| Tomato,as a kind of fruit and vegetable,is widely planted all over the world,has a huge market demand.Because of its rich nutrition and delicious taste,it is loved by the majority of consumers.But also because of its fragile skin,juicy pulp and short shelf life,it is easy to be infected by various diseases and produced by physical damage in the process of growth,picking,storage and transportation.Therefore,the prevention and control of postharvest diseases and the storage and preservation of tomato have always been a research topic.In this study,the control and storage of E-2-hexenal against Botrytis cinerea,which is one of the main diseases of postharvest tomato,were studied.In this paper,the integrity of Botrytis cinerea cells with E-2-hexenal treated was observed,and the inhibition mechanism of E-2-hexenal on Botrytis cinerea was studied by transcriptome sequencing analysis.The activities and quality indexes of defense enzymes and antioxidant enzymes in tomato plants and fruits were measured after E-2-hexenal fumigation and induction.The main results are as follows:(1)Inhibition mechanism experiment of Botrytis cinerea:after treatment with E-2-hexenal,the surface of spore and mycelium of Botrytis cinerea shrinks,sags,twists and deforms,breaks seriously,and internal solutes leak seriously.PI staining experiment results show that the spores of Botrytis cinerea in treatment group are stained by different degrees compared with control.Further determination of E-2-hexenal on the extracellular conductivity,p H,internal solutes and K~+of Botrytis cinerea were carried out.The results showed that extracellular p H decreased,extracellular conductivity,intracellular solute and K~+leakage increased with the increase of concentration in the treatment group,and 3893 significantly differentially expressed genes were obtained in the transcriptome sequencing experiment,of which1949 were up-regulated and 1944 were down regulated;Glycolysis/gluconeogenesis,fatty acid biosynthesis and metabolism,sterolhormone biosynthesis and sterol biosynthesis were affected.By analyzing the changes of ergosterol biosynthesis related genes,it was found that there were four up-regulated genes:ERG1,ERG 3,ERG25 and ERG26,and three down regulated genes:ERG 7,ERG 26 and ERG 27.The above results showed that E-2-hexenal treatment could destroy the integrity of cell membrane by affecting the oxidative phosphorylation of Botrytis cinerea,glycolysis/gluconeogenesis and ergosterol synthesis,so as to achieve the bacteriostatic effect.(2)Experiment of tomato plant fumigation induction:the wide type tomato plant(A57)growing to flowering stage was fumigated in a sealed container with 0.5μΜE-2-hexenal for 24h,the results showed that E-2-hexenal fumigation could induce the resistance of tomato leaves to Botrytis cinerea,and the diameter of lesion in the treatment group was 26.92%lower than that in control;the water-soluble antibacterial activity of tomato leaves in the treatment group showed that the germination rate of spores in the treatment group were much lower than that in control;E-2-hexenal fumigation could induce tomato plants in different degrees.The activities of PAL,POD,LOX,PPO and the content of total phenols were increased,and the accumulation of flavonoids was also induced.The results showed that E-2-hexenal fumigation could enhance the resistance to Botrytis cinerea by inducing the activities of defense enzymes and antioxidant enzymes.(3)The experiment of tomato fruit fumigation induction:0.005%,0.01%and0.02%(w/w)E-2-hexenal were used to fumigate the pretreated tomato for 24 hours in a closed space.The results showed that E-2-hexene treatment could effectively inhibit the natural incidence rate and decay rate of tomato fruit,reduce the hardness damage of tomato and weight loss percentage,and maintain p H value of postharvest tomato.The increase of TSS,total phenol and flavonoid content can also induce postharvest tomato to increase the antioxidant activities of PAL,CAT,POD,SOD and other defense and antioxidant enzymes,so as to enhance the ability of tomato to resist pathogens,maintain the high quality of tomato during storage and prolong its shelf life.The inhibition effect of 0.01%E-2-hexenal was the best. |
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