Gene codes cracked for strawberries and chocolate

Teams of scientists have cracked the genetic codes of the wild strawberry and a certain type of cacao used to make fine chocolate, work that should help breeders develop better varieties of more mainstream crops.

The wild strawberry is closely related to important food crops such as apples, peaches, pears and raspberries, as well as cultivated strawberries, so its gene map will help breeders of these plants to produce new varieties, the researchers said.

"Because farmers have been cross-breeding and hybridizing food crops for centuries to improve traits, they tend to have large complicated genomes but the wild strawberry's is relatively small so we can get access to all of these useful genes comparatively easily," said Dan Sargent of Britain's Biotechnology and Biological Sciences Research Council (BBSRC) Crop Science Initiative, who worked on the project.

In a study published in the journal Nature Genetics on Sunday, Sargent and an international team of researchers found that the wild strawberry genome has around 35,000 genes, about one and a half times the number that humans have, and most of these will also be in cultivated varieties, they said.

"This will accelerate research that will lead to improved crops, particularly commercial strawberries," said Todd Mockler, of Oregon State University, one of the lead researchers on the team in the United States.

"It could lead to fruit that resists pests, smells better, tolerates heat, requires less fertilizer, has a longer shelf life, tastes better or has an improved appearance."

In a separate study in the same journal, French researchers said they had sequenced almost all of the genome for the Criollo variety of the cacao plant, Theobroma cacao - a tropical tree crop used to make chocolate.

The work, which the scientists said found almost 29,000 genes and covered 76 percent of the estimated full genome, should help the genetic improvement of cacao crops. The cocoa tree was first cultivated approximately 3,000 years ago and about 3.7 million tons of cocoa is currently produced each year.

The group working on the strawberry genes, which involved more than 70 researchers in five continents, sequenced the wild plant's genome by breaking it up into millions of short segments which were sequenced individually and then reassembled.

Plants tend to have far more complex DNA than animals, and the scientists identified 34,809 genes in the wild strawberry. Humans have around 20,000 to 25,000 genes.

Scientists said in August they had decoded and published almost all of the highly complex genome of wheat, a staple food for more than a third of the world's people.

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By Kate Kelland

LONDON