conference schedule and program with abstracts - Horticulture ...

O-32
Integrating ecophysiology and quantitative genetics to analyse the control of
transpiration by the rootstock under drought conditions
E. Marguerit*, C. Van Leeuwen, S. Delrot, N. Ollat
UMR “Ecophysiology and Functional Genomic of Grapevine” INRA, University of
Bordeaux, ENITA, ISVV, Villenave d’Ornon, France
*Corresponding author: e-marguerit@enitab.fr
Water is the main limiting factor for yield in viticulture. Vine water status also strongly impacts
grape quality. The objective of this work is to analyze the genetic determinism of drought
responses induced by the rootstock. The mapping pedigree used consisted of 138 F1 individuals
derived from the interspecific cross of V. vinifera ‘Cabernet Sauvignon’ (CS) × V. riparia
‘Gloire de Montpellier’ (RGM). ‘Cabernet Sauvignon’ was the scion grafted on each rootstock of
this population. The experiment was carried out in pots, in a greenhouse. Water retention
properties of the substrate were primarily determined. Transpiration was evaluated daily by
weighing each pot individually with a 150 scale platform. Irrigation was applied in the mid
morning in order to compensate exactly for the difference between the daily water loss due to
transpiration in a particular pot and the loss of water calculated to obtain the desired level of
water stress. Leaf area measurements were performed weekly in order to calculate the daily
transpiration per unit of leaf area. After ten days without any stress, progressive water limitation
was applied for ten days and followed by a stable water deficit stress for 15 days. These
phenotypic measurements were recorded in 2007, 2008, and 2009. The fraction of transpirable
soil water (FTSW) was used to define the intensity of the water stress. The response curves of
transpiration to FTSW in each pot were assessed and mathematically adjusted. A large variability
was observed in the studied population. QTL analysis was then performed with the coefficients
of transpiration response curves. The inflexion point of transpiration response curve to FTSW
was used as a plasticity trait of transpiration regulation. MultiQTL software permitted us to
consider statistically the three years of investigation. Stable QTLs were detected on four linkage
groups. These results demonstrate that transpiration regulation of the scion by the rootstock is
determined genetically. This is the first genetic quantitative study taking into account
transpiration plasticity to evaluate the water stress tolerance. These results could improve the
understanding of the interaction relation between the scion and the rootstock.
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