Study On Induced Resistance To Postharvest Disease And Its Fresh-keeping Effect Of Potato Glycoalkaloids On Lycium Barbarum L. Fresh Fruits

Lycium barbarum L.is a traditional Chinese medicine,fresh fruit can better play its role in promoting metabolism and scavenging free radicals,while avoiding the loss of functional components.However,because the fresh fruits of Lycium barbarum L.are not easy to preserve after being picked,they are easy rot at normal temperature and lose their edible value.At present,the main prevention and control of postharvest diseases are chemical fungicides.But the chemical fungicides have the characteristics of high residue,strong toxicity,easy to cause environmental pollution and not easy to degrade.Therefore,it is a hot topic to find the substitute of chemical fungicides to prevent the postharvest diseases of fruit.At present,there are few reports on the preservation and preservation of fresh fruit of Lycium barbarum L..In this study,the fruit of Postharvest Lycium barbarum was used as the test material,after the treatment of the plant source active substance,potato glycoalkaloids?TGA?,the induction effect of potato glycoalkaloid on postharvest diseases of Lycium barbarum fruits and the inhibition effect on the main rot pathogenic fungi in the postharvest were studied.In addition,the changes of resistance related substances and related defense enzymes activities in fruits were determined,and the mechanism of potato glycoalkaloids inducing the disease resistance of Lycium barbarum fruits was preliminarily explored,so as to provide references for the application of potato glycoalkaloids in the control of postharvest fruit diseases.The main results are as follows:1.A total of 4 major rot pathogenic fungi in the postharvest fruit of Lycium barbarum were isolated from the experiment.The results of morphological and molecular biological identification showed that:4 kinds of rot pathogenic fungi were Fusarium sp.,Alternaria alternata strain JL-19,Alternaria tenuissima strain JL-7w and Alternaria sp.isolate G-54,respectively.2.In vitro,potato glycoalkaloids have a certain inhibitory effect on the main rot pathogenic fungi in the postharvest fruit of Lycium barbarum.With the increase of the concentration,the inhibitory effect was gradually enhanced.Among them,potato glycoalkaloids had the strongest inhibitory effect on Fusarium sp.,followed by Alternaria sp.isolate G-54,and Alternaria alternata strain JL-19 was weaker,the Alternaria tenuissima strain JL-7w was the weakest.3.Different concentrations?0.05 g/m L,0.10 g/m L,0.15 g/mL,0.20 g/mL,0.25g/mL?of potato glycoalkaloids could significantly reduce the disease index of the fresh fruit of the Postharvest Lycium barbarum.It can induce the resistance effect of fresh fruit of Lycium barbarum on postharvest diseases,and the effect of 0.15g/m L induction is the best.4.After the treatment of potato glycoalkaloids?TGA?,the contents of MDA and O₂^-in the fruits of Lycium barbarum were reduced after harvest,CAT activity is obviously suppressed.The activities of PPO,POD,PAL,SOD,CHT and GLU have increased in varying degrees.The secondary metabolites,including phenolic substances,lignin and flavonoids,have increased to some extent.The content of vitamin C and proline increased significantly.It is indicated that TGA treatment can induce systemic and comprehensive resistance to pathogens and improve disease resistance of fruits by inducing changes in morphology,physiology and biochemistry of fruits.