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基于SSR分子标记的广西杉木第2代种子园遗传多样性与指纹图谱构建

Genetic Diversity and Fingerprint Construction of the Second Generation Seed Orchard of Cunninghamia lanceolata in Guangxi Based on SSR Markers

  • 摘要: 利用SSR分子标记技术对广西杉木第2代种子园的119个无性系进行遗传多样性检测,采用邻接法对参试无性系进行聚类分析,构建DNA指纹图谱。结果表明:22个SSR标记共检测出154个等位基因,平均等位基因数为7,平均有效等位基因数为2.988,平均Shannon's信息指数为1.249、平均观测杂合度为0.611、平均期望杂合度0.632、平均固定指数为0.041、平均多态信息含量为0.587、平均无效等位基因频率为0.030。119个无性系分成5个类群,平均遗传分化系数为0.046,平均遗传距离为0.140,平均基因流为4.318,5%的遗传变异来源于群体间,2%的变异来自于个体间,93%变异来源于个体内,表明不同类群间的遗传分化系数和遗传距离较小,基因流较大,遗传变异主要存在个体内,遗传背景较为单一,遗传分化不明显。利用PIC值排名靠前的9对SSR引物可将119杉木无性系区分开,以此构建了119份杉木无性系的DNA指纹图谱,并生成二维码。鉴于第2代杉木种子园遗传分化程度较小,在后期种子园升级改造过程中,可增添部分特异种质以提高其遗传多样性。

     

    Abstract: To assess the genetic diversity and facilitate the management and identification of clones in the second-generation Cunninghamia lanceolata seed orchard, this study employed Simple Sequence Repeat (SSR) markers to analyze 119 clones from the second-generation seed orchard in Guangxi Provence,China. The results showed that 22 SSR primer pairs detected a total of 154 alleles. The mean number of alleles (Na) was 7, while the mean effective number of alleles (Ne) was 2.988. The average Shannon's information index (I) was 1.249. The mean observed heterozygosity (Ho) and expected heterozygosity (He) were 0.611 and 0.632, respectively, resulting in a mean fixation index (F) of 0.041. The average polymorphism information content (PIC) was 0.587, and the average null allele frequency was 0.030. Using the neighbor-joining method for cluster analysis,the 119 clones were divided into 5 groups.The average genetic differentiation coefficient of 0.046, the average genetic distance of 0.140 and an average gene flow of 4.318. 5% of the genetic variation originated from between populations, 2% from between individuals and 93% from within individuals.This indicates that the genetic differentiation coefficient and genetic distance between different groups were small, the gene flow was relatively high, and the genetic variation mainly existed within individuals,the genetic background was relatively homogeneous, and genetic differentiation was not significant. A subset of nine SSR primer pairs successfully distinguished all 119 clones. Based on these, a DNA fingerprint database was constructed, and unique QR codes were generated for each clone. This study provideed a reliable technical foundation for the precise identification of Cunninghamia lanceolata clones and supports future hybrid breeding programs.

     

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