Selection and establishment of charophyte algae model organisms (CharMod)

陆地植物的起源是单系的，最有可能是来自一个单一的成功殖民化的陆地栖息地的淡水轮藻。五亿年前。可以得出这样的结论：与绿色藻类不同，陆地植物的轮藻祖先必然携带有遗传编码的生物化学和分子适应机制，使它们能够适应陆地上遇到的极端环境。了解轮藻的哪些特征（链藻）藻类进化成陆地植物，适应最剧烈的栖息地变化。一个主要原因是-到目前为止-只有很少的注意力放在轮藻中的环境适应性特征上，这是因为缺乏完善的模式生物。因此，我们的联合项目CharMod寻求：（a）从轮藻纲、鞘毛藻纲和接合藻纲中鉴定具有模式生物潜力的种质，这些纲代表与陆地植物最密切相关的纲。我们的目标是鉴定具有相对小的基因组的快速生长的生物体，其能够在无菌条件下在体外进行其生命周期，（B）为所选择的加入物建立基因组和转录组水平的序列资源，（c）建立遗传修饰这些藻类的工具，及（d）进行渗透压和激素信号的概念验证比较实验。预期借由提供健全的模式生物，利用相关的序列数据和实验工具，这一项目将帮助日益壮大的科学界研究导致现存轮藻祖先在陆地定居的分子适应性。

Land plants are monophyletic in origin, most probably deriving from a single successful colonization of the terrestrial habitat by a freshwater charophyte alga ca. 500 million years ago. It can be concluded that the charophyte ancestors of land plants, in contrast to the green algae, must necessarily have carried genetically encoded biochemical and molecular adaptive mechanisms enabling them to adapt to the environmental extremes encountered on land.To deepen our evolutionary understanding, and to meet the challenge of maintaining and improving food production, it is essential to learn which traits enabled charophyte (streptophyte) algae to evolve to land plants, adapting to one of the most drastic habitat changes conceivable.One main reason that - so far - only little attention has been paid to traits enabling environmental resilience in charophyte algae is the lack of well established model organisms.Hence, our joined project CharMod therefore seeks: (a) to identify accessions with model organism potential from Charophyceae, Coleochaetophyceae and Zygnematophyceae, representing the classes most closely related to land plants. We aim to identify fast growing organisms with relatively small genomes, capable to perform their life cycle in vitro under axenic conditions, (b) to establish sequence resources on genomic and transcriptomic level for selected accessions, (c) to establish tools to genetically modify these algae, and (d) to carry out proof of concept comparative experiments on osmotic stress and hormonal signaling.It is expected that by providing robust model organisms, related sequence data and experimental tools, this project will help a growing scientific community to perform research on the molecular adaptations having led to the colonization of land by the ancestors of extant charophyte algae.