Molecular Markers for Portuguese pine wood quality

Maritime pine (Pinus pinaster Ait.) is an important commercial species in southwest Europe. In Portugal, P. pinaster is one of the most important native species, covering 1Mha, is the only source of long fibre for pulp and paper and the main source for solid sawn timber industries. A tree improvement plan has been developed since the early 80s with the aim of increasing volume per hectare and stem conformation. The introduction of wood quality selection criteria is now considered an important objective of breeding programmes. Such selection is however hampered by the lack of information for wood quality traits, not only at the genetic but also at the industrial levels. Wood quality can only be defined in terms of particular end use, and may involve several traits (e.g. density, wood heterogeneity, wood chemical composition and fibre properties). Mean density is acknowledged to be the best single predictor of wood mechanical properties. Lignin, polysaccharides and extractives must also be considered, having direct consequences for production costs and final product quality.

Single nucleotide polymorphisms (SNPs) and indels are an essentially inexhaustible source of polymorphic markers for use in association studies that are based on candidate genes. Haplotypes associated with agronomic performance will provide excellent diagnostic tools for marker-assisted breeding and facilitate identification and molecular cloning of genes controlling complex agronomic characters.

The aim of this project is to use polymorphic sequences of candidate genes expressed during the synthesis of wood (e.g. CAD and PAL) to associate specific SNPs alleles with specific wood characteristics of Portuguese pine trees. We will use 184 trees from a progeny test set at Mata de Leiria, coming from the open cross of 46 plus trees maintained at Mata do Escaroupim. The specific objectives of the project are:

1 Assess of genetic parameters for growth, stem and branch characteristics and selection of plus trees the progeny trial

2 Assess the variability and heritability of density components and mechanical properties of the wood

3. Assess the variability and heritability of chemical composition traits (extractives, lignin amount and quality and polysaccharides)

4. Identify the relevant haplotypes of the polymorphic sequences and chose the SNPs to be used

5. Genotype the trees for the chosen SNPs

6. Associate specific alleles with specific wood characteristics