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Wheat pathogen surveillance system set to expand through new investment

Written by Julian Bañuelos-Uribe on . Posted in Press releases.

One of the world’s largest crop pathogen surveillance systems is set to expand its analytic and knowledge systems capacity to protect wheat productivity in food vulnerable areas of East Africa and South Asia.

Researchers announced the Wheat Disease Early Warning Advisory System (Wheat DEWAS), funded through a $7.3 million grant from the Bill & Melinda Gates Foundation and the United Kingdom’s Foreign, Commonwealth & Development Office, to enhance crop resilience to wheat diseases.

The project is led by David Hodson, principal scientist at CIMMYT, and Maricelis Acevedo, research professor of global development and plant pathology at Cornell University’s College of Agriculture and Life Sciences. This initiative brings together research expertise from 23 research and academic organizations from sub-Saharan Africa, South Asia, Europe, the United States and Mexico.

Wheat DEWAS aims to be an open and scalable system capable of tracking important pathogen strains. The system builds on existing capabilities developed by the research team to provide near-real-time model-based risk forecasts and resulting in accurate, timely and actionable advice to farmers. As plant pathogens continue to evolve and threaten global food production, the system strengthens the capacity of countries to respond in a proactive manner to transboundary wheat diseases.

The system focuses on the two major fungal pathogens of wheat known as rust and blast diseases. Rust diseases, named for a rust-like appearance on infected plants, are hyper-variable and can significantly reduce crop yields when they attack. The fungus releases trillions of spores that can ride wind currents across national borders and continents and spread devastating epidemics quickly over vast areas.

Wheat blast, caused by the fungus Magnaporte oryzae Tritici, is an increasing threat to wheat production, following detection in both Bangladesh and Zambia. The fungus spreads over short distances and through the planting of infected seeds. Grains of infected plants shrivel within a week of first symptoms, providing little time for farmers to take preventative actions. Most wheat grown in the world has limited resistance to wheat blast.

“New wheat pathogen variants are constantly evolving and are spreading rapidly on a global scale,” said Hodson, principal investigator for Wheat DEWAS. “Complete crop losses in some of the most food vulnerable areas of the world are possible under favorable epidemiological conditions. Vigilance coupled with pathogen-informed breeding strategies are essential to prevent wheat disease epidemics. Improved monitoring, early warning and advisory approaches are an important component for safeguarding food supplies.”

Previous long-term investments in rust pathogen surveillance, modelling, and diagnostics built one of the largest operational global surveillance and monitoring system for any crop disease. The research permitted the development of functioning prototypes of advanced early warning advisory systems (EWAS) in East Africa and South Asia. Wheat DEWAS seeks to improve on that foundation to build a scalable, integrated, and sustainable solution that can provide improved advanced timely warning of vulnerability to emerging and migrating wheat diseases.

“The impact of these diseases is greatest on small-scale producers, negatively affecting livelihoods, income, and food security,” Acevedo said. “Ultimately, with this project we aim to maximize opportunities for smallholder farmers to benefit from hyper-local analytic and knowledge systems to protect wheat productivity.”

The system has already proven successful, contributing to prevention of a potential rust outbreak in Ethiopia in 2021. At that time, the early warning and global monitoring detected a new yellow rust strain with high epidemic potential. Risk mapping and real-time early forecasting identified the risk and allowed a timely and effective response by farmers and officials. That growing season ended up being a production record-breaker for Ethiopian wheat farmers.

While wheat is the major focus of the system, pathogens with similar biology and dispersal modes exist for all major crops. Discoveries made in the wheat system could provide essential infrastructure, methods for data collection and analysis to aid interventions that will be relevant to other crops.

Researchers from ZARI check for wheat blast in experimental plots. (Photo: Batiseba Tembo/ZARI)

Wheat blast has made the intercontinental jump to Africa

Written by Madeline Dahm on . Posted in Press releases.

