凹脉金花茶的遗传多样性和群体遗传结构分析

Analysis of genetic diversity and population genetic structure of Camellia impressinervis

关键词:  凹脉金花茶, 基因分型测序技术, 极小种群物种, 遗传多样性, 群体遗传结构

Key words:  Camellia impressinervis, genotyping-by-sequencing(GBS), extremely small population species, genetic diversity, population genetic structure

摘要:

为进一步了解极小种群物种凹脉金花茶(Camellia impressinervis)的遗传多样性和群体遗传结构,该研究采用基因分型测序技术(GBS)对广西分布的4个居群56份凹脉金花茶样品进行简化基因组测序,并对其遗传多样性和群体遗传结构等进行分析。结果表明:(1)从56份凹脉金花茶样本中获得高质量单核苷酸多样性(SNP)位点4 014 956个,Q20和Q30的平均值分别为98.74%和95.35%,GC含量分布范围为41.70%～45.67%。(2)下雷陇恒居群(CI-LH)的期望杂合度(H_e=0.201 4)、核苷酸多样性(P_i=0.211 7)、近交系数(F_is=0.126 1)最高,弄岗卜那居群(CI-BN)的观测杂合度(H_o=0.171 6)、核苷酸多样性(P_i=0.180 3)、近交系数(F_is=-0.023 0)最低,群体间基因流强度(N_m)的范围为1.151 3～4.557 7,平均值为2.212 2。(3)聚类分析、主成分分析与居群遗传结构分析表明,56份凹脉金花茶可被分为4个类群。综上认为,凹脉金花茶具有中等程度的遗传多样性和遗传分化水平,建议加强对CI-BN居群的就地保护,在条件成熟的情况下实施回归引种,以实现其居群恢复和扩大。此外,加强栖息地保护以及禁止人工挖掘对于保持其遗传多样性至关重要。该研究结果为凹脉金花茶的遗传保育和有效保护提供科学依据。

Abstract:

This study aimed to further elucidate the genetic diversity and population genetic structure of Camellia impressinervis, a species with extremely small populations, through the application of genotyping-by-sequencing(GBS). A total of 56 individuals from four populations distributed across two nature reserves in Guangxi, China, were subjected to reduced-representation genome sequencing, and comprehensive analyses of genetic diversity and population genetic structure were conducted. To provide a scientific basis for the genetic conservation and effective protection of this species. The results were as follows:(1)A total of 4 014 956 high-quality single-nucleotide polymorphism(SNP)loci were identified across the 56 individuals, with mean Q20 and Q30 values of 98.74% and 95.35%, respectively, and GC content ranging from 41.70% to 45.67%.(2)The Xialei Longheng population(CI-LH)exhibited the highest expected heterozygosity(H_e = 0.201 4), nucleotide diversity(P_i=0.211 7)and inbreeding coefficient(F_is=0.126 1). In contrast, the Nonggang Buna population(CI-BN)demonstrated the lowest observed heterozygosity(H_o=0.171 6), nucleotide diversity(P_i=0.180 3), and inbreeding coefficient(F_is=-0.023 0). Estimates of gene flow intensity(N_m)among populations varied between 1.151 3 and 4.557 7, with an average of 2.212 2.(3)Cluster analysis, principal component analysis, and population genetic structure analysis collectively indicated that the 56 samples of C. impressinervis could be grouped into four distinct clusters. In conclusion, C. impressinervis exhibits moderate levels of genetic diversity and genetic differentiation. It is recommended to strengthen in-situ conservation for the CI-BN population, and when feasible, implement reintroduction to promote population recovery and expansion. Additionally, enhancing habitat protection and prohibiting on artificial excavation are crucial for maintaining its genetic diversity. The research results provide a scientific basis for the genetic conservation and effective protection of C. impressinervis.