Tiny Proteins Could Help Cotton Fend off Fungi By
Tiny natural proteins derived from moths, frogs and other organisms
could give cotton plants a potent anti-fungal agent, new research
Studies conducted by microbiologist Anthony De Lucca and colleagues
show that certain proteins, called peptides, kill Aspergillus
flavus and Fusarium fungi. De Lucca is part of an
Service team thats exploring the peptides potential
as a built-in defense for cotton.
A. flavus is a soil-dwelling fungus that can contaminate
cottonseed with a poisonous substance called aflatoxin. Federal law
prohibits farmers from selling as livestock feed any seed containing
more than 20 parts per billion of aflatoxin. Fusarium inflicts
costly root rots.
Cotton farmers ordinarily apply chemical pesticides to preempt
aflatoxin contamination. De Luccas team envisions a more
environmentally-friendly approach-- genetically engineering cotton
plants to make the fungicidal peptides on their own.
Their first order of business: Identify the smallest, most potent
peptides possible that the entire plant can produce to kill fungal
attackers. One promising peptide is cecropin A, found in cecropia moth
caterpillars. The insects make the peptide to protect themselves from
infection. Another fungicidal peptide is demaseptin, which some frogs
secrete in their moist skin.
In the test tube, cecropin A killed 100 percent of dormant and
germinating forms of Fusarium fungi within 30 minutes
exposure. It also killed nearly all the spores of germinating A.
flavus. Scientists conducted the tests using peptide
concentrations similar to those that a genetically engineered plant
Potency against these fungi isnt the only criterion De Luccas
team seeks. You can read more about the tricky task of getting plants
to mimic these peptides in the June issue of Agricultural Research,
a monthly publication of ARS. The story is also on the World Wide Web
Scientific contact: Anthony De Lucca,
and Feed Safety Research Unit, ARS
Research Center, New Orleans, La., phone (504) 286- 4253, fax
(504) 286-4419, firstname.lastname@example.org.