Scientists observe wheat blast in Zambia's Mpika district. (Photo: Batiseba Tembo/ZARI)
Scientists observe wheat blast in Zambia’s Mpika district. (Photo: Batiseba Tembo/ZARI)

Wheat blast, a fast-acting and devastating fungal disease, has been reported for the first time on the African continent. In an article published in the scientific journal PLoS One, a team of scientists confirmed that symptoms of wheat blast first appeared in Zambia during the 2018 rainy season, in experimental plots and small-scale farms in the Mpika district, Muchinga province.

Researchers from the International Maize and Wheat Improvement Center (CIMMYT), the US Department of Agriculture – Foreign Disease Weed Science Research Unit (USDA-ARS) and the Zambian Agricultural Research Institute (ZARI) participated in this study.

Wheat blast poses a serious threat to rain-fed wheat production in Zambia and raises the alarm for surrounding regions and countries on the African continent with similar environmental conditions. Worldwide, 2.5 billion consumers depend on wheat as a staple food and, in recent years, several African countries have been actively working towards reducing dependence on wheat imports.

“This presents yet another challenging biotic constraint to rain-fed wheat production in Zambia,” said Batiseba Tembo, wheat breeder at ZARI and lead scientist on the study.

A difficult diagnosis

Researchers from ZARI check for wheat blast in experimental plots. (Photo: Batiseba Tembo/ZARI)
Researchers from ZARI check for wheat blast in experimental plots. (Photo: Batiseba Tembo/ZARI)

“The first occurrence of the disease was very distressing. This happened at the spike stage, and caused significant losses,” Tembo said. “Nothing of this nature has happened before in Zambia.”

Researchers were initially confused when symptoms of the disease were first reported in the fields of Mpika. Zambia has unique agro-climatic conditions, particularly in the rainfed wheat production system, and diseases such as spot blotch and Fusarium head blight are common.

“The crop had silvery white spikes and a green canopy, resulting in shriveled grains or no grains at all… Within the span of seven days, a whole field can be attacked,” Tembo explained. Samples were collected and analyzed in the ZARI laboratory, and suspicions grew among researchers that this may be a new disease entirely.

Tembo participated in the Basic Wheat Improvement Course at CIMMYT’s global headquarters in Mexico, where she discussed the new disease with Pawan Singh, head of Wheat Pathology at CIMMYT. Singh worked with Tembo to provide guidance and the molecular markers needed for the sample analysis in Zambia, and coordinated the analysis of the wheat disease samples at the USDA-ARS facility in Fort Detrick, Maryland, United States.

All experiments confirmed the presence of the fungus Magnaporthe oryzae pathotype Triticum (MoT), which causes the disease.

“This is a disaster which needs immediate attention,” Tembo said. “Otherwise, wheat blast has the potential to marginalize the growth of rain-fed wheat production in Zambia and may threaten wheat production in neighboring countries as well.”

Wheat blast spreads through infected seeds and crop residues, as well as by spores that can travel long distances in the air. The spread of blast within Zambia is indicated by both mechanisms of expansion.

Wheat blast has expanded rapidly since it was initially discovered in Brazil in 1985. (Map: Kai Sonder/CIMMYT)
Wheat blast has expanded rapidly since it was initially discovered in Brazil in 1985. (Map: Kai Sonder/CIMMYT)

A cause for innovation and collaboration

CIMMYT and the CGIAR Research Program on Wheat (WHEAT) are taking action on several fronts to combat wheat blast. Trainings and international courses invite participants to gain new technical skills and knowledge in blast diagnostics, treatment and mitigation strategies. WHEAT scientists and partners are also studying the genetic factors that increase resistance to the disease and developing early warning systems.

“A set of research outcomes, including the development of resistant varieties, identification of effective fungicides, agronomic measures, and new findings in the epidemiology of disease development will be helpful in mitigating wheat blast in Zambia,” Singh said.

“It is imperative that the regional and global scientific communities join hands to determine effective measures to halt further spread of this worrisome disease in Zambia and beyond,” Tembo expressed.

