title: Systems responses to progressive water stress in durum wheat.
abstract: Durum wheat is susceptible to terminal drought which can greatly decrease grain yield. Breeding to improve crop yield is hampered by inadequate knowledge of how the physiological and metabolic changes caused by drought are related to gene expression. To gain better insight into mechanisms defining resistance to water stress we studied the physiological and transcriptome responses of three durum breeding lines varying for yield stability under drought. Parents of a mapping population (Lahn x Cham1) and a recombinant inbred line (RIL2219) showed lowered flag leaf relative water content, water potential and photosynthesis when subjected to controlled water stress time transient experiments over a six-day period. RIL2219 lost less water and showed constitutively higher stomatal conductance, photosynthesis, transpiration, abscisic acid content and enhanced osmotic adjustment at equivalent leaf water compared to parents, thus defining a physiological strategy for high yield stability under water stress. Parallel analysis of the flag leaf transcriptome under stress uncovered global trends of early changes in regulatory pathways, reconfiguration of primary and secondary metabolism and lowered expression of transcripts in photosynthesis in all three lines. Differences in the number of genes, magnitude and profile of their expression response were also established amongst the lines with a high number belonging to regulatory pathways. In addition, we documented a large number of genes showing constitutive differences in leaf transcript expression between the genotypes at control non-stress conditions. Principal Coordinates Analysis uncovered a high level of structure in the transcriptome response to water stress in each wheat line suggesting genome-wide co-ordination of transcription. Utilising a systems-based approach of analysing the integrated wheat's response to water stress, in terms of biological robustness theory, the findings suggest that each durum line transcriptome responded to water stress in a genome-specific manner which contributes to an overall different strategy of resistance to water stress.
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Dimah Z
authors.initials: DZ
authors.lastname: Habash
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Marcela
authors.initials: M
authors.lastname: Baudo
authors.affiliation: Computational and Systems Biology, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Hindle
authors.affiliation: Computational and Systems Biology, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Powers
authors.affiliation: Computational and Systems Biology, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Defoin-Platel
authors.affiliation: Computational and Systems Biology, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Rowan
authors.initials: R
authors.lastname: Mitchell
authors.affiliation: Computational and Systems Biology, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Mansoor
authors.initials: M
authors.lastname: Saqi
authors.affiliation: Computational and Systems Biology, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Rawlings
authors.affiliation: Laboratoire D'agronomie, National Agricultural Research Institute of Tunisia, Ariana, Tunisia.
authors.forename: Kawther
authors.initials: K
authors.lastname: Latiri
authors.affiliation: Dept. of Vegetal Biology, Faculty of Biology, Barcelona, Spain.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Araus
authors.affiliation: Biotechnology Department, General Commission for Scientific Agricultural Research, Damascus, Syria.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Abdulkader
authors.affiliation: Dept. of Agroenvironmental Science and Technology, University of Bologna, Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tuberosa
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, United Kingdom.
authors.forename: David W
authors.initials: DW
authors.lastname: Lawlor
authors.affiliation: Biodiversity and Integrated Gene Management Program, International Center for Agricultural Research in the Dry Areas, Rabat, Morocco.
authors.forename: Miloudi M
authors.initials: MM
authors.lastname: Nachit
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology*; D054046:Plant Stomata / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D013312:Stress, Physiological / Q000235:genetics / Q000502:physiology*; D014908:Triticum / Q000235:genetics / Q000502:physiology*; D014867:Water; D014868:Water Deprivation / Q000502:physiology*
chemical_list: D014867:Water; D000040:Abscisic Acid