Sridhar Bhavani, head of rust pathology and molecular genetics and the International Maize and Wheat Improvement Center (CIMMYT), shared potential solutions for fighting back against wheat stem rusts like Ug99.
More than 200 new wheat varieties released by CIMMYT over the last ten years have contributed to reducing the spread of wheat stem rust in East Africa, where the disease originated. Scientists identify genes resistant to Ug99 and breed new varieties that are not susceptible to stem rust pathogens.
For long-term success, combining multiple resistant genes within a single variety is the way to go.
Firpo was born in Montevideo, Uruguay, where he received a BSc degree as an agronomy engineer in 1997 from the University of the Republic, College of Agronomy. His PhD degree in 2008 was from the Department of Plant Pathology at the University of Minnesota (UMN). He began his career as a postdoctoral research associate with the Department of Plant Pathology and the USDA-ARS Cereal Disease Lab, and then became a research assistant professor in the Department of Plant Pathology at UMN in 2017.
Firpo has been a vital member in the global cereal rust pathology community and contributed substantially to the fight against Ug99 and other virulent wheat stem rust races that have re-emerged around the world and pose serious threats to food security. Firpo’s contributions are not only within the realm of research of great impact, but also include training 79 scientists and facilitating the establishment of a world-class research group in Ethiopia. He has worked to improve international germplasm screening in Ethiopia. As a postdoctoral research associate, Firpo’s first assignment was to search for new sources of resistance to Ug99 in durum wheat, used for pasta, and related tetraploid wheat lines. That project took him to Ethiopia, where an international Ug99-screening nursery for durum wheat was established at Debre Zeit Research Center. He worked closely with researchers from the Ethiopian Institute of Agricultural Research (EIAR) and the International Maize and Wheat Research Center (CIMMYT) to improve the methodologies for screening and to provide hands-on training to researchers managing the international screening nursery. During a period of 10 years (from 2009 to 2019), he traveled to Ethiopia 21 times to evaluate stem rust reactions of US and international durum wheat germplasm and completed the screening of the entire durum collection (more than 8,000 accessions) from the USDA National Small Grains Collection.
Firpo’s research on sources and genetics of stem rust resistance led to discoveries of valuable genetic resistance in durum and other relatives of wheat. These sources of resistance have provided the needed diversity to ensure the development and sustainability of durable stem rust resistance.
With frequent epidemics and severe yield losses caused by stem rust in eastern Africa, establishing a functional rust pathology laboratory to support international screening, as well as to monitor and detect new virulences in the pathogen population, became a high priority for the international wheat research community. Utilizing the onground opportunities in Ethiopia, Firpo and his colleagues at the CDL and UMN enthusiastically participated in building up the rust pathology lab at the Ambo Plant Protection Center of EIAR. Firpo traveled to Ambo 11 times to provide hands-on training to staff and to develop cereal rust protocols to suit local conditions. He worked closely with colleagues at CDL, EIAR, and CIMMYT to secure and upgrade facilities, equipment and supplies to a standard that ensures reliable rust work will be carried out. As a result, the rust pathology lab at the Ambo Center became the only laboratory in eastern Africa, and one of a handful in the world, that can conduct high-quality race analysis of wheat stem rust samples and provide vital and necessary support for breeding global wheat varieties for rust resistance. Currently, the laboratory is playing a critical role in the global surveillance of the stem rust pathogen and supports wheat breeding efforts led by EIAR, CIMMYT, and the USDA.
Firpo has been passionate in supporting capacity building of human resources in Ethiopia and elsewhere. He has been eager to share his knowledge whenever he encounters an opportunity to do so. In addition to the direct training of the staff at the Ambo Center, Firpo accepted invitations to provide training lectures and hands-on field- and greenhouse-based workshops on rust pathology at three research centers in Ethiopia. He prepared training materials, delivered a total of 12 lectures and 10 practical sessions in three Ethiopia national workshops in 2014, 2015, and 2017. These workshops enhanced human resource development and technical capacity in Ethiopia in cereal rust pathology; participants included a total of 64 junior scientists and technical staff from nationwide research centers. Beyond Ethiopia, he was responsible for developing and implementing a six-week training program in cereal rust prevention and control for international scientists. This training program, under the aegis of the Stakman-Borlaug Center for Sustainable Plant Health in the Department of Plant Pathology, University of Minnesota, provided an experiential learning opportunity for international scientists interested in acquiring knowledge and practical skills in all facets of working with cereal rusts. The program trained 15 rust pathologists and wheat scientists from Ethiopia, Kenya, Pakistan, Nepal, Bhutan, Georgia, and Kyrgyzstan, ranging from promising young scientists selected by the USDA as Borlaug Fellows to principal and senior scientists in their respective countries. Many of these trainees have become vital partners in the global surveillance network for cereal rusts.
