Background

Secreted 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.

Results

We 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.

Conclusions

The 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.

中文翻译：

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稻瘟病菌的新型细胞死亡诱导效应蛋白的功能鉴定。

背景

分泌的效应蛋白在植物-真菌相互作用中起关键作用。的稻瘟病菌基因组编码的大量分泌蛋白质的。然而，大多数米曲霉分泌的蛋白质的功能仍有待表征。我们先前在植物表达的米曲霉基因中鉴定出851个编码假定分泌蛋白的基因，并鉴定了5个米曲霉细胞死亡诱导蛋白MoCDIP1至MoCDIP5。在本研究中，我们扩大了对新型MoCDIP蛋白鉴定的工作。

结果

我们在植物表达的米曲霉推定分泌蛋白基因中进行了98个以上的瞬时表达测定，并鉴定了8个诱导植物细胞死亡的新蛋白，从MoCDIP6到MoCDIP13。酵母分泌测定和截短表达分析表明，除了MoCDIP8以外，新型MoCDIPs的细胞死亡诱导活性还需要将蛋白分泌到细胞外空间的信号肽。重组MoCDIP6或MoCDIP7对水稻幼苗的外源处理导致对稻瘟病菌的抗性增强，表明这两种MoCDIPs触发了细胞死亡并引发了水稻的防御反应。

结论

新鉴定的MoCDIP6至MoCDIP13，以及先前鉴定的MoCDIP1至MoCDIP5，为进一步剖析稻瘟病菌相互作用的分子机制提供了有价值的靶标。