新托福阅读：Candy-maker releases cacao (cocoa) genome sequence online

M&M公司公布可可的基因序列组

The makers of M&Ms have decoded an essential recipe for some of their most popular products: the cacao tree's (Theobroma cacao) genome.

The sequence, posted online September 15 and available at no charge to the public, was assembled by Mars, Inc. in partnership with the U.S. Department of Agriculture's Agricultural Research Service and IBM.

The cacao or cocoa tree (the seeds of which are used to make cocoa powder and chocolate) joins other widely consumed crops, such as wheat, corn and rice, that have already had their genome sequenced. Many cacao-producing countries are relatively poor and lack the resources necessary for advanced genetic study of cacao, which is among the top 10 most heavily traded crops in the world, the researchers behind the genome note. The cacao plant is grown on some 17 million acres across the globe, and the largest producer, Cote d'Ivoire, hauled in some 1.3 million metric tons of cacao seeds in 2005.

The researchers are refining the data before submitting it for formal peer review and publication, but they note that the online version is "fully functional," according to Howard-Yana Shapiro, a plant scientist at Mars and adjunct professor at University of California Davis' College of Agriculture and Environmental Sciences. The public version of the genome is about 92 percent complete and has pinpointed about 35,000 genes, according to researchers working on the project. Mars' release comes before that of chocolate competitor Hershey, which had also been working to sequence the cacao tree's genome (with Pennsylvania State University and French labs), The New York Times reports.

The Mars scientists concede that mapping the cacao genome "was in our interest," says Juan Carlos Motamayor, a genetic researcher at Mars. But, he notes, the data also could help boost the livelihood of workers who grow and process cacao, many of whom live in poverty and work on small farms.

Cacao breeders will be able to start using the sequence data to select for traits such as yield and hardiness, as well as begin puzzling out plant defenses against cocoa blights, the researchers say. Cacao trees take several years to mature and can produce beans for decades. With hopes that the new information will eventually help producers double or triple their yields, Shapiro notes, the genome could go a long way toward creating "an economic model that is sustainable."

Cacao cultivation has more than doubled since the mid-1980s, but most of that growth has come from increased land use, not higher yields. A tree that produces more seedpods would be "a better use of land," Shapiro says. Sturdier, better-producing crops would also likely sweeten chocolate candy makers' bottom line by upping supply and lowering prices.