Plant & Animal Genomes XI Conference

January 11-15, 2003
Town & Country Convention Center
San Diego, CA

Workshop: Forest Trees
            

MAPPING OF QUANTITATIVE TRAIT LOCI CONTROLLING ADAPTIVE TRAITS IN COASTAL DOUGLAS-FIR. III. QTL BY ENVIRONMENT INTERACTIONS AND VERIFICATION

¹ Institute of Forest Genetics, US Forest Service-PSW, 2480 Carson Road, Placerville, CA, USA, 95667

² Weyerhaeuser Technical Center, 9777 Federal Way, WA, USA, 98603-9777

³ Department of Environmental Horticulture, University of California at Davis, Davis, CA, 95616

Douglas-fir displays strong adaptive responses to environmental signals such as photoperiod, moisture stress, winter chilling and spring temperatures. Genotype x environment interactions have been studied by traditional quantitative methods, but to date, the individual QTLs governing adaptive traits that interact with the environment have not been identified. We have produced a large number of clones (20 ramets from 460 progeny) from a 3-generation pedigree for the purpose of estimating QTL responding to environmental signals governing seasonal growth. Specifically, we tested 1) two levels of winter chill and three levels of spring flushing temperatures on spring terminal bud flush, and 2) two levels of daylength and two levels of moisture stress on growth cessation and related growth rhythm traits. Treatments were replicated for increased precision of phenotypic measurements. We used an all-marker interval mapping method for scanning the genome for the presence of QTLs, and single-factor ANOVA on individual markers for detection of QTL x treatment (QTLxT) interactions. Thirty-four (34) unique QTL were detected among all traits evaluated by interval mapping and the proportion of phenotypic variation explained by individual QTLs ranged between 0.7% and 9.5%. Treatments had a significant effect on phenotype and few to several QTLxT interactions were found for each trait. Co-location of QTLs and QTLxT interactions was frequently observed among traits associated with free-growth (from a lammas bud). The repeated detection (verification) of QTLs for terminal bud flush was evaluated within and between mapping populations. QTLs for bud flush were estimated at two test sites and in two greenhouse trials, and compared with QTLs for bud flush that were previously identified in full-sib progeny from an earlier mating of the same parents (Jermstad et al. 2001). Repeated detection of QTLs for terminal bud flush will be discussed.