Induced Pib Expression and Resistance to Magnaporthe grisea are Compromised by Cytosine Demethylation at Critical Promoter Regions in Rice

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...

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Bibliographic Details
Published in:Journal of integrative plant biology 2011-10, Vol.53 (10), p.814-823
Main Authors: Li, Yuan, Xia, Qiong, Kou, Hongping, Wang, Dan, Lin, Xiuyun, Wu, Ying, Xu, Chunming, Xing, Shaochen, Liu, Bao
Format: Article
Language:English
Subjects:
Azacitidine - pharmacology
binding sites
blast-resistance
cultivars
cytosine
Cytosine - metabolism
disease resistance
Disease Resistance - drug effects
Disease Resistance - genetics
DNA methylation
DNA Methylation - genetics
gene expression
Gene Expression Regulation, Plant - drug effects
genes
Genes, Plant
induced Pib expression
Magnaporthe - drug effects
Magnaporthe - physiology
Magnaporthe grisea
Oryza - drug effects
Oryza - genetics
Oryza - immunology
Oryza - microbiology
pathogens
PIB
Plant Diseases - genetics
Plant Diseases - immunology
Plant Diseases - microbiology
Plant Proteins - genetics
Plant Proteins - metabolism
promoter regions
Promoter Regions, Genetic
rice
Sequence Analysis, DNA
去甲基化
抗稻瘟病
核苷酸结合位点
水稻品种
真菌病原体
胞嘧啶
诱导表达
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Summary: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.
ISSN:1672-9072
1744-7909
DOI:10.1111/j.1744-7909.2011.01070.x