Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA.
Department of Botany, Functional Plant Biology, University of Innsbruck, Innsbruck, Austria.
Microb Ecol. 2021 Oct;82(3):770-782. doi: 10.1007/s00248-020-01679-3. Epub 2021 Jan 27.
Diverse algae possess the ability to recover from extreme desiccation without forming specialized resting structures. Green algal genera such as Tetradesmus (Sphaeropleales, Chlorophyceae) contain temperate terrestrial, desert, and aquatic species, providing an opportunity to compare physiological traits associated with the transition to land in closely related taxa. We subjected six species from distinct habitats to three dehydration treatments varying in relative humidity (RH 5%, 65%, 80%) followed by short- and long-term rehydration. We tested the capacity of the algae to recover from dehydration using the effective quantum yield of photosystem II as a proxy for physiological activity. The degree of recovery was dependent both on the habitat of origin and the dehydration scenario, with terrestrial, but not aquatic, species recovering from dehydration. Distinct strains of each species responded similarly to dehydration and rehydration, with the exception of one aquatic strain that recovered from the mildest dehydration treatment. Cell ultrastructure was uniformly maintained in both aquatic and desert species during dehydration and rehydration, but staining with an amphiphilic styryl dye indicated damage to the plasma membrane from osmotically induced water loss in the aquatic species. These analyses demonstrate that terrestrial Tetradesmus possess a vegetative desiccation tolerance phenotype, making these species ideal for comparative omics studies.
不同的藻类具有在不形成特殊休眠结构的情况下从极端干燥中恢复的能力。绿藻属 Tetradesmus（团藻目，绿藻门）包含温带陆生、沙漠和水生物种，为比较与相关分类群向陆地过渡相关的生理特征提供了机会。我们将来自不同栖息地的六个物种置于三种不同相对湿度（RH 5%、65%、80%）的脱水处理中，然后进行短期和长期复水。我们使用光合作用系统 II 的有效量子产率作为生理活性的替代物来测试藻类从脱水状态恢复的能力。恢复程度既取决于起源栖息地，也取决于脱水情况，只有陆生物种而不是水生物种能够从脱水中恢复。除了一种水生菌株能够从最温和的脱水处理中恢复外，每个物种的不同菌株对脱水和复水的反应相似。在脱水和复水过程中，两种水生和沙漠物种的细胞超微结构均保持一致，但亲脂性的 styryl 染料染色表明，水生物种的细胞膜因渗透诱导的水分流失而受损。这些分析表明，陆生 Tetradesmus 具有营养体干燥耐受性表型，使这些物种成为比较组学研究的理想选择。
