Solving intellectual puzzles is a rewarding activity for Bruce McClure, MU Professor of Biochemistry, as he seeks to unravel the mystery of plant mating. If McClure and his team of researchers can crack the code and understand how breeding barriers work within plants, they will be one step closer to their goal of “making the world better through agriculture.”
Doing maize genetics, according to one geneticist, is “really cool.” It is exactly this kind of enthusiasm that fuels Karen Cone, Professor of Biological Sciences at MU, who specializes in plant genetics. Asked to summarize what researchers in her field actually do, Cone laughs and responds, “Geneticists make mutants…a geneticist learns about the way something works in real life by screwing it up, trying to figure out what’s wrong with the mutant, and then inferring what is normal when the mutant isn’t there.” The mutants that Cone makes involve corn and purple pigmentation.
McClure always wanted to help the world through science, but plant genetics wasn’t part of his original grand plan. After college and a environmental biochemistry major, he took a position with a diet geneticist seeking to modify the nutritional value of maize. This job exposed McClure to genetic analysis and helped him realize that he could have an impact on the world through agriculture.
Cone’s current research seeks to understand the function of a group of genes called chromatin: “Chromatin is the complex of DNA and protein, which allows us as humans–or plants like corn–to pack a lot of DNA into the tiny nucleus of a cell.” The DNA duplex for both corn plants and humans is huge. As she explains, “we have about the same size genome, about three billion base pairs, but ours is really long. We pack about six feet of DNA in every cell,” each of which is only five microns across. That’s a heck of a lot of DNA!” How does all that DNA fit in there? “We’re smart,” suggests Cone, adding that “corn and humans do it the same way,” as does every organism with a nucleus. Therefore, her research on DNA packaging is applicable to every organism, because “from yeast, to mice, to humans, to plants—we all wrap up our DNA basically the same way.” It amounts to a sort of microscopic compressor system, which Cone describes as “amazing.” If researchers can better understand how this chromatin packaging occurs, they might eventually be able to control the process to their advantage.
One of Cone’s earlier research projects on corn genetics is the Maize Mapping Project. Funded by the National Science Foundation as part of the Plant Genome Research Program, the project involved a collaboration of investigators at MU, the University of Arizona, and the University of Georgia. Of the four-year project that was completed in 2002, Cone recounts: “Our goal was to make a map of the maize genome.” Using molecular methods and a genetic population tailored specifically for the project, Cone’s research team set about placing DNA “landmarks” onto the chromosomes. “When we finally finished the map,” she says, “there were over 10,000 landmarks on it!”
According to Karen Cone, Professor of Biological Sciences, one can learn a lot about any kind of genetic organism by doing genetics in a model: “Maize is considered to be a model genetic organism because what we learn in this organism is translatable to others.” Because it is a plant, she explains, there is the added advantage of seeds that can go dormant, stored for years until one wants to run additional crosses with them. Maize has other positive attributes as well; for example, it has separate male and female parts, and every kernel is a baby. With just one cross producing 300 to 800 progeny on each ear, Cone finds maize to be an ideal organism for genetic research.