【作者】 刘孟臣；

【导师】 周杰；

【作者基本信息】 山东农业大学 ， 果树学， 2007， 博士

【摘要】 分别用一氧化氮（NO）气体和外源乙烯熏蒸肥城桃果实以及NO溶液对猕猴桃果实浸果,研究了不同浓度NO处理对肥城桃和猕猴桃果实乙烯产生、可溶性蛋白、糖酸含量、丙二醛、超氧自由基、叶绿素含量和ACC含量,以及ACS、ACO、LOX、SOD、CAT、POD等果实软化过程相关酶活性的影响。结果表明,1000μl·L^-1外源乙烯熏蒸3 h促进了肥城桃果实乙烯释放、提高了果实中ACS和ACO的活性,而10μl·L^-1 NO熏蒸3 h明显抑制了果实内源乙烯释放,降低了果实中ACS和ACO活性。外源乙烯和NO协同处理(1000μl·L^-1乙烯/10μl·L^-1 NO熏蒸3 h)后,桃果实的ACS和ACO活性以及乙烯释放量等显著低于外源乙烯单独处理,而高于NO单独处理,表明NO处理可以降低外源乙烯对桃果实内源乙烯生物合成的催化作用。20μl L^-1 NO熏蒸处理保持了猕猴桃果实较低的可溶性糖含量和较高的可滴定酸、Vc含量,其果实中丙二醛和超氧自由基含量低于其他浓度的NO熏蒸处理(10和30μlL^-1 NO)。20μl L^-1 NO熏蒸降低了猕猴桃果实中LOX和POD活性,延缓了猕猴桃果实采后期间CAT活性的降低,显著提高了猕猴桃果实SOD活性,降低了猕猴桃果实中氢过氧化物的含量。用NO溶液浸果处理猕猴桃果实,也得到了类似的实验结果。气体熏蒸处理对猕猴桃果实叶绿素含量的影响不大。1μmol L^-1 NO溶液浸果处理后,叶绿素含量显著高于对照。0.5和2μmol L^-1 NO溶液浸果后叶绿素含量无显著差异,而两者均显著低于1μmol L^-1 NO处理。20μl L^-1 NO气体熏蒸后,猕猴桃果实中类胡萝卜素含量低于对照;1μmol L^-1.NO溶液浸果后内类胡萝卜素含量低于对照,且均低于其他浓度的NO处理。NO溶液与ACO的最佳反应时间是30 min,底物ACC的最佳浓度为2 mmol L^-1,作为酶促反应的辅因子,抗坏血酸钠和Fe²⁺的最适浓度分别为20 mmol L^-1和20μmolL^-1,碳酸氢钠的最适浓度为20 mmol L^-1。Lineweaver-Burk图显示NO是一种非竞争性抑制剂。NO与ACO反应的米氏常数K_m为3.4 mmol L^-1,抑制常数K_i为2.34μmol L^-1。更多还原

【Abstract】 The peach fruits（Prunus persica（L.） Batsch.,cv.Feicheng） were fumigated with 1000μl L^-1 ethylene,10μl L^-1 NO and 1000μl L^-1 ethylene/10μl L^-1 NO for 3 h,then stored at 1℃.Parts of Chinese gooseberry（Actinidia chinensis Planch.） were fumigated with 0,10,20 and 30μl·L^-1 NO for 3 h,then stored at 4 and 22℃.Other Chinese gooseberry were dipped with 0,0.5,1 and 2μmol L^-1 NO solutions for 10 min,then dried with wind,and stored at 4 and 22℃.The effects of different concentrations and ways of NO treatments on physiological indices of post-harvest fruit,including ethylene production rate,soluble protein,contents of sugar and acid,MDA,superoxide rdicals,chlorophyll and ACC contents,and activities of relevant enzymes from the fruits,including ACS,ACO,LOX,SOD,CAT,POD,were investigated.The results showed that fumigation with 1000μl·L^-1 exogenous ethylene promoted ethylene production,increased activities of ACS and ACO.Treatment with 10μl·L^-1 NO significantly inhibited the production of endogenous ethylene in fruit,reduced activities of ACS and ACO.The activities of ACS and ACO and ethylene production in fruit treated with 1000μl·L^-1 ethylene/10μl·L^-1 NO were significantly lower than those in fruit treated with exogenous ethylene,and higher than those in fruit treated with NO,suggesting that there were antagonistic actions between NO and exogenous ethylene.NO could inhibit biosynthesis of ethylene and catalysis of exogenous ethylene during ethylene biosynthesis in peach fruits.Chinese gooseberry fumigated with 20μl L^-1 NO had low content of soluble sugar and high content of titratable acids and Vc.Contents of MDA and superoxide radicals in Chinese gooseberry fumigated with 20μl L^-1 NO were lower than those in Chinese gooseberry fumigated with 10 and 30μl L^-1 NO.Fumigation with 20μl L^-1 NO reduced activities of LOX and POD in Chinese gooseberry,delayed the decrease of CAT activity during the late period of storage,significantly increased SOD activity,and decreased the content of hydrogen peroxide.Similar results were also found in Chinese gooseberry treated with NO solution.There were no significant differences in chlorophyll content in Chinese gooseberry fumigated with different concentrations of NO gas.However,the chlorophyll content in Chinese gooseberry soaked with 1μmol L^-1 NO was higher than that of the control.There were no differences in chlorophyll content in Chinese gooseberry soaked with 0.5 and 2μmol L^-1 NO,which were significant lower than treatment with 1μmol L^-1 NO.The carotenoid content in Chinese gooseberry fumigated with 20μl L^-1 NO was lower than that of the control, ande that in Chinese gooseberry soaked with 1μmol L^-1 NO were also lower than those of the control and treatments with other concentrations of NO。The optimal time of reaction between NO and ACC was 30 min,and proper concentration of ACC is 2 mmol L^-1.As cofactors of the enzymic reaction,the proper concentrations of Vc,NaHCO₃ and Fe²⁺ were 20 mmol L^-1,20 mmol L^-1 and 20μmol L^-1, respectively.The inhibition kinetics of NO analyzed by Based on Lineweaver-Burk’ theory, we demonstrated that the inhibition kinetics of NO for the oxidation of ACC in the catalysis of ACCO was expressed as a noncompetitive inhibition model and NO was called a noncompetitive inhibitor.The apparent Michaelis constant K_m and the inhibition constant of noncompetitive reversible inhibitor K_i were determined to be 3.4 mmol L^-1 and 2.34μmol L^-1, respectively.更多还原