Research On The Inhibitory Effect Of Antagonistic Bacteria Against Botrytis Cinerea

Botrytis cinerea infects fruits and vegetables to cause gray mold,which causes large quantities of fruits and vegetables rot and deteriorate and serious economic losses during storage.At present,chemical sterilization is mainly used to prevent post-harvest diseases of fruits and vegetables.However,the long-term use of chemical fungicide has some disadvantages,such as pathogen resistance,pesticide residue,and so on.Biological control is a research hotspot in the field of post-harvest disease control of fruits and vegetables,and has the advantages of low cost,safety,pollution-free.Moreover,it was confirmed that antagonistic bacteria had significant inhibitory effects on pathogenic bacteria causing disease of fruits and vegetables.In recent years,researches on biological control stagnate in the prevention and treatment methods,and the mechanism of inhibition of pathogenic bacteria and the practical application of antagonistic bacteria don't thoroughly studied.In this study,Yeast and Ginkgo biloba endophytes were used to study the antibacterial mechanism of Botrytis cinerea,the disease resistance after cucumber mechanical damage and the quality change of cucumber during storage.In order to lay a theoretical foundation for the biological control of Botrytis cinerea that causing post-harvest diseases of fruits and vegetables.The results were as follows:1.Using the growth rate method screened the inhibition of Botrytis cinerea from 9endophytics and 7 strains to yeast.The results showed that the inhibition rate of endophytic R1 and Hanseniaspora uvarum were the highest,which were 83.33%and 89.87%.R1 and Hanseniaspora uvarum were selected as the target strain,and R1 16S rRNA sequence was determined.Finally,the strain R1 was identified as the genus Corynebacterium,and it was named Variovorax sp.R1.2.The inhibitory effects of target strain Variovorax sp.R1 and Hanseniaspora uvarum on Botrytis cinerea were investigated by plate inhibition test.When the concentration of Variovorax sp.R1 was 10~9 CFU/mL,the inhibition rate against Botrytis cinerea was 84.93%;when the concentration of Hanseniaspora uvarum was 10~9 CFU/mL,the inhibition ratio against Botrytis cinerea was the highest,which was 93.37%,and the inhibition ratio increased with the increase of the concentration of bacteria.3.The inhibition mechanism of Hanseniaspora uvarum and Variovorax sp.R1 against Botrytis cinerea includeed:(1)Hanseniaspora uvarum,Variovorax sp.R1,and pyrimethanil destroyed the cell membrane of Botrytis cinerea,so that the conductivity of the culture medium increased,the cell membrane permeability of Botrytis cinerea increased,and the intracellular electrolyte extravasated,the bacterial protein content reduced.(2)Hanseniaspora uvarum,Variovorax sp.R1,and pyrimethanil reduced the activity of PPO and POD of Botrytis cinerea,and had relatively little effect on the activity of SOD enzyme,so that the protective effect of the resistant enzyme was weakened,and its inhibition effect against Botrytis cinerea exhibited.4.The results of the induction mechanism of resistance to postharvest disease of cucumber by Hanseniaspora uvarum and Variovorax sp.R1 were as follows:(1)The cucumber treated with Hanseniaspora uvarum and Variovorax sp.R1significantly increased PPO activity,POD activity,CAT activity,?-1,3-glucanase,total phenolic content,lignin content,total RNA content,which inhibited the accumulation of MDA content,enhanced the disease resistance of cucumber and protected cucumber from the persecution of pathogenic bacteria.(2)Increased total phenolic content and total RNA content of cucumber in pyridoxal treatment group,the results showed that pyrimethanil inhibited Botrytis cinerea and maintained the quality of cucumber during storage.5.Hanseniaspora uvarum,Variovorax sp.R1,pyrimethanil protected cucumbers from Botrytis cinerea by regulating cucumber resistance enzymes,inhibiting pathogens,which delayed the quality changes of cucumber such as weight,hardness,browning degree,titratable acid and VC.The results showed that Hanseniaspora uvarum,Variovorax sp.R1 and pyrimethanil all had inhibitory effect on Botrytis cinerea.After mechanical damage of cucumber,the treatment with Hanseniaspora uvarum,Variovorax sp.R1 and pyrimethanil all induced disease resistance of cucumber with different degrees and reduced the loss of nutrients during storage.Based on this study,it provided theoretical basis for post-harvest disease control of fruits and vegetables.