Plant geneticists find veritas in vino( Viticulture the growing of grapes (V...)

Viticulture, the growing of grapes (Vitis vinifera) chiefly to make wine, is an ancient form of agriculture, evidence of which has been found from the Neolithic and Early Bronze Ages. We have a detailed understanding of how nurture affects the qualities of a grape harvest leading to the concept of terroir (the range of local influences that carry over into a wine). The nature of the grapes themselves has been less well understood but our knowledge of this is substantially increased this week by the publication in the open-access journal PLoS ONE of a high quality draft genome sequence of a Pinot Noir grape by an Italian-based multinational consortium.

The genome of the grape is spread over 19 pairs of chromosomes and is around 504.6 megabases in length. The team of researchers, led by Dr Riccardo Velasco of the Istituto Agrario di San Michele all'Adige, used a shotgun sequencing approach, which has resulted in 10.7X coverage, 4.2X using pyrosequencing and 6.5X by Sanger sequencing. At the same time, the genome of the grape chloroplast was also sequenced and, remarkably, this was found to be identical to an independently determined sequence from a different strain of Pinot Noir that was published last year.

The grape, therefore, has a relatively small genome for a crop plant, similar to that of rice or poplar trees and much smaller than that of wheat or maize. Nevertheless, sequencing the genome was complicated by the degree of heterozygosity between pairs of chromosomes, some 11.2% of the sequence differing between homologous regions. There was so much variation, in fact, that Velasco describes it as like being in the presence of two genomes.

Moreover, the team discovered more than two million single nucleotide polymorphisms (individual letter changes in the grapes genetic blueprint) in 87% of the 29,585 identified genes. While this made sequencing the genome difficult, it now provides a massive library of inherent variation with
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