Functional metatranscriptomics of Antarctic biological soil crust algae: Identification of key genes for the survival under the extreme conditions of Antarctica

陆地绿色藻类是极地生物土壤结皮的重要组成部分。这些群落形成水稳定的聚集体，在初级生产、固氮、养分循环、保水和土壤稳定方面具有重要的生态作用。虽然关于北极和南极绿色藻类的现有数据通常非常有限，但它们在营养贫乏的环境中作为生态系统开发者的功能重要性被认为是很高的。最近，我们首次利用经典和分子生物学方法（元转录组学和元条形码）确定了藻类和蓝藻的生物多样性。在新项目中，我们希望使用南极BSC的元转录组来确定BSC内微藻的生理状态。为了实现这一目标，我们将元转录组内的序列分配给生物物种（属，科或其他合适的类别）。对于亚元转录组的功能分析，我们将比较（定性和定量）的序列与几个公共数据库（KOG; GEGG; GO）和可用的转录组。为了进一步分析，我们将比较亚元转录组与在实验室条件下（液体培养/平板培养、干燥、温度应激和光应激）培养南极克雷伯菌和球粘菌菌株获得的转录组。几个实验室转录组可用于克雷伯氏菌属。为了进一步与北极亚转录组进行比较，我们将在实验室中从另外两种克雷伯菌和两种从北极分离的球粘菌菌株中建立转录组。所获得的数据将首次允许使用分子数据在采样时在其自然栖息地原位处理极地藻类的生理状态。此外，对克雷伯菌属和Coccomyxa的亚元转录组进行比较，将有助于确定在南极生存的关键基因。

Terrestrial green algae are typical and abundant components of biological soil crusts (BSCs) in the Polar Regions. These communities form water-stable aggregates that have important ecological roles in primary production, nitrogen fixation, nutrient cycling, water retention and stabilization of soils. Although available data on green algae are generally very limited for the Arctic and Antarctica, their functional importance as ecosystem developers in nutrient poor environments is regarded as high. Recently, the biodiversity of algae and cyanobacteria has been determined by us for the first time using classical and molecular methods (Metatranscriptomics and Metabarcoding). In the new project, we want to use metatranscriptomes of Antarctic BSCs to determine the physiological status of the microalgae within the BSCs. To achieve this goal, we will assign the sequences within the metatranscriptomes to biological species (genera, families or other suitable categories). For functional analysis of the submetatranscriptomes we will compare (qualitatively and quantitatively) the sequences with several public databases (KOG; GEGG; GO) and the available transcriptomes. For further analysis, we will compare the submetatranscriptomes with transcriptomes obtained for cultures, of Antarctic Klebsormidium and Coccomyxa strains, under laboratory conditions (liquid culture/plate culture, desiccation, temperature stress and light stress). Several laboratory transcriptomes are available for Klebsormidium. For further comparison with the Arctic submetatranscriptomes we will establish transcriptomes in the laboratory from two additional Klebsormidium and two Coccomyxa strains isolated from the Arctic. The obtained data will allow for the first time to address the physiological status of polar algae in situ in their natural habitat at the time of sampling using molecular data. Furthermore, the comparison of the submetatranscriptomes for Klebsormidium and Coccomyxa will allow the identification of key genes for the survival within the Antarctic.