Research On The Screening Of Leaf Lpot Antagonistic Strains From Polygonatum Odoratum And Its Biocontrol Function

This study mainly used medicinal plant Polygonatum odoratum as the study material. In the first, pathogenic bacteria from leaves suffering from Polygonatum odoratum leaf spot were isolated and validated. Then endophytic fungi from healthy rhizomes of Polygonatum odoratum were isolated and purified, in which the antagonistic effect endophytic fungal through blocking pathogens were screened, and the fermentation condition of the best antagonistic endophytic fungi were optimized, and their actual results were monitored through field experiment. At last, antagonistic strains secondary metabolites composition were analyzed and detected by GC–MS. The main findings were as followed:By Isolating pathogenic bacteria from Polygonatum odoratum blades suffering leaf spot, verifying the isolated endophytes by Koch’s postulates, it is found that strain Y05 was one of the main pathogens caused Polygonatum odoratum leaf spot, throughing ITS1 / ITS4 sequence comparing and morphological identification, identified Strains Y05 as Alternaria solani, then worked on its biological characteristics.18 endophytic fungus endophytic fungi of health rhizome of Polygonatum odoratum deprived from by using tissue cut method were isolated and purified, in which several endophytic fungi were found having resistance effect on five pathogens. The strain DP06 had an obvious antagonistic effect on Alternaria solani which is a kind of pathogenic bacteria being mentioned above, which was identified as Fusarium oxysporum by sequencing and morphological ITS1 / ITS4, of which biological characteristics study results showed that 25℃ is the suitable temperature for the colony growth, pH 8 is the suitable pH value for the colony growth, glucose is the suitable carbon source for the colony growth, There was a little influence on growth rate under five nitrogen sources, but its grow speed was faster when in beef extract. The fermentation conditions of the strain DP06 were optimized on the basis of above study, and the optimal fermentation conditions were obtained by the response surface analysis: The optimal fermentation conditions were 24.55℃ for 13.29 days, 120 r/min-1, on this condition, the inhibitory activity reached to 82.25%.In field experiment, the author detected the fermentation liquid and extracted liquor extacted with methanol, chloroform, ethyl acetate, petroleum ether respectively, the results showed that the control effect of fermentation group was better than the other four groups, reached 65.72%, meanwhile the highest level of the disease was lower than the others. We got a variety of organic compounds which retained biological activity from the fermentation broth by detecting and analyzing with GC-MS, these compounds and their derivatives were widely used in the production of pesticides, bactericide, and other fields of daily chemical products. This study provides a theoretical foundation for the development of bio-control agents to prevent and treat the Polygonatum odoratum disease.