Ecological studies of aquatic moss pillars in Antarctic lakes 3. Light response and chilling and heat sensitivity of photosynthesis
Ecological studies of aquatic moss pillars in Antarctic lakes 3. Light response and chilling and heat sensitivity of photosynthesis
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发表时间：
2003-02
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通讯作者：
S. Kudoh;Y. Kashino;S. Imura
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作者：
S. Kudoh;Y. Kashino;S. Imura
采用PAM叶绿素荧光法测定了藓类植物Leptobryum sp.的光-光合作用关系，其是水生苔藓柱的主要成分，在琼脂平板上培养的细苔属物种中，以及在水生和陆生形式的假三角真藓中。平板培养的薄苔草的形态与生长在水生苔藓柱上的样品明显不同;前者的叶和芽明显增厚和扩大。尽管两种材料的形态差异很大，但它们的光-PS Ⅱ产量、光-非光化学猝灭和相对电子传递速率等光合光响应基本相同。另一方面，B. pseudotriquetrum收集的苔藓柱和陆生栖息地改变了很大。Leptobryum sp.的光-PS II产量和光-ETR关系表现出相当的阴株型响应，在任何光强下PS II有效产量都较低，最大ETR较低，光饱和点较低，而B. pseudotriquetrum从陆地栖息地表现出，而“太阳植物”型的反应。水生B。在所有光照强度下，假三角草的有效PS Ⅱ产量和ETR均最低。实验性地将冷/热胁迫添加到水生细苔属（Leptobryum sp.），PS Ⅱ的最大和有效得率与处理温度呈极窄的嗜冷关系。这些在细苔属植物中观察到的光合作用特征，荫生植物型光反应和对温度变化的非常幼稚的敏感性，表明该物种可以在水生生境中进行光合生长，但不能在严重的东南极陆生生境中生存或盛行。关键词：苔藓柱，光合作用，光变曲线，温度敏感性，南极
The light-photosynthesis relation was measured using a PAM chlorophyll fluorometric method in a moss, Leptobryum sp., which is the primary component of aquatic moss pillars, in cultured Leptobryum sp. on an agar plate, and in both aquatic and terrestrial forms of Bryum pseudotriquetrum. The morphology of the platecultured Leptobryum sp. was clearly di#erent from the sample growing on an aquatic moss pillar; the leaves and shoots were considerably thickened and enlarged in the former. In spite of the great di#erence of morphology, photosynthetic light responses such as light-PS II yield, -non-photochemical quenching and the relative rate of electron transport of both samples were nearly the same. On the other hand, the responses of B. pseudotriquetrum collected from a moss pillar and terrestrial habitat di#ered greatly. Light-PS II yield and light-ETR relationships of the Leptobryum sp. showed rather shade-plant type response, low e#ective PS II yield at any light intensity and low maximum ETR with low light saturation point, while B. pseudotriquetrum from a terrestrial habitat showed rather ‘sun-plant’ type responses. Aquatic B. pseudotriquetrum showed the lowest values of e#ective PS II yield and ETR at almost all light intensities among the present samples. Chilling/heating stress was experimentally added to the aquatic Leptobryum sp., and it was found that both maximum and e#ective yield of PS II showed quite narrow and cryophilic relationships with treatment temperatures. These photosynthetic features observed in the Leptobryum sp., shadeplant type light response and very naı̈ve sensitivity to the changes of temperature, suggest that the species can perform photosynthetic growth within the aquatic habitat; however, it cannot survive or prevail in the terrestrial habitat in severe East Antarctica. key words: moss pillar, photosynthesis, light curves, temperature sensitivity, Antarctic