Mapping of quantitative trait loci controlling adaptive traits in coastal Douglas-fir. II. Spring and fall cold-hardiness

Quantitative trait loci (QTLs) affecting fall and spring cold-hardiness wer e identified in a three-generation outbred pedigree of coastal Douglas-fir [Pseudotsuga meniziesii (Mirb.) Franco var. menziesii]. Eleven QTLs control ling fall cold-hardiness were detected on four linkage groups, and 15 QTLs controlling spring cold-hardiness were detected on four linkage groups. Onl y one linkage group contained QTLs for both spring and fall cold-hardiness, and these QTLs tended to map in close proximity to one another. Several QT Ls were associated with hardiness in all three shoot tissues assayed in the spring, supporting previous reports that there is synchronization of plant tissues during de-acclimatization. For fall cold-hardiness, co-location of QTLs was not observed for the different tissues assayed, which is consiste nt with previous reports of less synchronization of hardening in the fall. In several cases, QTLs for spring or fall cold-hardiness mapped to the same location as QTLs controlling spring bud flush. QTL estimations, relative m agnitudes of heritabilities, and genetic correlations based on clonal data in this single full-sib family, supports conclusions about the genetic cont rol and relationships among cold-hardiness traits observed in population sa mples of Douglas-fir in previous studies.