Pigeon pea genome sequence could boost yields

More than a billion people could soon benefit from improved yields of the important drought-resistant crop pigeon pea now that its genome has been sequenced by a global partnership.

The sequence, published online in Nature Biotechnology last week (6 November), should cut the time it takes to develop higher-yielding pigeon pea varieties from the 6–10 years required for traditional breeding techniques to three years with molecular techniques.

Researchers identified more than 48,000 genes in the legume, which is cultivated mainly by poor farmers on five million hectares of largely marginal land in Asia, Sub-Saharan Africa and parts of Latin America.

Pigeon pea is rich in protein, making it an ideal supplement to traditional cereal, banana or tuber-based diets, common in the developing world.

The genome sequence will enable researchers to use targeted genetic techniques and less guesswork to develop new high-yielding and disease- and stress-tolerant varieties of pigeon pea.

"Currently the realised yield is only one-third of the potential yield … because of several stresses such as disease or waterlogging," Rajeev Varshney, the lead scientist and coordinator for the project at the India-based International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), told SciDev.Net.

"I don’t know whether all stresses can be tackled simultaneously — nevertheless, if we could raise the crop productivity from 850 kilograms per hectare to 1,500 kilograms per hectare, for example, this would be a huge benefit to the farmers," Varshney said.

Varshney explained that if they have information on genes or molecular markers associated with desirable traits, scientists can screen large numbers of plants in the laboratory, rather than having to test plants for drought tolerance in the field and then continue to select for those traits over generations — saving time and money.

Damaris Odeny, a molecular biologist at South Africa’s Agricultural Research Council, told SciDev.Net: "The significance of this work will be huge …  Pigeon pea has multiple uses, is highly nutritious and can also be intercropped with other cereals without any significant yield effects and harvested over several seasons without tilling, which means there is no moisture loss from the soil.

"I believe this is a crop that all farmers lacking irrigation, and in areas where rainfall is unpredictable, should grow."

Varshney said that, like all legumes, pigeon pea improves soil quality. "It needs fewer inputs such as fertilisers compared with rice, maize, wheat or other pulses, and so we believe that there is higher probability that this crop can cope with climate change, especially in African and Asian countries."

He added that the genome sequence will enable scientists to determine which genes might be responsible for pigeon peas’ drought tolerance, which may also help develop that trait in other crops.

"We have identified putative drought tolerance genes in pigeon pea. As a result, it could be possible to enhance drought tolerance in other crops, especially legumes like soybean, chickpea, common bean."

Link to full paper in Nature Biotechnology