SMIL research team identified how to create pest-resistant varieties
Farmers around the world can follow prescribed agronomic practices to a tee, but when they are up against nature, sometimes they need a step up from technology. The Feed the Future Innovation Lab for Collaborative Research on Sorghum and Millet, SMIL, has discovered how to help Ethiopian farmers increase sorghum viability and yields.
The SMIL research project, Genetic Improvement of Sorghum for Resistance to Fungal Pathogens, focuses on solving problems for sorghum farmers in Ethiopia.
The management team for SMIL is based out of Kansas State University, with Dr. Tesfaye Mengiste of Purdue University as the principal investigator for this research project.
“Our objective is to increase the resiliency and food security of sorghum farmers and consumers in Ethiopia and West Africa. Dr. Mengiste’s novel proposal to improve host-plant resistance against crippling diseases endemic to sorghum in humid lowland areas of western Ethiopia will serve the broader sorghum development community and is a flagship global public good characteristic of the U.S. land grant mission. Apart from planting new seeds, the farm cost to this innovation is negligible," says Dr. Timothy Dalton, director of SMIL.
“This new variety, the Merera variety, has multiple benefits including resistance to pathogens, birds and, above all, better yields than the current varieties Ethiopian farmers have. With these improved traits and yield potential, it can mean a better livelihood for them,” says Dr. Mengiste.
One of the most significant of these pathogens, Anthracnose, attacks all parts of the plant – leaves, stalk and head. It leaves nothing that can be used for food, the primary sorghum use in Africa; or biofuels and animal feed, the primary sorghum use in the United States. The research focused on a genomics approach to mapping genes and exploring more than 2,000 Ethiopian sorghum germplasm through multiple location field trials over many years.
The newly discovered gene, named Anthracnose Resistance Gene1, or ARG1, is unique, according to Dr. Mengiste.
“Although some natural resistance to fungal disease was known in sorghum, genes that confer widespread resistance have not been identified,” he said. “It is remarkable that a single gene leads to resistance across a broad spectrum of fungi and multiple strains of the Anthracnose fungus.”
The regulation of the gene also is unusual. It is embedded in a second gene, and both genes appear to have been altered by small stretches of mobile DNA called transposable elements. “The gene in which ARG1 is embedded is an antisense RNA. Its expression is opposite to ARG1, which results in a situation where the two could interfere with each other,” said Damon Lisch, associate professor of botany and plant pathology at Purdue University who was involved in the research.
“All sorghum plants have some version of these two genes, but susceptible varieties of sorghum express a lot of the antisense RNA and very little of ARG1, which also appears to encode a nonfunctional protein,” he said. The disease-resistant version of ARG1 is expressed at a much higher level, encodes a functional protein, and is associated with an antisense RNA gene that is turned down, resulting in less interference.
“Insertion of transposable elements is often harmful,” he said. “However, in this case, it appears that the transposable elements have been beneficial by ‘reprogramming’ both genes to optimize resistance to fungal pathogens. In a way, it has fixed a broken system in the plants.”
“Transposable elements are known to be involved in some human and plant diseases, but their involvement in disease resistance is considered uncommon – for now,” he said. “With technological advancements, we are able to spot these parasitic strands of DNA within a gene sequence, and we are finding them everywhere. The genome is really an exciting ecosystem, and there is much more to discover within it.”
The technology will continue to evolve.
“Through this collaborative research supported by SMIL and the funding through USAID, we will continue to explore the rich Ethiopian germplasm to come up with the next resilient and high-yielding varieties,” Dr. Mengiste explains. “With better leveraging of recent genetic technologies, we will expedite the development of the new generation of varieties or those in the pipeline.”
“The variety was made available by the research center,” says a local farmer. “When they told us of its demonstration, we accepted and started producing it at our fields. We have found this sorghum is better than others. It resists drought. Increases productivity and gives better yield within a short time. The leaf is also used for cattle, so it has multiple uses.”
Now that the Merera varieties are available, the SMIL research team will continue to work with the Oromia Agricultural Research Institute-Bako Research Center and farmer cooperatives in-country to ensure seed is available for planting season and to help with the adoption of the technology in the region.
Another local farmer explains the opportunity with Merera varieties: “The past sorghum varieties get infested with disease and birds, but this one has the resistance to disease and birds. Therefore, if the seed is available, we plan to plant it in large contiguous plots.”
A major focus is growing the next generation of scientists.
SMIL ties in a focus of human and institutional capacity to every research project and this has become incredibly important in the era of COVID.
“This effort would not have been successful without a strong cadre of local scientists who have been part of the project,” Dr. Mengiste explains. “With the travel restrictions that came due to COVID, it has been a challenge to travel to make field visits, and local scientists went into full gear to close the gap.”
In addition to tapping into local, in-country resources in Ethiopia, Dr. Mengiste works with graduate students (M.S. and Ph.D.) sponsored by SMIL. “With this project, we continue to train plant pathology students in disease resistance breeding. Some of them are already doing wonderful things. I think those are the next generation who will continue the breeding research.”
As an Ethiopian, Dr. Mengiste wants to empower local farmers to impact their household income and food security through reliable sorghum varieties. “The work through SMIL demonstrates that the research eventually can reach the farmers and impact them. It also demonstrates that we can do some of the more fundamental work and focus it on developing practical solutions rather than addressing an academic problem.”
Dr. Dalton summarizes his excitement and encouragement with the launch of the Merera sorghum varieties in Ethiopia. “With the use of top-notch scientific genomic methods and research teams paired with empowered local farmers and research groups in Ethiopia, we were able to solve a problem through Ethiopia’s own sorghum varieties. Now the team will continue to focus on farmer adoption and growing the next generation of scientists.”
“Through this collaborative research supported by SMIL and the funding through USAID, we will continue to explore the rich Ethiopian germplasm to come up with the next resilient and high-yielding varieties. With better leveraging of recent genetic technologies, we will expedite the development of the new generation of varieties or those in the pipeline.”
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