The Mechanism Of Rice Disease-resistance Induced By The Protein Elicitor MoHrip1

Rice is an importance food crop worldwild, while the yield is reduced each year resulting from the disease damage such as the blast, which threaten the food requirement of world population. Elicitors are a kind of compounds which can induce the plant defense response, they protect plant from infection of pathogen and damage of disease by increasing the innate immune of plant. In recent years, elicitors isolated from pathogens have been reported, but the progeress of research in mechanism is relative slow.MoHrip1 is a secretion protein elicitor separated from the rice blast fungus Magnaporthe oryzae in our laboratory. It could increase the resistance of rice to rice blast and rice bacterial blight. To study the mechanism of MoHrip1 in inducing the rice disease resistance, we take rice treated with MoHrip1 to perform RNA-seq and digital gene expression profiling and analyse the relationship between rice disease-resistance induced by MoHrip1 and the transcriptional expression of rice genes. The endogenous level of salicylic acid and gibberellin is measured as well as the grow seedlings of rice after treated with MoHrip1. Then we get some results relate to mechanism of MoHrip1 induced disease-resistance. The results of this experiment are as follows:1. The sequencing data is acquired by RNA-seq and analysis by DGE technology. And 308 genes were revealed to be differential expressed genes in treated rice compared with the control one. Expression of these genes might be associated with resistance induced by MoHrip1. Base on the analysis of hierarchical clustering, it can be predicted that elicitor may activate the tryptophan pathway and induce the biosynthesis of auxin and other material derived from tryptophan in plant.2. The correlation between sequencing data and real-time PCR results was identified. Then the interesting genes were filtered and classified by the function and characteristic of the encoding products. According to the analysis, phytoalexin tends to be the major antibiotic material induced by MoHrip1 in rice. Phytoalexin may participated in the enhanced resistance induced by MoHrip1. Meanwhile 80 genes are selected to be specifically induced by MoHrip1, providing some candidate genes in research of elicitor interaction.3. Endogenous level of SA is found to be up-regulated in rice with MoHrip1 treatment. It suggests that the increased SA level is resulted from the activation of SA biosynthesis pathway gene and positive regulation of JA pathway repressor genes. Salicylic acid might be the major signal molecular induced by MoHrip1 in the resistance response.4. GA content and growth of rice treated with MoHrip1 is measured. It infers that increased GA content lead to the growth promotion of rice seedlings, and the enhanced crosstalk between JAZs and DELLAs induced by MoHrip1 resulting in the change of GA content.This study illustrated that protein elicitor could induce the differential expression of antibiotic biosynthetic genes and encoding genes of transcriptional factors, raise the endogenous level of SA to acquire disease resistance, provide new perspective and data in studying the mechanism of elicitor induced resistance. MoHrip1 could not only induce the plant resistance but also enhance the GA level to promote rice growth. It provides new data and inference to study the function of the elicitors.