Grape Vine Genome de-coded - better wines , lower pesticide usage and healthier drinks in prospect with GE ?
At the end of the 5th century BC, Thucydides claimed that the people of the Mediterranea - by this he was referring to a period between 2/3000 years BC emerged from barbarism when they learnt to cultivate and domesticate the olive tree and the vine. Not only as a source of food, but also of commerce.
Remarkably the Vitaceae are a large group of tropical / sub tropical woody and herbaceous lianas and only one genus, Vitis, produces edible berries - Vitis vinifera L. is the only species originating from Eurasia and it has been spread throughout the world by human cultivation.
France and Italy are the two largest vine growers in the EU for both the production of fruit and wine. In 2005 the The French–Italian Public Consortium for Grapevine Genome Characterization set up a joint project to determine the gene sequence of Vitis vitifera to speed up the understanding the geentics and to speed up development of newer and better varieties - they chose as the target plant, a highly developed self fertile Pinot Noir grape PN 40024. This was chosen due to it's high homozygosity (93%) , so that both copies of each chromosome pair carried the same version of most of the plant's genes.
Choice of this "vanilla" variety which forms the punchy core to many brands and world class Burgindies ( and not a few punchlines in the movie Sideways - in particular Stephanie's hidden stock of Romanee-Conti Richebourg - and the "in" jokes on Gaston Huet's Vouvrays -"And, ah, there's just, like, the faintest soupcon of, like, asparagus. And there's just a flutter of, like, a nutty Edam cheese." ) is important as extensive hybridization and selection for specific characteristics has left many strains carrying a mixture of genetic material which would confuse the search for the basic species genome.
Further details of the project here
Preliminary results have now been made available (Nature, 2007, DOI: 10.1038/nature06148
) for this, only the 4th complete plant genome sequence . Currently the genome has been sequenced for cultivated rice Oriza sativa - a monocotyledon , Poplar trees ,Populus sp.which is increasingly used for papermaking and is seen as a source of very fast growing biomass cellulose for bio - ethanol production, and the weed Arabidopsis. Animal feed crop Medicago and the tomato are also currently under study.
The draft sequence shows draft of the grapevine genome contains a set of 30,434 protein-coding genes less than the 45,555 protein-coding genes reported for Populus trichocarpa genome, and the 37,544 protein-coding genes identified inrice genome.
Unsurprisingly the grapevine proteome embodies large families of genes related to wine characteristics -
1. 43 genes have been identified with Stilbene synthases (STSs) drive the synthesis of resveratrol, the grapevine phytoalexin that has been associated with the health benefits associated with moderate consumption of red wine. Resveratrol is known to extend the life span of mice and other organisms.
Of these, 20 have previously been shown to be expressed after infection by Plasmopara viticola, thus confirming that they are likely to be functional.
2. 89 functional genes and 27 pseudogenes for the terpene synthases (TPSs) which drive the synthesis of terpenoids; these secondary metabolites are major components of resins, essential oils and aromas (their relative abundance is directly correlated with the aromatic features of wines) and are involved in plant–environment interactions. These results suggests a high diversification of grapevine monoterpene synthases that specifically produce C10 terpenoids present in aroma (such as geraniol, linalool, cineole and -terpineol).
It is hoped that public access to the whole genome will stimulate resesarch in to the identification of genes underlying the agricultural characteristics of the species, including domestication traits and especially those that that direct the metabolic pathways of terpenes and tannins which ocur in such large variety in the grapevine genome.
It may be possible to trace the diversity of wine flavours down to the genome level and assist in breeding selection for certain distinctive and desirable characteristics of the grape - perhaps boosting the resveratrol levels in grape juices for healthy non-alcoholic drinks.
As cultivated grapevines are highly susceptible to a large diversity of pathogens including powdery mildew Erysiphe necator , oidium and Pierce disease Vitis species such as V. riparia or V. cinerea, which are known to be resistant to several of these pathogens, and are interfertile with V. vinifera may be able to transfer resistance traits by breeding using advanced backcrosses or more directly by gene transfer (genetic engineering) - resulting the authors claim / hope in a reduction in pesticide use and consequently, costs of production.
However such prospects of genetic engineering don't excite everyone ...In 2005, a proposed ban (measure M) on planting or cultivating genetically altered crops for the next 10 years, divided Sonoma County, CA. Ultimately, voters rejected the ban, and similar prohibitions have been passed in Marin and Mendocino, CA. Currently U.S. regulations don't require labels detailing whether a food contains genetically modified ingredients.
A report by MKF Research, , "Economic Impact of California Wine 2004," prepared for the Wine Institute and California Association of Winegrape Growers said that the industry had a US$45.4 Bn. impact on the state's economy and provided provided 207,550 full-time equivalent jobs, with a total of US$7.6 billion in gross wages producing the No 1 agricultural product of the state by value with 4,805 grape growers and over 1,500 wineries and a highly developed tourist industry.
California is the fourth largest wine producer in the world after France, Italy and Spain. It accounted for US$643 million in wine exports in 2003 from US$537 million in 1998.