title: Structural mapping: how to study the genetic architecture of a phenotypic trait through its formation mechanism.
abstract: Traditional approaches for genetic mapping are to simply associate the genotypes of a quantitative trait locus (QTL) with the phenotypic variation of a complex trait. A more mechanistic strategy has emerged to dissect the trait phenotype into its structural components and map specific QTLs that control the mechanistic and structural formation of a complex trait. We describe and assess such a strategy, called structural mapping, by integrating the internal structural basis of trait formation into a QTL mapping framework. Electrical impedance spectroscopy (EIS) has been instrumental for describing the structural components of a phenotypic trait and their interactions. By building robust mathematical models on circuit EIS data and embedding these models within a mixture model-based likelihood for QTL mapping, structural mapping implements the EM algorithm to obtain maximum likelihood estimates of QTL genotype-specific EIS parameters. The uniqueness of structural mapping is to make it possible to test a number of hypotheses about the pattern of the genetic control of structural components. We validated structural mapping by analyzing an EIS data collected for QTL mapping of frost hardiness in a controlled cross of jujube trees. The statistical properties of parameter estimates were examined by simulation studies. Structural mapping can be a powerful alternative for genetic mapping of complex traits by taking account into the biological and physical mechanisms underlying their formation.
authors.affiliation: *These authors contributed equally to this work.
authors.forename: Chunfa
authors.initials: C
authors.lastname: Tong
authors.forename: Lianying
authors.initials: L
authors.lastname: Shen
authors.forename: Yafei
authors.initials: Y
authors.lastname: Lv
authors.forename: Zhong
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Wang
authors.forename: Sisi
authors.initials: S
authors.lastname: Feng
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Yihan
authors.initials: Y
authors.lastname: Sui
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Pang
authors.forename: Rongling
authors.initials: R
authors.lastname: Wu
mesh_terms: D000064:Acclimatization / Q000235:genetics / Q000502:physiology; D000465:Algorithms; D002874:Chromosome Mapping / Q000706:statistics & numerical data*; D019295:Computational Biology; D003198:Computer Simulation; D003433:Crosses, Genetic; D058266:Dielectric Spectroscopy; D056726:Genetic Association Studies / Q000706:statistics & numerical data; D018745:Genome, Plant; D016013:Likelihood Functions; D008957:Models, Genetic; D040641:Quantitative Trait Loci; D012044:Regression Analysis; D031957:Ziziphus / Q000235:genetics / Q000502:physiology
keywords: QTL mapping; complex phenotype; electrical impedance spectroscopy; structural components