The Cacao Genome (Chocolate) Sequencing War Revisited
Previously, BioJobBlog reported on the race between two groups led by the Mars and Hersey companies to sequence and decode the cacao (chocolate) tree genome. It should come as no surprise that the world’s two largest chocolate companies have pitted themselves against one another to decode the wonders of the cacao bean. After all, chocolate is big business and learning how to maximize yields, improve flavors and optimize the levels of cacao bean chemical components would be a boon to the company that was able to obtain the genetic information first!
Currently, most cacao farmers earn about $2 per day, but producers of fine cacao earn more. Increasing the productivity and ease of growing cacao can help to develop a sustainable cacao economy. The trees are now also seen as an environmentally beneficial crop because they grow best under forest shade, allowing for land rehabilitation and enriched biodiversity. Today, many growers prefer to grow hybrid cacao trees—rather than the original variety Theobroma cacao, Criollo)—that produce chocolate of lower quality but are more resistant to disease. Roughly five percent of the world’s current cocoa production is derived from Criollo cacao beans because of increased susceptibility to fungal diseases which results in higher costs and lower yields.
At the last installment of this ongoing saga, the Mars group, September 2010, released a statement that that they had beat the Hershey group and unraveled DNA sequence of the most common cacao bean variety that is used to manufacture most commercial chocolate.
The Mars researchers constructed a preliminary genomic map that covered over 70 per cent of the total cacao bean DNA sequence which is distributed over 10 chromosomes. These data were uploaded to The Cacao Genome Database which is publicly available as long as persons who access the data sign an agreement that stipulates that they “will not seek any intellectual property protection over the data, including gene sequences contained in the database. The Information Access Agreement allows any cacao breeders and other researchers to freely use the genome information to develop new cacao varieties.”
While the Mars group may have beat the Hersey group to the popular press, their research has not yet appeared in an academic journal for scientific scrutiny. Interestingly, the Hersey group yesterday announced that their version of the cacao genome was published in the most recent edition of Nature Genetics. According to the authors,
We sequenced and assembled the draft genome of Theobroma cacao (Criollo), an economically important tropical-fruit tree crop that is the source of chocolate. This assembly corresponds to 76% of the estimated genome size and contains almost all previously described genes, with 82% of these genes anchored on the 10 T. cacao chromosomes.
Analysis of this sequence information highlighted specific expansion of some gene families during evolution, for example, flavonoid-related genes. It also provides a major source of candidate genes for T. cacao improvement.
While Theobroma is often used to manufacture gourmet chocolates that particular variety of cacao tree often remains vulnerable to disease. Information gleaned from this study could be used to breed bioresistant varieties of Theobroma.
Further the authors noted:
Our analysis of the Criollo genome has uncovered the genetic basis of pathways leading to the most important quality traits of chocolate--oil, flavonoids and terpene biosynthesis […] It has also led to the discovery of hundreds of genes potentially involved in pathogen resistance, all of which can be used to accelerate the development of elite varieties of cacao in the future.”
Other genes that were identified include those for the production of cocoa butter, natural antioxidants, hormones, pigments, and aromas. BTW, for those of you who may be interested, cocoa was thought to be domesticated about 3,000 years ago in Central America; making it one of the world’s oldest domesticated tree crops.
It isn’t clear yet how the cacao genomes deciphered by the Mars and Hersey groups match up against one another. Regardless, the big winners here are chocolate lovers. What to you think the world stance will be on genetically engineered chocolate?
Oy!
Until next time...
Good Luck and Good Eating!!!!!
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snack on a piece of chocolate from time to time? Because of the growing incidence of tropical diseases, pests and global climate change, Mars, the giant candy maker (M&Ms, Snickers), 