Free radical scavenging and senescence in Iris tepals
Free radical scavenging and senescence in Iris tepals
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DOI：
10.1016/s0981-9428(01)01289-x
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发表时间：
2001-07-01
影响因子：
6.5
通讯作者：
van Doorn, WG
中科院分区：
文献类型：
--
作者：
Bailly, C;Corbineau, F;van Doorn, WG
鸢尾花（Iris x hollandica，cv. Blue Magic）出现花被片衰老的明显症状之前，大多数叶肉细胞都会死亡。我们研究了一些参与自由基清除的酶的作用。在花被片展开后的 4 天内，超氧化物歧化酶（SOD，EC 1.15.11）活性没有发生变化，尽管在可见衰老时（第 5 天）活性已变低。 SOD 产生过氧化物，这可能导致自由基进一步产生。过氧化物被过氧化氢酶（EC 1.11.1.6）或抗坏血酸过氧化物酶（APX，EC 1.11.1.11）还原。在鸢尾花被片中，APX活性远高于过氧化氢酶。过氧化氢酶活性逐渐升高，而APX活性直到第4天才保持不变，然后在出现视觉衰老症状时降至较低值。谷胱甘肽还原酶（GR，EC 1.6.4.2.）参与维持抗氧化剂谷胱甘肽，直到第 5 天才表现出活性变化，但同工酶活性在衰老之前发生变化。已知会增加自由基水平的处理，例如提高氧气浓度或将分离的花被放入含有一系列自由基清除剂/抗氧化剂的水溶液中，不会影响可见花被衰老的时间。结论是，衰老的早期过程似乎既与 SOD、APX 和过氧化氢酶自由基清除能力的减弱无关，也与 GR 活性的减弱无关。由于在出现可见的衰老症状时 SOD 和 APX 活性较低，因此在衰老的最后阶段可能会出现自由基清除能力减弱的情况。 (C) 2001 年科学与医学版 Elsevier SAS。
The visible symptoms of tepal senescence in Iris flowers (Iris x hollandica, cv. Blue Magic) are preceded by the death of most mesophyll cells. We investigated the role of some enzymes involved in free radical scavenging. During the 4 d following tepal unfolding, no changes occurred in superoxide dismutase (SOD, EC 1.15.11) activity, though activity had become low by the time of visible senescence (day 5). SOD produces peroxide, which may lead to further free radical production. Peroxide is reduced by catalase (EC 1.11.1.6) or ascorbate peroxidase (APX, EC 1.11.1.11). In Iris tepals, the activity of APX activity was much higher than that of catalase. Catalase activity gradually increased, whereas APX activity remained unchanged until day 4, then dropped to low values when visual senescence symptoms were expressed. Glutathione reductase (GR, EC 1.6.4.2.), involved in maintaining the antioxidant glutathione, exhibited no change in activity until day 5, but a change in isozyme activity occurred prior to senescence. Treatments known to increase free radical levels, such as elevated oxygen concentrations or placing isolated tepals in aqueous solutions containing a range of free radical scavengers/antioxidants, did not affect the time to visible tepal senescence. It is concluded that the early processes of senescence seem neither related to diminished free radical scavenging by SOD, APX and catalase, nor to diminished GR activity. As SOD and APX activities were low by the time visible senescence symptoms were expressed, diminished free radical scavenging may occur at the very last stages of senescence. (C) 2001 Editions scientifiques et medicales Elsevier SAS.