Genes Key to Protecting Chocolate Supply
By Don Comis
October 15, 2001
Anyone who needs a chocolate fix
would do well to fear witches broom, frosty pod rot and black pod.
A major supplier of chocolate lovers, Mars,
Inc., wants to protect the worlds cocoa beans from these and other
fungal diseases. Agricultural Research
Service scientists, led by plant geneticist Raymond J. Schnell at the ARS
Horticulture Research Station in Miami, Fla., have signed a research
agreement with Mars to develop more resistant cacao trees as quickly as
Large pods holding 20 to 60 cocoa beans rich with chocolate butter sprout
from cacao trees. The diseases rot mature pods. Witches broom gets its
name from the white, broomlike fungal structures that form on leaves, pods and
stems. It also inhibits new pod formation.
Witches broom has reduced Brazil from a net exporter to an importer of
cocoa beans. Frosty pod rot has closed farms in Ecuador, Colombia and Costa
Rica. Now, black pod rot threatens the West African plantations that supply
more than half of the worlds cacao. If the other two diseases were to
reach West Africa and join forces with black pod, the world could all but kiss
ARS scientists have found 75 cacao genes similar to resistance genes in
other plant species. These may help scientists breed more resistant varieties.
If the resistance genes are clustered together, the known genes could lead to
discovery of their neighbors.
The United States is working with Brazil, Costa Rica, Trinidad, Ecuador and
the United Kingdom. These countries have long-standing cacao breeding programs
and have supplied the range of plants needed to map the cacao genomes 10
Mars, Inc., has waived its patent rights to any new varieties that might
result from this research.
ARS is the U.S. Department of
Agricultures chief scientific research agency.