title: Why biosynthetic genes for chemical defense compounds cluster.
abstract: In plants, the genomic clustering of non-homologous genes for the biosynthesis of chemical defense compounds is an emerging theme. Gene clustering is also observed for polymorphic sexual traits under balancing selection, and examples in plants are self-incompatibility and floral dimorphy. The chemical defense pathways organized as gene clusters are self-contained biosynthetic modules under opposing selection pressures and adaptive polymorphisms, often the presence or absence of a functional pathway, are observed in nature. We propose that these antagonistic selection pressures favor closer physical linkage between beneficially interacting alleles as the resulting reduction in recombination maintains a larger fraction of the fitter genotypes. Gene clusters promote the stable inheritance of functional chemical defense pathways in the dynamic ecological context of natural populations.
authors.affiliation: Department of Plant Biology and Biotechnology, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Takos
authors.forename: Fred
authors.initials: F
authors.lastname: Rook
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics; D017343:Genes, Plant; D060434:Herbivory; D019684:Magnoliopsida / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005810:Multigene Family; D010935:Plant Diseases / Q000276:immunology; D010940:Plant Proteins / Q000096:biosynthesis*; D011110:Polymorphism, Genetic; D012641:Selection, Genetic
chemical_list: D010940:Plant Proteins