Preservation Effect And The Mechanism Study Of Pre-harvest 1-MCP Treatment On Cut Rose

As one of the four most famous cut flowers in the world,rose is of high commercial value,but its short shelf and vase life limits the expanding of the industry.In this study,rose cultivar‘Rosa hybrida cv.Carola'was used as experimental material.Pre-harvest 1-methylcyclopropene(1-MCP)treatment and flower collection were conducted under different parameters,then held the cut flowers in bottles to optimize 1-MCP application parameters by observing changes of the cut flower quality and vase life.Adopting the screened optimal 1-MCP treatment parameters,the effects of pre-harvest 1-MCP treatment and in addition to post-harvest PE50 packaging treatment on postharvest physiology and cold storage life of cut flowers was investigated,ethephon treatment was used as a negative control.Comparative study on effects of pre-harvest 1-MCP and ethephon treatment on the vase life,flower quality,energy level,energy metabolism related enzymes and antioxidant-related enzyme activities of cut rose was also performed,compensened with a adenosine triphosphate(ATP)supplementation test and differential expressed protein analysis.The research aimed at provide a theoretical basis and technical support for extending the post-harvest 1-MCP preservation technology to pre-harvest stage for cut flower industry a much more convenient and efficient approach of cut rose preservation.The results are as follows:(1)The optimal pre-harvest treatment parameters of 1-MCP were screened,which were stage?for the spraying time;10?L·L~-11 for the concentration of 1-MCP treatment;and 2 d after treatment for harvest time.Under these optimal parameters,the vase life of 1-MCP-treated flowers prolonged 2.5 d longer than control.(2)Pre-harvest 1-MCP spraying treatment extended the cold storage life of cut rose‘Carola'for 10 d compared with the control,and delayed the cut flower wilting duringstorage,inhibitedrespiration,ethyleneproduction,synthesisof1-aminocyclopropane-1-carboxylic acid(ACC)and the activity of ACC oxidase(ACO),and delayed the degradation of soluble protein.Although the combined treatment of 1-MCP and PE50 delayed the cut flower wilting and protein degradation in the early stage of storage,it caused physiological disturbance in the later stage of storage,which led to the decline of cut flower quality.(3)Pre-harvest 1-MCP spraying treatment increased superoxide dismutase(SOD)activity of the cut rose,delayed the increase of malondialdehyde(MDA)content,maintained high ATP content and energy charge level,and prolonged the vase life of the cut rose‘Carola'.Ethephon treatment increased the activity of peroxidase(POD)and polyphenol oxidase(PPO),decreased ATP content and energy level,and finally accelerated the senescence of cut rose.Pre-harvest ethylene regulation affects the aging process of cut rose‘Carola'through regulating energy balance and active oxygen metabolism.(4)ATP treatment effectively improved the endogenous ATP content and energy charge level of cut rose‘Carola',inhibited the decline of dry weight,maintained water balance,active oxygen balance and the integrity of cell membrane and mitochondria,thus prolonged vase life and improved the quality of cut rose flowers.Among different concentrations,0.5 mM ATP treatment was the best,and the vase life was extended by 2.1 d compared with the control.The ATP inhibitor,2,4-dinitrophenol(DNP)treatment,showed the opposite effect.(5)A total of 2030 proteins were identified using proteomics analysis based on iTRAQ technology.Among them,numbers of differential expressed proteins were:249(I/IV-CK),265(IV-CK/IV-M)and 346(IV-CK/IV-E).The up-regulated proteins affecting the naturally flowering and senescence process of cut rose mainly were the key enzymes in glycolysis pathway(EMP),programmed cell death related proteins,cell lignification enzyme,eukaryotic translation initiation factor,second messenger molecule synthases and so on.It reflected the metabolic characteristics of increased carbohydrate decomposition,new protein synchronous synthesis and cell senescence initiation during the flowering process of cut rose.Down-regulated proteins mainly consisted of cell-frame protein and functional protein,synthetase and transferase in macromolecular synthesis pathway,indicating that the disorder of DNA replication,gene expression and regulation of RNA metabolism occurred synchronously during flowering,and the synthesis of macromolecules was gradually inhibited.Therefore,the degradation of cytoskeleton and intracellular components happened.(6)Pre-harvest ethephon treatment up regulated membrane lipid peroxidation enzymes,carbohydrate degradation and metabolism(EMP)enzymes,programmed cell death related proteins significantly and down regulated stress-resistant proteins and reactive oxygen scavenging enzymes.1-MCP inhibited the expression of cell lignification enzyme,which acted opposite to ethylene,it also significantly promoted the expression of stress-resistant protein,however,the regulation effect of 1-MCP on other protein expressions showed no complementarity with that of ethephon.It is suggested that the mechanism of which 1-MCP delayed senescence cannot be simply understood as the inhibition of ethylene related biological processes but rather the overall effect of ethylene signal and level interference.The most prominent effect of1-MCP was inhibiting the decline of the resistance of cut rose.