Regulation By Nitric Oxide And Chilling Signal On Lipid Peroxidation And Antioxidant System In Cell Membrane Of Peaches During Storage

Nitric oxide(NO)is a kind of molecule messenger with bioactive.It can freely move through intracellular membrane structures to participate in various physiological and biochemical processes in the cell because of its lipid solubility.Chilling injury is an important environmental factor of plant growth and development,and cell membrane is an important part to sense chilling injury.Previous studies had shown that NO was an important factor in chilling response.It could effectively relieve chilling injury in plants and improve the storage quality of fruit.However,the mechanism of membrane lipid react with chilling signal during cold storage,the influence of NO and chilling signal on the composition and metabolism of cell membrane lipid,and the reactions in cell antioxidant system,have rarely been reported.Therefore,it is important to explore the mechanism of exogenous NO and chilling signal in fruit chilling injury.The mechanism of exogenous NO and chilling signal reacted with antioxidant system in plants has instructional significance for keeping fruit quality and prolonging the storage period.In this paper,Feicheng peaches were treated with different NO solutions(5?15?30 ?mol L-1)and c-PTIO solution(5 ?mol L-1),and then were stored at 0 oC and 25 oC.The regulation by nitric oxide and chilling signal on lipid peroxidation and antioxidant systemin cell membrane of peaches during storage were studied.Besides,cloning of Grx gene,expression and purification of Grx protein,and the interaction between NO and Grx protein in Feicheng peaches were also studied in this paper.The results showed that under the induction of chilling signal,peaches treated with 15 ?mol L-1 NO reduced the permeability of cell membrane and the MDA content.Besides,the activity of LOX in peach fruit significantly decreased.The activities of POD and APX in peaches treated with NO significantly increased.However,changes in the content of proline and the activities of SOD and CAT were not obvious compared with the control.Moreover,under the induction of chilling signal and 15 ?mol L-1 NO,the activitis of GR and APX in mitochondria was obvious increased,and the content of Grx had rapid increased during the early period storage.However,changes in MDHAR and DHAR activities as well as the contents of GSH and GSSG content were not obvious compared with those in room temperature.The results showed that exogenous NO could regulating the metabolism of cell membrane lipid and antioxidant system of Feicheng peach fruit in order to prolong the storage time.Based on the full-length mitochondrial Grx gene published by Genbank,the full-length cDNA of Grx is 513 bp and encodes 171 amino acids.The results of real time PCR showed that the expression of Grx gene was obviously increased in peaches treated with 15 ?mol L-1 NO while decreased in peaches treated with c-PTIO during the early period storage,but there was no obvious difference compared with the control peaches during late period storage.The recombinant Grx protein was expressed in Escherichia Coli and purified through Ni-chelating affinity chromatography.Changes in Ultraviolet and fluorescence spectra of Grx reacted with NO showed that NO could reduce the fluorescence intensity of Grx and cause fluorescence quenching.The fluorescence quenching was static quenching.The results from Scatchard model showed that NO could react with Grx to form a 1:1 compound.