基于果实性状和ISSR分子标记的荔枝种质遗传多样性分析及DNA指纹图谱构建

Genetic diversity analysis and DNA fingerprint construction of litchi germplasms based on fruit traits and ISSR molecular markers

  • 摘要: 目的 基于果实性状和ISSR分子标记对34份荔枝种质开展遗传多样性及聚类分析,并构建DNA指纹图谱,以期为荔枝种质资源分类鉴定、评价和创新利用提供理论参考。方法 以我国34份荔枝种质资源为研究对象,对其平均单果重、可溶性固形物含量、果形、龟裂片形状、缝合线是否明显等果实性状进行观测,并进行变异分析、多样性分析及相关分析,分别基于果实形状和ISSR分子标记进行聚类分析。最后基于ISSR分子标记检测结果构建DNA指纹图谱。结果 34份荔枝种质的单果重17.0~57.5 g,可溶性固形物含量13.0%~20.7%,果形有心形、近圆球形、卵圆形、椭圆形、歪心形,龟裂片形状有隆起、锥尖状突起、平滑,缝合线明显或不明显。果实性状的Shannon-Weaver多样性指数为0.67~1.97,其中缝合线是否明显最低,可溶性固形物含量最高。单果重与可溶性固形物含量呈极显著负相关(P<0.01),果形与龟裂片形状呈显著正相关(P<0.05)。基于果实性状的聚类结果显示,在欧氏距离为8时,供试材料被分为四大类,果实性状聚类结果与荔枝种质的果实缝合线是否明显相关性较强,其次是按果形和龟裂片形状进行聚类,且各类群包含不同地区的种质,说明聚类结果与地理分布无明显相关性。17条ISSR引物共扩增出191条条带,其中多态性条带165条,平均多态性比率86.39%,引物UBC835、UBC846和UBC879多态性比率高达100.00%;等位基因数(Na)为1.6875~2.0000,平均为1.8422,有效等位基因数(Ne)为1.2498~1.7177,平均为1.4470,Nei’s基因多样性指数(H')为0.16~0.40,平均为0.26,Shannon’s信息指数(I)为0.2616~0.5746,平均为0.4015。基于ISSR分子标记的聚类结果显示,34份荔枝种质的遗传相似系数为0.5916~0.8691,平均为0.7359,在遗传相似系数0.7100时,供试材料被分成四大类,各类群均包含多个地区的荔枝种质,聚类结果与地理分布无明显相关性,而与果实成熟期存在一定的相关性。ISSR引物UBC857可用于构建34份荔枝种质资源的DNA指纹图谱。结论 34份荔枝种质果实性状遗传多样性较丰富,但遗传相似系数较高,遗传基础较狭窄。基于果实性状的聚类结果与ISSR分子标记的聚类结果仅部分相同,均与地理分布无明显相关性,分别与荔枝种质的果实缝合线是否明显和果实成熟期存在相关性。引物UBC857可鉴别34份荔枝种质资源。

     

    Abstract: Objective This study aimed to conduct an analysis of genetic diversity and a cluster analysis of 34 litchi germplasms based on fruit traits and ISSR molecular markers, and construct a DNA fingerprint map, in order to provide theoretical references for the classification, identification, evaluation and innovative utilization of litchi germplasm resources.Method 34 litchi germplasms from the China were selected as the research objects. Their fruit traits such as average single fruit weight, soluble solid content, fruit shape, shape of scute-like segments and distinctness of suture were observed. Variation analysis, diversity analysis and correlation analysis were conducted and the cluster analysis was performed based on fruit shape and ISSR molecular markers, respectively. Finally, a DNA fingerprint map was constructed based on the ISSR molecular marker detection results.Result The single fruit weight of the 34 litchi germplasms ranged from 17.0 to 57.5 g, and the soluble solid content ranged from 13.0% to 20.7%. The fruit shapes included cordate, orbicular shape, oval shape, elliptical shape and oblique cordate. The shape of scute-like segments included swelling, sharp-pointed and smooth. The sutures were either clear or unclear. The Shannon-Weaver diversity index of fruit traits ranged from 0.67 to 1.97, with the lowest was shown in the suture distinctness and the highest shown in the soluble solid content. The single fruit weight had a significantly negative correlation with the soluble solid content (P<0.01), and the fruit shape had a significantly negative correlation with the shape of scute-like segments (P<0.05). The cluster analysis based on fruit traits showed that: when the Euclidean distance was 8, the tested materials were divided into four groups; the clustering results of fruit traits showed a strong correlation with the distinctness of the fruit suture in litchi germplasms; and clustering results of fruit shape and shape of scute-like segments showed that each category included germplasms from different regions, indicating that the clustering results had no obvious correlation geographical distribution. A total of 191 bands were amplified using 17 ISSR primers, of which 165 were polymorphic bands, with an average polymorphism ratio of 86.39%. The polymorphism ratios of primers UBC835, UBC846 and UBC879 were as high as 100%. The number of alleles (Na) ranged from 1.6875 to 2.0000, with an average of 1.8422. The effective number of alleles (Ne) ranged from 1.2498 to 1.7177, with an average of 1.4470. Nei’s gene diversity index (H') ranged from 0.16 to 0.40, with an average of 0.26. Shannon’s information index (I) ranged from 0.2616 to 0.5746, with an average of 0.4015. The cluster analysis based on ISSR molecular markers showed that: the genetic similarity coefficient of the 34 litchi germplasms ranged from 0.5916 to 0.8691, with an average of 0.7359; at a genetic similarity coefficient of 0.7100, the tested materials were divided into 4 groups, each group included germplasms from multiple regions, and the clustering results were not significantly correlated with geographical distribution, but were correlated with the fruit maturity period. The ISSR primer UBC857 could be used to construct the DNA fingerprint map of the 34 litchi germplasms.Conclusion The genetic diversity of fruit traits of the 34 litchi germplasms is relatively rich, but as the genetic similarity coefficient is relatively high, the genetic basis is rather narrow. The clustering results based on fruit traits and ISSR molecular markers are only partially consistent, and both showed no obvious correlation with geographic distribution, but are correlated with fruit suture distinctness and fruit maturity period of litchi germplasm, respectively. The primer UBC857 could be used to distinguish the 34 litchi germplasms.

     

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