title: A Polynucleotide Repeat Expansion Causing Temperature-Sensitivity Persists in Wild Irish Accessions of Arabidopsis thaliana.
abstract: Triplet repeat expansions underlie several human genetic diseases such as Huntington's disease and Friedreich's ataxia. Although such mutations are primarily known from humans, a triplet expansion associated genetic defect has also been reported at the IIL1 locus in the Bur-0 accession of the model plant Arabidopsis thaliana. The IIL1 triplet expansion is an example of cryptic genetic variation as its phenotypic effects are seen only under genetic or environmental perturbation, with high temperatures resulting in a growth defect. Here we demonstrate that the IIL1 triplet expansion associated growth defect is not a general stress response and is specific to particular environmental perturbations. We also confirm and map genetic modifiers that suppress the effect of IIL1 triplet repeat expansion. By collecting and analyzing accessions from the island of Ireland, we recover the repeat expansion in wild populations suggesting that the repeat expansion has persisted at least 60 years in Ireland. Through genome-wide genotyping, we show that the repeat expansion is present in diverse Irish populations. Our findings indicate that even deleterious alleles can persist in populations if their effect is conditional. Our study demonstrates that analysis of groups of wild populations is a powerful tool for understanding the dynamics of cryptic genetic variation.
authors.affiliation: School of Biological Sciences, Monash University Melbourne, VIC, Australia.
authors.forename: Amanda
authors.initials: A
authors.lastname: Tabib
authors.affiliation: School of Biological Sciences, Monash University Melbourne, VIC, Australia.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Vishwanathan
authors.affiliation: School of Biological Sciences, Monash University Melbourne, VIC, Australia.
authors.forename: Andrei
authors.initials: A
authors.lastname: Seleznev
authors.affiliation: Genetics and Biotechnology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, National University of Ireland Galway, Ireland.
authors.forename: Peter C
authors.initials: PC
authors.lastname: McKeown
authors.affiliation: Genetics and Biotechnology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, National University of IrelandGalway, Ireland; School of Biotechnology, Dublin City UniversityDublin, Ireland.
authors.forename: Tim
authors.initials: T
authors.lastname: Downing
authors.affiliation: School of Biological Sciences, Monash University Melbourne, VIC, Australia.
authors.forename: Craig
authors.initials: C
authors.lastname: Dent
authors.affiliation: School of Biological Sciences, Monash University Melbourne, VIC, Australia.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Sanchez-Bermejo
authors.affiliation: School of Biological Sciences, Monash University Melbourne, VIC, Australia.
authors.forename: Luana
authors.initials: L
authors.lastname: Colling
authors.affiliation: Genetics and Biotechnology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, National University of Ireland Galway, Ireland.
authors.forename: Charles
authors.initials: C
authors.lastname: Spillane
authors.affiliation: School of Biological Sciences, Monash University Melbourne, VIC, Australia.
authors.forename: Sureshkumar
authors.initials: S
authors.lastname: Balasubramanian
keywords: QTL analysis; ambient temperature; cryptic genetic variation; genetic modifier; natural variation; polynucleotide repeat; triplet expansion