Towards new, more resistant cassava varieties?

Cassava mosaic disease threatens cassava yields in Africa. Researchers have discovered a gene responsible for resistance to the virus of this disease. The discovery could help develop new varieties of cassava resistant to this disease.

According to scientists, the discovery of a gene resistant to the virus responsible for the disease devastating cassava mosaic disease could contribute to the development of more resistant cassava varieties and strengthen the Food Safety in sub-Saharan Africa.

In sub-Saharan Africa, the culture of cassava is limited by weeds and virus diseases, particularly cassava mosaic, caused by a group of viruses called geminiviruses.

Cassava mosaic is responsible for the loss of more than 80% of cassava crops, a staple food for more than 800 million people in sub-Saharan Africa.

Researchers say it was farmers in West Africa who noticed that while the majority of their cassava plants in the fields were dying due to the virus infection, a few plants were surviving.

"Understanding the genetic resources that induce resistance to geminiviruses is therefore important to ensure yields for cassava growers," says Wilhelm Gruissem, one of the researchers who documented thesurvey in the journal Nature Communications July 2022.

Wilhelm Gruissem, professor of biotechnology plants at the ETH in Zurich (Switzerland) entrusts SciDev.Net that cassava mosaic causes significant yield losses in sub-Saharan Africa and spreads to India and other regions or Southeast Asia.

Promising lines

Titus Alicai, study co-author and plant virologist at National Crops Resources Research Institute in Uganda, says the discovery means the government can develop and fund strategies to fight the disease.

“With these results, genetic markers closely related to cassava mosaic resistance can now be developed,” he said in an interview with SciDev.Net.

“This will make it more accurate, efficient and timely to select promising lines when developing new cassava varieties by enabling DNA-based screening of large populations in months rather than a whole year at each stage,” explains the searcher.

He adds that conventional breeding of new cassava varieties typically takes eight to ten years.

Titus Alicai says this finding can be used by policy makers to develop or improve action plans to control other viral diseases that plague cassava in Africa.

He also thinks this study could trigger similar findings essential to controlling related viruses that affect other crops.

“Our results provide evidence that can inform decisions by policy makers for increased financial support for science, research and development. No worry and innovations for the management of health plants,” he says.

Alfred Dixon, cassava specialist at the International Institute ofagriculture tropical Nigeria, agrees. He says 12-82% of cassava is lost due to cassava mosaic disease.

"This is an excellent study that will further strengthen the resilience of the système cassava seed company,” he said.

"Doing nothing would mean that the livelihoods of 800 million people are at risk and could be compromised," said Titus Alicai.

“Access to varieties resistant to cassava mosaic diseases would, on the other hand, lead to more yields and income in the farmers' pocket,” he notes.

For his part, Solomon Otu, plant breeder at the West Africa Center for Crop Improvement from the University of Ghana, says the results of this research could help strengthen the global cassava starch market and boost food security for millions of people.

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The original version of this article was produced by the English language edition of SciDev.Net for Sub-Saharan Africa.