Tree Genetics & Genomes

, Volume 8, Issue 4, pp 821–829

SNP discovery, gene diversity, and linkage disequilibrium in wild populations of Populus tremuloides

  • Colin T. Kelleher
  • Jennifer Wilkin
  • Jun Zhuang
  • Andrés Javier Cortés
  • Álvaro Luis Pérez Quintero
  • Thomas F. Gallagher
  • Jörg Bohlmann
  • Carl J. Douglas
  • Brian E. Ellis
  • Kermit Ritland
Original Paper

DOI: 10.1007/s11295-012-0467-x

Cite this article as:
Kelleher, C.T., Wilkin, J., Zhuang, J. et al. Tree Genetics & Genomes (2012) 8: 821. doi:10.1007/s11295-012-0467-x

Abstract

The use of single-nucleotide polymorphisms (SNPs) as molecular markers in plant studies has become increasingly common. With the development of these markers, there is an interest in determining levels of variation in natural populations. Here, we identify and characterize levels of SNPs in wild populations of aspen (Populus tremuloides Michx.). Four populations were sampled from Alberta and British Columbia in Western Canada. A total of 35 gene regions were selected for analysis. The loci selected are mainly involved in wood formation and include regions from genes for lignin biosynthesis, cellulose biosynthesis, and other cell wall compounds and a number of transcription factors. Other genes included those coding for growth hormones, disease resistance, and light responses. Primers were developed from conserved regions in multi-species EST alignments. Regions were PCR amplified, and products (approximately 500 to 1,000 bp) were assessed for levels of SNPs using Ecotilling. From a total of approximately 25 kb 462 SNPs were identified, over 18 SNPs/kb. Thus, SNPs are an abundant and potentially useful molecular marker in aspen. Gene diversity (heterozygosity) varied in the gene regions, with an overall average of HT = 0.18. Although gene diversity was considerable, genetic differentiation was low with the overall FST value being 0.004. A surrogate measure of linkage disequilibrium (LD) was calculated, and overall, the LD was shown to decay relatively rapidly with distance along the gene region. The results obtained from the wood formation genes in this study will enable further targeting of regions for association studies on lignin and cellulose variation in aspen and other Populus species.

Keywords

SNPsPopulus tremuloidesGene diversityWood formationLigninCellulose

Supplementary material

11295_2012_467_MOESM1_ESM.doc (64 kb)
Online resource 1Summary of the Ecotilling data showing the length of the gene region, the number of SNPs detected, the polymorphism rate per kilobase, and the gene diversity and genetic differentiation averaged across each gene region (DOC 64 kb)
11295_2012_467_MOESM2_ESM.pdf (84 kb)
Online resource 2Graphs showing the extent of LD in the different genes. The lengths analyzed were small, but the decay is still evident across all regions (PDF 84 kb)

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Colin T. Kelleher
    • 1
    • 2
  • Jennifer Wilkin
    • 1
  • Jun Zhuang
    • 1
  • Andrés Javier Cortés
    • 2
    • 3
  • Álvaro Luis Pérez Quintero
    • 2
    • 3
  • Thomas F. Gallagher
    • 3
  • Jörg Bohlmann
    • 1
    • 4
    • 5
  • Carl J. Douglas
    • 4
  • Brian E. Ellis
    • 1
  • Kermit Ritland
    • 5
  1. 1.Michael Smith LaboratoriesUniversity of British ColumbiaVancouverCanada
  2. 2.DBN Plant Molecular LaboratoryNational Botanic Gardens of IrelandGlasnevinIreland
  3. 3.School of Biology and Environmental ScienceUniversity College DublinBelfieldIreland
  4. 4.Department of BotanyUniversity of British ColumbiaVancouverCanada
  5. 5.Department of Forest SciencesUniversity of British ColumbiaVancouverCanada