title: GWA Mapping of Anthocyanin Accumulation Reveals Balancing Selection of MYB90 in Arabidopsis thaliana.
abstract: Induction of anthocyanin accumulation by osmotic stress was assessed in 360 accessions of Arabidopsis thaliana. A wide range of natural variation, with phenotypes ranging from green to completely red/purple rosettes, was observed. A genome wide association (GWA) mapping approach revealed that sequence diversity in a small 15 kb region on chromosome 1 explained 40% of the variation observed. Sequence and expression analyses of alleles of the candidate gene MYB90 identified a causal polymorphism at amino acid (AA) position 210 of this transcription factor of the anthocyanin biosynthesis pathway. This amino acid discriminates the two most frequent alleles of MYB90. Both alleles are present in a substantial part of the population, suggesting balancing selection between these two alleles. Analysis of the geographical origin of the studied accessions suggests that the macro climate is not the driving force behind positive or negative selection for anthocyanin accumulation. An important role for local climatic conditions is, therefore, suggested. This study emphasizes that GWA mapping is a powerful approach to identify alleles that are under balancing selection pressure in nature.
authors.affiliation: Laboratory of Plant Physiology, Wageningen University, Wageningen, The Netherlands.|Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands.
authors.forename: Johanna A
authors.initials: JA
authors.lastname: Bac-Molenaar
authors.affiliation: Laboratory of Plant Physiology, Wageningen University, Wageningen, The Netherlands.|Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands.
authors.forename: Emilie F
authors.initials: EF
authors.lastname: Fradin
authors.affiliation: Laboratory of Plant Physiology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Juriaan A
authors.initials: JA
authors.lastname: Rienstra
authors.affiliation: Laboratory of Plant Physiology, Wageningen University, Wageningen, The Netherlands.
authors.forename: Dick
authors.initials: D
authors.lastname: Vreugdenhil
authors.affiliation: Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands.
authors.forename: Joost J B
authors.initials: JJ
authors.lastname: Keurentjes
mesh_terms: D000483:Alleles; D000596:Amino Acids / Q000737:chemistry; D000872:Anthocyanins / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics*; D002147:Calmodulin / Q000737:chemistry; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000648:ultrastructure; D019143:Evolution, Molecular; D005787:Gene Frequency; D056726:Genetic Association Studies; D014644:Genetic Variation; D005838:Genotype; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D013053:Spectrophotometry; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D000596:Amino Acids; D000872:Anthocyanins; D002147:Calmodulin; C514560:PAP2 protein, Arabidopsis; D014157:Transcription Factors