title: New stable QTLs for berry weight do not colocalize with QTLs for seed traits in cultivated grapevine (Vitis vinifera L.).
abstract: BACKGROUND
  In grapevine, as in other fruit crops, fruit size and seed content are key components of yield and quality; however, very few Quantitative Trait Loci (QTLs) for berry weight and seed content (number, weight, and dry matter percentage) have been discovered so far. To identify new stable QTLs for marker-assisted selection and candidate gene identification, we performed simultaneous QTL detection in four mapping populations (seeded or seedless) with various genetic backgrounds.
  
  
  RESULTS
  For berry weight, we identified five new QTLs, on linkage groups (LGs) 1, 8, 11, 17 and 18, in addition to the known major QTL on LG 18. The QTL with the largest effect explained up to 31% of total variance and was found in two genetically distant populations on LG 17, where it colocalized with a published putative domestication locus. For seed traits, besides the major QTLs on LG 18 previously reported, we found four new QTLs explaining up to 51% of total variance, on LGs 4, 5, 12 and 14. The previously published QTL for seed number on LG 2 was found related in fact to sex. We found colocalizations between seed and berry weight QTLs only for the major QTL on LG 18 in a seedless background, and on LGs 1 and 13 in a seeded background. Candidate genes belonging to the cell number regulator CNR or cytochrome P450 families were found under the berry weight QTLs on LGs 1, 8, and 17. The involvement of these gene families in fruit weight was first described in tomato using a QTL-cloning approach. Several other interesting candidate genes related to cell wall modifications, water import, auxin and ethylene signalling, transcription control, or organ identity were also found under berry weight QTLs.
  
  
  CONCLUSIONS
  We discovered a total of nine new QTLs for berry weight or seed traits in grapevine, thereby increasing more than twofold the number of reliable QTLs for these traits available for marker assisted selection or candidate gene studies. The lack of colocalization between berry and seed QTLs suggests that these traits may be partly dissociated.
authors.affiliation: INRA, UMR AGAP, Batiment 21 2 place Viala, F-34060 Montpellier Cedex 1, France. doligez@supagro.inra.fr.
authors.forename: Agnès
authors.initials: A
authors.lastname: Doligez
authors.forename: Yves
authors.initials: Y
authors.lastname: Bertrand
authors.forename: Marc
authors.initials: M
authors.lastname: Farnos
authors.forename: Michel
authors.initials: M
authors.lastname: Grolier
authors.forename: Charles
authors.initials: C
authors.lastname: Romieu
authors.forename: Florence
authors.initials: F
authors.lastname: Esnault
authors.forename: Sonia
authors.initials: S
authors.lastname: Dias
authors.forename: Gilles
authors.initials: G
authors.lastname: Berger
authors.forename: Pierre
authors.initials: P
authors.lastname: François
authors.forename: Thierry
authors.initials: T
authors.lastname: Pons
authors.forename: Patrick
authors.initials: P
authors.lastname: Ortigosa
authors.forename: Catherine
authors.initials: C
authors.lastname: Roux
authors.forename: Cléa
authors.initials: C
authors.lastname: Houel
authors.forename: Valérie
authors.initials: V
authors.lastname: Laucou
authors.forename: Roberto
authors.initials: R
authors.lastname: Bacilieri
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Péros
authors.forename: Patrice
authors.initials: P
authors.lastname: This
mesh_terms: D002874:Chromosome Mapping; D005638:Fruit / Q000235:genetics* / Q000254:growth & development*; D056726:Genetic Association Studies; D040582:Inheritance Patterns / Q000235:genetics; D008126:Lod Score; D009929:Organ Size / Q000235:genetics; D010641:Phenotype; D040641:Quantitative Trait Loci / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D012639:Seeds / Q000235:genetics* / Q000254:growth & development*; D027843:Vitis / Q000235:genetics* / Q000254:growth & development*