Genetic parameters and QTL analysis of δ13C and ring width in maritime pine

Classical quantitative genetics and quantitative trait dissection analysis (QTL) approaches were used in order to investigate the genetic determinism of wood cellulose carbon isotope composition (delta (13) C, a time integrated estimate of water use efficiency) and of diameter growth and their relationship on adult trees (15 years) of a forest tree species (maritime pine). A half diallel experimental set-up was used to (1) estimate heritabilities for delta (13) C and ring width and (2) to decompose the phenotypic delta (13) C/growth correlation into its genetic and environmental components. Considerable variation was found for delta (13) C (range of over 3parts per thousand) and for ring width (range of over 5 mm) and significant heritabilities (narrow sense 0.17/0.19 for delta (13) C and ring width, respectively, 100% additivity). The significant phenotypic correlation between delta (13) C and ring width was not determined by the genetic component, but was attributable to environmental components. Using a genetic linkage map of a full-sib family, four significant and four suggestive QTLs were detected for delta (13) C, the first for delta (13) C in a forest tree species, as far as known to the authors. Two significant and four suggestive QTLs were found for ring width. No co-location of QTLs was found between delta (13) C and growth.