John Odipio, a scientist with Uganda’s National Crop Resources Research Institute (NaCCRI) who is currently pursuing his PhD in gene editing at the Donald Danforth Plant Science Center in St. Louis, Missouri, is using CRISPR to understand genes in cassava that can help resist pests and diseases affecting the plant.
African researchers are optimistic that gene editing will help solve the continent’s plant breeding challenges, especially the infestation of cassava brown streak virus (CBSV) that is ravaging the crop in Uganda and other East African countries.
Cassava is the third most important food crop in the tropics, comprising 30 to 50 percent of all calories consumed in sub-Saharan Africa. But yields have not increased in the past 25 years, due in large part to plant viruses that make the crop inedible.
In explaining his research, Odipio noted that he obtained a gene in cassava and edited it to cause change in the color of cassava leaves.
“For CRIPSR to work you need an enzyme called Cas9 and guided RNA,” he explained. “I obtained RNA within cassava to perform the bioinformatics process. Then I combined Cas9 with RNA to clone the edited cassava for growth. This is only possible after introducing it into a cell at the laboratory. From a single cell I have cloned cassava, which is growing into a whole plant but has changed color to whitish. This way I am able to know that the editing process has worked.”
Gene editing is a very precise tool, which gives it an edge over the genetic modification methods previously employed to try and solve the challenge of CBSV, Odipio said. He has come up with an extract using CRISPR to help the plants resist the disease and fight off the white flies that spread the virus from plant to plant.
Odipio has given his extracts to his NaCRRI colleagues, who are going to start the cassava breeding process using gene editing in their laboratory. Dr. Henry Wagaba, a NaCCRI expert on the gene silencing phenomena in plants, said a team of scientists are prepared to undertake research to understand if the technology can actually work in Uganda.
NaCCRI researchers will test the process that Odipio refined in a hybrid cassava variety currently being grown by farmers across the country. “The idea is to start gene editing technology research here in Uganda,” Wagaba said. “It will be the first of its kind and will enable us to move forward. What we shall do is to silence some piece of gene in the Nase 13 cassava variety and understand how it works in order to develop a variety which is clean from CBSV.”
The team is already in the process of securing an authorization permit from the National Council of Science and Technology, as required, and is set to start the research in February.
Odipio’s research team in the United States is also willing to extend its knowledge to address key challenges affecting African cassava farmers, such as CBSV, cassava mosaic virus (CMV) and weed control. They have developed cassava varieties that can tolerate the application of herbicide, which will reduce the need for manual weeding often performed by women in Africa. They are also pursuing cassava varieties rich in quality starch that can be used in industrial applications and traded in the international market.
Research is also under way on potential gene edited lines that flower early, thus shortening the breeding cycle and allowing scientists to deliver improved varieties to farmers more quickly. This will support timely development of climate resilient varieties. As this research progresses, Odipio is urging an update of African biosafety and regulatory systems in order to catch up with developments in scientific discoveries.
He is optimistic that African countries will support a friendlier regulatory environment for agricultural products bred using advanced technologies, including gene editing.
