Functional Identification of Novel Cell Death-inducing Effector Proteins from Magnaporthe oryzae

Xinrui Guo,Zonghua Wang,Yueqin Zheng,Songbiao Chen,Yijuan Han,Wende Liu,Dagang Tian,Wei Xie,Debin Zhong,Yan Lin,Yanhua He,Feng Wang,Zaijie Chen

doi:10.1186/s12284-019-0312-z

Abstract

BackgroundSecreted effector proteins play critical roles in plant-fungal interactions. The Magnaporthe oryzae genome encodes a large number of secreted proteins. However, the function of majority of M. oryzae secreted proteins remain to be characterized. We previously identified 851 in planta-expressed M. oryzae genes encoding putative secreted proteins, and characterized five M. oryzae cell death–inducing proteins MoCDIP1 to MoCDIP5. In the present study, we expand our work on identification of novel MoCDIP proteins.ResultsWe performed transient expression assay of 98 more in planta-expressed M. oryzae putative secreted protein genes, and identified eight novel proteins, MoCDIP6 to MoCDIP13, that induced plant cell death. Yeast secretion assay and truncation expression analysis revealed that the signal peptides that led the secretion of proteins to the extracellular space, were required for cell death inducing activity of the novel MoCDIPs except for MoCDIP8. Exogenous treatment of rice seedlings with recombinant MoCDIP6 or MoCDIP7 resulted in enhanced resistance to blast fungus, indicating that the two MoCDIPs trigger cell death and elicit defense responses in rice.ConclusionsThe newly identified MoCDIP6 to MoCDIP13, together with previously identified MoCDIP1 to MoCDIP5, provide valuable targets for further dissection of the molecular mechanisms underlying the rice-blast fungus interaction.

Highlights

Secreted effector proteins play critical roles in plant-fungal interactions
We further demonstrated that exogenous treatment of rice seedlings with recombinant MoCDIP6 and MoCDIP7 resulted in enhanced resistance to rice blast, indicating that the two M. oryzae cell death–inducing proteins (MoCDIPs) proteins trigger cell death and elicit defense responses in rice
Identification of eight M. oryzae cell death-inducing proteins We previously identified five in planta-expressed M. oryza secreted proteins, MoCDIP1 to MoCDIP5, as cell deathinducing proteins (Chen et al 2013)

Summary

Introduction

The Magnaporthe oryzae genome encodes a large number of secreted proteins. We previously identified 851 in planta-expressed M. oryzae genes encoding putative secreted proteins, and characterized five M. oryzae cell death–inducing proteins MoCDIP1 to MoCDIP5. Guo et al Rice (2019) 12:59 oryzae encodes a large number of putative secreted proteins (predicted between 739 to 2,470) (Dean et al 2005; Yoshida et al 2009; Choi et al 2010). Advances in functional identification of secreted effector proteins from M. oryzae have remarkably enhanced our understanding of the molecular mechanisms involved in rice-M. oryzae interactions (Liu et al 2014; Tang et al 2017)

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