Cacao, the plant source of chocolate, could be bred to be more plentiful — more resistant to drought and disease — thanks to research funded by one of the world’s largest privately owned companies, Mars Wrigley, and performed by genetic scientists at Huntsville’s HudsonAlpha Institute for Biotechnology.
Supply from millions of cacao farmers in West Africa, Southeast Asia and Latin America are under pressure of increasing consumption, a changing climate and fungal infections, in what a 2017 New York Times article called “a battle to save the world’s favorite treat.”
The breakthrough announced today by HudsonAlpha is the identification of an improved reference genome to guide farmers in crossbreeding and hybridization that can yield more productive cacao crops.
Cacao is a particularly delicate plant. It can only be grown within 20 degrees of the equator, and increasing temperature and decreasing humidity in the areas that currently produce cacao will mean the crop must be grown at higher elevations.
HudsonAlpha researchers say they have generated a new reference genome by using advanced long-read sequencers, producing a more reliable genetic benchmark than the first version, which was completed in 2010.
Cacao trees, like many modern crops, do not show a lot of genetic diversity. Most of the cacao trees worldwide come from a handful of clones selected in the 1940’s. Because the trees are so closely related, they have similar genetic weaknesses. If a disease reaches a group of cacao trees that doesn’t carry any genetic resistance to that disease, it can destroy the entire crop.
“Having so little genetic diversity leaves the cacao tree vulnerable,” says HudsonAlpha Faculty Investigator Jane Grimwood, PhD. “However, it also means that genes can be exchanged between trees, which gives researchers and farmers an opportunity.”
A reference genome allows you to identify parts of the genome you wish to see carried through to the next generation of plants, like genes that promote drought tolerance, increase yield or improve disease resistance.
This most recent effort was co-led by HudsonAlpha faculty investigators Grimwood and Jeremy Schmutz, who said of the project, “As our technology improves, we’re able to produce more detailed, versatile reference genomes, which are critical for the kind of rapid crop improvement you want to see with cacao.”