RT Journal Article SR Electronic T1 An ABA-GA bistable switch can account for natural variation in the variability of Arabidopsis seed germination time JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.06.05.135681 DO 10.1101/2020.06.05.135681 A1 Katie Abley A1 Pau Formosa-Jordan A1 Hugo Tavares A1 Emily Chan A1 Ottoline Leyser A1 James C.W. Locke YR 2020 UL http://biorxiv.org/content/early/2020/06/06/2020.06.05.135681.abstract AB Genetically identical plants growing in the same conditions can display heterogeneous phenotypes. Whether this phenotypic variability is functional and the mechanisms behind it are unclear. Here we use Arabidopsis seed germination time as a model system to examine phenotypic variability. We show extensive variation in seed germination time variability between Arabidopsis accessions, and use a multi-parent recombinant inbred population to identify two loci involved in this trait. Both loci include genes implicated in ABA signalling that could contribute to seed germination variability. Modelling reveals that the GA/ABA bistable switch underlying germination can amplify variability and account for the effects of these two loci on germination distributions. The model predicts the effects of modulating ABA and GA levels, which we validate genetically and by exogenous addition of hormones. We confirm that germination variability could act as a bet hedging strategy, by allowing a fraction of seeds to survive lethal stress.Competing Interest StatementThe authors have declared no competing interest.