conference schedule and program with abstracts - Horticulture ...

P-3
Identification of genes related to stenospermocarpy in table grape (Vitis vinifera L.)
X.C. Iommi* 1,2 , G. Ravest 1 , M. Guerrero 1 , B. Soto 1 , M. González-Agüero 1-3 , N. Mejia 1 ,
C. Muñoz 1 , P. Hinrichsen 1
1 Instituto de Investigaciones Agropecuarias. INIA. La Platina Exp Centre. Santiago, Chile;
2 Universidad Andrés Bello. Santiago, Chile; 3 The Plant Cell Biotechnology Millenium Nucleus
(PCB-MN), Santiago, Chile
Corresponding author: xcasanueva@gmail.com
The stenoespermocarpy is a common phenotype in some table grapes and is characterized
by the presence of seminal traces instead of complete formed seeds. This trait is highly
demanded in international markets and therefore it is in the best interest of many breeders to
create new seedless varieties. Genetic mapping analyses have identified a major QTL
(quantitative trait loci) responsible for over 50% of the stenoespermocarpic phenotype. This QTL
is located in linkage group 18, where the molecular marker VMC7F2 co-localize with
VvAGL11, a MADS-box transcription factor related to ovule development. Our aim is to
identify additional candidate genes involved in the stenoespermocarpy by combining phenotypic
analysis, QTL mapping, transcriptomic analysis and histological studies. QTL mapping was
based on an extensive phenotypic characterization using a reference population from a ‘Ruby
Seedless' x 'Sultanina' crossing, during 3 growing seasons. The results were partially comparable
with the QTLs identified in the same or other populations evaluated.A relevant QTL for seed and
berry size was mapped on linkage group 18, where the candidate gene VvAGL11 had been
previously mapped. Expression analysis of this gene through berry development during two
seasons, showed an increase in its expression after fruit set in seeded segregants, in contrast to
the seedless ones. We also have found two other QTLs in linkage groups 2 and 8, explaining
20% of the phenotype. These QTLs have been stable during 3 seasons and we are currently
saturating them with newly developed SSRs and AFLP markers to map the relevant genes. A
massive sequencing (RNA-Seq) will help to give additional support to the information obtained
through positional cloning. In addition, preliminary transcriptomic analyses have identified a
number of genes differentially expressed when comparing segregants exhibiting extreme
phenotypes for seed size. We are further characterizing the stenospermocarpic phenotype by
histological analysis, which shows a defect of the ovule outer integument in seedless segregants.
We will use histochemistry to further characterize all our candidate genes.
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