Effect Of 1-MCP On Several Fruits Senescence And Its Regulation Mechanism

1-Methylcyclopropene (1-MCP) could competitive binding to the ethylene receptor,block ethylene synthesis and its physiology effects; aminoethoxyvinylglycine (AVG) couldinhibit the conversion of ACC from Met, then decrease the ethylene production. Both of themcould retard fruit senescence by inhibiting the ethylene synthesis and action. In thisexperiment, Feicheng Peach (Prunus persica c.v. Fei-Cheng), Fuji apple (Malus domesticaBorkh c.v. Red Fuji) and Starking apple (Malus domestica Borkh c.v. Starking) were used tostudy the effects of 1-MCP on ethylene synthesis metabolism, antioxidant enzyme activity,softening and qualities in different fruits and its regulation mechanism. Strawberry(Fragariaananassa cv. Virginia), grape(Vitis vinifera-American hybrid c.v. Kyoho) and white winterpearmain apple (Malus domestica Borkh c.v. White Winter Pearmain)were also used asmaterials to study the effects of 1-MCP in this experiment. The effects of AVG sprayed 10 dbefore fruit harvest (DBFH) on ethylene synthesis and the qualities in Feicheng peach pre-and post-harvest were studied, too. The destination of this experiment was to further disclosethe physiological mechanism of 1-MCP on inhibiting ethylene synthesis, delaying fruitsoftening and retaining senescence in different fruits. We also expected that the results of thisexperiment would give a theoretical and practical support for the application of 1-MCP andAVG. The main results were as follows: 1 1-MCP showed significant inhibition on the endogenous ethylene production both inclimacteric and non-climacteric fruit after harvest, but increased the ethylene release rate ofFeicheng peach 4 d after storage at 20 ℃. 1-MCP also had a significant antagonism to theexogenous ethylene effects on the climacteric fruits, but did't in non-climacteric fruit. Studies showed that the main mechanism of 1-MCP inhibiting ethylene synthesis inStarking apple and Feicheng peach fruit lie in the stimulation to ACS activity in ethylenesystem Ⅰand the inhibition to it in system Ⅱ, and the inhibition on ACO activity rise in thewhole ethylene synthesis system. But 1-MCP didn't affect the ACO and ACS activity in vitro.Hence, the regulations of 1-MCP on the key enzymes in ethylene synthesis were related to the 4ethylene feedback regulation. In addition, 1-MCP could reduce the substrate of ethylenesynthesis by accelerating the conversion of MACC from ACC, which decreased the synthesisof ethylene. The content of MACC and ACC were significant correlation in 10-30 d or 15-30d in the fruit treated with ethrel or 1-MCP, respectively. The result also showed that the direct reason of 1-MCP inhibiting the senescence ofclimacteric fruit lie in delaying the conversion of system Ⅰ to system Ⅱ, hence slowed theethylene release climacteric, then delayed the fruit senescence progress. In addition, 1-MCPcould inhibit the acceleration of free radical to fruit senescence by maintaining higher SODactivity, decreasing active oxygen production rate, lipid membrane peroxide and MDAproduction. In Fuji apple, the total protein kinase activity was also inhibited by 1-MCP, andthis might decrease the ethylene signal transduction progress via protein phosphorylation,then retard the inducing effect of exogenous ethylene to fruit senescence. 1-MCP treatment had significantly decreased the wound ethylene production inStarking apple, which even lower than the intact apple. 2. 1-MCP could effectively delay the softening of climacteric fruit, such as Starking andFuji apples and Feicheng peach, but as different fruits had different softening mechanism, themechanism of 1-MCP inhibiting different fruit softening was different: in Starking apples, thekey enzyme to the softening is endo- and exo-PG, while during Feicheng peach fruit softening,the key enzyme was EGase before the 20th d and endo-PG after 20th d during storage at 0℃.1-MCP inhibited fruit softening mainly by in...