:metabolism*; D019175:DNA Methylation / Q000235:genetics*; D060467:Disease Resistance / Q000187:drug effects / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D020082:Magnaporthe / Q000187:drug effects / Q000502:physiology*; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D010940:Plant Proteins; D003596:Cytosine; D001374:Azacitidine