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    Scientists Have Sequenced the Genome of Cocoa to Make Better Tasting Chocolate

    Written by

    Jason Koebler

    Staff Writer

    Image via Cliff/Flickr

    Chocoholics, rejoice: Science is trying to make your Mars bar taste better. Well, technically, Mars is trying to make your Mars bar taste better. Scientists at the company (and Indiana University, and a few other places) have successfully sequenced the genome of one of the world's most commonly grown cocoa tree in an attempt to make certain varieties of chocolate taste less acidic. 

    That's no small feat: A similar project undertaken in 2011 found that one variety of the cocoa tree has more than 28,000 protein-coding genes; humans have just 23,000. Now, the new sequencing of a more common (and distinct from the variety sequenced in 2011) tree could lead to real changes in the industry. 

    There are many varieties of the cocoa tree, with one known as CCN 51 the most commonly grown in Latin America, where it accounts for large parts of the Brazilian, Ecuadorian, Peruvian, and Colombian economies. Worldwide, more than $100 billion is spent on chocolate each year, according to the World Cocoa Foundation. Cocoa trees are grown in more than 50 countries and the crop is creates roughly 45 million jobs worldwide.

    Before it makes it to the supermarkets, cocoa beans are harvested from pods, which eventually mature into one of five colors: red, purple, orange, yellow, and green. A Costa Rican variety known as Matina is one of the world's finest chocolates and is known for its mature green pods, which create high yields of good-tasting chocolate. CCN 51, on the other hand, has high yields and is resistant to many diseases that plague cocoa trees, but its red pods create chocolate with an acidic taste. That's a big problem for farmers who grow the variety, especially because cocoa is one of the few crops in which small farms provide more than 90 percent of the world's supply.

    To combat that, farmers have tried cross breeding CCN 51 with green-podded Costa Rican trees, but the quality of those beans is still inferior to that of Matina, and the cross breeding can result in what are known as "dud" trees, which is not a good thing for small farmers.

    "Because of its high yield and disease resistance, the most ubiquitous clone in large cacao plantations in Latin America is CCN 51," the researchers write. "Unfortunately, it has a rather undesirable flavor profile because of its high acidity and astringency, and also because it lacks desirable floral aromas."

    Turns out that one single DNA base change on the the plant's fourth chromosome accounts for the color of the pod, researchers described in Genome Biology this week. Scientists working at places such as the Ecuadorian Cacao Research Institute could then, using a process known as marker-assisted selection (basically a souped-up version of what farmers have been doing for decades), could sequence a tree's DNA before deciding which ones to breed. 

    "Identification of genes that regulate pod color therefore constitutes a crucial first step toward the development of a platform for marker-assisted selection (MAS) aimed at the development of high-yielding alternatives to CCN 51," they write. "The ability to screen young cacao seedlings with molecular markers and to select only those carrying alleles that result in green pods would greatly reduce the population sizes required for the laborious and expensive phenotypic evaluations of unlinked flavor and yield traits."

    All that means is better-tasting chocolate might be headed your way. And you didn't even have to do anything for it.