| Lycopersicon esculentum is an annual herb,solanaceae plant,which is moderately sensitive to salt.When plants were subjected to exogenous NaCl treatment,NaCl induced the enzyme activities of CAT,POD,LOX,and PAL in leaves,and obviously inhibited plant growth,compared to control.The volatile components of leaves was collected and analysed by SPME combined with GC-MS,and the results showed significant changes were occurred in terpenoids.Furthermore,we quantified and compared transcriptome changes by RNA-seq analysis,22,384 and 21,578 unigenes were obtained in the leaves between control and NaCl treatment groups by de novo transcriptome assembly,respectively.The total number of DEGs was 7210 after exposure to NaCl,including 6002 down-regulated and 1208 up-regulated genes.There are 3454 unigenes were mapped to 131 KEGG pathways,maninly those are involved in RNA transport,plant-pathogen interactions and plant hormone signal transduction.18 DEGs related to the synthesis of volatile substances were screened out,qRT-PCR analysis of the expression profiles of TPS,TPS38,FDS,TPS28,IPI,and GPS correspond well with RNA-seq a nalysis.E-2-hexenal,one of the main components of volatile substances,has significant effects on the control of Penicillium cyclopium and tomato fruits against postharvest penicillium.In vivo experiments,the spores of control group were full,mellow and smooth on the surface,while the spores treated with E-2-hexenal became irregular and depressed.The spores were 100%stained with PI,after treated with 2560 μL/L E-2-hexenal for 2 h,while control showed no redness in the fluorescence field.As the concentration of E-2-hexenal increases,the fluorescence value of the spores increases,and the intracellular solution of spores have a serious leakage,indicating that the spore cell membrane is seriously destroyed.The enzyme activities of SOD and CAT of spores were measured by spectrophotometry,and the results showed that the enzyme activity of spores treated with 640 μL/L E-2-hexenal increased significantly after 2 h of treatment,and decreased after 4 h of treatment,compared to control.ATP content was determinated by HPLC as the treatment concentration increases,the intracellular ATP content in spores decreases.Based on the results above,it is presumed that E-2-hexenal breaks cell membranes of spores,causing leakage of cell fluids,which makes cells unable to maintain the homeostasis of the internal environment,thereby destroy the growth and reproduction of spores.In vitro experiments,the fruit decay rate,fruit quality(water loss rate,hardness,vitamin C,pH,TSS and color index),physiological quality(total phenol,malondialdehyde)and related enzyme activities were detected.The results showed that the higher the concentration of E-2-hexenal,the better the inhibitory effect of Penicillium cyclopium.E-2-hexenal reduced the decay rate of fruit significantly,maintained fruit quality,induced several key enzymes activities in fruits,increased the synthesis of total phenols,and reduced the accumulation of malondialdehyde in fruit cells.In a word,E-2-hexenal improved the tomato fruit resistance to Penicillium cyclopium.Liposome encapsulation of E-2-Hexenal was prepared by membrane dispersion method,a single factor experiments was designed to determined the conditions for liposome synthesis preliminarily:temperature at 35℃,with ratio of PDA and DMPC at 3:2,concentration of DMPC is 1 mg/mL.The encapsulation efficiency of liposome is 32.9%,and it was confirmed that the liposome encapsulates have an effective inhibitory effect on Penicillium cyclopium. |
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