| Zlatifolia is a traditional aquatic product of China.It is rich in nutritive value,rich in trace elements and essential amino acids necessary for humans,and has certain medicinal value.However,z.latifolia mainly concentrates on harvesting in the hot season,and the shelf life can only be maintained for 2 to 3 days.Therefore,it is of great significance to study the mechanism of z.latifolia aging after harvest.The experiment uses Z.latifolia in late June in the Dabie Mountains of Anhui Province,the effects of 1-methy ley elopropene(1-MCP)and ethylene treatment on senescence-associated respiratory metabolism and cellular ultrastructure during storage at normal temperature(25?)were studied.In order to explore the molecular mechanism of 1-methyleyelopropene(l-MCP)and ethylene(ETH)treatments regulate the postharvest senescence of Zizania latifolia,the changes of proteome in Z.latifolia mitochondria during storage at 25? for 0(control),3 and 6 days were investigated by using iTRAQ labeling combined with 2D-LC-MS/MS techniques.The main findings are as follows:1.The results showed that the 1-MCP treatment significantly retarded the increase of L,a*,b*value and weight loss of Z.latifolia.The respiratory intensity and reducing sugar content were significantly lower than those in the control.The treatment also promoted the activities of superoxide dismutase(SOD)and cytochrome c oxidase(CCO)while inhibited succinatedehydrogenase(SDH)and peroxidase(POD)activities compared with the control,which resulted in a relatively low relative leakage rate and malondialdehyde(MDA)content.After 6 days storage at 25?,the integrity of cell structure was still maintained.Ethephon(ET)treatment maiuly increased L value,SDH and CCO activities and respiratory intensity,promoted the decrease of reducing sugar content at the first 3 days of storage.It had opposite effects on reactive oxygen species(ROS)metabolism compared with 1-MCP treatment,which further accelerated the degradation of cell structure.However,it had a certain inhibitory effect on increase of a*,b*value and weight loss.These results suggested that 1-MCP treatment could significantly inhibited the respiratory metabolism and ROS production,maintained the energy metabolism balance and cell structural integrity,and therefore retard the postharvest senescence of Z.latifolia.2.A total of 1908 proteins were identified with two or more peptides,of which 315 proteins showed a significant(P<0.05)change in relative quantitation based on 2-fold difference.Gene ontology(GO)annotation and KEGG Pathway analysis of these differentially expressed proteins revealed that the metabolic pathways,carbon metabolism,biosynthesis of amino acids,biosynthesis of antibiotics,biosynthesis of secondary metabolites,2-oxocarboxylic acid metabolism,arginine biosynthesis,alpha-Linolenic acid metabolism and glyoxylate and dicarboxylate metabolism in postharvest Z.latifolia mitochondria were significantly(P<0.05)enriched during storage at 25?.Compared with the control,1-MCP treatment significantly(P<0.05)enriched the citrate cycle(TCA),pentose phosphate pathway(PPP),alanine,aspartate and glutamate metabolism,Valine,leucine and isoleucine degradation and C5-branched dibasic acid metabolism pathways.The post-harvest aging is closely related to respiratory metabolism and concomitant substances,energy and active oxygen metabolism,programmed cell death and cell structure degradation.Accelerated metabolism of carbohydrates,proteins,amino acids,etc.,rapid consumption and loss of nutrients,and low energy and material basis;respiratory metabolic pathways change,respiratory electron transport chain weakens,oxidative phosphorylation is blocked,energy loss occurs;active oxygen stress increases,apoptosis and calcium signal pathway-related protein expression are initiated;secondary metabolite synthesis increases,and lignin synthesis accelerates. |
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