Science and Nature

How to develop a drought-resistant chickpea? Look at its genome map

How to develop a drought-resistant chickpea? Look at its genome map thumbnail

Next time you eat channa masala, thank your ancestors who first domesticated the legume 10,000 years ago. The history of chickpea domestication starts in the Fertile Crescent, a crescent-shaped region in the Middle East, known for the Mesopotamian civilisation. Now, by sequencing the genomes of 3,366 chickpea lines from 60 countries, an international team has created a chickpea genetic variation map which will help create better drought- and heat-tolerant and disease resistant crops for the future.

The team identified 29,870 genes that include 1,582 previously unreported novel genes. “We started the study in 2014 and tracked how the legume has changed during domestication, migration and improvement techniques done by plant scientists,” explains lead author Professor Rajeev K. Varshney. He is the Research Program Director at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India and one of the corresponding authors of the paper published last week in Nature.

The team has identified 56 promising lines that can be used to develop enhanced varieties. They also propose three crop breeding strategies to enhance the crop productivity for 16 agronomic traits e.g. yield, seeds weight, flowering time, plant height, etc. while avoiding the erosion of genetic diversity.

How chickpeas were domesticated and migrated

About 10,000 years ago, chickpeas, wheat and barley were domesticated in the Fertile Crescent and around the same time corn was grown in South America and rice in Asia. The first humans chose to grow the varieties that had softer seed coats and were easier to chew and eat. They also looked for bigger seed sizes and those with higher yields. In the early 19th century with a boom in plant breeding, we now have chickpeas that have better seed colour, seed size, and soft coats. “But over the years, the seeds might have lost the genes conferring resistance to diseases and those that helped it survive the heat and drought. We have also lost genetic diversity and majority of varieties developed from only a few lines today,” adds Prof. Varshney.

Study lead Rajeev Varshney in a chickpea field. (ICRISAT)

Though India is today the largest producer and consumer of chickpeas, the legume had to travel a great deal to reach our country. “I guess there might have been two paths -one via North Africa and South Asia, and the other via the Mediterranean region, Black Sea, Central Asia including Afghanistan. The name Kabuli channa is probably derived from Kabul, the capital of Afghanistan,” he adds.

Why study chickpeas?

Chickpeas are grown in more than 50 countries and is the world’s third-most cultivated legume. It is an important source of dietary protein for those who don’t consume meat. The researchers note that with the growing global population, there will be less supply and more demands to be met. Producing nutrient rich, climate resistant chickpea varieties could come to the rescue.

“Genomic resources are crucial for accelerating the rate of genetic gains in crop improvement programs. It is hoped that the knowledge and resources made available through this study will help breeders across the world revolutionise chickpea breeding without eroding its genetic diversity,” said Dr Arvind Kumar, Deputy Director General-Research, ICRISAT in a release.

Asked about the future studies needed, Prof Varshney said: “We would like to understand genome architecture and genome diversity of the entire chickpea germplasm collection. It will be great to understand the entire set of genes and haplotypes in the entire germplasm collection…At the same time, it is imperative to start utilisation of genome information from this study for developing climate resilient, high-yielding and nutrition rich varieties.”

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