title: Haplotyping, linkage mapping and expression analysis of barley genes regulated by terminal drought stress influencing seed quality.
abstract: BACKGROUND
  The increasingly narrow genetic background characteristic of modern crop germplasm presents a challenge for the breeding of cultivars that require adaptation to the anticipated change in climate. Thus, high priority research aims at the identification of relevant allelic variation present both in the crop itself as well as in its progenitors. This study is based on the characterization of genetic variation in barley, with a view to enhancing its response to terminal drought stress.
  
  
  RESULTS
  The expression patterns of drought regulated genes were monitored during plant ontogeny, mapped and the location of these genes was incorporated into a comprehensive barley SNP linkage map. Haplotypes within a set of 17 starch biosynthesis/degradation genes were defined, and a particularly high level of haplotype variation was uncovered in the genes encoding sucrose synthase (types I and II) and starch synthase. The ability of a panel of 50 barley accessions to maintain grain starch content under terminal drought conditions was explored.
  
  
  CONCLUSIONS
  The linkage/expression map is an informative resource in the context of characterizing the response of barley to drought stress. The high level of haplotype variation among starch biosynthesis/degradation genes in the progenitors of cultivated barley shows that domestication and breeding have greatly eroded their allelic diversity in current elite cultivars. Prospective association analysis based on core drought-regulated genes may simplify the process of identifying favourable alleles, and help to understand the genetic basis of the response to terminal drought.
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr.3, 06466 Gatersleben, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Worch
authors.forename: Kalladan
authors.initials: K
authors.lastname: Rajesh
authors.forename: Vokkaliga T
authors.initials: VT
authors.lastname: Harshavardhan
authors.forename: Christof
authors.initials: C
authors.lastname: Pietsch
authors.forename: Viktor
authors.initials: V
authors.lastname: Korzun
authors.forename: Lissy
authors.initials: L
authors.lastname: Kuntze
authors.forename: Andreas
authors.initials: A
authors.lastname: Börner
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wobus
authors.forename: Marion S
authors.initials: MS
authors.lastname: Röder
authors.forename: Nese
authors.initials: N
authors.lastname: Sreenivasulu
mesh_terms: D001483:Base Sequence; D018533:Biomass; D050260:Carbohydrate Metabolism / Q000235:genetics; D002874:Chromosome Mapping; D055864:Droughts; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D005819:Genetic Markers; D005964:Glucosyltransferases / Q000235:genetics; D006239:Haplotypes / Q000235:genetics*; D001467:Hordeum / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics*; D013045:Species Specificity; D013213:Starch / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D005819:Genetic Markers; D012333:RNA, Messenger; D013213:Starch; D005964:Glucosyltransferases; C022699:sucrose synthase