卵囊藻科的分类修订与系统学研究

Oocystaceae is a freshwater family of Chlorophyta, Trebouxiophyceae. Cells are solitary or colonial, cell walls composed of several layers, cells propagate by autosporulation, daughter cells remain for some time to all their life enclosed in the expanded mother cell wall. The species of this family are common planktonic groups of freshwater ecosystems as a indicator for clean water. The project will collect samples from diverse habitat, and culture them in lab. With the fixed specimens and purified algal strains, we will examine their normal morphology, life history, ultrastructure, and also get the sequence of 18s rDNA, rbcL and ITS for phylogenetic analysis of Oocystaceae. The final result will revise the taxonomy system, especially for the biggest genera Oocystis, the project can discuss the phylogeny of the genus within the family, and those outgroups close to Oocystaceae. The project will rich China algal flora, the result also clearly defined Oocystaceae and the genera Oocystis; Powful data can help us to understand the origin of introns in the 18S rRNA gene, and its effect on green algal species divergence, give more knowledge on the evolution line of eukaryotic algae included taxa whose cell arrangement can be solitary, colonial, dendroid, and to filamentous.

卵囊藻科属绿藻门共球藻纲，为单细胞或群体、细胞壁分层、以似亲孢子进行无性繁殖，子代细胞常包含在老细胞壁中并持续生活。卵囊藻科种类为淡水生态系统常见类群，多数是真性浮游种类，是清洁水体的指示种。本项目将基于我国丰富多样的水体生境类型，进行全面大范围的活体采集，通过室内进行分离纯化和藻种保藏，对卵囊藻科种类进行系统的形态学、生活史和超微结构观察，结合形态学结果和多片段分子序列数据的系统发育分析，对卵囊藻科进行分类学整理和修订，探讨科下各属间的系统关系，重点关注对象为其中最大的卵囊藻属。研究结果丰富我国淡水藻类区系，明确界定卵囊藻科、卵囊藻属; 数据资料也有助于我们理解绿藻18s序列内含子起源及其对物种分化的影响，探讨真核藻类结构体制从单细胞向群体、集结体、树状群体到丝状体的演化路线。

卵囊藻科为淡水生态系统常见类群，多数是真性浮游，以典型的似亲孢子无性繁殖，子代细胞常在老细胞壁中存留较长时间。该科种类分布非常广泛，是清洁水体的指示种。但依据形态学的经典分类系统包含类群不明确，分类特征界定不清。.在我国不同生境中分离纯化藻株146株，新增分子序列649条。鉴定卵囊藻科19个属，26种。其中发表新属5个---拟游丝藻属，暗囊藻属，密囊藻属，拟四瓣藻属和网囊藻属；新种8个---胶被游丝藻、间隔拟游丝藻、亚盐生暗囊藻、团集密囊藻、简单拟四瓣藻、小形拟四瓣藻、团集拟四瓣藻和云南网囊藻；重新确认暗丝藻属有效；基于分子数据确认褐胞藻属属于卵囊藻科，而肾形藻属由原共球藻纲卵囊藻科变更到绿藻纲环藻目。另有中国新记录属2个、新记录种4个。.通过对大量藻株进行形态观察和文献梳理，未发现有无蛋白核的卵囊藻属物种，建议将湖生卵囊藻作为新指定模式种。.基于多分子标记联合系统树，建议将卵囊藻科至少包括6个亚科，认为卵囊藻科存在从基部到顶端经历了一条细胞体积逐渐变小，叶绿体数量逐渐变少，结构体制由复杂到简单的进化路线。.基于高通量数据的拼接组装结果，新获得了7株卵囊藻科植物的叶绿体基因组数据，均为完整的环状结构，大小为96.67-136.31 kb。各亚科的代表类群除牧野藻亚科以外，叶绿体基因组结构大体相似。牧野藻亚科的代表种土佐牧野藻的叶绿体基因组上具有一个明显的大片段的倒置和基因重排以及一个明显扩张IR区。.卵囊藻科18S rDNA序列内含子插入率约为37%，具有7个稳定的插入位点，以1153位及549位最多，均属于I型内含子。两类主要的内含子均具有以水平转移的方式进行物种间的同源重组的可能性。