外源抗氧化剂对高温胁迫下苹果果皮组织酶活性的影响

Effect of Exogenous Antioxidants on the Enzymatic Activities in Fruit Peel Tissues under High-temperature Stress

以红富士苹果为试材,通过施用维生素C(Vc)、苯甲酸钠(SBN)、半胱氨酸(Cys)、维生素E(VE)以及Vc复配剂(Vc+柠檬酸或Vc+6 BA),研究不同种类外源抗氧化剂对高温胁迫下果皮组织5′核苷酸酶、脂氧合酶以及抗坏血酸过氧化物酶活性的影响。结果表明:随着环境胁迫温度的升高,果皮组织中脂氧合酶活性增大,而5′核苷酸酶和抗坏血酸过氧化物酶的活性降低,说明在高温胁迫下,果皮组织氧化胁迫作用显著增强。施用外源抗氧化剂后,能够不同程度地提高果实抗氧化能力。在高温胁迫下,果实脂氧合酶活性与对照相比呈下降趋势,而5′核苷酸酶活性呈上升趋势,施用Vc和2种复配Vc酶活性极显著提高;同样,抗坏血酸过氧化酶活性也呈上升趋势。比较几种抗氧化剂对提高果实抗氧化能力的效果,以施用维生素C(尤其是配合施用6 BA或柠檬酸)最为明显。

By immersion of fruits in solutions of ascorbic acid (ASA), sodium beneoate (SBN), cysteine (Cys) and vitamin E (V_E), the effect of different types of exogenous antioxidants on the activities of 5′-nucleodase, LOX and APX in fruit peel tissues under high-temperature stress was examined with Fuji apples so as to ascertain the mechanism of fruit resistance to heat stress and explore possible preventive practices. The results indicated that, LOX activity increased but APX and 5′-nucleodase activities decreased as high temperature stresses were accentuated, showing an enhancement of oxidative stress that may cause a decline in membrane stabilization. For example, LOX activity increased by 25.2% but 5′-nucleodase and APX activities decreased by 25.55% and 28.8% on average, respectively, at 48 ℃ as compared to 25 ℃, which substantially means that high temperature stress could aggravate fruit oxidative status. However, LOX activity reduced while APX and 5′-nucleodase activities rose with fruits pretreated with exogenous antioxidants in comparison with the control. Under 48 ℃ stress, LOX activity in fruits treated with 4 kinds of antioxidants reduced by 7.2%-7.9% and there appeared a significant decrease of LOX activity in fruits treated with 2 kinds of combined ASA antioxidants; 5′-nucleodase activities were enhanced slightly by treatment with SBN, significantly with V_E and Cys and very significantly with two combined ASA antioxidants. Likewise, APX activities rose significantly or very significantly as compared with the control.In a comparison of different exogenous antioxidants, it could be concluded that treatments with ASA, especially mixed with 6-BA or citric acids, resulted in the best improvement in fruit antioxidative capability.