Working in collaboration with CDL and international scientists, Firpo has been closely involved in global surveillance of the stem rust pathogen, spurred by monitoring the movements of, and detecting, new variants in the Ug99 race group. Since 2009, he and the team at the CDL have analyzed 2,500 stem rust samples from 22 countries, described over 35 new races, and identified significant virulence combinations that overcome stem rust resistance genes widely deployed in global wheat varieties. Among the most significant discoveries were the identification of active sexual populations of the stem rust pathogen in Kazakhstan, Georgia, Germany, and Spain that have unprecedented virulence and genetic diversities. More than 320 new virulent types (or races) were identified from these sexual populations. Evolution in these populations will present continued challenges to wheat breeding. Research in race analysis has provided valuable pathogen isolates that are used to evaluate breeding germplasm to select for resistant wheat varieties and to identify novel sources of stem rust resistance.
Artificial Intelligence (AI) and Machine Learning (ML) are increasingly being applied across a diverse range of disciplines. Many aspects of our lives and work are now benefiting from these technologies. Disease recognition, for both human and plant health, is no exception. Ever more powerful AI/ML techniques are now opening up exciting opportunities to improve surveillance, monitoring and early warning for disease threats.
“The value of tools like PlantVillage Nuru is that we can greatly increase the coverage and speed of surveillance,” says CIMMYT scientist and disease surveillance expert Dave Hodson. “Trained pathologists can only visit a limited number of fields at fixed times in the season. With tools like Nuru, extension agents and farmers can all contribute to field surveys. This can result in much faster detection of disease outbreaks, better early warning and improved chances of control”.
New advances in AI/ML technology are now promising even greater improvements in these already powerful tools. CIMMYT scientists have had a long-standing partnership with the PlantVillage group, working to try and develop improved diagnostics for important wheat diseases such as rusts and blast. Considerable progress in developing automated diagnostics for wheat diseases has already been made, but the introduction of advanced image segmentation and tiling techniques promises to be a major leap forward.
“Advances in computer science are constantly happening and this can benefit the mission of CGIAR and PlantVillage,” explains David Hughes, Dorothy Foehr Huck and J. Lloyd Huck Chair in Global Food Security at Penn State and founder of PlantVillage.
“Image segmentation and tiling techniques are a great example. They used to require intensive computing requirements. Now due to advances in computer science these powerful techniques are becoming more accessible and can be applied to plant disease problems like wheat rusts.”
By using these image segmentation and tiling techniques the developers at PlantVillage are now seeing a major improvement in the ability to automatically and accurately detect wheat rusts from in situ photos. “We could not identify rusts with the older approaches but this segmentation and tiling tool is a game changer. The computer goes pixel by pixel across the images which is well suited to diseases like rusts that can be spread across the leaf or stem of the plant. The computer now has a much more powerful search algorithm.”
The team led by Pete McCloskey, lead A.I. engineer at Plant Village, actually used a multi-step process. First they removed the background to help the machine focus in on the leaf. They then digitally chopped the leaf into segments giving the AI a further helping hand so it can focus in and find the rust. Then the whole leaf is stitched together and the rust is highlighted to help humans working in the PlantVillage cloud system.
Fig: Examples of manual, hand labelled images (top rows) compared to AI generated images using segmentation and tiling (bottom rows) for stem rust (upper image panel) and stripe rust (lower image panel).
