Identification of quantitative trait loci influencing annual height- and diameter-increment growth in loblolly pine (Pinus taeda L.)

Quantitative trait loci (QTLs) for annual height- and diameter-increment gr owth were estimated in each of two three-generation loblolly pine pedigrees . Annual height-increment was measured in three consecutive years in the BA SE pedigree and in four consecutive years in the QTL pedigree. Annual diame ter-increment was measured only in the QTL pedigree for two consecutive yea rs. An interval mapping-approach was used to estimate the number of QTLs, t he magnitude of QTL effects, and their position on genetic linkage maps. Th irteen different height-increment and eight different diameter-increment QT Ls were detected. suggesting that the these traits are, at least in part, c ontrolled by a few genes of large effect. Little evidence was found for the expression of individual QTLs in multiple years or in multiple genetic bac kgrounds. These results were discussed in terms of the power of the experim ent and their consequences for marker-assisted breeding.