国产兜兰属植物系统发育和遗传多样性分析

Analysis of phylogeny and genetic diversity of Paphiopedilum species from China

  • 摘要:目的】解析国产兜兰属种质间的系统进化关系,明确各组群间的遗传距离与遗传相似系数,为科学制定保护策略以实现兜兰属资源可持续保育提供理论依据。【方法】以迁地保存的31份国产兜兰属种质和2份国外兜兰属种质为核心试验材料,以1份美洲兜兰属种质为外群,选用筛选出的iPBS和ISSR引物分别扩增34份种质基因组DNA,通过人工判读扩增电泳图谱生成二元原始数据矩阵后,采用NTSYS-pc 2.1进行多维标度分析,并利用PopGen 1.32计算遗传多样性指数。【结果】综合iPBS和ISSR分子标记的亲缘关系分析结果显示,在遗传相似系数0.37处可将33份兜兰属种质划分为5个组群(I~V),其中,第I组群、第II组群、第III组群、第IV组群分别对应经典分类学中的小萼亚属、宽瓣亚属、兜兰亚属兜兰组及兜兰亚属单花斑叶组,第V组群则是兜兰亚属多花长瓣组与多花短瓣组的集合。兜兰属种质的物种水平遗传多样性iPBS分子标记:有效等位基因数(Ne)为1.5969,期望杂合度(He)为0.3492,Shannon多样性信息指数(I)为0.5210;ISSR分子标记:Ne为1.5515,He为0.3340,I为0.5068明显高于组群水平遗传多样性(iPBS分子标记:Ne为1.4274,He为0.2730,I为0.4292;ISSR分子标记:Ne为1.3733,He为0.2492,I为0.4027),说明兜兰属植物在物种水平上表现出明显的遗传分化特征,已形成多个不同的遗传组群;小萼亚属、兜兰亚属兜兰组、兜兰亚属单花斑叶组的组群遗传多样性水平位居前3。兜兰属不同组群间存在一定的遗传分化,但整体上保持较高的遗传相似性。基于iPBS分子标记的分析结果显示,兜兰亚属兜兰组与兜兰亚属单花斑叶组的亲缘关系最近,宽瓣亚属与兜兰亚属单花斑叶组的亲缘关系最远;基于ISSR分子标记的分析结果显示,兜兰亚属多花长瓣组和多花短瓣组集合与兜兰亚属单花斑叶组的亲缘关系较近,小萼亚属与宽瓣亚属的亲缘关系最远。【结论】我国分布的兜兰属种质主要集中在小萼亚属、宽瓣亚属、兜兰亚属兜兰组、兜兰亚属单花斑叶组及兜兰亚属多花长瓣组5个组群,其中小萼亚属、兜兰亚属兜兰组、兜兰亚属单花斑叶组3个组群的遗传多样性水平较高;兜兰属组群间存在明显的遗传分化,暗示着各组群可能经历了较长时间的遗传隔离或存在明显的地域适应性。

     

    Abstract:Objective】This study aimed to analyze the phylogenetic relationship between native Paphiopedilum germplasms in China, clarify genetic distances and coefficients of genetic similarity, providing theoretical basis for formula-ting strategies of sustainable conservation of Paphiopedilum resources.【Method】Using 31 Paphiopedilum germplasms from China and two exotic Paphiopedilum germplasms conserved ex situ as the core experimental materials, and one Phragmipedium germplasm as the outgroup, iPBS and ISSR primers were selected to amplify the genomic DNA of the 34 germplasms. A binary raw data matrix was generated by manually scoring the amplification electrophoretograms, and multidimensional scaling analysis was performed using NTSYS-pc 2.1, with genetic diversity indexes calculated using PopGen 1.32.【Result】The combined iPBS and ISSR molecular marker-assisted phylogenetic analysis results revealed that when the coefficient of genetic similarity was 0.37, 33 Paphiopedilum germplasms were divided into five groups (I-V). The Group I, Group II, Group III, and Group IV were corresponded to subg. Parvisepalum, subg. Brachypetalum, subg. Paphiopedilum sect. Paphiopedilum, subg. Paphiopedilum sect. Barbata in classical taxonomy, and Group V was a collection of subg. Paphiopedilum sect. Pardalopetalum and subg. Paphiopedilum sect. Cochlopetalum. The genetic diversity at species level of Paphiopedilum germplasms iPBS molecular marker: effective number of alleles (Ne) was 1.5969, expected heterozygosity (He) was 0.3492, Shannon diversity information index (I) was 0.5210; ISSR molecular marker: Ne was 1.5515, He was 0.3340, and I was 0.5068 was obviously higher than that at group level (iPBS molecular marker: Ne was 1.4274, He was 0.2730,and I was 0.4292; ISSR molecular marker: Ne was 1.3733, He was 0.2492, and I was 0.4027). This revealed that Paphiopedilum plants showed marked genetic differentiation at species level, forming multiple distinct genetic groups, as subg. Parvisepalum, subg. Paphiopedilum sect. Paphiopedilum, and subg. Paphiopedilum sect. Barbata exhibiting the top three genetic diversity among groups. Genetic differentiation was found between groups of Paphiopedilum, but the overall genetic similarity remained high. Analysis results based on iPBS molecular markers showed that subg. Paphiopedilum sect. Paphiopedilum and subg. Paphiopedilum sect. Barbata shared the closest relationship, while subg. Brachypetalum and subg. Paphiopedilum sect. Barbata shared the farthest relationship; analysis results based on ISSR molecular markers showed that the collection of Paphiopedilum sect. Pardalopetalum and subg. Paphiopedilum sect. Cochlopetalum had the closest relationship with subg. Paphiopedilum sect. Barbata, while subg. Parvisepalum and subg. Brachypetalum shared the farthest relationship.【ConclusionPaphiopedilum germplasms in China are primarily distributed across five groups: subg. Parvisepalum, subg. Brachypetalum, subg. Paphiopedilum sect. Paphiopedilum, subg. Paphiopedilum sect. Barbata, and subg. Paphiopedilum sect. Pardalopetalum, among which the three groups (subg. Parvisepalum, subg. Paphiopedilum sect. Paphiopedilum, and subg. Paphiopedilum sect. Barbata) show high genetic diversity level. Obvious genetic differentiation is found between Paphiopedilum groups, implying that the groups have undergone long-term genetic isolation or possess distinct regional adaptations.

     

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