云南石蕊共生藻形态及分子系统学研究  

Morphological and Molecular Study of Algal Photobiont Associated with the Lichen-forming Fungus Cladonia yunnan

作　　者：李博 闫湉溦 石瑛[2] LI Bo;YAN Tianwei;SHI Ying(School of Geographical Science, Taiyuan Normal University, Jinzhong, Shanxi 030619, China;2Department of Life Biology, Taiyuan Normal University, Jinzhong, Shanxi 030619, China)

机构地区：[1]太原师范学院地理科学学院,山西晋中030619 [2]太原师范学院生物系,山西晋中030619

出　　处：《西北植物学报》2020年第11期1866-1873,共8页Acta Botanica Boreali-Occidentalia Sinica

基　　金：国家自然科学基金(31500172);山西省高等学校创新项目(2019L0778);山西省“1331工程”重点创新团队建设计划(TD201718);山西省重点研发计划(201803D31054)。

摘　　要：该研究以2016年采自云南凤凰山的云南石蕊(Cladonia yunnan)为材料,在无菌条件下,采用微量微管吸法和直接法分离纯化培养云南石蕊共生藻,利用光学显微镜观察共生藻细胞的形态结构特征,并对该共生藻进行分子系统学分析。结果表明:(1)从云南石蕊中仅分离到1种共生藻,该藻细胞大小约2.5~6μm,球形或椭球形,单细胞,不运动,色素体片状,无性繁殖,含有中央蛋白核和淀粉粒,且3~5个细胞包裹在粘液状的胶壳中,细胞核不可见。(2)该共生藻主要形态学特征与自由生活的胶球藻高度相似,根据采集地及形态特征将其命名为云南胶球藻(Coccomyxa sp.YN)。(3)基于对云南石蕊分子数据(rbcL,ITS)构建的云南石蕊共生藻的系统发育关系显示,云南胶球藻与胶球藻聚为一枝;ITS2 rRNA二级结构分析发现,云南胶球藻与胶球藻具有几乎一致的ITS2 rRNA二级结构。该研究首次揭示了胶球藻属(Coccomyxa)藻细胞与石蕊科地衣共生,且云南胶球藻与胶球藻具有高度一致的亲缘关系,而“地衣化”使两者细胞形态特征有明显差异,推测共生藻细胞可能是由自由生活的藻细胞进化而来。In this study,Cladonia yunnan was collected from the Fenghuang Mountains of southwest China in 2016.The algal photobiont of C.yunnan was successfully cultivated by dilution pipetting and direct methods under axenic conditions.Based on both morphological examination and phylogenetic analysis of molecular data,the results showed that:(1)the investigated photobiont was the only algae isolated from the C.yunnan,spherical or ellipsoidal,asexual reproduction,non-motile unicellular green alga(cell size of approximately 2.5 to 6μm),containing a parietal chloroplast with a central pyrenoid surrounded by starch.3-5 cells enfold in a mucilaginous jelly.The cell nucleus was barely visible.(2)Based on our morphological characterization,the photobiont was similar to Coccomyxa subellipsoidea(free-living).The photobiont is accordingly named Coccomyxa sp.YN with YN referring to the collection location(Yunnan,China).(3)Based on rbcL and ITS data,Coccomyxa sp.YN and C.subellipsoidea constituted one clade.ITS2 secondary structure were compared between Coccomyxa sp.YN and C.subellipsoidea.They have almost identical ITS2 secondary structure.Overall,this study reveals for the first time that Coccomyxa was the photobiont of Cladoniaceae.Coccomyxa sp.YN was closely related to C.subellipsoidea.Nonetheless,based on our morphological characterization,the Coccomyxa sp.YN may be modified in the lichenized state that is distinct from the closely related C.subellipsoidea.We speculate that photobionts may have evolved from free-living algal cells.

关 键 词：胶球藻 共生藻 蛋白核 云南石蕊 

分 类 号：Q949.2[生物学—植物学] Q789