Wheat is the world’s most widely grown crop in terms of land use and is a staple of many economies worldwide. But it’s at risk to diseases such as wheat rust that can devastate harvests, lead to crop failures and famine.
Wheat rusts are present in all wheat growing areas worldwide, with resource-poor regions in East Africa and South Asia hardest hit by disease epidemics where it can wipe out a field in just days. For instance, Ethiopia is the largest wheat producer in sub-Saharan Africa and in 2010 a wheat yellow rust outbreak devastated its wheat crop, with 600,000 hectares affected and losses estimated at $250m.
Wheat rust can spread rapidly on wind currents across thousands of miles, causing enormous losses, unless farmers regularly spray expensive and environmentally-damaging fungicides and grow rust-resistant wheat varieties. However, new pathogen variants frequently emerge and overcome the resistance that is introduced and there is also the risk that the pathogens could become tolerant to fungicide application. Therefore, as the pathogen evolves, maintaining resilience in the field is an ongoing challenge. That’s why it is so important to track its movement and alert farmers so that they are able to take action.
Whilst it is not possible to stop new wheat rust strains from developing, detecting them early means appropriate control strategies can be tailored to limit their further spread and protect farmers. And, that is exactly what the Disease Early Warning Advisory System (DEWAS) project was created to do.
Led by the International Maize and Wheat Improvement Center (CIMMYT) and Cornell University, DEWAS is one of the world’s largest crop pathogen surveillance and advisory systems, protecting wheat productivity in vulnerable areas of East Africa and South Asia. Involving many organisations across the world, it seeks to provide farmers with advanced warning of potential outbreaks of wheat rust and blast. The data it provides enables farmers to take action to protect their wheat crops during the growing season with the right sort of fungicides. It also helps them to make decisions about which variety of crop to sow for the next season.
The latest iteration of the project – Global Surveillance and Advisory System (GSAS) – has expanded this capability to Latin America and major maize diseases, connecting researchers across countries to create an international disease response system to rapidly respond to new and emerging threats.
At Norwich Research Park, a team of researchers, under the guidance of Group Leader, Prof Diane Saunders, OBE, at the John Innes Centre, has had key roles in the DEWAS and now GSAS projects. Their particular expertise lies in genomics and the development of high resolution genotyping methods to sequence and type strains of the wheat rust pathogens.
The new system they created is called MARPLE diagnostics and can type wheat rust strains in just two days after collecting field samples. This allows farmers to know exactly which strain is present in their fields, in near real-time, to guide the most appropriate action. This methodology has now been deployed across East Africa and South Asia and is bringing the capacity for real-time disease diagnostics, for the first time, to resource-poor regions.
To monitor the movement of rust outbreaks, rust pathologists (or field researchers), travel across wheat growing regions, scouring farmers’ fields looking for signs of rust infection. Collecting and identifying these rust samples helps record how different strains are spreading on the wind to new areas.
Previously, these researchers had to send samples of infected wheat plants overseas for strain typing, which could take months. This meant that they were always on the back foot reacting to something that could already have changed by the time they got the results back.
Now, with the MARPLE diagnostics system, results can be generated within just 48 hours by the researchers based in the affected area, supporting immediate action and ensuring those in these regions maintain ownership of the results and decision-making in the fight against the wheat rusts.
Prof Saunders notes, “Knowing exactly which wheat rust strain is present in a farmer’s field is critical information that helps tailor guidance within the early warning system and provides more effective control of disease outbreaks”.
Prof Saunders and her team provide training to researchers using the MARPLE diagnostics system and connect them to other MARPLE diagnostics hubs across the world so that a global view can be created and opportunities are opened for them to share knowledge and solutions with their neighbours.
Prof Saunders’ microbiology background is in plant pathology, specifically studying fungal pathogens. As a microbiologist, she has studied rice blast, ash dieback, potato late blight and cereal rusts, among others. Her lab focuses on responding to emerging and re-emerging plant pathogens that particularly pose a significant threat to agriculture.
She was recognised for her outstanding scientific contributions to plant science, agriculture and dedication to supporting women in STEMM with an OBE in the King’s Birthday Honours 2024.
Prof Saunders is hugely passionate about training the next-generation of plant scientists, including supporting researchers in countries with few opportunities to access high-level training in various areas of need. She is also highly dedicated to promoting gender parity in wheat research, establishing the hugely successful “Women in Wheat” career mentoring program at the John Innes Centre in collaboration with The Sainsbury Laboratory to address the dire gender imbalance in wheat research.