APS Abstract of Presentation

Isolation and functional analysis of novel secreted proteins in Magnaporthe oryzae
P. SONGKUMARN (1), S. Chen (1), R. Venu (1), M. Gowda (1), G. Wang (1)
(1) The Ohio State University, Department of Plant Pathology, Columbus, OH 43202
Phytopathology 98:S148

Rice blast disease, caused by fungus Magnaporthe oryzae, is one of the most serious diseases of rice. To elucidate the molecular basis of interactions between rice and M. oryzae upon infection, we employed a multifaceted approach that combined Robust-Long SAGE (RL-SAGE) and Massively Parallel Signature Sequencing (MPSS) sequencing method and bioinformatics analysis to identify secreted protein genes in M. oryzae-infected rice leaves. A total of 217 putative secreted proteins genes of M. oryzae were found to express in planta. Three primary candidate of secreted protein genes; MG14, MG20, and MG23 were amplified and cloned. Transient expression assay in rice protoplasts and agro-infiltration assay have been performed for functional analysis. We found that MG14 and MG20 induced cell death in rice protoplasts. Moreover, a full-length MG20 significantly induced cell death in rice protoplasts when compared with a truncated version (without signal peptide). Interestingly, agro-infiltration of a full-length MG20, but not truncated version induced cell death in Nicotiana benthamiana, suggesting that this protein might be active in apoplast. Protein domain search indicated that MG14 is predicted to be an extracellular membrane-associated protein with a CFEM domain. Also, a zinc binding site was found in MG20. Characterization of these fungal secreted proteins and their targets might provide new insights into the functional interaction of secreted proteins with host proteins.

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