QTLs and candidate genes for wood properties in maritime pine (Pinus pinaster Ait.)

A three-generation outbred pedigree of 186 individuals was used to identify the genomic regions involved in the variability of chemical and physical wood properties of Pinus pinaster. A total of 54 quantitative trait loci (QTLs) was detected, with an average of 2.4 QTLs per trait. Clusters of wood properties QTLs were found at several points in the genome, suggesting the existence of pleiotropic effects of a limited number of genes. The colocalizations observed in this study are in accordance with the genetic correlations previously reported in the literature. In addition, in an attempt to identify the genes underlying the QTLs, nine wood quality candidate genes involved in cell wall structure were localized on the genetic map. Only one of them, Korrigan, a gene encoding for a P 1-4 endo-glucanase known in Arabidopis thaliana to be involved in polysaccharide biosynthesis, co-localized with a wood quality QTL cluster involved in hernicellulose content and fibre characteristics. This finding is in accordance with results previously reported for this gene regarding its expression variability (transcriptome and proteome levels) and patterns of molecular evolution. The pertinence of this result will be tested in more rigorous designs in order to identify early selection predictors for wood quality.