Effects Of Epichlo(?) Endophyte On Seed Associated Fungi And Disease Resistance Of Wild Barley Under Salt Stress Conditions

Wild barley(Hordeum brevisubulatum)as an elite forage is widely planted in northern China due to its good cultivation of resilience.In this study,symbiosis of wild barley and Epichlo? bromicola endophyte was main experimental material.Seed-borne fungus from seeds of the symbiosis were isolated and cultured.Then their pathogenicity were determined on seedling growth as well as physiological and biochemical indexes under salt stress conditions.The findings are as follows:1.Speciesand infection rate of seed-borne fungus on wild barley seed were clarified.Both of sterilized and unsterilized seeds with endophytic fungi(E+)and without endophytic fungi(E-)were isolated.Then results showed that: for sterilized seeds,isolation ratio of seed-borne fungus on E+ and E-seeds were 70.5 % and 68 %respective;for unsterilized seeds,isolation ratio of seed-borne fungus on E+ and Eseeds were 86% and 84% respective.No matter what,the isolation ratio of seed-borne fungus on E+ seeds was higher than the isolation rate of seed-borne fungus on Eseeds but without significant difference(P<0.05).Analysis of two factors shows that sterilization method had significant influence on isolation ratio of seed-borne fungus(P<0.05);E+ and E-had no significant influence on isolation ratio of seed-borne fungus(P>0.05);the interaction of sterilization and endophyte had no significant influence on isolation ratio of seed-borne fungus(P>0.05).On unsterilized E+ and Eseeds,10 species of fungus were isolated and these 10 fungus belong to 4 genus.Alternaria alternata,A.brassicae,A.infectoria,A.tenuissima and Bipolaris sorokiniana were isolated from sterilized E+;A.alternata,A.brassicae,A.mali,A.tenuissima,Coniothyrium aleuritis and Stemphylium vesicarium were isolated from sterilized E-.8 species of fungus were isolated from sterilized E+ and E-seeds and these 8 fungus belong to 4 genus.A.Brassicae,A.compacta,A.tenuissima,B.sorokiniana and F.incarnatum were isolated from sterilized E+;Alternaria alternata,A.brassicae,A.compacta,A.infectoria,A.solani,A.tenuissima,B.sorokiniana,Fusarium avenaceum and Peyronellaea pinodella were isolated from sterilized E-.2.Influences of 13 seed-borne fungus on wild barley seed germination and seedling growth clarified.Determination of the effect of interaction between Epichlo?endophyte and pathogenic fungi on wild barley and the results showed that:seed-borne fungus influenced wild barley seed germination and seedling to a certain degree.Germination rate of E+ seeds and biomass of seedling were higher than that of Eseeds.A.alternata,B.sorokiniana and F.avenaceum had significant inhibition effects on seed germination of wild barley and seedling growth and thus were identified as pathogenic fungus.3.Influences of seed-borne pathogenic fungi on endophytic fungal symbiont of wild barley under salt stress were clarified.Under indoor salt stress,above-mentioned3 species of pathogenic fungus such as A.alternata,B.sorokiniana and F.avenaceum were inoculated to measure influences on growth of wild barley and its physiological and biochemical indexes.The results showed that: after being infected with pathogenic fungus,the plant height and tiller number of wild barley showed a trend of increase first and then decrease with increase in NaCl concentration and the plant height and tiller number of E+ wild barley were higher than that of E-wild barley(P<0.05);for wild barley,the content of propanedione and proline showed a trend of increase first and then decrease with increase in NaCl concentration.Besides,for E+wild barley,content of malondialdehyde(MDA)was lower than that of E-wild barley(P<0.05)while for E+ wild barley,content of proline was higher than that of E-wild barley(P<0.05);the chlorophyll content for wild barley decreased with increase in NaCl concentration and the chlorophyll content in E+ wild barley was higher than that of E-wild barley(P<0.05);content of peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)showed a trend of increase first and then decrease with increase in salt concentration and the contents of three kinds of enzyme in tissue of E+ wild barley were higher than that in E-wild barley(P<0.05).Moreover,wild barley infected with pathogenic fungus under salt stress,the content of total C and P in plant tissue decreased;with increase in NaCl concentration while the overall content of N increased with increase in NaCl concentration;with increase in NaCl concentration,the content of ergot alkaloids in tissue of wild barley increased and the interaction of different pathogenic fungus and different NaCl concentration had no significant influence on content of ergot alkaloids in tissue of wild barley(P>0.05).