AMES, Iowa – A team of USDA and Iowa State University researchers has helped to sequence the genomes of the two closest relatives of the cultivated peanut, an advancement that could lead to the development of varieties more resistant to pests and environmental stress.
Steven Cannon, an ISU collaborator assistant professor of agronomy and a researcher for the U.S. Department of Agriculture’s Agricultural Research Service, worked with the International Peanut Genome Initiative, a group of crop geneticists, to complete the genome sequences of two close relatives of the cultivated peanut. Both those sequences have been made available to researchers and plant breeders across the globe to aid in the breeding of more productive, more resilient peanut varieties.
The ARS/Iowa State team – which also included Ethalinda Cannon, a researcher in the ISU Molecular, Cellular and Developmental Biology Program, and Sudhansu Dash, an assistant scientist in the ISU Virtual Reality Applications Center – assembled the primary genome sequence pieces into strings of DNA that represent the full chromosomes of two peanut ancestors that gave rise to the modern peanut.
The peanut variety grown in fields today is the result of a rare, natural merger of the genomes of two wild species that grew in northern Argentina between 5,000 and 10,000 years ago. The result is a genome with twice as many chromosomes as either of the progenitor species, Cannon said. The International Peanut Genome Initiative project sequenced the somewhat simpler genomes of the progenitor species in order to map the modern peanut’s genome structure, he said.
Cannon said the genome assembly project was more complex than others he’s worked on. The ISU and ARS team worked intensely for about four months to stitch together information from eight genetic maps and many clues from sequence comparisons between the two progenitor species, he said.
“Although the genomes of these wild peanut species are each about the same size as soybean – each with a little more than a billion DNA bases – the peanut genomes had about four times as many pieces to assemble into chromosomes,” he said. “It’s kind of like putting together a couple of 1,500-piece jigsaw puzzles.”
In addition to helping assemble the genome sequence, Cannon said the ISU/ARS team built a web site (http://peanutbase.org) to provide access to the genetic data and the genome sequences to researchers and plant breeders worldwide.
“The sequences provide researchers access to 96 percent of all peanut genes in their genomic context, opening the door to breeding drought-resistant, disease-resistant and higher-yielding varieties that will require less fertilizer and pesticide,” Cannon said.
Sequencing of the peanut genome represents the latest chapter in Iowa State University’s rich connection to the development of the peanut as an agricultural staple. George Washington Carver, who attended Iowa State, developed hundreds of uses for the peanut. Andrew Manu, the George Washington Carver Chair in Agronomy at Iowa State, said the gene-sequencing project fits well with Carver’s legacy.
“Iowa State University continues to keep the memory and legacy of Carver alive through teaching, research, and extension,” Manu said. “In celebration of his 150th anniversary, scientists from the USDA Agricultural Research Service affiliated with ISU have announced the successful sequencing of the genomes of the ancestors of cultivated peanut, a plant Carver worked on. This work is setting the stage for a characterization and comprehension of the traits that complement Carver’s work in terms of adaptation to environmental factors and the quality and quantity of products that Carver developed. This is a great leap in the science of peanuts and also in the memory and legacy of George Washington Carver.”
The International Peanut Genome Initiative brings together scientists from the United States, China, Brazil, India and Israel to delineate peanut genome sequences, characterize the genetic and phenotypic variation in cultivated and wild peanuts and develop genomic tools for peanut breeding. Project funding was provided by the peanut industry through The Peanut Foundation, the Chinese government, and USDA-ARS, and Mars Inc.