Geneticists Map Genome Of An Important Global Crop: The Peanut
April 3, 2014

Geneticists Map Genome Of An Important Global Crop: The Peanut

April Flowers for - Your Universe Online

Peanuts are seemingly everywhere in the US. From cooking oils to candy bars, peanuts are a part of our lives, and a big business. And now, for the first time, a multinational group of crop geneticists has sequenced the peanut genome.

The researchers are from the International Peanut Genome Initiative (IPGI), led by Scott Jackson, who serves as chair of the IPGI. Jackson is also the director of the University of Georgia Center for Applied Genetic Technologies in the College of Agricultural and Environmental Sciences.

The peanut (Arachis hypogaea), also called the groundnut, is an important global crop. In the developed world, it is viewed as a cash crop, while in developing countries it is a valuable sustenance crop. Approximately 24 million hectares of peanuts are farmed each year around the world, producing around 40 million metric tons of the oil-and protein-rich legume.

"The peanut crop is important in the United States, but it's very important for developing nations as well," Jackson said. "In many areas, it is a primary calorie source for families and a cash crop for farmers."

The IPGI team plans to make the genome sequence available to other researchers and plant breeders to help in developing more productive and more resilient plant varieties.

"Improving peanut varieties to be more drought-, insect- and disease-resistant can help farmers in developed nations produce more peanuts with fewer pesticides and other chemicals and help farmers in developing nations feed their families and build more secure livelihoods," said plant geneticist Rajeev Varshney of the International Crops Research Institute for Semi-Arid Tropics in India, who serves on the IPGI.

The researchers have been working to sequence the peanut genome for several years. The peanut has been bred for intensive cultivation for thousands of years, but genetically it was relatively unknown. According to Peggy Ozias-Akins, a plant geneticist on the UGA Tifton campus who also works with the IPGI and is director of the UGA Institute of Plant Breeding, Genetics and Genomics, this is because the peanut's genetic structure is very complex.

"Until now, we've bred peanuts relatively blindly, as compared to other crops," said IPGI plant geneticist David Bertioli of the Universidade de Brasília. "We've had less information to work with than we do with many crops, which have been more thoroughly researched and understood."

The reason for the complexity is that the current crop of peanuts is the result of a natural cross between two completely separate wild species—Arachis duranensis and Arachis ipaensis. This cross happened in northern Argentina between 4,000 and 6,000 years ago. Today's peanut is a polyploid, which means that the species can carry two separate genomes. The scientists designate these as A and B subgenomes.

In order to map the structure of the contemporary peanut, the research team sequenced the genomes of the two ancestral species—providing them with access to 96 percent of all peanut genes in their genomic context. The sequences have also provided a molecular map required to breed drought- and disease-resistant, lower-input and higher yielding varieties of peanuts.

Samples of the two wild species had been collected and conserved in germplasm banks. These samples allowed the IPGI researchers to have a better understanding of the peanut genomic structure - A. duranenis serves as a model for the A subgenome of the cultivated peanut while A. ipaensis represents the B subgenome.

Being able to differentiate between the two structures will allow future researchers in gene marker development—the determination of links between a gene's presence and a physical characteristic of the plant. The sequences will also allow scientists to trace the history of domestication for the peanut, which has been marked by increases in seed number and size. Other researchers are able to access the genome sequence assemblies and other information here.

"While the sequencing of the peanut can be seen as a great leap forward in plant genetics and genomics, it also has the potential to be a large step forward for stabilizing agriculture in developing countries," said Dave Hoisington, program director for the U.S. Agency for International Development Feed the Future Peanut and Mycotoxin Innovation Lab, which is hosted at UGA.

"With the release of the peanut genome sequence, researchers will now have much better tools available to accelerate the development of new peanut varieties with improved yields and better nutrition," he said.