Data from: Metazoan mitochondrial gene sequence reference datasets for taxonomic assignment of environmental samples

Mitochondrial-encoded genes are increasingly targeted in studies using high-throughput sequencing approaches for characterizing metazoan communities from environmental samples (e.g., plankton, meiofauna, filtered water). Yet, unlike nuclear ribosomal RNA markers, there is to date no high-quality reference dataset available for taxonomic assignments. Here, we retrieved all metazoan mitochondrial gene sequences from GenBank, and then quality filtered and formatted the datasets for taxonomic assignments using taxonomic assignment tools. The reference datasets—‘Midori references’—are available for download at www.reference-midori.info. Two versions are provided: (I) Midori-UNIQUE that contains all unique haplotypes associated with each species and (II) Midori-LONGEST that contains a single sequence, the longest, for each species. Overall, the mitochondrial Cytochrome oxidase subunit I gene was the most sequence-rich gene. However, sequences of the mitochondrial large ribosomal subunit RNA and Cytochrome b apoenzyme genes were observed for a large number of species in some phyla. The Midori reference is compatible with some taxonomic assignment software. Therefore, automated high-throughput sequence taxonomic assignments can be particularly effective using these datasets.在利用高通量测序（high-throughput sequencing）技术解析环境样本（如浮游生物、小型底栖动物（meiofauna）、过滤水样）中的后生动物（metazoan）群落的相关研究中，线粒体编码基因正日益成为靶向研究对象。然而，与核核糖体RNA标记（nuclear ribosomal RNA markers）不同，截至目前尚无适用于分类学归属指派（taxonomic assignments）的高质量参考数据集。本研究从GenBank数据库中调取了所有后生动物线粒体基因序列，随后对数据集进行质量过滤与格式标准化处理，以适配各类分类学归属指派工具。该参考数据集命名为Midori参考数据集（Midori references），可通过www.reference-midori.info下载获取。该数据集提供两个版本：（I）Midori-UNIQUE版本，包含每个物种对应的全部独特单倍体型（haplotypes）序列；（II）Midori-LONGEST版本，为每个物种仅保留一条最长的序列。总体而言，线粒体细胞色素氧化酶亚基I（Cytochrome oxidase subunit I）基因是序列丰度最高的基因。不过，在部分动物门中，线粒体核糖体大亚基RNA与细胞色素b脱辅基酶（Cytochrome b apoenzyme）基因的序列可在大量物种中被检测到。Midori参考数据集可兼容部分分类学归属指派软件。因此，利用此类数据集开展自动化高通量序列分类学归属指派工作可获得极佳效果。