title: Association analysis of photoperiodic flowering time genes in west and central African sorghum [Sorghum bicolor (L.) Moench].
abstract: BACKGROUND
  Photoperiod-sensitive flowering is a key adaptive trait for sorghum (Sorghum bicolor) in West and Central Africa. In this study we performed an association analysis to investigate the effect of polymorphisms within the genes putatively related to variation in flowering time on photoperiod-sensitive flowering in sorghum. For this purpose a genetically characterized panel of 219 sorghum accessions from West and Central Africa was evaluated for their photoperiod response index (PRI) based on two sowing dates under field conditions.
  
  
  RESULTS
  Sorghum accessions used in our study were genotyped for single nucleotide polymorphisms (SNPs) in six genes putatively involved in the photoperiodic control of flowering time. Applying a mixed model approach and previously-determined population structure parameters to these candidate genes, we found significant associations between several SNPs with PRI for the genes CRYPTOCHROME 1 (CRY1-b1) and GIGANTEA (GI).
  
  
  CONCLUSIONS
  The negative values of Tajima's D, found for the genes of our study, suggested that purifying selection has acted on genes involved in photoperiodic control of flowering time in sorghum. The SNP markers of our study that showed significant associations with PRI can be used to create functional markers to serve as important tools for marker-assisted selection of photoperiod-sensitive cultivars in sorghum.
authors.affiliation: Institute of Plant Breeding, Seed Science, and Population Genetics, University of Hohenheim, 70593 Stuttgart, Germany.
authors.forename: Sankalp U
authors.initials: SU
authors.lastname: Bhosale
authors.forename: Benjamin
authors.initials: B
authors.lastname: Stich
authors.forename: H Frederick W
authors.initials: HF
authors.lastname: Rattunde
authors.forename: Eva
authors.initials: E
authors.lastname: Weltzien
authors.forename: Bettina I G
authors.initials: BI
authors.lastname: Haussmann
authors.forename: C Thomas
authors.initials: CT
authors.lastname: Hash
authors.forename: Punna
authors.initials: P
authors.lastname: Ramu
authors.forename: Hugo E
authors.initials: HE
authors.lastname: Cuevas
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Paterson
authors.forename: Albrecht E
authors.initials: AE
authors.lastname: Melchinger
authors.forename: Heiko K
authors.initials: HK
authors.lastname: Parzies
mesh_terms: D000350:Africa, Central; D000354:Africa, Western; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics / Q000378:metabolism; D056931:Cryptochromes / Q000235:genetics; D035264:Flowers / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D017343:Genes, Plant; D056726:Genetic Association Studies; D005819:Genetic Markers; D015810:Linkage Disequilibrium; D008954:Models, Biological; D010641:Phenotype; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D012641:Selection, Genetic; D045868:Sorghum / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D013045:Species Specificity; D013997:Time Factors
chemical_list: D056931:Cryptochromes; D005819:Genetic Markers; D010940:Plant Proteins