The genome of millet sequenced

Le pilon et le mortier s'utilisent pour égrener les céréales et les moudre. Village aux alentours de Réo, Burkina Faso. © IRD / Daina Rechner

A study coordinated by an international consortium of French (IRD), Indian and Chinese researchers has enabled the genome sequence for millet to be obtained for the first time. This discovery improves our understanding of the organisation and evolution of the genome of this cereal, which provides food security of the poorest people in the world. Secondly, because it provides new prospects for selecting or improving varieties of millet which may be better equipped to cope with climate change for almost 100 millions people. These results are published in the journal Nature Biotechnology on September 18th 2017.

A little-studied "orphan" species
Millet (Pennisetum glaucum), also known as "pearl millet", is a cereal that belongs to the family of small-seeded grasses, grown in the most arid areas of the planet in Africa, within the Sahel region and in Asia, especially in India. Suited to the dry conditions and relatively infertile soil, millet offers food security to almost 100 million people, thanks to the high nutritional quality of its seeds (which contain between 8% and 19% protein). It is also used to feed cattle and sheep.

As climatic models predict rising temperatures and an increase in the number of extreme climatic events, millet may play a key role in providing food security for the growing population of countries in the Sahel region. Unlike rice, corn and wheat, for which there have been many sequencing studies, the international scientific community has until now shown relatively little interest in decoding and analysing the millet genome.

The genome of millet decoded
Coordinated by Institut de Recherche pour le Développement (IRD), the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India and Beijing Genomics Institute (BGI) in China, the study published in Nature Biotechnology involved 63 researchers in ten countries[1].

They identified a standard genome sequence for millet, containing more than 38,000 genes. They then sequenced the genome for close to 1,000 varieties of cultivated millet and their wild ancestors, in order to analyse their structure, genetic diversity and the evolution of the genome for this cereal. This research enabled the team to trace the origin of millet domestication, found to have taken place almost 4,500 years ago at the border between Mali and Niger.

It highlighted genes that slow down the loss of water from the leaves (thus conserving hydration), as well as other genes related to withstanding dry conditions.

A cereal of the future?
Genome sequencing opens up new perspectives for millet, a staple cereal for farming in Africa and beyond. This is because this newly-acquired knowledge about the millet genome is going to enable the development of new varieties (cross-breeding, selection of genes of interest), which are better suited to rising temperatures and more resistant to pests.

This pioneering study provides a large quantity of information on the genes of this "neglected" cereal. By decoding its genome, millet could see its production increase in the coming decades. This would supplement the production of other cereals perhaps less well equipped to cope with climate change, thus contributing to the food security of a worldwide population expected to exceed nine billion people by 2050.

[1] France, India, China, United States, United Kingdom, Senegal, Niger, Germany, Austria and Italy.

Full bibliographic information
Rajeev K. Varshney et al. Pearl millet genome sequence provides a resource to improve agronomic traits in arid environments, Nature Biotechnology, 18 septembre 2017, doi:10.1038/nbt.3943

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