title: Quantitative trait loci influencing forking defects in an outbred pedigree of loblolly pine.
abstract: The use of wood as an industrial raw material has led to development of plantation forestry, in which trees are planted, managed, and harvested as crops. The productivity of such plantations often exceeds that of less-intensively-managed forests, and land managers have the option of choosing specific planting stock to produce specific types of wood for industrial use. Stem forking, or division of the stem into two or more stems of roughly equal size, is a character trait important in determining the quality of the stem for production of solid wood products. This trait typically has very low individual-tree heritability, but can be more accurately assessed in clonally-replicated plantings where each genotype is represented by several individual trees. We report results from a quantitative trait mapping experiment in a clonally-replicated full-sibling family of loblolly pine (Pinus taeda L.).
  
  
  
  Quantitative trait loci influencing forking defects were identified in an outbred full-sibling family of loblolly pine, using single-nucleotide polymorphism markers. Genetic markers in this family segregated either in 1:2:1 (F2 intercross-like segregation) or 1:1 ratio (backcross-like segregation). An integrated linkage map combining markers with different segregation ratios was assembled for this full-sib family, and a total of 409 SNP markers were mapped on 12 linkage groups, covering 1622 cM. Two and three trait loci were identified for forking and ramicorn branch traits, respectively, using the interval mapping method. Three trait loci were detected for both traits using multiple-trait analysis.
  
  
  
  The detection of three loci for forking and ramicorn branching in a multiple-trait analysis could mean that there are genes with pleiotropic effects on both traits, or that separate genes affecting different traits are clustered together. The detection of genetic loci associated with variation in stem quality traits in this study supports the hypothesis that marker-assisted selection can be used to decrease the rate of stem defects in breeding populations of loblolly pine.
authors.affiliation: Cooperative Tree Improvement Program, Department of Forestry & Environmental Resources, North Carolina State University, Raleigh, USA.|Present address: Dow AgroSciences, Indianapolis, IN, USA.
authors.forename: Jin S
authors.initials: JS
authors.lastname: Xiong
authors.affiliation: Cooperative Tree Improvement Program, Department of Forestry & Environmental Resources, North Carolina State University, Raleigh, USA.
authors.forename: Steven E
authors.initials: SE
authors.lastname: McKeand
authors.affiliation: Cooperative Tree Improvement Program, Department of Forestry & Environmental Resources, North Carolina State University, Raleigh, USA.
authors.forename: Fikret
authors.initials: F
authors.lastname: Isik
authors.affiliation: Department of Plant Sciences, University of California, Davis, USA.|Present address: University of Connecticut, Storrs, CT, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Wegrzyn
authors.affiliation: Department of Plant Sciences, University of California, Davis, USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Neale
authors.affiliation: Department of Statistics and Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA.
authors.forename: Zhao-Bang
authors.initials: ZB
authors.lastname: Zeng
authors.affiliation: Universidade de São Paulo - ESALQ, Saõ Paulo, Brazil.|Present address: SAS Institute, Cary, NC, USA.
authors.forename: Luciano
authors.initials: L
authors.lastname: da Costa E Silva
authors.affiliation: Department of Forestry & Environmental Resources, North Carolina State University, Raleigh, NC, 27695-8008, USA. ross_whetten@ncsu.edu.
authors.forename: Ross W
authors.initials: RW
authors.lastname: Whetten
mesh_terms: D000465:Algorithms; D001947:Breeding; D002874:Chromosome Mapping; D056726:Genetic Association Studies; D008040:Genetic Linkage; D005819:Genetic Markers; D005838:Genotype; D015233:Models, Statistical; D010375:Pedigree; D010641:Phenotype; D041603:Pinus taeda / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D019655:Quantitative Trait, Heritable
chemical_list: D005819:Genetic Markers
keywords: MAS; Outbred; Pinus taeda; QTL; Stem forking; Tree breeding; Wood quality