This exciting new development in rapid, accurate field detection of wheat rusts now needs validation and improvement. As with all AI/ML applications, numbers of images included in the models really improve the quality of the final predictions. “The success of any machine learning model is rooted in the quality and quantity of the data it is trained on,” notes McCloskey. “Therefore, it is critical to source vast and diverse amounts of high-quality images from around the world in order to develop a global wheat rust recognition system.” In this aspect we hope that the CIMMYT global wheat community can help drive the development of these exciting new tools forward.
CIMMYT and PlantVillage are hoping to expand the current wheat rust image dataset and as a result produce an even more valuable, public good, disease detection tool. Given the extensive field work undertaken in wheat fields around the world by CIMMYT staff and partners, we hope that you can help us. Any photos of wheat rusts (stem, stripe and leaf rust) in the field would be valuable.
We would like to have images with one infected leaf or stem per image, it should be vertical in the image so you can see the whole leaf or stem segment. The leaf or stem needs to be in focus and should be roughly centered in the image. It helps to hold the tip of the leaf away from the stem, so it is outstretched and flat. Ideally for training data, the leaf should have only one type of rust and no other disease symptoms. It is okay to have other leaves/stems/soil/sky in the background. It is also okay to have hands and other body parts in the image.
Below are some example images. Any images can be uploaded here.
Sample images show a variety of wheat rusts (stem, stripe and leaf rust) in the field. (Photos: CIMMYT)
For more information contact Dave Hodson, CIMMYT (d.hodson@cgiar.org) or Pete McCloskey, PlantVillage (petermccloskey1@gmail.com).
“We want to feed the people, we don’t want them to go hungry. We have to do something to make sure there is food on the table. That is where my motivation is… Let there be food to eat.”
— Ruth Wanyera, 2019
The International Maize and Wheat Improvement Center (CIMMYT) has long attributed its widespread impact and reach to strong collaborations with national agricultural research systems (NARS) around the world. Today, CIMMYT — and especially the Global Wheat Program and the CGIAR Research Program on Wheat — wish to honor one long-term collaborator whose work and dedication to wheat research has had abiding positive effects beyond her home region of sub-Saharan Africa.
Ruth Wanyera, national wheat research program coordinator at the Kenya Agricultural and Livestock Research Organization (KALRO), has spent her more than 30-year career dedicated to plant protection research, fueled by her motivation to “feed the people.” She was one of the first scientists to recognize stem rust in east Africa and has been one of CIMMYT’s strongest allies in fighting the devastating wheat disease, stem rust Ug99.
National Wheat Coordinator Ruth Wanyera (third from right) gives a lesson to pathology interns in the field of a fungicide efficiency trial at KALRO Njoro Research Station, Nakuru, Kenya. (Photo:CIMMYT)
A long-term relationship with CIMMYT
Sridhar Bhavani, senior scientist and head of Rust Pathology and Molecular Genetics at CIMMYT has worked closely with Wanyera and her team since the mid-2000s.
“Ruth is a passionate researcher who has tirelessly dedicated her entire career to cereal pathology, and as a team, we coordinated the stem rust phenotyping platform for over a decade and had great successes on multiple international projects,” he said.
CIMMYT’s relationship with Wanyera’s team strengthened when Nobel Prize Laureate Norman Borlaug visited the Kenyan research facility to observe the emerging threat of stem rust. Upon witnessing how serious the outbreak had become, Borlaug organized an emergency summit in Nairobi in 2005, famously “sounding the alarm” for swift and concerted action on stem rust, and ultimately leading to the establishment of the BGRI.
“Ruth and her team of dedicated scientists from KALRO have not only made Kenya proud but have also made a remarkable contribution to the global wheat community in mitigating the threat of stem rust Ug99,” says Bhavani. “Ruth has mentored master’s and PhD students who are now leading researchers at KALRO. She has elevated the research capacity of KALRO to international repute.”
Two recent wheat breeding projects helped extend the CIMMYT-KALRO partnership beyond Kenya. The Durable Rust Resistance in Wheat (DRRW) and Delivering Genetic Gain in Wheat (DGGW) projects brought in a partnership with the Ethiopia Institute for Agricultural Research (EIAR) to establish and operate stem rust phenotyping platforms that addressed the global threat of Ug99 and other serious stem rust races, and helped provide solutions for the region. Thanks to KALRO’s screening efforts at the CIMMYT-KALRO Stem Rust Screening Platform in Njoro, Kenya, CIMMYT-derived rust-resistant varieties now cover more than 90% of the wheat farming area in Kenya and Ethiopia.
