Posted on March, 16, 2022 at 09:25 am
Researchers have prepared an extensive genome map of the protein-rich chickpea, by sequencing its genetic material, which helped confirm its origin and migration and discover new genes to aid crop improvement.
This makes chickpea (Cicer arietinum), an important source of protein, carbohydrates and minerals, among the small group of crops with such an extensive genome map. It is extensively cultivated in more than 50 countries, mostly in South Asia and sub-Saharan Africa, and is important for nutritional security.
There is a need for improved crop varieties with higher yields, improved nutrition, and disease- and pest-resistance to meet the increasing food and nutrition security demands, particularly in South Asia and sub-Saharan Africa. The crop also enriches soil fertility by adding significant amounts of nitrogen.
An international team of 57 researchers from 41 organisations across 11 countries assembled the pan-chickpea genome, by sequencing the genomes of 3,366 chickpea lines taken from 60 countries. The effort, described as “the largest effort of its kind for any plant” was led by the International Crops Research Institute for the Semi Arid Tropics (ICRISAT) in Hyderabad. The scientists identified 1,582 novel chickpea genes that were previously unreported, their report in Nature says.
“This is entirely new, and this is the largest plant genome sequencing project not only in chickpea but also for any plant species,” Rajeev Kumar Varshney, Director, State Agricultural Biotechnology Centre, Murdoch University, Australia. Varshney, who is one of the authors of the study, was at ICRISAT previously.
“This study highlights genetic bottlenecks, identifies genetic load, and also present haplotypes and genomic breeding stories,” Varshney said. “This was never studied before.”
The research is important also from evolutionary biology perspective as it helps understand the centre of origin and migration of chickpea, he added.
The scientists used whole-genome sequencing to confirm the history of chickpea’s origin in the Fertile Crescent — a crescent-shaped region in the Middle East spanning modern-day Iraq, Syria, Lebanon, Palestine, Israel, Jordan, northern Egypt and western Iran. The area is considered the birthplace of agriculture as its geography and climate supported crop growth which, in turn, led to a shift in lifestyle from hunter-gatherer communities to agricultural communities.
The genome sequencing helped the scientists identify two paths of diffusion or migration of chickpea to the rest of the world. One path indicates diffusion to South Asia and East Africa, and the other suggests diffusion to the Mediterranean region, probably through Turkey, as well as to the Black Sea and Central Asia, up to Afghanistan, the report says.
The analysis found chromosomal segments and genes that show signatures of selection during domestication, migration and improvement.
“The research provides a complete picture of genetic variation within chickpea and a validated roadmap for using the knowledge and genomic resources to improve the crop,” the report in Nature adds.
The scientists also located the regions in the chromosomes, which contain the genetic material, which contain harmful mutations responsible for limited genetic diversity and decreased fitness; as well as genes for crop improvement-related traits. The information can help in the transfer of beneficial genes from one species to another, as well as help purge the deleterious genes either through genomics-assisted breeding or gene editing, the report says.
The scientists have proposed three crop breeding strategies based to enhance crop productivity for 16 traits, and at the same time avoid loss of genetic diversity.
Source: Mongabay