陕北黄土高原生物结皮中7种微藻的形态与分子生物学鉴定

陕北黄土高原实施退耕还林后,生物结皮成为其典型的地表覆盖类型,含有丰富的土生藻类,对固定土壤和促进养分循环具有极其重要的作用。该研究通过平板法与水滴稀释法对陕北黄土高原生物结皮土生藻类进行分离培养,采用光学显微镜观察结皮微藻的形态特征,并对单藻种进行分子鉴定,为黄土高原生物结皮藻类的研究奠定基础。结果显示:(1)共纯化获得7种结皮藻类,经光学显微镜初步确定,其中5株为绿藻、2株为蓝藻。(2)5株绿藻SM-2-1、DB-2-1、DB-2-2、SD-1和SD-2的序列长度分别为664 bp、663 bp、662 bp、589 bp和688 bp,GC含量分别为33.43%、49.47%、50.15%、50.76%和51.01%;2株蓝藻YJ-3、YJ-2的序列长度分别为570 bp和465 bp,GC含量分别为46.31%和49.03%。(3)序列比对并构建系统树分析发现,5株结皮绿藻可分为4个分支,分别为栅藻科(Scenedesmaceae)2株(DB-2-1和SM-2-1)、衣藻目(Chlamydomonadales)、环藻科(Sphaeropleaceae)、真眼点藻科(Eustigmataceae),但5株绿藻的5.8S+ITS2序列在属内差异小、非常保守,极易确定到属;2株蓝藻YJ-3和YJ-2聚在同一大类分支的伪鱼腥藻科(Pseudanabaenaceae)中,但分别归于不同的属。研究认为:5株结皮绿藻中DB-2-1藻株是Scotiellopsis属的一种、SM-2-1归于尖带藻属(Acutodesmus)、DB-2-2可能是红球藻属(Haematococcus)的一物种、SD-1是Ankyra属的一物种、SD-2归于真眼点藻属(Eustigmatos);2株生物结皮蓝藻中YJ-3可能是伪鱼腥藻科的一新物种、YJ-2可能是细鞘丝藻属(Leptolyngbya)亲缘关系较近的一新物种。

Morphological and Molecular Biological Identification of Seven Algae from Biological Crust of Northern Shaanxi in Loess Plateau

After the conversion from farmland to forest of northern Shaanxi Province in Loess Plateau, biocrust has become a typical surface cover type, which is rich in soil algae and plays an extremely important role in fixing soil and promoting nutrient cycling. In this study, soil algae of northern Shaanxi in Loess Plateau were isolated and cultivated by coating plate method and water droplet dilution method. Morphological characteristics of microalgae were observed by optical microscope, and molecular identification of single algae was carried out, which laid a foundation for the study of bio crusted algae of northern Shaanxi in Loess Plateau. The results showed that: (1) a total of 7 species of crusted algae were purified and identified by optical microscopy, among which 5 were green algae and 2 were cyanobacteria. (2) The sequence lengths of five green alage strains of SM 2 1, DB 2 1, DB 2 2, SD 1 and SD 2 were 664 bp, 663 bp, 662 bp, 589 bp and 688 bp, and GC contents were 33.43%, 49.47%, 50.15%, 50.76%, 51.01%, respectively; The sequence lengths of YJ 3 and YJ 2 strains of cyanobacteria were 570 bp and 465 bp, and GC content was 46.31% and 49.03%, respectively. (3) Sequence alignment and phylogenetic tree analysis showed that the 5 green algae could be divided into four clades: Scenedesmaceae (2 strains: DB 2 1 and SM 2 1), Chlamydomonadales, Shaeropleaceae and Eustigmataceae, respectively. And the 5.8S+ITS2 sequences of the 5 green algae showed little difference within the genus and were very conservative, which made it easy to identify the genus. 2 strains of cyanobacteria, YJ 3 and YJ 2, were clustered in the same big branch of Pseudanabaenaceae, but they belonged to different genus. The research suggests that DB 2 1 was a species of Scotiellopsis, SM 2 1 belonged to Acutodesmus, DB 2 2 belonged to Haematococcus, SD 1 was a species of Ancyra, and SD 2 belonged to Eustigmatos.YJ 3 may be a new species of Pseudanabaenaceae, and YJ 2 may be a new species of Leptolyngbya.