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By Jerome Bossuet
A team of agricultural researchers from Asia, Australia, Europe and North America, led by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), has decoded the genome of the chickpea, a nutritious grain legume for many of the world’s poor.
This research breakthrough, announced in the journal Nature Biotechnology this week, will help chickpea farmers become more resilient to emerging climate challenges such as rising temperatures, a drier climate and new pests. The chickpea genome map will enable crop breeders to accelerate screening for urgently needed traits such as drought and heat tolerance, early maturity and insect resistance.
“Making the chickpea genome available to the global research community is an important milestone in bringing chickpea improvement into the 21st century to address nutritional security of the poor,” says David Bergvinson, senior programme manager for science and technology at the Bill & Melinda Gates Foundation, which has provided funding for this work and other legume research. “We look forward to seeing how researchers around the globe will harness this resource to increase chickpea productivity against the backdrop of climate change in the developing world.”
Domesticated in the Mediterranean region over 7,000 years ago, chickpea is a major grain legume crop, grown globally on 11.5 million hectares. India is the largest producer, accounting for 70 percent of global supply, as well as the biggest consumer.
A highly nutritious staple crop, chickpea is rich in protein (containing two or three times more than cereals), energy, vitamins and minerals. It is the richest source of fibre, a vital part of a healthy diet as it facilitates digestion.
Chickpea is an essential ingredient in Mediterranean and South Indian cuisine, and is cooked in many ways, including channa dal (a spicy soup), curries, flour and dough-based fritters.
It is a crucial source of nutrition for poor families. In India, roasted chickpea flour, called sattu, is the main meal for hard-working manual labourers such as the doliwala tribal porters in the Jharkhand mountainous region because it is energising and affordable.
The U.N. World Food Programme is currently exploring chickpea paste as a ready-to-use food to address malnutrition. It has been provided after floods in India’s Bihar state and as a product called Wawa mum in Pakistan.
Chickpea also promotes environmentally sustainable agriculture. Being a legume, its ability to fix atmospheric nitrogen helps improve soil fertility, and it is often intercropped to increase the yields of other crops.
Because of its deep tap root system, chickpea can withstand drought conditions by extracting water from deeper layers in the soil. As a result, it is often grown as a second crop using residual moisture.
Yet, despite these valuable qualities, chickpea is far from achieving its potential. The average yield is around 800kg/hectare compared with around 2 tonnes/hectare in optimum conditions.
“Chickpea occupies a pride of place in the struggle against protein hunger. In spite of its importance to human nutrition and farmers’ livelihoods, scientific attention to this crop using frontier technologies has been rather limited,” says M.S. Swaminathan, the father of India’s green revolution.
Now the hope is that the chickpea genome breakthrough will help develop this crop, giving yields a much-needed boost – even more important due to the predicted expansion of water-scarce regions and declining soil fertility.
With the draft genome sequence, scientists identified an estimated 28,269 genes that make up the chickpea plant. And by analysing the genome, scientists have identified candidate genes for disease resistance, drought and heat tolerance and early maturity (plants that grow more quickly can be harvested earlier before dry spells). This will help develop superior and more resilient varieties that are essential to adapt to warmer and drier climates.
Previously, chickpea breeders had about 2,000 genetic markers to screen critical traits. Today, the extensive chickpea genome sequencing - publicly accessible with no intellectual property restrictions - has revealed around several million markers, which will speed up work.
“Having open access to the complete genomes of key staple crops such as chickpea is rapidly changing the work of our plant breeders,” says Frank Rijsberman, CEO of the CGIAR Consortium, an international network of agricultural research centres, including ICRISAT. “It is becoming critically important to the work of CGIAR to develop improved crop varieties.”
For example, researchers may discover what makes certain chickpea varieties survive during dry periods when others fail. Or how to make chickpea more resistant to particularly damaging pests and diseases such as the pod borer insect which causes annual yield losses of 20 to 30 percent in India.
“Having the new chickpea sequence as a reference will significantly speed up and reduce the costs of screening for the ‘good genes’ in the collections of chickpea varieties and wild relatives. Research will be more proactive to respond to future agriculture challenges such as increasing temperature and emerging pests,” says Varshney.
The genome sequence data could possibly halve the time to breed a new variety, which now takes four to eight years, he adds.
William Dar, ICRISAT’s director general, believes the research breakthrough will bring multiple benefits. “In the face of growing global food insecurity and scarcer natural resources, we must reinforce the double role of pulses and chickpea in particular: nutrition and soil fertility,” he explains.
“Investing in modern crop improvement technologies for smallholder farmer crops such as chickpea will help make this staple crop more productive and resilient, for the benefit of many poor farmers and consumers in developing countries,” he adds.
Jerome Bossuet is a communications specialist for ICRISAT.