title: RNA-Seq analysis identifies genes associated with differential reproductive success under drought-stress in accessions of wild barley Hordeum spontaneum.
abstract: BACKGROUND
  The evolutionary basis of reproductive success in different environments is of major interest in the study of plant adaptation. Since the reproductive stage is particularly sensitive to drought, genes affecting reproductive success during this stage are key players in the evolution of adaptive mechanisms. We used an ecological genomics approach to investigate the reproductive response of drought-tolerant and sensitive wild barley accessions originating from different habitats in the Levant.
  
  
  RESULTS
  We sequenced mRNA extracted from spikelets at the flowering stage in drought-treated and control plants. The barley genome was used for a reference-guided assembly and differential expression analysis. Our approach enabled to detect biological processes affecting grain production under drought stress. We detected novel candidate genes and differentially expressed alleles associated with drought tolerance. Drought associated genes were shown to be more conserved than non-associated genes, and drought-tolerance genes were found to evolve more rapidly than other drought associated genes.
  
  
  CONCLUSIONS
  We show that reproductive success under drought stress is not a habitat-specific trait but a shared physiological adaptation that appeared to evolve recently in the evolutionary history of wild barley. Exploring the genomic basis of reproductive success under stress in crop wild progenitors is expected to have considerable ecological and economical applications.
authors.affiliation: Department of Evolutionary and Environmental Biology, University of Haifa, Mt. Carmel 31905, Haifa, Israel. sariel.hubner@botany.ubc.ca.|Current address: Department of Botany, University of British Columbia, Vancouver, Canada. sariel.hubner@botany.ubc.ca.
authors.forename: Sariel
authors.initials: S
authors.lastname: Hübner
authors.affiliation: Department of Evolutionary and Environmental Biology, University of Haifa, Mt. Carmel 31905, Haifa, Israel. korol@research.haifa.ac.il.
authors.forename: Abraham B
authors.initials: AB
authors.lastname: Korol
authors.affiliation: Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, D-70593, Stuttgart, Germany. karl.schmid@uni-hohenheim.de.
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Schmid
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000483:Alleles; D005075:Biological Evolution; D055864:Droughts; D060146:Ecotype; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D001467:Hordeum / Q000235:genetics* / Q000502:physiology*; D058977:Molecular Sequence Annotation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000235:genetics; D017423:Sequence Analysis, RNA / Q000379:methods*; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D012333:RNA, Messenger