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作 者 ：孙锦,贾永霞,郭世荣*,李娟

期 刊 ：生态学报 2009年 29卷 8期 页码：4361~4371

关键词：海水；菠菜(Spinacia olerancea L.)；叶绿体；活性氧；叶绿素；

Keywords:seawater, spinach（Spinacia olerancea L.）, chloroplast, reactive oxygen species, chlorophyll,

摘 要 ：以海水敏感品种圆叶菠菜和耐海水品种‘荷兰3号’为试材，采用水培方法，研究了海水胁迫对菠菜（Spinacia olerancea L.）叶绿体活性氧（ROS）和叶绿素（Chl）代谢的影响。结果表明，海水胁迫下，2个菠菜品种叶绿体内超氧阴离子（O-?2）产生速率、过氧化氢（H2O2）和丙二醛（MDA）含量显著升高，并且圆叶菠菜的提高幅度大于‘荷兰3号’；圆叶菠菜叶绿体内的超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）活性和抗坏血酸（AsA）、还原型谷胱甘肽（GSH）含量均低于‘荷兰3号’，而过氧化物酶（POD）活性高于‘荷兰3号’；光氧化剂甲基紫精（MV）进一步使2个菠菜品种叶绿体内O-?2产生速率加快、H2O2含量提高、膜质过氧化加重，活性氧清除剂AsA明显降低了菠菜叶绿体内ROS水平，缓解了由MV造成的严重的膜质过氧化伤害。海水胁迫下，2个菠菜品种叶片叶绿素b（Chlb）、叶绿素a（Chla）及其合成前体物质原叶绿素酸（Pchl）、镁原卟啉Ⅸ（Mg-protoIX）、原卟啉Ⅸ（ProtoⅨ）和尿卟啉原Ⅲ（UroⅢ）含量明显降低，而胆色素原（PBG）和δ-氨基酮戊酸（ALA）积累，Chl合成受到阻碍，并且圆叶菠菜的受阻程度大于‘荷兰3号’；MV进一步加剧了这种受阻程度，而AsA部分缓解了由海水胁迫和MV造成的阻碍作用。海水胁迫明显提高了圆叶菠菜叶片叶绿素酶（Chlase）活性而对‘荷兰3号’没有影响，MV处理对圆叶菠菜Chlase活性的影响程度大于‘荷兰3号’，但AsA对2个品种叶片Chlase活性没有明显影响。上述结果说明，海水胁迫下，菠菜叶绿体内ROS与Chl代谢密切相关，不仅通过叶绿体膜的氧化伤害使Chl降解，而且使Chl合成的PBG向UroⅢ转化步骤受阻。耐海水品种‘荷兰3号’叶绿体清除ROS主要通过SOD和AsA-GSH循环系统，清除能力较强，减轻了ROS对叶绿体膜的氧化损伤和Chl合成的受阻程度，并且海水胁迫对其Chlase活性的影响较小；而海水敏感品种圆叶菠菜叶绿体清除ROS主要依赖于SOD和POD，对ROS的清除能力有限，从而导致了ROS大量积累，叶绿体膜的氧化损伤和Chl合成的受阻程度严重，并且海水胁迫显著提高了Chlase活性，加剧了Chl降解。

Abstract:The effects of seawater stress on metabolism of reactive oxygen species (ROS) and chlorophyll (Chl) in chloroplast of two spinach cultivars, Yuanye spinach (seawater sensitive cultivar) and Helan No.3 (seawater tolerant cultivar) were investigated by hydroponics. The results showed that production rate of superoxide radical (O?2), content of hydrogen peroxide (H2O2) and malonaldehyde (MDA) in chloroplast of two spinach cultivars were remarkably increased by seawater with higher rate in cv. Yuanye; Under the stress of seawater, the activity of anti-oxidation enzyme such as superoxide dismutase (SOD), ascorbic acid peroxidase (APX) and glutathione reductase (GR), and the content of antioxidant such as ascorbic acid (AsA) and glutathione reduced (GSH) in chloroplast of cv. Yuanye were lower than those of cv. Helan No.3, while peroxidase (POD) activity in chloroplast of cv.Yuanye was higher than that of cv. Helan No.3; The supplement of methyl viologen (MV), the photo-oxidant, enhanced the production rate of O?2, the content of H2O2 and MDA in chloroplast of two spinach cultivars, while the addition of AsA, the eliminator for ROS, decreased ROS level and alleviated oxidization of plasmolemma. The content of chlorophyll b (Chlb), chlorophyll a (Chla) and precursor of Chl such as protochlorophyll (Pchl), Mg-protoporphyrinⅨ (Mg-ProtoIX), protoporphyrinⅨ(ProtoⅨ) and uroorphyrinogenⅢ (UroⅢ) was remarkably decreased, but the content of porphobilinogen (PBG) and δ-aminolevulinic acid (ALA) was increased by the stress of seawater, which lead to inhibition for Chl synthesis, and the inhibition was aggravated by MV and eliminated by AsA. Chlorophyllase (Chlase) activity in the leaves of cv. Yuanye was improved while it was not influenced in the leaves of Helan No.3 under seawater stress. The Chlase activity in the leaves of cv. Yuanye was more greatly affected by MV treatment than that of Helan No.3, however, Chlase activity of two cultivars was not influenced by AsA. These results suggest that ROS is closely related to Chl metabolism, which not only injure plasmolemma but also inhibit the process of transformation of PBG to UroⅢ as a result of Chl decomposition. In seawater tolerant cultivar (cv. Helan No.3), the ROS elimination is mainly depended on SOD and AsA-GSH system, which could alleviate oxidation injury of ROS to chloroplast membrane and inhibition of Chl synthesis, and Chlase activity was less influenced by seawater stress; while in seawater sensitive cultivar (cv. Yuanye), it is mainly depended on SOD and POD, which has limited ability to eliminate ROS and lead to accumulate mass ROS to severe oxidation injury of chloroplast membrane and inhibition of Chl synthesis, and Chlase activity was significantly improved by seawater stress, which enhanced Chl decomposition.

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