狗牙根小尺度克隆多样性及空间遗传结构研究

Study on Fine-scale Clonal Diversity and Spatial Genetic Structure of Bermudagrass

为探讨狗牙根(Cynodon dactylon)克隆结构的形成机制与生境异质性和干扰之间的关系,本文利用9对SSR引物研究了3个不同生境狗牙根的克隆多样性及空间遗传结构,结果表明:供试狗牙根存在较高水平的克隆多样性,其中样方b最高(PD=0.5,D=0.95,E=0.89),样方a次之(PD=0.41,D=0.92,E=0.87),样方c最低(PD=0.16,D=0.25,E=0.00)。3个样方共鉴别出46个基株。样方a的基株数为17,样方b为22,样方c为7。空间自相关分析显示狗牙根在20 cm和50 cm处存在显著的空间遗传结构。样方b,c的狗牙根存在高水平的空间遗传结构,样方a空间遗传结构较弱。混交度表明,由于不同的基因型相互混杂,样方a,b的克隆生长是游击型的生长策略,而样方c不同基因型之间混杂程度低,边缘明显,属于密集型的生长策略。狗牙根的克隆多样性和空间遗传结构与繁殖体散播方式、异质性生境以及人为干扰密切相关。

In order to explore the formation mechanism of clonal structure of bermudagrass(Cynodon dactylon)and its correlation with habitat heterogeneity and disturbance,nine pairs of SSR primer were used to study the clonal diversity and spatial genetic structure of bermudagrass in three different habitats.The results showed that:1)The tested bermudagrass exhibited a high degree of clonal diversity.The clonal diversity level of quadrat b was the highest(PD=0.5,D=0.95,E=0.89),followed by quadrat a(PD=0.41,D=0.92,E=0.87),and quadrat c was the lowest(PD=0.16,D=0.25,E=0.00).A total of 46 genets were identified in the three quadrats.The number of genets in quadrat a was 17,quadrat b was 22 and quadrat c was 7.2)Spatial autocorrelation analysis showed that bermudagrass had significant spatial genetic structure at 20 cm and 50 cm.3)The S p value showed that high levels of spatial genetic structure were present in the bermudagrass of quadrats b and c,and the spatial genetic structure of quadrat a was weak.4)Because different genotypes were mixed together,the mingling index revealed that the clonal growth of quadrat a and b was a guerrilla growth strategy,while the mixed degree of different genotypes of quadrat c is low and the edge is obvious,which belongs to the phalanx strategy.The clonal diversity and spatial genetic structure of bermudagrass are closely related to the propagule dispersal mode,heterogeneous habitat and human disturbance.