Read the study:

Detection and characterization of fungus (Magnaporthe oryzae pathotype Triticum) causing wheat blast disease on rain-fed grown wheat (Triticum aestivum L.) in Zambia

Interview opportunities:

Pawan Kumar Singh, Senior Scientist and Head of Wheat Pathology, International Maize and Wheat Improvement Center (CIMMYT)

Batiseba Tembo, Wheat Breeder, Zambian Agricultural Research Institute (ZARI)

For more information, or to arrange interviews, contact the media team:

Rodrigo Ordóñez, Communications Manager, CIMMYT. r.ordonez@cgiar.org

Acknowledgements

Financial support for this research was provided by the Zambia Agriculture Research Institute (ZARI), the CGIAR Research Program on Wheat (WHEAT), the Australian Centre for International Agricultural Research (ACIAR), and the US Department of Agriculture’s Agricultural Research Service (USDA-ARS). 

The Basic Wheat Training Program and Wheat Blast Training is made possible by support from investors including the Australian Centre for International Agricultural Research (ACIAR), WHEAT, the Indian Council of Agricultural Research (ICAR), Krishi Gobeshona Foundation (KGF), the Swedish Research Council (SRC) and the United States Agency for International Development (USAID).

The Accelerating Genetic Gains in Maize and Wheat (AGG) project is funded by the Bill & Melinda Gates Foundation, the UK Foreign, Commonwealth & Development Office, the United States Agency for International Development and the Foundation for Food and Agricultural Research (FFAR).

About CIMMYT

The International Maize and What Improvement Center (CIMMYT) is the global leader in publicly-funded maize and wheat research and related farming systems. Headquartered near Mexico City, CIMMYT works with hundreds of partners throughout the developing world to sustainably increase the productivity of maize and wheat cropping systems, thus improving global food security and reducing poverty. CIMMYT is a member of the CGIAR System and leads the CGIAR programs on Maize and Wheat and the Excellence in Breeding Platform. The Center receives support from national governments, foundations, development banks and other public and private agencies. For more information visit staging.cimmyt.org.

What is wheat blast?

Written by Matthew O'Leary on . Posted in Explainers. 7 Comments on What is wheat blast?

What is wheat blast disease?

Wheat blast is a fast-acting and devastating fungal disease that threatens food safety and security in tropical areas in South America and South Asia. Directly striking the wheat ear, wheat blast can shrivel and deform the grain in less than a week from the first symptoms, leaving farmers no time to act.

The disease, caused by the fungus Magnaporthe oryzae pathotype triticum (MoT), can spread through infected seeds and survives on crop residues, as well as by spores that can travel long distances in the air.

Magnaporthe oryzae can infect many grasses, including barley, lolium, rice, and wheat, but specific isolates of this pathogen generally infect limited species; that is, wheat isolates infect preferably wheat plants but can use several more cereal and grass species as alternate hosts. The Bangladesh wheat blast isolate is being studied to determine its host range. The Magnaporthe oryzae genome is well-studied but major gaps remain in knowledge about its epidemiology.

The pathogen can infect all aerial wheat plant parts, but maximum damage is done when it infects the wheat ear. It can shrivel and deform the grain in less than a week from first symptoms, leaving farmers no time to act.
The pathogen can infect all aerial wheat plant parts, but maximum damage is done when it infects the wheat ear. It can shrivel and deform the grain in less than a week from first symptoms, leaving farmers no time to act.

Where is wheat blast found?

First officially identified in Brazil in 1985, the disease is widespread in South American wheat fields, affecting as much as 3 million hectares in the early 1990s. It continues to seriously threaten the potential for wheat cropping in the region.

In 2016, wheat blast spread to Bangladesh, which suffered a severe outbreak. It has impacted around 15,000 hectares of land in eight districts, reducing yield on average by as much as 51% in the affected fields.

Wheat-producing countries and presence of wheat blast.
Wheat-producing countries and presence of wheat blast.

How does blast infect a wheat crop?

Wheat blast spreads through infected seeds, crop residues as well as by spores that can travel long distances in the air.

