Effects Of Pathogenic Claviceps Purpurea To Symbiotic Epichlo? Gansuensis In Achnatherum Inebrians

Symbiotic fungal endophyte-Epichlo? gansuensis and pathogenic fungus-Claviceps purpurea are common species of Clavicipitaceae on drunken horse grass(Achnatherum inebrians).Research on the physiology,biochemistry,transcriptome and metabolome of the drunken horse grass through the interaction of endophytic fungi and pathogenic fungus.The main finding are as follows:(1)It is fould that Epichlo? endophyte infection decreased the effects of C.purpurea infection on drunken horse grass by reducing ergot incidence and disease index by 49.5% and 28.81,respectively.Inoculation with pathogen and endophyte induced the activity of defence pathways,photosynthesis and plant hormone,including increased superoxide dismutase(SOD),peroxidase(POD)activity,proline(Pro),chlorophyll content,photosynthetic rate,Abscisic Acid(ABA),cytokinin(CTK),salicylic acid(SA)and melatonin(MT)concentration,reduced malondialdehyde(MDA)content.The structural equation models showed that endophyte indirectly reduced the incidence of ergot disease by affecting malondialdehyde(MDA)content.(2)It is fould that a total of 550 metabolites were detected,some marker metabolites,including flavonoids,free fatty acids,amino acids,alkaloids and other substances could be considered by plots of the principal component scores based on UPLC-ESI-MS/MS metabonomics,which were commonly higher in E+(endophyteinfected)plants than those in E-(endophyte-free)plants.These marker metabolites were influenced by endophyte and pathogen.Epichlo? endophyte increased metabolic compounds which relate to biosynthetic pathway of Isoflavones,thiamine(VB1)and carbon metabolism.Here,the results indicated that Epichlo? endophyte has the ability to enhance A.inebrians to pathogen stress.(3)It is fould that Epichlo? endophyte could increase the content of free fatty acids in host plants such as arachidonic acid,elaidic acid,stearic acid,and oleic acid after infection with pathogen.The amino acids such as betaine proline,glutathione and Lproline were 12.73,2.02 and 1.34 times of those of uninfected plants,respectively;Quercetin 3-o-methyl ether,occlusin O-malonylhexoside,apigenin 8-C-pentanoside,methyl gallate and occlusin were 5.31,1.98,1.40,1.65 and 4.59 times higher than those of uninfected plants,respectively.The content of indole alkaloids such as indole-5-carboxylic acid,indole-3-ethanol and indole-3-carboxylic acid increased,and the production of antimicrobial substances enhanced the overall health level of drunken horse grass,and thus improved the resistance of drunken horse grass to ergot.(4)It is fould that regulation mechanism of endophyte and pathogen interaction at molecular level,including GO and KEGG enrichment analysis of “peroxidase”,“peroxidase membrane”,“chitinase activity”,“ascorbic acid pathway” and“photosynthesis” and other plant stress resistance related pathways.The expression of PR protein genes,such as PR-2 and PR-6,was significantly up-regulated in E+ plants.The expression of photosynthesis-related regulatory genes was also significantly upregulated.The indole-3-pyruvate monooxygenase gene and other alkaloid synthesis genes such as Dam W and Eas F genes were also significantly up-regulated.(5)Transcriptome,metabolome,and physiological and biochemical data analysis found that the regulations of “peroxidase”,“peroxisome membrane”,“ascorbic acid pathway”,photosynthesis and alkaloid synthesis gene synthesis genes significantly upregulated expression in E+ plants,the same in the physiological,biochemical and metabolome data,peroxidase activity,glutathione,plant net photosynthetic rate and indole alkaloids all increased significantly(P<0.05).