Scientists Pick Apart Fungus for Genetic Clues
By Jan Suszkiw
October 5, 2006
Using the tools of molecular
genetics, Agricultural Research Service (ARS) scientists are deconstructing the
toxin-making machinery of the fungus Fusarium verticillioides to find
clues to its contamination of corn.
Contamination of corn by fumonisin, a mycotoxin produced by the fungus, can
diminish the quality and value of the kernels or render them unsafe to eat,
Kendra. He is a microbiologist at the ARS National Center for Agricultural
Utilization Research (NCAUR)
in Peoria, Ill.
There, Kendra and ARS research colleagues
Butchko, Ronald Plattner and
Proctor are searching for genes that enable F. verticillioides to
produce the mycotoxin, as well as to rot the ears and stalks of susceptible
corn. Clues emerging from an examination of such genes and how they work in
concert may reveal a chink in the fungus armor worth exploiting. One
possibility is to formulate sprays that disrupt the fungus toxin
synthesis, or perhaps its formation of critical spore pigments, according to
Kendra, who oversees NCAURs
First, though, Kendras team, together with collaborators from five
other research institutions, must finish compiling the equivalent of
genetic snapshots of the fungus. They want to capture them during
particular fungal stages, such as while its germinating, spreading
through the plants vascular system, or making fumonisin.
One high-tech tool used to do this is the microarray. It enables the
detection of genetic activity in tiny snippets of ribonucleic acid material
taken from the fungus. The work, begun in 2001, has led to the identification
of nucleic acid sequences for 80 percent of F. verticillioides genes,
Some early findings include microarray evidence that many of the same genes
the fungus uses to infect field corn are also active during its attacks on
sweet corn varieties. The scientists also identified a new fumonisin gene,
FUM20, plus nine others that may regulate its synthesis, according to a
story in the October 2006 issue of Agricultural Research magazine.
That issue highlights agency food safety research.
ARS is the U.S. Department of
Agricultures chief scientific research agency.