摘要
用核基因组rDNA的内转录间隔区（ITS）和叶绿体rbcL基因对小球藻属（Chlorella）6株小球藻的种间和种内关系进行了分析。克隆序列与GenBank数据库检索到的相关小球藻序列（ITS和rbcL序列各为15条）一起进行比较分析。结果显示：ITS序列长度在小球藻种内高度保守，在种间变异较大；而rbcL序列长度在种间和种内水平都高度保守。15株小球藻ITS序列间遗传距离在0．000～0．663之间；而15株小球藻rbcL序列间距离在0．000～0．216之间。6株实验藻中原始小球藻F-2与蛋白核小球藻F-5、F-9近似种内关系；蛋白核小球藻820与普通小球藻Cvq亲缘关系极近；椭圆小球藻Ce与其它5株小球藻亲缘关系最远。研究表明将变异程度较高的核ITS序列与相对保守的叶绿体rbcL基因相结合可以用于小球藻系统发生分析和分子鉴定。
Chlorella is one of the most important economically unicellular green algae, but its hundreds of varieties make it difficult to be distinguished based only on the morphological, physiological and biochemical features. To analyze the interspecies and intraspecies relationships and genetic variation of Chlorella species, two kinds of molecular markers were applied. One was the internal transcribed spacer （ITS） of nuclear rDNA and the other was the chloroplast rbcL gene encoding ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit. The 6 Chlorella strains studied included C. pyrenoidosa F-5, F-9, 820, C. protothecoides F-2, C. vulgaris Cvq and C. ellipsoidea Ce. In addition to sequences retrieved from GenBank, a total 15 ITS and 15 rbcL sequences were carried out by sequence comparison, genetic distance calculation and phylogenetic tree construction, respectively. Results showed that the length of ITS region was almost the same among species intrasections, but the length of ITS1 and ITS2 varied significantly between species. However, the length of rbcL sequence was always conservative at inter- and intraspecies levels. The genetic distances of 15 ITS sequences ranged from 0. 000 to 0. 663, and those of 15 rbcL sequences varied from 0. 000 to 0. 216. The phylogenetic relationships among the 6 ChloreUa strains drawn by ITS and rbcL were as follows： First, C. protothecoides F-2 showed very close relationship with C. pyrenoidosa F-5 and F-9. Second, C. p37enoidosa 820 clustered closely with C. vulgaris Cvq. Third, C. ellipsoidea Ce showed the farthest distance with the other five Chlorella strains. This paper indicated that phylogenetic analysis and molecular identification of the genus Chlorella could be validated based on the combination of the highly variable ITS sequence and the relatively conservative chloroplast rbcL gene.
出处
《水产学报》
CAS
CSCD
北大核心
2009年第4期565-571,共7页
Journal of Fisheries of China
基金
国家自然科学基金(30700610)
浙江省教育厅项目(20040899)
宁波市自然科学基金项目(2006A610084)
