热处理与内源H2O2对黄瓜抗冷性和抗氧化酶活性的影响

摘要

Effect of heat treatment and pretreatment (prior to heat treatment) with dimethylthiourea (DMTU, a trap for H2O2) on cell membrane injury and metabolism of reactive oxygen species in cucumbers stored at 2℃was investigated. The content of malondialdehyde (MDA), the chilling injury index and electrolyte leakage in control cucumbers were increased during the cold storage;H2O2 content, the activities of superoxide dismutase (SOD) and catalase (CAT) exhibited an initial fast increase followed by a reduction;the activities of peroxidase (POD) and ascorbate peroxidase (APX) were decreased with storage time. Heat treatment alleviated the chilling injury development, enhanced the endogenous H2O2 content during early storage, postponed the increase of MDA content and increased the activities of CAT, APX and SOD in cucumbers stored at low temperature. However, heat treatment had no significant effect on POD activity, suggesting that the enzyme did not play a key role in chilling tolerance in relation to antioxidant activity. On the contrary, DMTU treatment counteracted heat treatment-induced tolerance in cucumbers, exhibiting higher chilling injury index and MDA content, and decreased activities of CAT and APX. It is suggested that H2O2 mediated chilling resistance induced by heat treatment in cucumbers.%研究热处理和二甲基硫脲(DMTU)抑制内源H2O2再进行热处理，对2℃贮藏条件下荷兰小黄瓜冷害发生率、细胞膜系统以及活性氧代谢的影响。对照组黄瓜在冷藏过程中，冷害发生率、膜渗透率和丙二醛(MDA)含量均呈上升趋势，H2O2含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性先上升后下降，而过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性随贮藏时间的延长而降低。热处理可以抑制低温贮藏中黄瓜冷害发生率和膜渗透率的增加，提高贮藏初期H2O2含量，减少MDA的积累，提高黄瓜CAT、APX、SOD的活性，POD活性在贮藏前后未发生明显变化，表明POD不是抗冷系统中的关键因子。抑制内源H2O2后进行热处理的黄瓜冷害发生率和MDA含量显著高于热处理组，而CAT、APX的活性受到抑制。结果表明，热处理可以减轻黄瓜冷害的发生，提高抗氧化酶的活性。抑制内源H2O2后进行热处理的黄瓜抗冷性降低，表明初期内源H2O2在热处理诱导的黄瓜抗冷性中发挥重要作用。