UNIVERSITY PARK, Pa. -- Scientists in a Penn State research program have developed a process to clone genetically identical cocoa trees from cocoa flowers, which could enhance cocoa plant quality on a large scale. And that, in turn, could increase cocoa farming profitability and stabilize the supply of cocoa beans on the global market.
"Right now, cocoa plants are grown from seed, and these plants vary greatly in their yield and disease resistance," explains Mark Guiltinan, associate professor of plant molecular biology in the College of Agricultural Sciences. "In some cases, up to 50 percent of the trees can be substandard. By selecting the best trees and producing identical clones, we potentially can increase plant productivity on farms."
Guiltinan and a team of scientists soon will begin a long-term field test of cloned cocoa plants at the Union Vale Estate on Saint Lucia Island in the West Indies (located off the northern coast of South America). The estate is owned by Edmund Opler, chief executive officer of World's Finest Chocolate Inc.
The Penn State team, funded by the American Cocoa Research Institute, collected flowers from 14 of the most productive cocoa trees on the estate. As a control, they also collected flowers from several of the worst trees. The flowers were flown back to Penn State's University Park campus, where individual cells from the buds were grown into full-sized plants. Guiltinan says the process, called "somatic embryogenesis," replicates a more complete plant than those derived from grafting.
"Plants produced from grafts do not develop a tap root that can sustain the plant in adverse conditions," Guiltinan explains. "Grafted plants also grow in the shape of a bush and have to be pruned during growth to resemble a natural cocoa tree. In Brazil alone, there are 660 million cocoa plants, which means a lot of pruning."
The plants produced from the flower cells have been grown in Penn State greenhouses for the past year. By June, the cloned cocoa plants will be planted in a Union Vale Estate field together with plants grown from grafts and from seed. Over the next three to five years, researchers will measure growth rates, pod production and chocolate-making quality.
"When plant breeders find a superior plant, the idea is to make more of them," Guiltinan says. "A tree grown from a single cell is genetically identical to the parent tree from which the flower was isolated. This means plant breeders can choose plants that are best adapted to a particular geographic area or are resistant to certain diseases."
Guiltinan says the cocoa tree cloning project on Saint Lucia will take years to implement on a large scale because the plants take four to five years to mature enough for scientists to gauge yield, production and disease resistance. "Corn breeders can produce three generations of plants in one year," Guiltinan points out. "Cocoa will take 15 years to reach the same stage of development."
If tests prove positive, then cocoa-producing nations can increase production of promising lines of cocoa plants. "Brazil currently has 600 million plants susceptible to disease, and breeders there have only a few hundred plants from which to start a breeding program," Guiltinan explains.
Guiltinan says the economic implications of Penn State's research are significant. Most cocoa is grown on small farms in five countries: Brazil, Ghana, Indonesia, the Ivory Coast and Malaysia. If breeding programs can produce plants particularly well-suited for different growing areas, farmers' incomes will increase. In addition, the elimination of boom-or-bust crop cycles will help stabilize world cocoa production, which would benefit Pennsylvania's $4 billion chocolate industry. Pennsylvania is the country's top chocolate-producing state.
Increased cocoa production also may have an ecological benefit, Guiltinan says. The cocoa plants are a sustainable crop for tropical ecosystems because they are grown for long periods of time. The plants also require a large canopy of shade trees for growth, which offers superior habitat for migratory birds and other wildlife. In addition, cocoa farms could act as connective greenways between islands of rainforest habitat.
In addition to the Penn State cloning process, which has a provisional patent, Guiltinan's team also is starting a genetic engineering research program to breed plants resistant to disease and pests.
By injecting a plant with the DNA of a natural pesticide, horticulturists can breed plants resistant to such pests as the cocoa pod borer, which is the major pest in Malaysia, or the myrid, an insect that infests cocoa crops in the Ivory Coast. Similar treatments for such plant diseases as witch's broom, pod rot and cocoa swollen shoot virus could be engineered into the genetic blueprint for cocoa plants, Guiltinan says.
"Forty percent of the cocoa crop is lost to disease and pests every year," Guiltinan says. "That's billions of dollars lost to the economies of cocoa-producing countries."
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EDITORS: For more information, contact Mark Guiltinan at 814-863-7958.
Contacts: John Wall jtw3@psu.edu 814-863-2719 814-865-1068 fax