Rising temperatures and frequency of extreme climate events like heat waves in many parts of the world will lead to a drop in major staple crop production. Now, the decoding and sequencing of the pearl millet (bajra in Hindi) genome by a global team of 65 scientists from 30 research institutions has revealed critical coping strategies.
The analysis of the genetic variability among a thousand pearl millet lines has led to a better understanding of the ability of this dryland cereal to survive soaring temperatures (over 42oC) and its exceptional drought tolerance. This discovery may also help develop climate adaptation strategies in other important cereal crops.
The research co-led by the International Crops Research Institute for Semi-Arid Tropics (ICRISAT), India, BGI-Shenzhen, China and the French National Research Institute for Sustainable Development (IRD), used the latest innovations in DNA sequencing and analysis to identify new genetic tools like molecular markers related to drought and heat tolerance, as well as other important traits (better nutrition profile, pest resistance). This will catalyse breeding efforts to improve this crucial staple food for millions of people in arid and semi-arid Africa and Asia in particular.
Pearl millet is rich in nutrients yet delivers low yields
Pearl millet [Cenchrus americanus (L.) Morrone] is a nutritious drylands cereal, rich in protein, fibre and essential micronutrients like iron, zinc and folate. Nutrition studies have shown that this cereal has the potential to fight iron deficiency, the most widespread micronutrient deficiency and major cause of anaemia, affecting the health and development of a third of the world’s population. Pearl millet is grown on about 27 million hectares worldwide and is a daily food for more than 90 million people, among the most vulnerable in arid and semi-arid Africa and Asia. It is also an important source of fodder for millions of farms. However, pearl millet yields have remained low over the last six decades, as this cereal is mainly grown in poor soil conditions without irrigation, with minimal or no fertiliser and other agricultural inputs.
Investment in genetic research for this smallholder crop has been inadequate and breeders have had limited genetic information to develop high yielding superior varieties and hybrids that respond to farmers’ constraints. This pearl millet genome research has led to a better understanding of its genetic variability, and researchers have identified candidate genes of very important traits, such as heat tolerance, or resistance to downy mildew, a very damaging millet disease.
For instance, pearl millet has an extraordinary capacity to resist baking heat. Professor Rajeev Varshney, ICRISAT, who coordinated the Pearl Millet Genome Sequencing Consortium, said “Most cereals like rice or maize cannot support temperatures over 30 to maximum 35 degrees Celsius when they start forming their grain, whereas pearl millet will fill its grain in air temperatures of up to 42 degrees.” He added, “We have found that compared to other cereals like wheat, rice or maize, pearl millet has a more diverse repertoire of genes for natural wax proteins, which act as thermal protection for the plant.”
Such heat resistance is crucial as climate experts forecast further heat waves in years to come. Dr. David Bergvinson, Director General of ICRISAT, explained why this genome discovery is key in our changing climate. “This research will lead to delivery of high yields of pearl millet in farmer fields in the marginal environments in Africa and Asia. Identifying better genes for heat tolerance in pearl millet can also help other crops like wheat, rice and maize become more climate change ready, showing the importance of investing in so called ‘orphan’ or neglected crops.”
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