Ruth Wanyera receives the Kenya Agricultural Research Award (KARA), during the High Panel Conference on Agricultural Research in Kenya. (Photo: CIMMYT)
The partnership continues to grow
Continued collaboration with Ruth’s team at KALRO will be essential in the new Accelerating Genetic Gains in Maize and Wheat for Improved Livelihoods (AGG) project. AGG — which aims to accelerate the development and delivery of more productive, climate-resilient, gender-responsive, market-demanded, and nutritious wheat varieties in in sub-Saharan Africa and South Asia — has a particular focus on enhanced collaboration with national partners such as KALRO.
Its success is also closely tied to the Njoro Stem Rust Screening Platform — which, since its establishment in 2008, has conducted crucial screening for over 600,000 wheat lines, varieties, varietal candidates, germplasm bank accessions and mapping populations. Wanyera’s leadership in the Platform, alongside that of CIMMYT wheat scientist Mandeep Randhawa, plays a major role in screening, monitoring, and clearing seed in time for sowing.
As Hans Braun, former director of the CIMMYT Global Wheat Program said, “Without our national agriculture research system partnerships, CIMMYT would become obsolete.”
Indeed, the unparalleled wealth of knowledge, skills, and research facilities of the CGIAR as a whole would not be so uniquely impactful if it weren’t for the 3000+ partnerships with national governments, academic institutions, enthusiastic farmers, private companies and NGOs that help carry out this work.
CIMMYT’s historic and continued impact depends on close international partnerships with scientists and leaders like Ruth Wanyera, and we congratulate her on her numerous awards, thank her for her collaboration, and wish her a pleasant retirement.
With new pathogens of crop diseases continuously emerging and threatening food production and security, wheat breeder and wheat rust pathologist Mandeep Randhawa and his colleagues at the International Maize and Wheat Improvement Center (CIMMYT) and the Kenya Agricultural and Research Organization (KALRO) are working tirelessly to identify new sources of rust resistance through gene mapping tools and rigorous field testing.
With wheat accounting for around 20% of the world’s calories and protein, outbreaks of disease can pose a major threat to global food security and farmer livelihoods. The most common and prevalent diseases are wheat rusts — fungal diseases that can be dispersed by wind over long distances, which can quickly cause devastating epidemics and dramatically reduce wheat yields.
To tackle the problem, Randhawa and his colleagues work on developing improved wheat varieties by combining disease-resistant traits with high yielding ones, to ensure that farmers can get the best wheat yields possible while evading diseases.
Screening for disease
A native of the Punjab state of India, Randhawa joined CIMMYT as a Post-doctoral Fellow in Wheat Rust Resistance Genetics in 2015. He now works as a CIMMYT scientist and manages the Stem Rust Screening Platform in Njoro, Kenya, which supports screening against stem rust of up to 50,000 wheat lines per year from as many as 20 countries. Over the last 10 years about 650,000 wheat lines have been evaluated for stem rust resistance at the facility.
“The platform’s main focus is on evaluation of wheat lines against the stem rust race Ug99 and its derivative races prevalent in Eastern to Southern Africa, the Middle East and Iran,” explains Randhawa. Ug99 is a highly virulent race of stem rust, first discovered two decades ago in Uganda. The race caused major epidemics in Kenya in 2002 and 2004.
“East African highlands are also a hotspot for stripe wheat rust so, at the same time, we evaluate wheat lines for this disease,” adds Randhawa.
The facility supports a shuttle breeding scheme between CIMMYT Mexico and Kenya, which allows breeders to plant at two locations, select for stem rust (Ug99) resistance and speed up the development of disease-resistant wheat lines.
“Wheat rusts in general are very fast evolving and new strains are continuously emerging. Previously developed rust-resistant wheat varieties can succumb to new virulent strains, making the varieties susceptible. If the farmers grow susceptible varieties, rust will take on those varieties, resulting in huge yield losses if no control measures are adopted,” explains Randhawa.
