White spruce is our cornerstone species for molecular marker development and marker-assisted tree breeding applications. We have been conducting large-scale association studies in unstructured populations by genotyping thousands of SNPs and candidate genes (total of 20M genotypes). Preliminary results suggest that the association genetics approach based on candidate genes will yield numerous markers to carry forward into validation and value demonstration experiments. Single-gene and multiple-gene approaches (MGS, multiple-gene selection) relying on Bayesian statistics will be used to identify high priority candidate genes in which SNP coverage will be intensified. We will also test and develop genomic selection (GS) by genotyping several hundred biparental progenies from breeding groups in the Quebec breeding population for thousands of gene loci.
We aim to validate diagnostic markers from previous and current association genetics work (see Figure). For example, breeding values from a large-scale first-generation breeding population will be compared with predictions from MGS. We have also shown that SNPs in expressed genes may be involved in adaptive population differentiation; therefore, we will investigate diagnostic markers in natural populations with the aim of monitoring functional natural genetic diversity. These marker discovery approaches and findings will be transferred to black spruce to broaden impacts and applications of this work in boreal forests. The outcomes of these objectives will be integrated to define marker systems that could assist tree breeding in two of the most important conifers and most reforested species for eastern and central Canada.
- Identify suites of diagnostic markers for variation in wood, growth and adaptation in juvenile and mature trees of white spruce, aiming to explain a useful part of the phenotypic variation for application in tree breeding.
- Support findings of marker-trait associations with functional and expression data.
- Evaluate the potential for using CNVs or PAVs as a source of sequence polymorphisms relevant for marker development.
- Validate groups of markers by testing marker/trait associations in independent populations and assessing the utility for MAS and GS in breeding populations developed by partners.
- Demonstrate the benefits of marker-based selections by measurement of wood yield and timber value recovery.
- Delineate range-wide patterns of diagnostic markers in natural populations of white spruce.
- Transfer to black spruce: identify and validate SNP markers of candidate genes for growth and adaptation.
Development of MAS for wood properties and growth in white and black spruces