conference schedule and program with abstracts - Horticulture ...

O-36
New insight into the genetics of color in grape
A. Fournier-Level* 1 , L. Le Cunff 2 , A. Doligez 1 , P. Hugueney 4 , J.M. Souquet 4 ,
V. Cheynier 4 , A. Ageorges 4 , P. This 1
1 UMR DIAPC INRA-Montpellier Supagro, Montpellier, France; 2 UMT GenoVigne, IFV-
INRA-Montpellier Supagro, Montpellier, France; 3 UMR SVQV, INRA Colmar, Colmar, France;
4 UMR Sciences pour l’oenologie INRA-Montpellier Supagro, Montpellier, France
*Corresponding author: Alexandre_Fournier-Level@brown.edu
Performing combined QTL and association mapping studies using the combination of synthetic
lines and natural diversity represents an opportunity to develop the full picture of the genetic
variation for quantitative traits and ultimately to identify the causal mutations. This approach was
performed in order to decipher the genetic architecture of anthocyanin composition in berry skin,
a crucial trait for both wine quality and human nutrition. Grapes may either be white or colored,
ranging from the lightest pink to the darkest purple tones depending on the amount of
anthocyanins accumulated in the berry skin. Based on the study of total content of anthocyanins
in the skin of mature berries of both a segregating population of 191 progenies and a core
collection of natural resources (141 individuals), we identified 2 QTLs for the traits accounting
for 62% and 7.1% of the total variation, respectively. With the positional information provided
through this QTL mapping, we identified in both cases Myb candidate genes and identified SNPs
markers in high linkage with total content of skin anthocyanins. Using a multivariate regression
method, we demonstrated that six polymorphisms accounted for 86% of the observed variation.
All these polymorphisms either led to structural changes in the MYB proteins or differences in
the VvMybAs promoters. Colour tones of skin are not only due to the overall pigment
concentration but also to the presence of different types of pigments and in particular the level of
methylation. A similar analysis was performed for the level of anthocyanin methylation in skin
anthocyanins. Two QTLs were identified accounting for 37% and 17% of the trait variation
respectively. Association mapping, transcriptomic analysis and enzymatic tests enabled the
identification of two mutations in a structural gene functionally linked to the difference in
methylation of anthocyanins. The use of natural diversity thus helped to reduce QTL to a set of
QTNs, gave a clearer picture of how isogenes combined their effects to shape the quantitative
traits, and revealed the relative influence of different cis-and trans-regulatory elements on these
quantitative traits.
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