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April 2001
Ag genomics may bring benefits faster
than human genomics
WEST LAFAYETTE, Ind. – This February scientists made headlines when they published the sequence of the human genome – the so-called "code of life."
But although the Human Genome Project grabs headlines, perhaps the bigger story in biology will be in plant and animal genomics: the first benefits to society are likely to come from these areas, where it is generally easier and less controversial to utilize genetic information, according to Randy Woodson, director of Purdue University's Office of Agricultural Research Programs.
"Agricultural genomics is well behind human genomics," he says "But we can adapt the tools used in the Human Genome Project to find solutions for problems in food much faster than drugs for human problems can be brought to the market."
Genomics uses automated laboratory equipment and high-power computers to identify all of the genes in an organism. These genetic road maps can be used to create genetically modified organisms, such as Bt corn. Genetic information also can provide an advantage to traditional crop and animals breeders that was unthinkable 10 years ago.
"Genomics is much, much more than biotechnology," Woodson says. "Understanding the genome of a crop or animal doesn't always mean we'll modify the organism's genes. Once we know what every gene in an organism does, following a trait through a traditional breeding program becomes much, much easier. If you're wanting to increase disease resistance in plants or animals, for example, you don't have to grow the plants or animals to maturity and subject them to years of testing to see if the trait is there. You can look at their DNA and know whether it's there or not."
Here are examples of plant and animal genomics projects under way at Purdue University:
Plant genome information may double the efficiency of crops within a decade
Environmental stresses such as frost, heat and drought cause massive crop-yield losses each year – more, in fact, than losses from insects and weeds.
Ray Bressan, professor of horticulture and director of Purdue's Center for Plant Environmental Stress Physiology, and Mike Hasegawa, a Purdue horticulture professor, are using plant genomics to combat stress losses.
A small weed that is a cousin to the mustard plant, Arabidopsis– which is to plant scientists what the lab mouse is to medical researchers – is leading Bressan, Hasegawa and other scientists around the world to a better understanding of how plants withstand these stresses. Scientists use Arabidopsis to learn the function of plant genes. This is done by creating a plant that lacks a single gene, and growing the plant to maturity to determine the missing gene's function.
Purdue researchers have created more than 300,000 genetically altered plants, and scientists at other institutions have created hundreds of thousands of additional genetically altered plants. "For all practical purposes, the genome is saturated; there has been a mutation for every gene," Bressan says.
Because plant genes are identical, or very similar, in nearly all species, information from these experiments will be rapidly applied to commercial crops. Bressan says the accumulating knowledge about plant biology will cause almost unfathomable changes in agriculture; he says scientists have learned as much in the past three years as in the previous 100 about how crops and other plants withstand environmental stresses.
"We'll soon be able to produce more crops with less pesticides, less fuel, less fertilizer, fewer trips over the field." he says. "We'll produce much more with much less.
"A couple of years ago I wouldn't have predicted this. But I now think that within a decade it will be possible to have crops that can withstand the stresses of early spring and late fall to such an extent that farmers could plant two crops of corn, soybeans or wheat each year."
CONTACT: Ray Bressan, (765) 494-1336; bressan@hort.purdue.edu.
Genome techniques help save endangered and reintroduced wildlife
Small populations of reintroduced or endangered animals can die out because of problems brought on by inbreeding. Gene Rhodes, a Purdue wildlife biologist, is improving the odds for these animals through research into the genomes of wildlife.
"Genetic variation is the currency of evolution," Rhodes says. "By having a variety of genes in the population, the animals have the ability to adapt to their environment."
If a small population of wild animals is faced with a crisis, such as a harsh winter or a new disease, they may all succumb if they are too genetically similar. But if there is sufficient genetic variability, some of the animals will survive because they are better equipped to deal with the crisis.
In some species, only a small fraction of the original genetic variation remains. "We've seen this with the cheetah, with the northern elephant seal and with hundreds of other species," Rhodes says.
Rhodes identifies specific gene markers on the genomes of animals he is studying and then looks to see if markers also are found in the genomes of other individual animals. Local wildlife biologists then know whether they need to introduce new animals to improve the genetic variability.
"Wildlife biology has never been one of the big biology thrusts," Rhodes says. "But the genome mapping projects in humans and other species are spinning off technologies that we can use in wildlife management."
CONTACT: Gene Rhodes, (765) 494-3601; gener@fnr.purdue.edu.
Improving the pollination of crops
Natalia Dudareva, assistant professor of reproductive biology in Purdue's Department of Horticulture, has found new insights into the genetics of floral scents – insights that might result in sweeter smelling roses, plus a bouquet of other benefits.
Improving floral scent is a goal of the $20 billion per year floriculture industry, but it also is important to agriculture. Almost three-fourths of all crops depend on insect pollinators attracted by floral scents. Honeybees alone are responsible for pollinating one-third of U.S. crops.
Many fruits must be pollinated multiple times to produce fruit, and the number of pollinations helps determine the fruit's size and quality. "For watermelon it takes about 12 times to have quality fruit, and it takes 25 pollinations for strawberries to maximize berry size," Dudareva says.
Improving the floral scents of fruit trees and plants would be a benefit for fruit farmers, Dudareva says.
"Plants didn't evolve to produce their scents for the benefit of humans," Dudareva says, "but floral scents sometimes influenced the decisions humans made about which plants to cultivate."
CONTACT: Natalia Dudareva, (765) 494-1325; dudareva@hort.purdue.edu.
Stopping killer bee genes from entering North American hives
Highly aggressive stinging behavior in Africanized honeybees – the so-called "killer bees" – is disruptive to agriculture and can be dangerous to humans.
These Africanized bees are established in most of South America, Mexico and in the southern region of the United States. Understanding their aggressive behavior is important for much of U.S. agriculture – and not just for honey producers – because one-third of the food produced in the United States comes from plants pollinated by honeybees. Already many beekeepers in Mexico have stopped keeping beehives because of the eager stingers. There is a need for information to enable bee breeders to identify Africanized bees and prevent the spread of the stinging trait into commercial bee populations in the United States.
Purdue entomologist Greg Hunt, in collaboration with Ernesto Guzman-Novoa of Mexico's agricultural research service, used gene mapping techniques more commonly used in plant genetics to locate the genes that influence behavior in Africanized bees.
"We have developed specific gene markers that predict the probability of queen bees having the African version of stinging genes so it will be easier for breeders to avoid using them," Hunt says. "Now that we have the markers we can selectively breed for gentle bees."
The DNA markers are available to other scientists to determine if honeybee populations in their regions have genes for aggressive behavior. This research also could lead to the isolation of genes that influence bee behavior and suggest ways to decrease stinging incidents.
CONTACT: Greg Hunt, (765) 494-4605; ghunt@entm.purdue.edu.
Writer: Steve Tally, (765) 494-9809; tally@aes.purdue.edu
Purdue News Service: (765) 494-2096; purduenews@purdue.edu
Related Web sites:
Genomics backgrounder
Purdue genomics program
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