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Protein Elicitor PemG1 from Magnaporthe grisea Induces Systemic Acquired Resistance (SAR) in Plants

October 2011 , Volume 24 , Number  10
Pages  1,239 - 1,246

Dong-Hai Peng,1 De-Wen Qiu,2 Li-Fang Ruan,1 Chen-Fei Zhou,1 and Ming Sun1

1State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; 2Institute of Plant Protection of Chinese Academy of Agricultural Sciences, Beijing 100081, China

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Accepted 20 June 2011.

Elicitors can stimulate defense responses in plants and have become a popular strategy in plant disease control. Previously, we isolated a novel protein elicitor, PemG1, from Magnaporthe grisea. In the present study, PemG1 protein expressed in and purified from Escherichia coli improved resistance of rice and Arabidopsis to bacterial infection, induced transient expression of pathogenesis-related (PR) genes, and increased accumulation of hydrogen peroxide in rice. The effects of PemG1 on disease resistance and PR gene expression were mobilized systemically throughout the rice plant and persisted for more than 28 days. PemG1-induced accumulation of OsPR-1a in rice was prevented by the calcium channel blockers LaCl3, BAPTA, EGTA, W7, and TFP. Arabidopsis mutants that are insensitive to jasmonic acid (JA) and ethylene showed increased resistance to bacterial infection after PemG1 treatment but PemG1 did not affect resistance of mutants with an impaired salicylic acid (SA) transduction pathway. In rice, PemG1 induced overexpressions of the SA signal-related genes (OsEDS1, OsPAL1, and OsNH1) but not the JA pathway-related genes (OsLOX2 and OsAOS2). Our findings reveal that PemG1 protein can function as an activator of plant disease resistance, and the PemG1-mediated systemic acquired resistance is modulated by SA- and Ca2+-related signaling pathways.

© 2011 The American Phytopathological Society