作 者 ：汪晓峰, 任红旭, 孙国钧
期 刊 ：植物生态学报 2005年 29卷 2期 页码：331-337
Keywords:Altitudes, Rhodiola quadrifida, Rhodiola gelida, Antioxidants, Adaptation,
摘 要 ：以分布于乌鲁木齐河源区天山中段不同海拔高度的四裂红景天（Rhodiola quadrifida）（3 500～3 805 m）及长鳞红景天（R. gelida）（3 805～4 010 m）为试材，通过对比分析两种红景天在一连续的海拔梯度上种内及种间叶片膜脂过氧化及抗氧化保护系统的变化，初步探讨植物对于高山极端环境的适应机制。结果显示，分布于海拔较高的长鳞红景天其叶片中膜脂过氧化产物丙二醛(MDA)的含量明显高于分布海拔较低的四裂红景天，而两种红景天种内膜脂过氧化水平则没有随海拔升高呈现出明显差异。此外，抗氧化保护酶CAT，POD，SOD，GR和ASA-POD的活性与非酶促抗氧化剂ASA、GSH的含量不仅在种间存在有明显差异，长鳞红景天中明显高于四裂红景天，而且在两种红景天种内亦随海拔升高有不同程度地提高。表明当海拔升高时，虽然环境条件渐趋恶劣，对植物造成的氧化胁迫增强，但红景天脂膜保护系统的功能亦相应加强，从而增强了其抵抗逆境胁迫的能力。其中以过氧化物酶POD的活性变化最为显著：在3 805 m以下海拔区，于四裂红景天叶片中均未检测到该酶活性，而分布海拔较高的长鳞红景天叶片中该酶活性则随海拔升高明显增强，推测POD可能在红景天适应特殊生境中起着重要的作用，亦可能与高海拔区长鳞红景天取代四裂红景天有关。
Abstract:Alpine environments are characterized by rapid changes in climate, and leaves of alpine plants are routinely exposed to high light intensities at low temperatures. The fact that there seems to be no impairment of photosynthesis by high light and low temperatures under field conditions indicates a very well regulated system of carbohydrate turnover together with a functional system of antioxidants. To study the mechanisms of adaptation of alpine plants, we investigated the antioxidative defense capacity in leaves of two alpine plants, Rhodiola quadrifida and R. gelida. Field investigations were carried out on the slopes of Tianshan Mountain near the Tianshan Glacier NO. 1. Along this slope, R. quadrifida was found between 3 500 and 3 805 m and R. gelida was found between 3 805 and 4 010 m. The two species coexisted at 3 805 m. Plant specimens used in this experiment were collected at 50 m intervals from 3 610 to 3 900 m. Our results showed that the malondialdehyde (MDA) content in leaves of R. gelida was significantly greater than that in R. quadrifida, suggesting that R. gelida might suffer more serious oxidative stress compared to R. quadrifida． The fact that R. gelida can survive and maintain normal metabolism at high elevations suggests that it might be an adaptive mechanisms to endure serious oxidative stress in this harsh environment. The increase in the activities of antioxidative enzymes, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) as well as the contents of reduced glutathione (GSH) and ascorbic acid (AsA), in the leaves of R. gelida suggested a combined and balanced enhancement of antioxidants to improve stress resistance in alpine plant leaves. Among all the antioxidative enzymes examined, peroxidase (POD) was quite distinct from others. Activity of POD was below the limits of detection in leaves of R. quadrifida collected from elevations lower than 3 805 m, but enhanced activity was observed in leaves of R. gelida as altitude increased implying that POD might play an important role in plant adaptation to alpine environments. Given the inverse relationship between growth rate and peroxidase activity demonstrated in many plant developmental systems, in-depth studies on the role of peroxidases in adaptation of R. gelida to high altitudes are warranted.