conference schedule and program with abstracts - Horticulture ...

Association genetics in relation with berry size variation in grapevine
(Vitis vinifera)
C. Houel* 1 , I. Le Clainche 1 , A. Canaguier 1 , A-F. Adam Blondon 1 , R. Bounon 2 , A. Bérard 2 , M-C.
Le Paslier 2 , D. Brunel 2 , L. Torregrosa 3 , R. Bacilieri 3 , S. Nicolas 3 , T. Lacombe 3 , A. De Reeper 3 ,
J-P. Peros 3 , P. This 3 , J. Chaïb 4 , M. Thomas 4 , M-S. Vernerey 5 , O. Coriton 5
1 UMR INRA-CNRS-Univ Evry Génomique Végétale, Evry, France; 2 UMR INRA-SupAgro-
IRD Diversité et Adaptation des Plantes Cultivées, Montpellier, France; 3 Unité INRA Etude du
Polymorphisme des Génomes de Végétaux, Evry, France; 4 CSIRO Plant Industry, PO BOX 350,
Glen Osmond South Australia, Australia; 5 UMR INRA-Agrocampus Rennes Amélioration des
Plantes et Biotechnologies Végétales, Le Rheu, France
*Corresponding author: houel@evry.inra.fr
Berry size is an important trait both for yield (table grapes) and in relation to quality (wine
grapes). The final size of an organ is dependent on cell number, cell size and/or number of
carpel. Indeed it has been shown that cell number is a major determinant of fruit size variability
in Solanaceae and Prunus, whereas a preliminary study on a small sample of grapevine
genotypes suggested that the variability of berry size resulted from cell volume enlargement. At
present only few genes involved in fruit size variation have been identified, mainly in
Solanaceae and none in grapevine. Our aims are: (1) to check, in a large sample of grapevine
genotypes, the relative importance of cell volume enlargement, number of cell and carpel in
berry size variation, (2) to develop association genetics approaches with candidate genes for
berry size and (3) to study the DNA polymorphism along the region carrying the fleshless berry
locus (flb) in order to detect possible selection pressures in cultivated varieties. The flb locus was
identified in a grapevine natural mutant which present berries with a size reduced by 20 times
and circular seeds similar to wild grapevine berries. The ovaries and the berries of 3 subpopulations
of cultivated Vitis vinifera genotypes (279), which represent the genetic and
phenotypic variability of berry size, have been phenotyped. Preliminary results on a small
sample of individual (27) suggested that the final berry size was determined at early stage of
berry development. The ovarian size just before fertilization was variable and proportional to the
final berry size. However the ovarian cell number or size seemed to explain the final berry size
differently according to sub-populations. Several mechanisms and probably several genes would
be involved in the variation of the berry size in these sub-populations. These data are currently
under validation on the whole set of 279 individuals. In parallel, 44 candidate genes, orthologous
to genes known to be involved in flower or fruit development and/or co-localizing with berry
size QTLs (Quantitative Trait Locus) and/or expressed during grapevine berry development,
have been partially or totally sequenced in 47 genotypes which reflect all the genetic diversity of
66