Magnaporthe oryzae-Secreted Protein MSP1 Induces Cell Death and Elicits Defense Responses in Rice.

Yiming Wang, Jingni Wu, Sang Gon Kim, Kenichi Tsuda, Ravi Gupta, Sook-Young Park, Sun Tae Kim, Kyu Young Kang,

Molecular plant-microbe interactions : MPMI, January 18, 2016

The Magnaporthe oryzae snodprot1 homolog (MSP1), secreted by M. oryzae, is a cerato-platanin family protein. msp1-knockout mutants have reduced virulence on barley leaves, indicating that MSP1 is required for the pathogenicity of rice blast fungus. To investigate the functional roles of MSP1 and its downstream signaling in rice, recombinant MSP1 was produced in E. coli and assayed for its functionality. Application of MSP1 triggered cell death and elicited defense responses in rice. MSP1 also induced H2O2 production and autophagic cell death in both suspension-cultured cells and rice leaves. Protein kinase(s) triggered cell death, and jasmonic acid and abscisic acid enhanced cell death, while salicylic acid suppressed it. We demonstrated that the secretion of MSP1 into the apoplast is a prerequisite for triggering cell death and activating defense-related gene expression. Furthermore, pre-treatment of rice with a sub-lethal MSP1 concentration potentiated resistance to the pathogen. Taken together, our results showed that MSP1 induces a high degree of cell death in plants, which might be essential for its virulence. Moreover, rice can recognize MSP1, resulting in the induction of pathogen-associated molecular pattern-triggered immunity.

Pubmed Link: 26780420