Discovery And Identification Of Active And Effective Substances In Oleander Oriented To Resistance To Rhizoctonia Solani

The main research in this experiment is to find the active substances which can effectively inhibit Rice Sheath Blight from the fresh leaves of oleander.It lays a foundation for the research of plant-based pesticides for rice sheath blight.The specific results are as follows:1.The growth rate method was used to determine the antibacterial activity of oleander fresh leaf crude extract against Rhizoctonia solani,and the single factor experiment was conducted to select the best single factor condition for antibacterial effect;the uniform design experiment was set up to determine the mycelial growth length by the growth rate method,and the multiple regression equation was analyzed to finally select the best single factor condition for antibacterial effect The process parameters were optimized.The results of single factor test showed that different solvents were anhydrous ethanol;different extraction time was 30min;different extraction times was once;different extraction temperature was 30 ℃;different solid-liquid ratio was 1:10.Based on the above factors,the uniform design experiment was carried out under the best experimental conditions,and the process model was optimized by multiple regression equation.The optimal antibacterial extraction process parameters were obtained as follows: 80% ethanol concentration,150 min extraction time,once extraction and 40 ℃ extraction temperature.2.The chemical components of the crude extracts of the fresh leaves of the oleander were separated by alcohol extraction,MCI column and polyamide column.Uused to determine the antibacterial activity of the chemical components isolated from the crude extract of the fresh leaves of the oleander against the Rhizoctonia Fusarium and to judge the cooperative effect of different chemical components by growth rate method.The results showed that terpenoids,cardiac glycosides and flavonoids could inhibit rice sheath blight,and the flavonoids were the strongest,and other components were synergetic.3.The changes of the indexes of the conductivity,morphology,malondialdehyde and soluble protein content of the bacteria solution were measured by setting up the antagonistic Rhizoctonia at different time,so as to judge the physiological and biochemical effects of the crude extract of the fresh leaves of the oleander on the physiological and biochemical characteristics of the Sclerotinia.The results showed that the conductivity of the solution was increased obviously;the treated mycelium was small and fractured;the content of malondialdehyde increased with the increase of treatment time;the soluble protein content decreased with time in the first six hours,and the latter six hours increased with time Increase.4.The content of the crude extract of the fresh leaves of the oleander was determined by TLC.The three chemical substances separated from the ketones of the fresh leaves of the oleander were determined by polyamide column.The components were identified as flavonoids by infrared spectrum.Then,the separated substances were analyzed by mass spectrometry.The three substances were estimated to be trihydroxyflavone and 3,6-di-tert-butyl flavone and o-methyl-pentahydroxyflavone.