木姜叶柯SRAP-PCR反应体系优化、引物筛选及验证

Optimization of SRAP-PCR reaction system,primer screening and verification for Lithocarpus litseifolius

  • 摘要: 【目的】建立一套适用于木姜叶柯SRAP-PCR的最佳反应体系,筛选出应用于木姜叶柯种质资源遗传多样性分析的多态性引物,为后续木姜叶柯保护遗传学研究及其开发利用提供科学依据。【方法】采用单因素试验和正交试验相结合的方法,对SRAP-PCR扩增效果的主要影响因素(模板DNA用量、dNTPs浓度、Taq DNA聚合酶用量和引物浓度)进行优化。利用最佳反应体系筛选出适用于木姜叶柯的SRAP多态性引物。【结果】优化获得木姜叶柯SRAPPCR最佳反应体系(20.00 μL):10×PCR Buffer 2.00 μL,Taq DNA聚合酶1.50 U,dNTPs 0.25 mmol/L,引物浓度0.600μmol/L和模板DNA 30.00 ng。各因素对木姜叶柯PCR扩增效果影响程度排序:引物浓度>dNTPs浓度>Taq DNA聚合酶用量>模板DNA用量。应用优化后的SRAP-PCR最佳反应体系和筛选到的20对多态性引物对3个居群的24个木姜叶柯样本进行SRAP-PCR扩增,结果发现4对SRAP引物从3个野生木姜叶柯居群24个样本中共扩增出38个位点,每对引物平均扩增出9.5个位点,其中多态性位点共21个,多态性比率为55.26%。3个木姜叶柯居群的平均等位基因数(Na)、平均有效等位基因数(Ne)、Nei’s基因多样性(H')和Shannon’s信息指数(I)分别为1.55、1.30、0.18和0.27,总遗传多样性(Ht)、居群内遗传多样性(Hs)和遗传分化系数(Gst)分别为0.18、0.11和0.36,基因流(Nm)为0.90(<1.00),说明3个居群间存在一定程度的基因交流,但基因交流程度有限。【结论】木姜叶柯SRAP-PCR扩增效果对引物浓度最敏感。建立木姜叶柯的SRAP-PCR最佳反应体系和筛选到的SRAP引物扩增条带清晰稳定,多态性丰富,能较好地反映出不同木姜叶柯个体和居群间的亲缘关系,可应用于木姜叶柯种质资源的遗传多样性和遗传结构分析。

     

    Abstract: 【Objective】To establish an optimal reaction system applicable to SRAP-PCR of Lithocarpus litseifolius, and screen out polymorphic primers for the genetic diversity analysis of L. litseifolius germplasm resources,thereby providing scientific basis for the subsequent studies on conservation genetics and its development and utilization.【Method】 The combination of single-factor experiment and orthogonal experiment was adopted to optimize the main influencing factors(template DNA amount,dNTPs concentration,Taq DNA polymerase amount and primer concentration)affecting the amplification effect of SRAP-PCR. Using optimal reaction system,SRAP polymorphic primers suitable for L. litseifolius were screened.【Result】The optimal reaction system for SRAP-PCR of L. litseifolius(20.00 μL)was obtained as follows: 10×PCR Buffer 2.00 μL,Taq DNA polymerase 1.50 U,dNTPs 0.25 mmol/L,primer concentration 0.600 μmol/L and template DNA 30.00 ng. The degree of influence of each factor on the PCR amplification effect of L. litseifolius was ranked as follows:primer concentration > dNTPs concentration > Taq DNA polymerase amount > template DNA amount. Using the optimized SRAP-PCR optimal reaction system and the selected 20 pairs of polymorphic primers for SRAP-PCR amplification of 24 samples from 3 populations of L. litseifolius,it was found that 4 pairs of SRAP primers amplified a total of 38 loci from the 24 samples of the 3 wild populations,with an average of 9.5 loci per pair of primers. Among them,21 loci were polymorphic,with a polymorphic rate of 55.26%. The average number of alleles(Na),average effective number of alleles(Ne),Nei’s gene diversity(H'),and Shannon’s information index(I)of the 3 populations of L. litseifolius were 1.55,1.30,0.18 and 0.27 respectively. The total genetic diversity(Ht),within-population genetic diversity(Hs),and genetic differentiation coefficient(Gst)were 0.18,0.11 and 0.36 respectively. The gene flow(Nm)was 0.90(<1.00),indicating that there was a certain degree of gene exchange among the 3 populations,but the degree of gene exchange was limited.【Conclusion】The amplification effect of SRAP-PCR of L. litseifolius is most sensitive to primer concentration. The established optimal reaction system of SRAP-PCR of L. litseifolius and the selected SRAP primers produce clear and stable amplification bands with rich polymorphism,which can better reflect the genetic relationships among different individuals and populations,and can be applied to the analysis of genetic diversity and genetic structure of L. litseifolius germplasm resources.

     

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