Identification of QTLs influencing wood property traits in loblolly pine (Pinus taeda L.). I. Physical wood properties

Physical wood property traits for loblolly pine (Pinus taeda L.) were analyzed for the presence of quantitative trait loci (QTLs) in a three-generation outbred pedigree. These traits include wood specific gravity (wsg), volume percentage of latewood (vol%), and microfibril angle (mfa). Phenotypic data were collected for rings 2–11 for wsg and vol%, and rings 3, 5 and 7 for mfa. Both earlywood and latewood were analyzed for each trait. An interval mapping approach designed for an outbred pedigree was used to estimate the number of QTLs, the magnitude of QTL effects, and their genomic position. Nine unique QTLs were detected for composite traits (average of all rings) for wsg, five for vol%, and five for mfa. The majority of these QTLs were verified by analyses of individual-ring traits. Additional QTLs for each trait were also detected by these individual-ring analyses. Most QTLs for wsg were specific to either earlywood or latewood, whereas each QTL for mfa was detected for both earlywood and latewood. Before these QTLs are utilized in a breeding program, they should be verified in larger experiments and in different genetic and environmental backgrounds.