Helping and sharing
For Randhawa, helping farmers is the main goal. “Our focus is on resource-poor farmers from developing countries. They don’t have enough resources to buy the fungicide. Using chemicals to control diseases is expensive and harmful to the environment. So in that case we provide them solutions in the form of wheat varieties which are high yielding but they have long-lasting resistance to different diseases as well.”
Under the Borlaug Global Rust Initiative, Randhawa and his team collaborate with KALRO to facilitate the transfer of promising wheat lines with high yield potential and rust resistance to a national pipeline for soon-to-be-released wheat varieties.
When he is not screening for wheat rusts diseases, Randhawa also organizes annual trainings on stem rust diagnosis and germplasm evaluation for young wheat breeders and pathologists from developing countries. More than 220 wheat researchers have been trained over the last decade.
Mandeep Randhawa (left) talks to the participants of the 11th annual training on stem rust notetaking and germplasm evaluation. (Photo: Jerome Bossuet/CIMMYT)
A farmer at heart
Randhawa always had an interest in agricultural science. “Initially, my parents wanted me to be a medical doctor, but I was more interested in teaching science to school students,” he says. “Since my childhood, I used to hear of wheat and diseases affecting wheat crops, especially yellow rust — which is called peeli kungi in my local language.” This childhood interest led him to study wheat genetics at Punjab Agricultural University in Ludhiana, India.
His mentors encouraged him to pursue a doctorate from the Plant Breeding Institute (PBI) Cobbitty at the University of Sydney in Australia, which Randhawa describes as “the mecca of wheat rust research.” He characterized two new stripe rust resistance genes formally named as Yr51 and Yr57 from a wheat landrace. He also contributed to the mapping of a new adult plant stem rust resistance gene Sr56.
Coming from India, his move to Australia was a pivotal moment for him in his career and his identity — he now considers himself Indian-Australian.
If he had not become a scientist, Randhawa would be a farmer, he says. “Farming is my passion, as I like to grow crops and to have rich harvest using my scientific knowledge and modern technologies.”
At CIMMYT, Randhawa has a constant stream of work identifying and characterizing new sources of rust resistance. “Dealing with different types of challenges in the wheat field is what keeps me on my toes. New races of diseases are continuously emerging. As pests and pathogens have no boundaries, we must work hand-in-hand to develop tools and technologies to fight fast evolving pests and pathogens,” says Randhawa.
He credits his mentor Ravi Singh, Scientist and Head of Global Wheat Improvement at CIMMYT, for motivating him to continue his work. “Tireless efforts and energetic thoughts of my professional guru Dr. Ravi Singh inspire and drive me to achieve research objectives.”
Two hybrid wheat varieties that are resistant to stem rust disease are set to be released to Kenyan farmers later this year. Mandeep Randham, wheat breeder and geneticist at International Maize and Wheat Improvement Center said that the two varieties, ‘Kenya Jacana’ and ‘Kenya Kasuku’ have high yields and resistant to stem rust disease known as U99. Read more here.
Matthew Rouse, a researcher with the United States Department of Agriculture (USDA) Agricultural Research Service (ARS), has been named the winner of the 2018 Norman Borlaug Award for Field Research and Application. Rouse is recognized for his essential leadership efforts to contain and reduce the impact of Ug99, a devastating new race of the stem rust pathogen that poses a serious threat to the world’s wheat crops and food security.
The Norman Borlaug Award for Field Research and Application is presented annually to a young extension worker, research scientist or development professional who best emulates the dedication, perseverance, and innovation demonstrated by Norman Borlaug while working in the field with Mexican farmers in the 1940s and ’50s.
“When I learned that I was selected for the Borlaug Field Award, I was humbled by both the legacy of Norman Borlaug and by the fact that any impact I made was a part of collaborations with talented and hard-working individuals at USDA-ARS, the University of Minnesota, CIMMYT, the Ethiopian Institute of Agricultural Research, and other national programs,” Rouse said.
