GENET archive


GENES & PLANTS: Grapevine genome sequenced by French and Italian researchers

                                  PART 1

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SOURCE: Technology Review, USA

AUTHOR: Michael Gibson


DATE:   27.08.2007

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Researchers have cleared the way for genetically modified wine.

A group of Italian and French scientists have produced a high-quality draft of the genome sequence for the pinot noir grapevine, the first sequence made for a fruit crop.

The research group, called the French-Italian Public Consortium for Grapevine Genome Characterization <>, has made the genetic code available to the public to speed up the process of identifying the genes underlying particular traits, such as those involved in disease resistance. The group’s findings were published in this week’s issue of Nature.

”Now people have the tools to identify the genes of importance in the grapevine,” says Jean Weissenbach, a geneticist who was part of the sequencing effort at Genoscope, in France. ”They will be able to find the specific genes which confer resistance to diseases, and, in time, to understand the differences among the various types of vines.”

The team’s analysis of the sequence shows that the genes involved in the metabolizing of tannins and terpenes--the molecules that contribute to a wine’s aroma, texture, and taste--have been selectively amplified by breeding over thousands of years.

”Mankind has selected varieties that were more interesting from their point of view, with more copies of those terpene and tannin genes appearing in successive generations,” Weissenbach says.

The researchers also found that the number of genes responsible for producing resveratrol had increased over thousands of years. Resveratrol is a compound known to extend the life span of mice and other organisms.

The information contained in the genome sequence makes the grapevine ripe for genetic engineering. Grapevines are highly susceptible to a variety of pathogens, including powdery mildew, oidium, and Pierce disease. But some varieties of grapevine resist these diseases.

Once the genes related to these diseases are identified, and disease-resistant grapevines are sequenced, the susceptible grapevine could potentially be modified by breeding or gene transfer.

”I think having the sequence of a grapevine genome is extremely useful,” says Peggy Lemaux, a microbiologist at the University of California, Berkeley. Lemaux is involved in similar research, focusing on using genetic engineering to understand and improve cereals and grasses. The grapevine project is going to require some time and work, she says, ”not only identifying the disease-related genes in the grapevine, but also sequencing the pathogens to find what it is that allows them to attack.”

Vintners currently incur large costs fighting diseases like powdery mildew, mainly by using an array of chemical sprays. If a disease-resistant grape could be engineered without diminishing its quality, some vintners would welcome it.

”We spend a fair amount of dollars ... [and] time fighting powdery mildew in the vineyard through a spray schedule,” says Stephen Reustle, owner and wine maker at Reustle Prayer Rock Vineyards, in Oregon, a region known for its pinot noir. ”From a general point of view, a disease-resistant pinot noir grape would be a real economic benefit to the vineyard owner.”

Still, there is reluctance among many wine farmers to use genetically modified organisms. In 2005, a proposed ban on planting or cultivating genetically altered crops divided Sonoma County, CA. Ultimately, voters rejected the ban, but similar prohibitions have been passed in Marin and Mendocino, CA.

”It’ll be a long time before we can use this,” says Steve Smit, head of vineyard operations for Constellation Wines, the purveyor of the Robert Mondavi label. ”There are a lot of good arguments on both sides: you no longer have to use chemicals, but maybe you’re changing something that’s important elsewhere in the ecosystem.”

                                  PART 2

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SOURCE: Yahoo News, USA

AUTHOR: Agence France Press, France, by Marlowe Hood


DATE:   26.08.2007

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PARIS (AFP) - Scientists in France and Italy have deciphered the complete genetic code for the plant producing wine grapes, according to a study published Sunday.

While the findings will do nothing to enhance the mystique of winemaking, they could pave the way for gene-based manipulations to boost flavour and improve resistance against disease.

Dozens of researchers analyzing the Pinot Noir varietal of Vitis vinifera, the core species from which virtually all grape wine is made, found twice as many genes contributing to aroma than in other sequenced plants, suggesting that wine flavours could be traced to the genome level.

The French-Italian Public Consortium for Grapevine Genome Characterisation, which collectively authored the study, also gained crucial insights into the genetic evolution of plants over the last 200 million of years.

V. vinifera is only the fourth complete genetic sequence ever produced for a flowering plant, and the first for a fruit crop.

The other three are rice, the poplar, and Thale Cress, a species of wild plant related to mustard and cabbage.

Pinot Noir, the signature grape of the famous Burgundy wine region in northern France, was selected because of its inbred genotype, which made it easier to sequence.

The study, published in the British journal Nature, will be of enormous interest to global grape growing and wine industries eager to diminish costly plant disease and enhance the flavour of a product that generates some 200 billion dollars (150 billion euros) a year in revenue.

”It is strategic for a species as economically important as the grape vine to develop the tools and genetic resources” to resist pathogens and improve quality, wrote Anne-Francoise Adam-Blondon, one of the authors, in explaining the origin of the Franco-Italian initiative.

The researchers discovered that V. vinifera had large ”families” of genes ”directly correlated with the aromatic features of wine,” especially related to tannins and terpenes.

Tannins, astringent compounds found in the grape skin and seeds -- especially red grapes -- adds body and structure needed for aging, and are considered essential for producing a balanced wine. They are also thought to help prevent hardening of the arteries.

Terpenes are the main ingredient in the essential oils of many plants and flowers widely used as natural flavour additives for food, and in fragrances. In wines, they are especially concentrated in the Muscat grape, where they exude floral tones of rose and violet.

The study also identified the genetic source in the plant of resveratrol, the anti-oxidant in red wine that been widely associated with health benefits ranging from anti-aging to boosting anti-viral treatments.

Perhaps even more important to winemakers than manipulating molecules related to taste -- which is sure to generate controversy -- is the potential to make V. vinifera more resistant to diseases that causes tens of millions of dollars in damage every year.

Research is already underway, noted Adam-Blondon, to isolate a gene that could increase resistance to oidium, a common form of mildew to which Pinot Noir is especially vulnerable.

This would also help reduce the use of chemicals in grape growing, she added, pointing out that in France that grape vines account for three percent of farm land cultivated, but 20 percent of herbicides used.



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