This article is available from: http://www.biomedcentral.com/1471-2164/8/424
[Background] Single-nucleotide polymorphisms (SNPs) are the most abundant type of DNA sequence polymorphisms.
Their higher availability and stability when compared to simple sequence repeats (SSRs) provide enhanced possibilities
for genetic and breeding applications such as cultivar identification, construction of genetic maps, the assessment of
genetic diversity, the detection of genotype/phenotype associations, or marker-assisted breeding. In addition, the
efficiency of these activities can be improved thanks to the ease with which SNP genotyping can be automated. Expressed
sequence tags (EST) sequencing projects in grapevine are allowing for the in silico detection of multiple putative sequence
polymorphisms within and among a reduced number of cultivars. In parallel, the sequence of the grapevine cultivar Pinot
Noir is also providing thousands of polymorphisms present in this highly heterozygous genome. Still the general
application of those SNPs requires further validation since their use could be restricted to those specific genotypes.
[Results] In order to develop a large SNP set of wide application in grapevine we followed a systematic re-sequencing
approach in a group of 11 grape genotypes corresponding to ancient unrelated cultivars as well as wild plants. Using this
approach, we have sequenced 230 gene fragments, what represents the analysis of over 1 Mb of grape DNA sequence.
This analysis has allowed the discovery of 1573 SNPs with an average of one SNP every 64 bp (one SNP every 47 bp in
non-coding regions and every 69 bp in coding regions). Nucleotide diversity in grape (π = 0.0051) was found to be similar
to values observed in highly polymorphic plant species such as maize. The average number of haplotypes per gene
sequence was estimated as six, with three haplotypes representing over 83% of the analyzed sequences. Short-range
linkage disequilibrium (LD) studies within the analyzed sequences indicate the existence of a rapid decay of LD within the
selected grapevine genotypes. To validate the use of the detected polymorphisms in genetic mapping, cultivar
identification and genetic diversity studies we have used the SNPlex™ genotyping technology in a sample of grapevine
genotypes and segregating progenies.
[Conclusion] These results provide accurate values for nucleotide diversity in coding sequences and a first estimate of
short-range LD in grapevine. Using SNPlex™ genotyping we have shown the application of a set of discovered SNPs as
molecular markers for cultivar identification, linkage mapping and genetic diversity studies. Thus, the combination a highly
efficient re-sequencing approach and the SNPlex™ high throughput genotyping technology provide a powerful tool for
grapevine genetic analysis.
This work was funded by GRAPEGEN, a collaborative
project funded by Genoma España and Genome Canada.
Peer reviewed