title: Mapping epigenetic quantitative trait loci (QTL) altering a developmental trajectory.
abstract: Genetic variation in a quantitative trait that changes with age is important to both evolutionary biologists and breeders. A traditional analysis of the dynamics of genetic variation is based on the genetic variance-covariance matrix among different ages estimated from a quantitative genetic model. Such an analysis, however, cannot reveal the mechanistic basis of the genetic variation for a growth trait during ontogeny. Age-specific genetic variance at time t conditional on the causal genetic effect at time t - 1 implies the generation of episodes of new genetic variation arising during the interval t - 1 to t. In the present paper, the conditional genetic variance estimated from Zhu's (1995) conditional model was partitioned into its underlying individual quantitative trait loci (QTL) using molecular markers in an F2 progeny of poplars (Populus trichocarpa and Populus deltoides). These QTL, defined as epigenetic QTL, govern the alterations of growth trajectory in a population. Three epigenetic QTL were detected to contribute significantly to variation in growth trajectory during the period from the establishment year to the subsequent year in the field. It is suggested that the activation and expression of epigenetic QTL are influenced by the developmental status of trees and the environment in which they are grown.
authors.affiliation: Department of Statistics, University of Florida, Gainesville 32611, USA. rwu@stat.ufl.edu
authors.forename: Rongling
authors.initials: R
authors.lastname: Wu
authors.forename: Chang-Xing
authors.initials: CX
authors.lastname: Ma
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: George
authors.initials: G
authors.lastname: Casella
mesh_terms: D000704:Analysis of Variance; D002874:Chromosome Mapping; D004777:Environment; D005819:Genetic Markers; D019684:Magnoliopsida / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D013997:Time Factors; D014197:Trees / Q000235:genetics* / Q000254:growth & development
chemical_list: D005819:Genetic Markers