title: Environmental aridity is associated with cytotype segregation and polyploidy occurrence in Brachypodium distachyon (Poaceae).
abstract: • The ecological and adaptive significance of plant polyploidization is not well understood and no clear pattern of association between polyploid frequency and environment has emerged. Climatic factors are expected to predict cytotype distribution. However, the relationship among climate, cytotype distribution and variation of abiotic stress tolerance traits has rarely been examined. • Here, we use flow cytometry and root-tip squashes to examine the cytotype distribution in the temperate annual grass Brachypodium distachyon in 57 natural populations distributed across an aridity gradient in the Iberian Peninsula. We further investigate the link between environmental aridity, ploidy, and variation of drought tolerance and drought avoidance (flowering time) traits. • Distribution of diploids (2n = 10) and allotetraploids (2n = 30) in this species is geographically structured throughout its range in the Iberian Peninsula, and is associated with aridity gradients. Importantly, after controlling for geographic and altitudinal effects, the link between aridity and polyploidization occurrence persisted. Water-use efficiency varied between ploidy levels, with tetraploids being more efficient in the use of water than diploids under water-restricted growing conditions. • Our results indicate that aridity is an important predictor of polyploid occurrence in B. distachyon, suggesting a possible adaptive origin of the cytotype segregation.
authors.affiliation: Departamento Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Paraje las Lagunillas s/n, 23071, Jaén, Spain.|Department of Biology, Institute for Genome Sciences and Policy, Duke University, PO Box 90338, Durham, NC 27708, USA.
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Manzaneda
authors.affiliation: Departamento Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Paraje las Lagunillas s/n, 23071, Jaén, Spain.
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Rey
authors.affiliation: Departamento Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Paraje las Lagunillas s/n, 23071, Jaén, Spain.
authors.forename: Jesús M
authors.initials: JM
authors.lastname: Bastida
authors.affiliation: Department of Biology, Institute for Genome Sciences and Policy, Duke University, PO Box 90338, Durham, NC 27708, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Weiss-Lehman
authors.affiliation: Department of Biology, Institute for Genome Sciences and Policy, Duke University, PO Box 90338, Durham, NC 27708, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Raskin
authors.affiliation: Department of Biology, Institute for Genome Sciences and Policy, Duke University, PO Box 90338, Durham, NC 27708, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mitchell-Olds
mesh_terms: D058431:Brachypodium / Q000166:cytology* / Q000235:genetics*; D002247:Carbon Isotopes; D020090:Chromosome Segregation / Q000235:genetics*; D055864:Droughts; D060146:Ecotype; D004777:Environment; D035264:Flowers / Q000502:physiology; D005843:Geography; D016015:Logistic Models; D011123:Polyploidy; D011891:Rain; D013030:Spain; D013997:Time Factors; D014867:Water / Q000502:physiology
chemical_list: D002247:Carbon Isotopes; D014867:Water