Blast appears sporadically on wheat and grows well on numerous other plants and crops, so rotations do not control it. The irregular frequency of outbreaks also makes it hard to understand or predict the precise conditions for disease development, or to methodically select resistant wheat lines.

At present blast requires concurrent heat and humidity to develop and is confined to areas with those conditions. However, crop fungi are known to mutate and adapt to new conditions, which should be considered in management efforts.

How can farmers prevent and manage wheat blast?

There are no widely available resistant varieties, and fungicides are expensive and provide only a partial defense. They are also often hard to obtain or use in the regions where blast occurs, and must be applied well before any symptoms appear — a prohibitive expense for many farmers.

The Magnaporthe oryzae fungus is physiologically and genetically complex, so even after more than three decades, scientists do not fully understand how it interacts with wheat or which genes in wheat confer durable resistance.

Researchers from the International Maize and Wheat Improvement Center (CIMMYT) are partnering with national researchers and meteorological agencies on ways to work towards solutions to mitigate the threat of wheat blast and increase the resilience of smallholder farmers in the region. Through the USAID-supported Cereal Systems Initiative for South Asia (CSISA) and Climate Services for Resilient Development (CSRD) projects, CIMMYT and its partners are developing agronomic methods and early warning systems so farmers can prepare for and reduce the impact of wheat blast.

CIMMYT works in a global collaboration to mitigate the threat of wheat blast, funded by the Australian Centre for International Agricultural Research (ACIAR), the CGIAR Research Program on Wheat (WHEAT), the Indian Council of Agricultural Research (ICAR) and the Swedish Research Council (Vetenskapsrådet). Some of the partners who collaborate include the Bangladesh Wheat and Maize Research Institute (BWMRI), Bolivia’s Instituto Nacional de Innovación Agropecuaria y Forestal (INIAF), Kansas State University and the Agricultural Research Service of the US (USDA-ARS).

L.M. Suresh (center-right), Maize Pathologist at CIMMYT and Head of the MLN Screening Facility, facilitates a training on MLN with national partners. (Photo: CIMMYT)

How a disease without borders was contained

Written by Rodrigo Ordóñez on . Posted in Features.

It’s been eight years since maize lethal necrosis (MLN) was first reported on the African continent. When it appeared in Kenya’s Bomet County in 2011, a sense of panic swept across the maize sector. Experts quickly realized that all maize varieties on the market were susceptible to this viral disease, which could wipe out entire maize fields.

Spearheaded by the International Maize and Wheat Improvement Center (CIMMYT), a rapid regional response involving national agriculture research systems (NARS), national plant protection organizations and seed sector partners was set up. The response involved multiple approaches: rigorous surveillance, epidemiology research, disease management across the seed value chain, and screening and fast-tracking of the MLN-tolerant maize breeding program.

Now, CIMMYT and its partners are reflecting on the tremendous impact of transboundary coalition to contain the devastating disease.

“Country reports show there are now much less incidents of MLN in the region. We have effectively contained this disease as no new country in sub-Saharan Africa reported MLN since Ethiopia in 2014. This is a great achievement of an effective public private partnership,” noted B.M. Prasanna, Director of CIMMYT’s Global Maize Program and the CGIAR Research Program on Maize.

He was speaking at the closure workshop for the MLN Diagnostics and Management project and the MLN Epidemiology project on October 15-17, 2019, in Nairobi, Kenya. Experts from research, plant health and seed sector organizations from eastern and southern Africa reflected on the tremendous impact of the transboundary coalition to contain MLN across the region.

“The outbreak of the disease in Uganda in 2012 was a huge challenge as all the maize varieties and hybrids on the market were susceptible. With the support of CIMMYT and other partners in the national agriculture research systems, we got access to Bazooka, a high-yielding, drought- and MLN-tolerant maize variety that has helped in containing the disease,” said Godfrey Katwere, marketing manager for NASECO.

Until now, 19 MLN-tolerant and -resistant hybrids have been released, helping to keep the disease away from farmers’ fields and to stop its spillover to non-endemic countries in sub-Saharan Africa.

