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    毛秀红, 闫少波, 葛磊, 王丽, 张锋, 董玉峰, 臧真荣, 李善文. 毛白杨微核心种质构建方法的探讨[J]. 北京林业大学学报, 2023, 45(2): 58-67. DOI: 10.12171/j.1000-1522.20210150
    引用本文: 毛秀红, 闫少波, 葛磊, 王丽, 张锋, 董玉峰, 臧真荣, 李善文. 毛白杨微核心种质构建方法的探讨[J]. 北京林业大学学报, 2023, 45(2): 58-67. DOI: 10.12171/j.1000-1522.20210150
    Mao Xiuhong, Yan Shaobo, Ge Lei, Wang Li, Zhang Feng, Dong Yufeng, Zang Zhenrong, Li Shanwen. Study on construction method of microcore germplasm of Populus tomentosa[J]. Journal of Beijing Forestry University, 2023, 45(2): 58-67. DOI: 10.12171/j.1000-1522.20210150
    Citation: Mao Xiuhong, Yan Shaobo, Ge Lei, Wang Li, Zhang Feng, Dong Yufeng, Zang Zhenrong, Li Shanwen. Study on construction method of microcore germplasm of Populus tomentosa[J]. Journal of Beijing Forestry University, 2023, 45(2): 58-67. DOI: 10.12171/j.1000-1522.20210150

    毛白杨微核心种质构建方法的探讨

    Study on construction method of microcore germplasm of Populus tomentosa

    • 摘要:
        目的  探讨构建微核心种质的方法,旨在为精准选择毛白杨杂交亲本或研究材料提供科学依据,为其他物种构建微核心种质提供参考。
        方法  本研究利用荧光SSR分子标记对272份毛白杨样本进行分子基因型检测,计算每个样本对总体遗传多样性的贡献值,从大到小全部排序,计算新排序的前25%、20%、15%、10%、5%、2.5%、2%和1.5%共8个取样比例的平均有效等位基因数(Ne)、平均Shannon信息指数(I),平均期望杂合度(He)和平均多态信息指数(PIC)值等,分析微核心种质的代表性,通过与前面的取样比例以及原始种质的相应参数进行比较,确定合适的微核心种质取样比例。利用t检验进行统计学验证。根据所有引物的峰值,构建每份微核心种质的指纹图谱。基于指纹图谱的差异,分析挖掘特异等位基因。
        结果  (1)当取样比例由25%逐渐降为2%时,Ne、He和PIC这3个重要的遗传多样性参数分别逐渐达到最大值,而I在取样比例为10%时达到最大值。(2)当取样比例为2%时,Ne、I、He和PIC值分别是3.513、1.254、0.643和0.597,均大于272份原始种质的相应值2.075、0.825、0.432和0.364,表明构建的微核心种质有效去除了遗传冗余,具有丰富的遗传多样性。(3)t检验结果表明:所构建的微核心种质与原始种质的遗传多样性无显著差异,具有可靠的代表性,可以作为微核心种质。(4)不论10%、5%还是2%取样比例,杂交种质所占比例均大于50%。(5)218号样品在11号位点拥有特异等位基因,261号样品在16号位点拥有特异等位基因,263号样品在7号位点拥有特异等位基因。
        结论  毛白杨微核心种质最为科学、可信、简约和高效的取样比例为2% ~ 10%,其中最精准的取样比例为2%。如果种质资源数目较大,可以根据遗传多样性适当降低取样比例;如果基数较小,可以适当升高。建议以后构建核心种质或者微核心种质时,不要先人为进行分组,而是先根据每个样品对总体遗传多样性的贡献从大到小排序。本研究从分子水平证明杂交种质在种质资源保存和林木遗传育种中占有重要地位,将为其他物种微核心种质构建提供参考。

       

      Abstract:
        Objective  The method of constructing microcore germplasm was discussed to provide scientific basis for precise selection of hybrid parents or research materials of P. tomentosa, and to provide reference for other species to construct microcore germplasm.
        Method  In this study, molecular genotypes of 272 P. tomentosa samples were detected by fluorescent SSR molecular markers. The contribution value of each sample to the overall genetic diversity was calculated and sorted from large to small. Then, the representativity of microcore germplasm was analyzed and the appropriate sampling proportion was determined by comparing the average effective number of alleles Ne, the average Shannon’s information index I, the average expected heterogenicity He and the average polymorphic information content PIC values obtained by sampling proportion of top 25%, 20%, 15%, 10%, 5%, 2.5%, 2% and 1.5%. Finally, t test was used for statistical verification. According to the band-shaped results of all SSR primers, fingerprints of each microcore germplasm were formed. According to the difference of fingerprint, the specific alleles were analyzed and excavated.
        Result  When the sampling proportion gradually decreased from 25% to 2%, three important genetic diversity parameters of Ne, He and PIC gradually reached the maximum values, respectively, while I reached the maximum value when the sampling proportion was 10%. When the sampling ratio was 2%, the values of Ne, I, He and PIC were 3.513, 1.254, 0.643 and 0.597, respectively, which were all greater than 2.075, 0.825, 0.432 and 0.364 of the original germplasm, indicating that we had effectively removed the genetic redundancy, and the constructed microcore germplasm had abundant genetic diversity. The t test results showed that there was no significant difference in genetic diversity between the constructed microcore germplasm and the original germplasm, which was reliable and representative and could be used as the microcore germplasm. The proportion of hybrid germplasm was more than 50% regardless of the sampling proportion of 10%, 5% or 2%. Sample 218 had a specific allele at locus 11, sample 261 had a specific allele at locus 16, and sample 263 had a specific allele at locus 7.
        Conclusion  When the sampling ratio of microcore germplasm of poplar is 2%−10%, it is the most scientific, reliable, simple and efficient, among which the most accurate sampling ratio is 2%. If the number of germplasm resources is large, it can be appropriately reduced according to the genetic diversity, and on the contrary, it can be increased appropriately. It is suggested that when constructing core germplasm or microcore germplasm in the future, rather than grouping, each sample is firstly ranked from largest to smallest according to its contribution to overall genetic diversity. It is proved from the molecular level that hybrid germplasm plays an important role in the conservation of germplasm resources and the genetic breeding of trees. At the same time, this study also provides reference for the construction of microcore germplasm of similar species.

       

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