Defense, welfare programs and the economy tend to captivate the national conscience of federal affairs, but few tend to recognize the value of corn to the U.S. Comprising more than 80 million square acres of farmland and raking in $20 billion in government subsidies, this grain stands out as the backbone of American agriculture.
However, corn is not perfect. Any threat posed to the crop would affect the economy with consequences that span outside of the agricultural realm. This is why Jim Holland and Peter Balint-Kurti have dedicated the past eight years of their work to researching the crop’s resistance to disease.
Holland and Balint-Kurti, University professors and USDA researchers, started looking at corn genes responsible for blight resistance nearly a decade ago due to government demands. Although Southern leaf blight, the rapid discoloration and death of plant tissue, has not affected corn production recently, a blight epidemic of 1971 accounted for a loss of 710 million bushels, 12 percent of national corn production, according to records published in Science.
“I work on corn because the USDA recognized that it’s the most important crop in this country,” Holland said. “From a federal perspective, we need to be working on things of economic importance.”
Holland said corn is an ideal organism to work on, particularly due to its complex traits. Throughout the ongoing research process, Holland and Balint-Kurti have studied millions of genetic variations, identifying 50 gene sequences associated with disease resistance. Each plant carries corresponding genes for resistance, but resistance depends on whether the plant has alleles, or a version of a gene, that produce the resistant phenotype. For example, humans all have the genes for blood type. It’s the particular alleles of these genes that differentiate the actual blood type.
Southern leaf blight is no longer a considerable problem in the U.S., but it still plagues farmers in hot, humid climates, according to Balint-Kurti. Southeast Asia, parts of Africa and Latin America still suffer from crop losses caused by the fungus that destroys the leaves’ ability to photosynthesize.
“More than 95 percent of corn in this country is field corn,” Balint-Kurti said. “Field corn, used for feed, is not affected because blight isn’t prevalent in the Midwestern Corn Belt. But, Southern leaf blight is a problem for seed production and a moderate problem in this part of the country.”
The researchers started their work at research farms around the state, dealing with infected plant populations. At certain points in the experiment, Holland and Balint-Kurti infected fields with the disease.
“We inoculated the fields with sorghum grains that were already infected,” Kristen Kump, a research assistant, said. Kump researched under Holland and Balint-Kurti while studying for her master’s degree in crop science. “We irrigated the fields so it was moist enough for the fungus to grow.”
Balint-Kurti, a specialist in maize disease, recognized 50 different parts of corn’s genetic sequence that contribute to Southern-leaf-blight resistance.
“It appears that a bunch of genes are involved in disease resistance, and now we need to understand better how these genes work to increase resistance,” Balint-Kurti said. “Once we have identified a gene in the genome, we can move it into different varieties with conventional breeding. You don’t need biotechnology to achieve that. You can just do it by breeding.”
This is good news for the agricultural community. Mankind has been breeding and crossing plants since prehistoric times. Once the research reveals which precise genes will affect the disease resistance, breeding can translate these findings into real benefits.
“We’re not in the business [of] making commercial hybrid seed,” Holland said. “But seed companies can use this study to make the best crosses and [can] relatively easily now breed resistance into their material.”
Genetically modified and disease resistant seeds already exist, ranging from potatoes to soybeans.
“The genome sequence of corn was completed in 2009, so it’s a great resource to work with,” Holland said. “Now we are focusing on the variation among sequences of different corn varieties.”
Despite the economic gains associated with resistant seed, the researchers have no intentions patenting their discoveries.
“We do the research and make it public,” Balint-Kurti said. “Other researchers or companies can use these results.”
Although blight is not a significant problem in the continental U.S., resistant crops would benefit North Carolina greatly, due to demand from hog and chicken farms.
“With all the pigs and chickens N.C. raises, it makes sense to just produce corn locally, from a cost perspective,” Holland said.
More resistant crops also require fewer pesticides, which not only benefits the environment, but also saves farmers money.
Although corn may appear to be a basic, overlooked part of life, its uniform and substantial production keeps the U.S. agriculturally and economically stable; therefore the University has invested tremendous resources to keep the national agriculture and the University’s leading role in crop sciences secure.
