Genome code of cultivated groundnut cracked

ng.3517-F2In a scientific breakthrough that promises accelerated gene discovery and development of improved cultivars, researchers have completed high quality sequencing of the ancestral genomes of groundnut. This will lead to better groundnut varieties with enhanced pod and oil yield, greater resistance to diseases, tolerance to drought and heat, and better oil quality.

The groundnut grown today is the result of hybridization between two wild species, Arachis duranensis (V14167, A-genome ancestor) andA. ipaensis (K30076, B-genome ancestor). The hybrid was cultivated by ancient inhabitants of South America. Since the ancestors were two different species, today’s groundnut is a tetraploid, ie, it carries two separate genomes which are designated A and B sub-genomes.

Comparison of the DNA sequences of one of the wild species with the cultivated groundnut showed that they are 99.96% identical.

“It’s almost as if we had travelled back in time and sampled the same plant that gave rise to cultivated peanuts from the gardens of these ancient people,” said David Bertioli, International Peanut Genome Initiative (IPGI) plant geneticist of the Universidade de Brasília, who is the lead author of the paper and Visiting Professor, University of Georgia, USA.

The breakthrough was made by researchers of IPGI, led by the University of Georgia and published online in Nature Genetics on 22 February.

ICRISAT is a member of the IPGI and was involved in project planning, defining the strategy and also contributed to data analysis for the discovery. The IPGI, is a multi-national group of crop geneticists with 39 scientists from 26 organizations in six countries engaged in the groundnut genome sequencing project.

To map the groundnut’s genome structure, researchers sequenced the two ancestral parents, because together they represent the cultivated groundnut. The sequences provide researchers access to 96% of all groundnut genes in their genomic context. The genome sequence assemblies and additional information are available at http://peanutbase.org/browse_search .

The new groundnut genome sequence will be available to researchers and plant breeders across the globe to aid in the breeding of groundnut varieties with desired traits. It is also useful for crop improvement to enable sustainable and resilient groundnut production that will improve the livelihoods of smallholder farmers. The genome map can also be used to harness genetic diversity by broadening the genetic base of cultivated groundnut genepool.

The wild groundnut species. Arachis ipaensis (left) and Arachis duranensis (right) that provide the genetic blueprint for today’s modern varieties. Photo: Merritt Melancon/University of Georgia

The wild groundnut species. Arachis ipaensis (left) and Arachis duranensis (right) that provide the genetic blueprint for today’s modern varieties. Photo: Merritt Melancon/University of Georgia

“Rich in protein and edible oil, groundnut is central to the financial and nutritional well-being of millions of farmers and consumers across the semi-arid tropics of Asia and sub-Saharan Africa,” said Dr David Bergvinson, Director General, ICRISAT.

Groundnut (Arachis hypogaea) is an important crop both commercially as well as nutritionally. Globally, farmers cultivate about 25.7 million ha of groundnut each year, producing about 42 million tons. While the oil and protein rich legume is seen as a cash crop in the developed world, it remains an important subsistence crop in developing nations.

“Improving groundnut varieties to be more drought, insect and disease resistant using the genome sequence, can help farmers in developing nations produce more groundnuts with fewer pesticides and other chemicals and help these farmers feed their families and build more secure livelihoods,” said Dr Rajeev Varshney, Research Program Director – Grain Legumes and Director, Center of Excellence in Genomics, ICRISAT.

ICRISAT led a global research partnership for decoding the genome sequence of pigeonpea in 2011, chickpea in 2013 and is currently leading the genome sequencing of pearl millet.

For more on groundnut see ExploreIT – groundnut:  http://exploreit.icrisat.org/profile/Groundnut/250

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