Rouse has been an essential collaborator for a wide range of crucial projects to protect the world’s wheat crops. His research supports more than 20 breeding programs in the U.S. and 15 wheat genetics programs around the world, including those at CIMMYT. As the coordinator of ARS’s spring wheat nursery project in Ethiopia and Kenya, he has provided Ug99 resistance genes to breeders worldwide, accelerating the process for incorporating enhanced stem rust protection into wheat varieties.
Rouse also collaborated with CIMMYT in 2013, when a race of stem rust unrelated to Ug99 caused an epidemic in Ethiopia. He rapidly assembled a team of scientists from CIMMYT, the Ethiopian Institute of Agricultural Research (EIAR) and USDA-ARS, and developed a research plan to establish four stem rust screening nurseries. This led to the selection of promising new wheat breeding lines by Ethiopian and CIMMYT scientists and the rapid 2015 release of the variety ‘Kingbird’ in Ethiopia, which was shown to be resistant to four of the most dangerous races of stem rust in addition to Ug99.
Wheat stem rust was reported by the Greeks and Romans, and the latter sacrificed to the gods to avoid disease outbreaks on their wheat crops. Photo: CIMMYT/Petr Kosina
As reported today in Communications Biology, an international team of researchers led by the John Innes Centre, U.K., found that 80 percent of U.K. wheat varieties are susceptible to the deadly stem rust strain. The group also confirmed for the first time in many decades that the stem rust fungus was growing on barberry bush, the pathogen’s alternate host, in the UK.
“This signals the rising threat of stem rust disease for wheat and barley production in Europe,” said Dave Hodson, senior scientist at the International Maize and Wheat Improvement Center (CIMMYT) and co-author on the study.
A scourge of wheat since biblical times, stem rust caused major losses to North American wheat crops in the early 20th century. Stem rust disease was controlled for decades through the use of resistant wheat varieties bred in the 1950s by scientist Norman Borlaug and his colleagues. Widespread adoption of those varieties sparked the Green Revolution of the 1960s and 70s.
In 1999 a new, highly-virulent strain of the stem rust fungus emerged in eastern Africa. Spores of that strain and variants have spread rapidly and are threatening or overcoming the genetic resistance of many currently sown wheat varieties. Scientists worldwide joined forces in the early 2000s to develop new, resistant varieties and to monitor and control outbreaks of stem rust and yellow rust, as part of collaborations such as the Borlaug Global Rust Initiative led by Cornell University.
Barberry is a shrub found throughout the temperate and subtropical regions. Photo: John Innes Centre
The Communications Biology study shows that 2013 U.K. stem rust strain is related to TKTTF, a fungal race first detected in Turkey that spread across the Middle East and recently into Europe. It was the dominant race in the 2013 stem rust outbreak in Germany and infected 10,000 hectares of wheat in Ethiopia’s breadbasket the same year.
Because disease organisms mutate quickly to overcome crop resistance controlled by single genes, researchers are rushing to identify new resistance genes and to incorporate multiple genes into high-yielding varieties, according to Ravi Singh, CIMMYT wheat scientist who participated in the reported study.
“The greatest hope for achieving durable resistance to rust diseases is to make wheat’s resistance genetically complex, combining several genes and resistance mechanisms,” Singh explained.
Barberry, which serves as a spawning ground for the stem rust fungus, was largely eradicated from the U.K. and U.S. last century, greatly reducing the spread and genetic diversification of rust disease races. Now barberry is being grown again in the U.K. over the last decade, according to Diane G.O. Saunders, John Innes Centre scientist and co-author of the study.
“The late Nobel laureate Norman Borlaug said that the greatest ally of the pathogen is our short memory,” Saunders stated. “We recommend continued, intensive resistance breeding. We would also welcome work with conservationists of endangered, barberry-dependent insect species to ensure that planting of common barberry occurs away from arable land, thus safeguarding European cereals from a large-scale re-emergence of wheat stem rust.”
Click here to read the John Innes Centre media release about the Communications Biology report and view the report.
David Hodson, senior scientist with CIMMYT, trains South Asian wheat scientists on the use of handheld surveillance and monitoring devices. Hodson directs the rusttracker.org global wheat rust monitoring system for the Delivering Genetic Gain in Wheat (DGGW) project. Credit: CORNELL/Linda McCandless
EL BATAN, Mexico (CIMMYT) – Scientists are concerned over the proliferation of highly virulent fungal wheat diseases, including two new races of yellow rust – one in Europe and North Africa, the other taking hold in East Africa and Central Asia – and a new race of stem rust emerging in Europe.
