Fungicide May Blast Global Rice Disease
By Ben Hardin
April 9, 2001
Rice blast, the most important fungal
disease of rice plants worldwide, and other diseases may some day be controlled
by a natural fungicide produced by a specially fed bacterium collected from a
central Illinois hog farm.
The U.S. Department of Agriculture has
applied for a patent on the bioconversion process developed by
Agricultural Research Service scientists
at the National Center for Agricultural
Utilization Research (NCAUR), Peoria, Illinois. ARS is USDAs chief
scientific research agency.
The bacterium, a strain of Pseudomonas aeruginosa, was found
in hog manure. The strain converts ricinoleic acid to the new fungicidal
compound, 7,10,12-trihydroxy-8 (E)-octadecenoic acid (TOD). Ricinoleic
acid is a major component of imported castor oil, but someday it may be
economically made from oil of genetically modified oilseeds such as
U.S-produced soybeans. Castor beans are produced primarily in India.
In a laboratory batch process, the P. aeruginosa strain
converted up to 45 percent of ricinoleic acid into TOD. Scientific
collaborators of a major chemical company sprayed rice plants with a dilute--5
parts per million--solution of TOD and inoculated the plants 24 hours later
with Pyricularia grisea, the fungus that causes rice blast. Five
days after the inoculations, sprayed plants had only about 29 percent as much
fungal growth as unsprayed plants.
Now the scientists are researching ways to scale up production of TOD for
further experiments on P. grisea and other fungi and insect pests
of crops and stored products. Laboratory tests, using the dilute solutions, so
far have also shown inhibition of fungi that cause rice sheaf blight and peach
The P. aeruginosa strain is one of more than 80,000 microbial
strains of potential agricultural and industrial importance maintained in the
ARS Culture Collection (NRRL) at
NCAUR in Peoria.
Scientific contacts: Ching T. Hou and Tsung Min Kuo, ARS National
Center for Agricultural Utilization Research, Peoria, Ill.; phone (309)
681-6263, fax (309) 681-6686, firstname.lastname@example.org,