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Food formulas

Scientists try to decipher genomes that give produce, grains, and livestock their nuanced tastes

By Carolyn Y. Johnson
Globe Staff / January 24, 2011

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For centuries, chefs have been devising new ways to combine foods to create innovative dishes. Now, scientists are using the powerful tools of modern biology to decipher the genomic recipes that give rise to the fragrant flesh of a strawberry or the complex bitter flavor of dark chocolate.

The studies are not just academic: As researchers learn how genes are linked to different traits, they hope to breed crops or livestock that are hardier, tastier, or healthier.

Last month, in the journal Nature Genetics, international teams of scientists published the genomes of the cocoa plant and the woodland strawberry — the newest additions to a growing genomic buffet. Staples like corn and rice have been sequenced, as well as chickens, golden delicious apples, and pinot noir grapes. Researchers are gaining insight into genes that give rise to the melt-in-your-mouth taste of chocolate or the fresh smell of cucumbers.

“Traditionally, plant breeders have been guided in their selection by the traits that they can see,’’ said Tom Davis, a professor of plant biology and genetics at the University of New Hampshire and a member of the Strawberry Genome Sequencing Consortium. “We are trying to make it possible for breeders to be guided also by the genes that the plants have’’ that give rise to desirable traits, which might range from some nuance of flavor to natural resistance to disease or pests.

Genomes are being deciphered by large, international consortiums of scientists funded by private and public sources that can range from the National Science Foundation to big-brand chocolate manufacturers such as Hershey Corp. or Mars Inc.

In the decade since researchers decoded the first human genome, such analyses have become quicker and cheaper, allowing many more plants and animals to be sequenced. A catalog of the genes in a plant or animal is a starting point into questions diners and farmers care about, just as the human genome was a critical tool to begin unraveling major questions about human disease and biology.

“We can breed potentially for types of plants with higher levels of a certain kind of flavor — fruity notes, raisiny notes, nutty notes . . . it will help us to understand the genetic basis of flavor,’’ said Mark Guiltinan, a professor of plant molecular biology at Pennsylvania State University. “Especially the gourmet, high-end chocolate manufacturers are interested.’’

Guiltinan, one of the lead authors of the recent cocoa genome paper, said that researchers have found potentially important clues in the plant’s roughly 29,000 genes. They have identified a candidate gene that may play a role in the hardness of cocoa butter, a trait of possible interest for chocolate makers who want candy bars that do not melt in warm climates.

Davis, a member of the large international consortium that sequenced the woodland strawberry — an ancestor of the cultivated strawberries on supermarket shelves — said his lab is working on finding genes that are unique to that fruit. He is searching for the clues as to what makes a strawberry a strawberry, and the research could shed light on other related crops, such as apples, peaches, and almonds.

Instead of using the genome as a resource for making genetically modified foods, many researchers are focused on finding ways to use the genetic information to breed better plants. With greater information about the genetic basis of different traits, breeders might be able to make more informed choices about which plants to select and cross-breed.

The biggest opportunity may come in breeding plants that are naturally more resistant to disease, pests, or droughts — allowing farmers to use fewer chemical pesticides or allowing a crop to thrive in different types of environmental conditions.

Guiltinan pointed out, for example, that poor cocoa farmers could benefit significantly from a better yield and disease-resistant plants. According to the Nature Genetics paper, disease and insects cause about 30 percent of the cocoa crop to be lost each year.

Grant Cramer, a professor of biochemistry and molecular biology at the University of Nevada, is a part of the International Grape Genome Program, with an interest in developing drought-resistant grape vines.

In 2007, the pinot noir genome was first published in the journal PLoS ONE, and Cramer said that at least 50 varieties of grapes are now being sequenced.

Genetics may give scientists and farmers insights into the biological processes that lead to a peppery note or a fruitiness in wine.

“We prune them, we pull leaves off of them to shape the canopy and allow more light exposure,’’ Cramer said. “There are a lot of intense practices done in grape vines, and we can start to understand more what those practices are doing.’’

Carolyn Y. Johnson can be reached at cjohnson@globe.com.

“We can breed
potentially for types
of plants with higher
levels of a certain kind
of flavor — fruity notes,
raisiny notes, nutty
notes . . . it will help us to understand
the genetic
basis of flavor.’’
MARK GUILTINAN
Professor of plant molecular biology at Pennsylvania State University