By Marlene Cimons, National Science Foundation
Fusarium graminearum is a notorious fungus that infects major crops, such as wheat, barley and corn, causing significant economic hardship for the agricultural industry, often with catastrophic losses. It also can be toxic to animals, including humans.
Infection with this pathogen causes a devastating disease commonly known as “scab,” which reduces yield by causing sterility and shrunken kernels, and contaminating the grain with mycotoxins. The disease has shown up on farms in at least 18 U.S. states, with estimated costs of more than $3 billion since 1990, according to the U.S. Wheat and Barley Scab Initiative.
“It is one of the most economically destructive diseases in agriculture,” says Joseph E. Flaherty, associate professor of biology and director of undergraduate research at Coker College, a private comprehensive college in Hartsville, S.C. “It causes yield loss as plants become infected, and it also produces harmful toxins that contaminate otherwise uninfected plants and harvested grain.”
The fungal toxins can pose a health hazard to humans and livestock, and contaminate otherwise uninfected plants. “If you feed contaminated grain to your livestock, for example, this may cause weight-loss and death,” Flaherty says. “Even if small amounts of toxins enter our food supply, significant health risks follow. This is very important, both to our economy and to human health.”
The fungus reproduces asexually, “meaning it makes a type of spore called a conidium,” Flaherty says. “These conidia can be carried by wind and dispersed from field to field, and from plant to plant. Fusarium spores have been found 30,000 feet in the air, and they can travel over vast areas.”
Flaherty’s goal is to discover specific genes in the fungus that control reproduction, and understand exactly how they function. The hope is that the information will lead to targeted ways to disrupt the process--a new compound, for example--that also could be applicable to control other fungal pathogens as well.
“We hope to target spore production,” Flaherty says. “If we can identify the genes involved in allowing the fungus to make spores, we will be much closer to understanding the complex orchestration of events leading to this developmental stage and come closer to exploiting a vulnerable target. And if the fungus can no longer make spores, then it’s no longer a problem.”
Flaherty is studying the genetics of Fusarium under a National Science Foundation (NSF) Faculty Early Career Development (CAREER) award, which he received in 2009 as part of NSF’s American Recovery and Reinvestment Act. The award supports junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research within the context of the mission of their organization. NSF is funding his work with about $502,000 over five years.
The educational component of the grant allows him to provide Coker’s undergraduates with research experiences they wouldn’t otherwise have, since the college is not a research-oriented school, nor does it offer graduate degrees. “I feel very fortunate to be able to do high-level research involving undergraduate students, because I am at a teaching-centered institution that historically wouldn’t receive federal funding for research,” he says.
In addition to the experiments he and his students conduct at the college, Flaherty’s research collaborators host his students in their own labs during the summer. His research partners include scientists at Purdue University, the University of Arkansas, Southern Illinois University and North Carolina State University.
“Field studies are focused on understanding the effects of crop selection on Fusarium populations, and student-driven projects are facilitated by collaborations with scientists from government, industry and academia,” he says. “Thanks to these collaborators, I can maintain cutting edge research and offer these experiences to students who otherwise wouldn’t have the opportunity to carry out university-level research.”
In the lab, Flaherty uses quantitative real-time polymerase chain reaction (qPCR) and microarray technology to examine the organism’s genes. “These innovative tools allow us to examine patterns of gene expression at remarkable accuracy and sensitivity,” he says.
“We’ve looked at all its genes and how they are expressed,” he adds. “We’ve done experiments to identify candidate genes under conditions when they are making spores, and also conditions where the fungus isn’t making spores. We’ve also identified a series of developmental mutants that no longer can make spores, and those who make spores all the time when normal strains wouldn’t. Having all these comparisons allows us to robustly identify genes specifically involved in the developmental stages of the fungus.”
The fungus has more than 13,000 genes. Thus far, his team has identified 39 candidate genes involved in spore production. “The next step is to characterize them at the molecular level,” he says. “Proportionally, very few fungal genes have been characterized at the molecular level, and none directly involved in development have been characterized. We will be pioneers in identifying those genes involved in asexual development. More than likely, there will be several genes involved. The answers are within our reach.”
Flaherty is one of a number of researchers involved in the effort to combat this agricultural menace. Since 1997, federal, state and private sector scientists have worked closely with growers, millers and food processors from across the country to design and fund a system to find effective control measures against Fusarium.
“One of our biggest problems is: how are we going to grow more food for an ever-expanding population?” Flaherty says. “If we figure out how to control this fungus, and others, that could greatly enhance our capacity to feed the world.”
Reader Comments (