Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR 97331, USA; Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, USA.
Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, USA.
Harmful Algae. 2021 Mar;103:102005. doi: 10.1016/j.hal.2021.102005. Epub 2021 Mar 10.
The genome sequences of 16 Nostocales cyanobacteria have been determined. Most of them are complete or near-complete genome sequences derived by long-read metagenome sequencing of recent harmful algal blooms (HABs) in freshwater lakes without the potential bias of culture isolation. The genomes are all members of the recently recognized ADA clade (Driscoll et al., Harmful Algae, 77:93, 2018), which we argue represents a genus. We identify 10 putative species-level branches within the clade, on the basis of 91-gene phylogenomic and average nucleotide identity analyses. The assembled genomes each correspond to a single morphotype in the original sample, but distinct genomes from different HABs in some cases correspond to similar morphotypes. We present data indicating that the ADA clade is a highly significant component of current cyanobacterial HABs, including members assigned to the prevalent Dolichospermum and Aphanizomenon genera, as well as Cuspidothrix and Anabaena. In general, currently used genus and species names within the ADA clade are not monophyletic. We infer that the morphological characters routinely used in taxonomic assignments are not reliable for discriminating species within the ADA clade. Taxonomic revisions will be needed to create a genus with a single name (we recommend Anabaena) and to adopt species names that do not depend on morphological traits that lack sufficient discrimination and specificity, while recognizing the utility of some easily observable and distinct morphologies.
16 株 Nostocales 蓝藻的基因组序列已被测定。它们大多数是完整或近乎完整的基因组序列，这些序列源自淡水湖中最近有害藻华（HAB）的长读长宏基因组测序，没有培养分离的潜在偏差。这些基因组均属于最近被认可的 ADA 进化枝（Driscoll 等人，《有害藻类》，77：93，2018），我们认为该进化枝代表了一个属。我们根据 91 个基因系统发育和平均核苷酸同一性分析，在进化枝内识别出 10 个可能的种级分支。组装的基因组各自对应原始样本中的单个形态型，但在某些情况下，来自不同 HAB 的不同基因组对应于相似的形态型。我们提供的数据表明，ADA 进化枝是当前蓝藻 HAB 的一个非常重要的组成部分，包括分配给流行的 Dolichospermum 和 Aphanizomenon 属的成员，以及 Cuspidothrix 和 Anabaena 属的成员。一般来说，目前在 ADA 进化枝内使用的属和种名不是单系的。我们推断，在分类学分配中常规使用的形态特征对于区分 ADA 进化枝内的物种不可靠。需要进行分类修订，创建一个具有单个名称的属（我们建议使用 Anabaena），并采用不依赖于缺乏足够区分度和特异性的形态特征的种名，同时认识到一些易于观察和明显的形态的实用性。
