Isolation On Endophytic Fungus Rfom Spiraea Decne And Inhibition Activitie To Plant Pathogens

Endophyte is a potentially valuable study microbial resources, not only topromote this host plant metabolites in vivo conversion of synthesis, and theirendophyte secondary metabolites produced by the new structure to replace depletingplant resources, has great application value and development potential. This researchobtains endophytic fungi XXB07and XX10from Spiraea, which strikinglyantagonized kinds of plant pathogens. In this present paper，biological characteristicsand antimicrobial activities of the strains were studied. The main results are asfollows:1. Thirty-nine endophyte isolates were obtained from healthy roots, stems andleaves of Spiraea. The results of the preliminary experiments exhibited that21endophyte isolates strong antagonized six plant pathogens, Cytosporamandshurica(CM), Colletotrichum gloeosporioides(CG),Phytophthora capsici(PC),Fusarium oxysporum(FO),Fusarium graminearum(FG) and Botrytis cinerea (BC).Especially, the endophyte XXB7and XXT10strain. The strain XXB7has significanteffect on pathogens and the inhibition rates to Phytophthora capsici, Cytosporamandshurica, Fusarium graminearum and Botrytis cinerea were more than71.5%,70.8%,48.2%and41.3%.The strain XXT10has significant effect on pathogens andthe inhibition rates to Cytospora mandshurica, Colletotrichum gloeosporioides,Fusarium oxysporum and Fusarium graminearum were more than73.2%,72.5%,39.5%and47.2%2. The XXB7and XXT10strains were identified as Alternaria based on ITSrDNA sequence analysis. Biological characteristics researched different conditions intemperature, pH value, carbon and nitrogen sources, cultural media. The res ults are asfollowed: The proper growth temperature of the two strains was28℃-32℃. Suitablefor two strains the growth in the pH range from6to10. Sucrose and lactose wereXXB7and XXT10the optimum carbon source. Tryptone and peptone were the bestnitrogen XXB7and XXT10. Two strains grow best in PDA medium.3. Bioassay results in vitro revealed the inhibitory rates of broth and myuceliumof methonal extracts against plant pathogenic fungi at the concentration of200mg/land500mg/l. The inhibitory rates of strain XXB7’s broth and myucelium ofmethonal extracts were37.39%,22.18%,62.86%and36.47%against Phytophthoracapsici at the concentration of200mg/l and500mg/l. While the inhibitory rates of strain XXT10’s broth and myucelium of methonal extracts were17.17%,67.07%,69.10%and80.38%against Colletotrichum gloeosporioides at theconcentration of200mg/l and500mg/l.