Metarhizium Anisopliae Induced Peanut Roots Response To Establish Endosymbiosis

It is known that the entomopathogenic fungus Metarhizium anisopliae is widely used as biocontrol agents to suppress pests in the field,and has shown high potential efficiency in control of soil-dwelling pests including a variety of white grubs.Recent studies revealed there is mutualism that M.anisopliae promotes root growth while obtain own survival chance as an endophyte.The understanding of the molecular mechanism of plant responses to beneficial M.anisopliae will be useful to enhance the dual effect of controlling pests and promoting plant growth.In the experiment,M.anisopliae and pathogenic Fusarium oxysporum were used for comparative analysis of plant response by the transcriptome,different expression of predictively symbiotic-related genes at m RNA and protein levels.1.The transcriptome analysis on peanut roots responded to M.anisopliae and F.oxysporum.Among 203 differentially expressed genes,the immune related genes were significantly suppressed in peanut roots inoculated by either of the two fungi,which allow infection and symbiosis establishment.Especially the defense-related genes such as disease-resistant transcription factors and JA-mediated immune responses were excited by only F.oxysporum.The up-regulated genes induced by only M.anisopliae were enriched in the pathways of the plant growth,such as sugar,nitrogen and lipid metabolisms.These results initially revealed the common and difference in molecular interaction of the host plant with beneficial and pathogenic fungi.2.The m RNA and protein expression analysis of the key genes of the plant-fungi interaction.The candidative 28 genes were selected on the basis of previous transcriptome data.The results of the gene expression by RT-q PCR and PRM showed that the genes related recognition receptors,of MAPK cascade and immunity were down-regulated in either treatment of the two fungi,and F.oxysporum caused a stronger suppression.The growth-promoted and symbiosis-related genes were significantly up-regulated in M.anisopliae treatment.It suggested that both fungi actively suppressed the host immunity for successful colonization and infection,and M.anisopliae meanwhile coordinatively activated the symbiotic signalling and growth promotion to introduce the establishment of symbiosis.3.The adhesin-like protein1 gene Mad1 cloning and expression.The Mad1 was cloned from M.anisopliae c DNA and sequenced.Its open reading frame includes 2136 bp encoding 711 aa and 74.8KD protein.The recombinant expression vector was constructed and Pichia pastoris eukaryotic expression system was established.The expressed and purified Mad1 protein was used in treatment of peanut root in vitro.The results showed that Mad1 induced down-regulated expression of host defense-related genes and promoted the suppression of the immune response.It was proved that the Mad1 is involved in the inducing inhibition of plant immunity which may be the beginning of a symbiotic relationship.The experiment above indicated that M.anisopliae can regulate host plant immunosuppression and coordinatively growth metabolism to establish symbiotic relationship.It would provide theoretical basis for exploring the persistent mechanism of M.anisopliae.