conference schedule and program with abstracts - Horticulture ...

O-39
Polymorphisms in VvPel associate with variation for berry texture
A.M. Vargas 1 , M.T. de Andrés, J. Ibáñez* 2
Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario. Finca El Encín,
Alcalá de Henares, Spain
1 Present address: Centro de Biotecnología y Genómica de Plantas (CBGP) INIA-UPM. Campus
de Montegancedo, Pozuelo de Alarcón, Spain; 2 Present address: Instituto de Ciencias de la Vid y
del Vino. Complejo Científico Tecnológico, Logroño, Spain
*Corresponding author: javier.ibanez@icvv.es
The identification of the genes involved in traits of interest, and the understanding of its
interaction with other genetic or environmental factors, are among the main aims of genetic
studies on cultured plants today. Berry texture is a quality trait of great importance in table
grapes, where ‘crunchy’ berries are especially appreciated. Nevertheless, no QTL or related gene
has been described for this trait so far. In this work, the gene VvPel, which codes for a pectate
lyase in grapevine, was selected as a candidate gene to carry out an association study. Pectate
lyase is a cell wall degrading enzyme that catalyses the eliminative cleavage of de-esterified
pectin, which is a major component of the primary cell walls of many higher plants. The gene
was chosen because previous studies in other species have reported a relation between this
enzyme and fruit softening. Different analyses were carried out to complement the association
test: the population structure, the nucleotide and haplotype diversity, the protein structure, the
existence of selection and the linkage disequilibrium (LD) were evaluated in the gene VvPel.
Firstly, a core collection of 96 table grape accessions was built from a collection of 322 table
grape accessions maintained in the Finca El Encín (IMIDRA), using a reiterated maximization
procedure. This core collection contained the 98% of the total morphological and molecular
diversity existing in the complete collection. Diverse texture parameters were measured in this
collection by means of a texturo-meter and several morphological descriptors related with berry
and bunch dimensions were studied. VvPel was sequenced in the core collection, and 32 SNPs
and 15 haplotypes were identified. LD was low enough to provide a high resolution power, and
neutrality tests pointed out to the possible existence of balanced selection over the gene in the
collection. Some of the polymorphisms associated significantly with texture parameters,
explaining part of the variation found for the trait. These results constitute the beginning of the
dissection of the complex trait berry texture in table grapes.
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