| Along with the improvement of the role played by economic forest in the sustainable development of forestry economy,the problem of economic forest diseases and insect pests has become the focus of resource protection.At present,the prevention and control of forest disease is rely on too much the chemical agents,which caused pesticide residues exceed the standard on forest and the surrounding environment,it affected ecological efficiencies of economic forest,fruit quality,human health and natural enemies in the forest seriously.Therefore,to develop a new type of unharmful pesticide with its own characteristics of high efficient,low toxicity,environmental protection and low costs become an urgent problem.As a new kind of natural extraction substance,total glycoalkaloid have some potential in inhibiting plant pathogenic fungi,but there is no systematic study on its anti-fungi mechanism.In this study,we searched the sensitive strains by tested the anti-fungi activity of potato glycoalkaloids on common economic forest plant pathogenic fungi.In order to prove the anti-fungi mechanisms initially,the effects of total glycoalkaloids on cell structure,cell morphology and substance metabolism was tested.The results were as following:1.The active products of total glycoalkaloid extacts had certain anti-fungi activity effect on five test fungi in vitro respectively:Fusarium solani,Marssonina juglands,Capnodiume leaophilum,Alternaria alternata,Colletotrichum gloeosporioides.With the increasing concentration of potato glycoalkaloid,the inhibitory effects of drug on the test fungi were gradually increased.Among which,the inhibitory effects of total glycoalkaloid extacts on the Fusarium solani was best,with the EC50 being 0.3036 g·m L-1.2.Studies on the stability of total glycoalkaloid show that the inhibitory effects of total glycoalkaloid extacts on the Fusarium solani was best with the environments condition of 25℃,all-optical,a p H of alkali conditions.The anti-fungi activity of total glycoalkaloids was the best when the p H value reach 9.0 and it had a good thermal stability.3.TEM showed that hyphal cell wall vesicular downs,outer structure wasn’t completed,the cell membrane wasn’t continuous,mitochondria structure becamedisordered and inclusion was exosmosed under total glycoalkaloids.It has a significant effect on the morphology and structure of bacteria.4.Metabolic studies show that the cell membrane permeability was change,a lot of inclusions of lipid,protein and carbohydrate were exosmosed,the hydrolysis of reducible carbohydrate was hindered,the nutrient absorption of bacteria was affected under total glycoalkaloids.These results show that substance catabolism was inhibited when the Fusarium solani was treated with different concentrations. |
