外源茉莉酸甲酯处理对冬枣冷藏抗氧化代谢及褐变的影响

Effect of Exogenous Methyl Jasmonate Treatment on Antioxidant Metabolism and Browning of Post-harvest Jujube Fruit during Cold Storage

摘要:

为探讨外源茉莉酸甲酯（MeJ）对冬枣（Zizyphus Jujuba Mill.）果实冷藏过程中抗氧化系统及褐变的影响，试验采用50、100和200 μmol/L MeJ熏蒸处理冬枣果实24 h，以空气处理为对照，测定在2±0.5 ℃贮藏过程中果实硬度、腐烂率、呼吸速率、超氧阴离子（O2-?）产生速率、过氧化氢（H2O2）、丙二醛（MDA）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）、抗坏血酸（AsA）、还原型谷胱甘肽（GSH）、多酚氧化酶（PPO）和总酚变化。结果表明，冷藏过程中MeJ处理显著延缓果实硬度下降，抑制呼吸速率和腐烂率，减少O2-?、H2O2和MDA积累，维持较高的SOD、CAT和POD活性及AsA和GSH含量，降低PPO活性，增加总酚含量。通过主成分分析得到腐烂率、O2-?、H2O2、MDA和PPO是评价MeJ作用效果的主要因素，且100 μmol/L MeJ处理对维持冷藏冬枣品质、提高果实抗氧化能力和抑制褐变的作用效果最显著。

Abstract:

We aimed to investigate the effect of methyl jasmonate (MeJ) treatment on the antioxidant system and browning of post-harvest jujube (Zizyphus jujuba Mill.) fruit during cold storage. Fruits were treated with 50, 100, and 200 μmol/L MeJ for 24 h. Control fruits and MeJ-treated fruits were sealed in air and stored at 2±0.5 ℃. Fruit firmness, decay index, respiration rate, superoxide anion production rate,and the content levels of hydrogen peroxide, malonaldehyde (MDA), ascorbic acid (AsA), glutathione (GSH), and total phenols (TP), as well as the activity levels of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO) were evaluated for all groups. Results showed that, during cold storage, MeJ treatments significantly delayed the decrease of fruit firmness; inhibited the respiration rate and decay index; decreased the accumulation of superoxide anion, hydrogen peroxide, and MDA; maintained higher activities of SOD, CAT, and POD; maintained levels of AsA and GSH; lowered the level of PPO activity; and increased TP content. Principal component analysis showed that the decay index, superoxide anion production rate, hydrogen peroxide content, MDA content, and PPO activity were the main factors that influenced the efficacy of MeJ. Furthermore, the 100 μmol/L MeJ treatment was most effective in maintaining fruit quality, enhancing antioxidant capacity, and inhibiting browning during cold storage.