The collaborative Global Rust Reference Center (GRRC) hosted by Aarhus University in Denmark and including the International Maize and Wheat Improvement Center (CIMMYT) and the International Center for Agricultural Research in the Dry Areas (ICARDA), was instrumental in identifying the new races of yellow and stem rust.
A strategic tool developed by David Hodson, a senior scientist with CIMMYT plays a key role in monitoring the movement of wheat-rust pathogens, helping farmers combat the disease in time to save crops and prevent food insecurity.
“We see an alarming increase in severe disease, more disease diversity and rapid spread,” said Hodson, who invented the Rust Tracker field surveillance tool.
Last year, the Italian island of Sicily was badly hit by a strain of wheat stem rust – an event not seen in Europe since the 1950s, following concerted efforts by wheat breeders to eliminate it.
Stem rust appears as a reddish-brown fungal build-up on wheat stems or leaves, stunting and weakening plants, preventing kernels from forming, leading to shriveled grain and potential crop losses of 50 to 100 percent.
Dispersal modeling, undertaken by the University of Cambridge and the UK Met Office, which forecasts weather and climate change, indicates that spores from the Sicilian outbreak could potentially have spread within the Mediterranean wheat growing region, but scientists are unsure whether they will successfully over-winter, surviving and proliferating, according to a recent story in the journal Nature.
EARLY WARNING
“Several factors may be influencing the changes and rapid spread: increased travel and trade; increasing pathogen populations; more uniform cropping systems and also climate change, but the rapid changes we are observing highlight the need for an enhanced early-warning system,” said Hodson, a member of an international team of scientists collaborating under the Delivering Genetic Gain in Wheat (DGGW) project administered by Cornell University through the Borlaug Global Rust Initiative (BGRI).
Scientists engaged with the major four-year international project – which has a budget of $34.5 million due to grants equalling $24 million from the Bill & Melinda Gates Foundation and a recent $10.5 million grant from UK Aid (Britain’s Department for International Development, or DFID) – use comparative genomics and big data to develop new wheat varieties. The aim is to help governments provide smallholder farmers in the developing world with seeds incorporating resilience to environmental stresses and diseases through local entrepreneurial distributors.
“The sooner farmers are notified of a potential rust outbreak, the better chance they have to save their crops through fungicides or by planting resilient wheat varieties,” Hodson said.
“It’s a constant challenge. We’re always on the lookout for new diseases and variants on old diseases to put the wheels in motion to aid governments who can distribute seeds bred specifically to outsmart rusts.”
However, the long-term sustainability of these vital disease-monitoring systems is uncertain. Despite the significant investments, challenges remain, Hodson said.
“It’s worrying that just as stem rust is re-appearing in Europe we’re at risk of losing the only stem rust pathotyping capacity in Europe at GRRC, due to a funding shortfall. Given the threats and changes we are observing, there really is a critical need for a long-term strategy to address major crop diseases.”
TRACKER ORIGINS
The online Rust Tracker was originally conceived as a tool to battle stem rust, including the lethal Ug99 race, which since its discovery in 1998 has spread from Uganda into the Middle East and is now found in 13 countries. If Ug99 takes hold in a field it can completely wipe out a farmer’s crop. In developing countries, farmers have more difficulty accessing and affording fungicides, which can potentially save a crop.
Under the Durable Rust Resistance in Wheat project, the predecessor to the DGGW project, BGRI-affiliated scientists aimed to prevent the spread of Ug99 into the major global breadbaskets of China and India. So far, they have succeeded in keeping it in check and raising awareness among governments and farmers of its potentially devastating impact.
“Researchers and farmers are connected in the global village,” Hodson said. “Plant pathogens know no borders. We must leave no stone unturned in our efforts to understand the dynamics of wheat rusts, how they’re changing, where they’re spreading and why. If wheat scientists can help prevent a food crisis, we’re doing our job to help maintain political and economic stability in the world.”
