Rippin Martin, Borchhardt Nadine, Karsten Ulf, Becker Burkhard
Department of Biology, Botanical Institute, University of Cologne, Cologne, Germany.
Department of Biology, University of Rostock, Rostock, Germany.
Front Microbiol. 2019 Aug 6;10:1730. doi: 10.3389/fmicb.2019.01730. eCollection 2019.
Biological soil crusts (BSCs) are complex communities of autotrophic, heterotrophic, and saprotrophic (micro)organisms. In the polar regions, these biocrust communities have essential ecological functions such as primary production, nitrogen fixation, and ecosystem engineering while coping with extreme environmental conditions (temperature, desiccation, and irradiation). The microalga is commonly found in BSCs all across the globe. The ecophysiological resilience of various species to desiccation and other stresses has been studied intensively. Here we present the results of transcriptomic analyses of two different species, and , isolated from Antarctic and Arctic BSCs. We performed desiccation stress experiments at two different temperatures mimicking fluctuations associated with global change. Cultures grown on agar plates were desiccated on membrane filters at 10% relative air humidity until the photosynthetic activity as reflected in the effective quantum yield of photosystem II [Y(II)] ceased. For both species, the response to dehydration was much faster at the higher temperature. At the transcriptome level both species responded more strongly to the desiccation stress at the higher temperature suggesting that adaptation to cold conditions enhanced the resilience of both algae to desiccation stress. Interestingly, the two different species responded differently to the applied desiccation stress with respect to the number as well as function of genes showing differential gene expression. The portion of differentially expressed genes shared between both taxa was surprisingly low indicating that both species adapted independently to the harsh conditions of Antarctica and the Arctic, respectively. Overall, our results indicate that environmental acclimation has a great impact on gene expression and the response to desiccation stress in .
生物土壤结皮（BSCs）是由自养、异养和腐生（微）生物组成的复杂群落。在极地地区，这些生物结皮群落具有重要的生态功能，如初级生产、固氮和生态系统工程，同时还要应对极端环境条件（温度、干燥和辐射）。微藻在全球各地的生物土壤结皮中普遍存在。对各种微藻物种在干燥和其他胁迫下的生态生理恢复力已进行了深入研究。在此，我们展示了从南极和北极生物土壤结皮中分离出的两种不同微藻物种——[物种名1]和[物种名2]的转录组分析结果。我们在两个不同温度下进行了干燥胁迫实验，模拟与全球变化相关的波动。在琼脂平板上生长的培养物在相对空气湿度为10%的膜过滤器上进行干燥处理，直到光系统II的有效量子产率[Y(II)]所反映的光合活性停止。对于这两个物种，在较高温度下对脱水的反应要快得多。在转录组水平上，两个物种在较高温度下对干燥胁迫的反应更强烈，这表明适应寒冷条件增强了两种藻类对干燥胁迫的恢复力。有趣的是，这两种不同的物种在显示差异基因表达的基因数量和功能方面，对施加的干燥胁迫反应不同。两个分类群之间共享的差异表达基因部分出奇地低，这表明这两种微藻物种分别独立适应了南极和北极的恶劣条件。总体而言，我们的结果表明环境适应对微藻中的基因表达和对干燥胁迫的反应有很大影响。
