Faculty of Science, Department of Botany, Charles University, Benátská 2, 128 00, Prague, Czech Republic.
Institute of Criminalistics Prague, Strojnická 27, 170 89, Prague, Czech Republic.
Microb Ecol. 2023 Aug;86(2):763-776. doi: 10.1007/s00248-022-02105-6. Epub 2022 Sep 2.
Filamentous green algae of the genus Zygnema are an essential part of hydro-terrestrial ecosystems. Despite several studies on their resistance to natural stresses, little is known about the composition of their assemblages and the changes they undergo over time. Two sites at altitudes above 2200 m a.s.l. in the Austrian Alps were selected for a 2-year observation period and sampled five times. Molecular phylogenetic analysis of the 152 isolated strains of Zygnema sp. was performed based on the rbcL and trnG sequences. Seven genotypes were found at these sites during the samplings, but their proportion varied throughout the seasons. The site with a more stable water regime also had a more stable representation of genotypes, in contrast to the site with fluctuating water availability. The mats formed resistant pre-akinetes at the end of the season with reduced photosynthetic activity. Contrary to expectations, the mats were not exposed to extremely cold temperatures in winter due to snow cover. Some genotypes have been previously observed at this site, indicating that the population composition is stable. This work highlights the importance of resistant pre-akinetes in surviving winter conditions, the ability of algae to re-establish mats, and the need to address the hidden diversity of the genus Zygnema.
水丝蚓属的丝状绿藻是水生陆地生态系统的重要组成部分。尽管已经有几项关于其对自然胁迫抗性的研究，但对于它们的组合成分及其随时间的变化知之甚少。在奥地利阿尔卑斯山海拔 2200 米以上的两个地点选择了为期 2 年的观测期，并进行了五次采样。根据 rbcL 和 trnG 序列对分离的 152 株水丝蚓属的 152 株菌株进行了分子系统发育分析。在这些采样点发现了 7 种基因型，但它们的比例在整个季节中都有所不同。与水供应不稳定的地点相比，水系统更稳定的地点的基因型代表也更稳定。在季节结束时，藻垫形成了具有抗逆性的前动体，光合作用活性降低。与预期相反，由于积雪覆盖，冬季藻垫并未暴露在极低的温度下。一些基因型以前在该地点观察到过，这表明种群组成是稳定的。这项工作强调了耐逆前动体在冬季条件下生存的重要性、藻类重新建立藻垫的能力，以及需要解决水丝蚓属的隐藏多样性问题。
