Light, Temperature, and Desiccation Effects on Photosynthetic Activity, and Drought-Induced Ultrastructural Changes in the Green Alga Klebsormidium dissectum (Streptophyta) from a High Alpine Soil Crust
Light, Temperature, and Desiccation Effects on Photosynthetic Activity, and Drought-Induced Ultrastructural Changes in the Green Alga Klebsormidium dissectum (Streptophyta) from a High Alpine Soil Crust
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DOI：
10.1007/s00248-011-9924-6
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发表时间：
2012-01-01
影响因子：
3.6
通讯作者：
Holzinger, Andreas
中科院分区：
文献类型：
--
作者：
Karsten, Ulf;Holzinger, Andreas
世界性的绿色藻类克雷伯藻属（Klebsormidiales，Streptophyta）的成员是生物土壤结皮等陆地微生物群落的典型组成部分，具有许多重要的生态功能。在本研究中，Klebsormidium dissectum（Gay）Ettl & Gartner分离自奥地利蒂罗尔阿尔卑斯山的高山土壤地壳。在不同的控制非生物条件下的生长和光合作用方面的生理性能进行了研究，并与应用的处理下的超微结构变化进行了比较。K.解剖显示非常低的光需求，反映在生长模式和光合效率。温度从5A ℃升高到40 A ℃，对呼吸耗氧和光合放氧产生不同的影响。而在低温（5-10A摄氏度），呼吸是不可检测的或在一个非常低的水平，光合作用是相对较高的，在最高温度下，呼吸不受影响，光合作用强烈抑制，指出两个生理过程之间的温度敏感性的强烈差异。虽然K.短时间的干燥对多裂叶藓的生长影响很大，复水后仅部分恢复，但该种在5%的相对湿度下仍能存活3周。K.夹层细胞具有5.6埃+/-0.3 μ m的细胞宽度和8.4埃+/-2.0 μ m的细胞长度。干燥的细胞显示出细胞宽度（对照的46%）和细胞长度（对照的65%）的强烈减少。此外，在干燥的细胞中，较少的线粒体被DIOC 6染色，并且受损的质膜被FM 1-43染色检测到。高压冷冻固定以及化学固定允许可视化的超微结构变化所造成的干燥。在这样的细胞中，细胞核和叶绿体仍然明显完整，但极薄的细胞壁（75-180 nm）基本上变形。细胞质电子致密，线粒体改变。虽然K.多裂叶的特点是广株种，所有的生理生态和超微结构的数据表明敏感性干燥。然而，不断发生的分裂成较小的单位丝导致改善自我保护，因此可能代表一种生活策略，以更好地生存在暴露的高山土壤结皮的干旱更长的时间。
Members of the cosmopolitan green algal genus Klebsormidium (Klebsormidiales, Streptophyta) are typical components of terrestrial microbiotic communities such as biological soil crusts, which have many important ecological functions. In the present study, Klebsormidium dissectum (Gay) Ettl & Gartner was isolated from a high alpine soil crust in the Tyrolean Alps, Austria. Physiological performance in terms of growth and photosynthesis was investigated under different controlled abiotic conditions and compared with ultrastructural changes under the treatments applied. K. dissectum showed very low light requirements as reflected in growth patterns and photosynthetic efficiency. Increasing temperatures from 5A degrees C to 40A degrees C led to different effects on respiratory oxygen consumption and photosynthetic oxygen evolution. While at low temperatures (5-10A degrees C), respiration was not detectable or on a very low level, photosynthesis was relatively high, Reversely, at the highest temperature, respiration was unaffected, and photosynthesis strongly inhibited pointing to strong differences in temperature sensitivity between both physiological processes. Although photosynthetic performance of K. dissectum was strongly affected under short-term desiccation and recovered only partly after rehydration, this species was capable to survive even 3 weeks at 5% relative air humidity. K. dissectum cells have a cell width of 5.6 A +/- 0.3 mu m and a cell length of 8.4 A +/- 2.0 mu m. Desiccated cells showed a strongly reduced cell width (46% of control) and cell length (65% of control). In addition, in desiccated cells, fewer mitochondria were stained by DIOC6, and damaged plasma membranes were detected by FM 1-43 staining. High-pressure freeze fixation as well as chemical fixation allowed visualizing ultrastructural changes caused by desiccation. In such cells, the nucleus and chloroplast were still visibly intact, but the extremely thin cell walls (75-180 nm) were substantially deformed. The cytoplasm appeared electron dense and mitochondria were altered. Although K. dissectum can be characterized as euryoecious species, all ecophysiological and ultrastructural data indicate susceptibility to desiccation. However, the steadily occurring fragmentation of filaments into smaller units leads to improved self protection and thus may represent a life strategy to better survive longer periods of drought in exposed alpine soil crusts.