CIMMYT team members check for traces of the maize chlorotic mottle virus (MCMV) in maize plants during a visit to the MLN screening facility in Naivasha, Kenya. (Photo: Joshua Masinde/CIMMYT)
CIMMYT team members check for traces of the maize chlorotic mottle virus (MCMV) in maize plants during a visit to the MLN screening facility in Naivasha, Kenya. (Photo: Joshua Masinde/CIMMYT)

Science in action

The MLN screening facility, established in Naivasha in 2013, has been key to a better understanding of the disease and to setting up MLN hybrid tolerance and resistance breeding efforts. The facility, funded by the Bill & Melinda Gates Foundation and the Syngenta Foundation for Sustainable Agriculture, has supported public and private partners to screen over 200,000 germplasm with around 300,000 rows of maize.

State-of-the-art epidemiology research has been carried out to identify how the disease could be transmitted and the best diagnostics methods along the seed value chain.

MLN is caused by the combination of the maize chlorotic mottle virus (MCMV) and any of the viruses belonging to the Potyviridae family.

As part of the project, studies showed that moist soil had higher MCMV virus loads than dry soil. The studies — conducted by Benham Lockhart of University of Minnesota and Peg Redinbaugh, a professor at Ohio State University and Research Leader and Research Plant Molecular Geneticist at USDA — indicated that MCMV can stay active in runoff water, and helped in understanding how the disease is transmitted and how to define management protocols.

“Crop debris may also act as source of MCMV inoculum but for a limited period of up to two months,” said L.M. Suresh, CIMMYT Maize Pathologist, in reference to soil transmission studies conducted by CIMMYT. “A host-free period of two months is, therefore, recommended for effective management of MLN,” he noted.

Rapid and low-cost MLN-causing virus detection methods such as immunostrips and ELISA-based tests were adopted at scale.

“After optimizing the protocols for MLN viruses’ diagnosis suitable for African systems, we transferred these technologies to [national plant protection organizations] and seed companies, not just within the endemic countries but also to the non-endemic countries in southern and west Africa, through intensive trainings,” Prasanna explained. “We created a digital MLN surveillance tool under the Open Data Kit (ODK) app for NPPOs and other stakeholders to effectively carry out MLN surveillance on the ground. The survey information is captured in real time in farmers’ and seed production fields coupled with rapid immunostrips MLN tests,” he remarked.

According to Francis Mwatuni, Project Manager of the MLN Diagnostics and Management project, this proactive and collaborative surveillance network has been an important outcome that helped curb MLN from spreading to non-endemic regions. “In 2016, we only had 625 surveillance points. By 2019, the surveillance points in all the target countries stood at 2,442, which intensified the alertness on MLN presence and how to effectively deal with it,” Mwatuni said. In total, 7,800 surveillance points were covered during the project implementation period.

Over 100 commercial seed firms have also been trained on how to produce MLN-free seed to facilitate trade within the endemic nations and to ensure the disease is not transferred to the non-endemic countries via contaminated seeds.

Participants at the MLN projects closure workshop stand for a group photo. (Photo: Joshua Masinde/CIMMYT)
Participants at the MLN projects closure workshop stand for a group photo. (Photo: Joshua Masinde/CIMMYT)

Sustaining the fight

Researchers continue to work to lessen MLN’s resurgence or new outbreaks. In 2018, incidents in all endemic countries, except Ethiopia, declined sharply. One suggested explanation for the upsurge in Ethiopia, especially in the northwestern region, was reduced use of pesticide for fall armyworm control, as compared to previous years where heavy application of these pesticides also wiped out MLN insect vectors, such as maize thrips and aphids.

At the end of the projects, partners urged for the scale-up of second-generation MLN-tolerant and -resistant varieties. They explained farmers would fully benefit from recent genetic gains of the new improved varieties and its protection against MLN.

“Despite the success registered, MLN is still a major disease requiring constant attention. We cannot rest as we redirect our energies at sustaining and building on the gains made,” said Beatrice Pallangyo, principal agricultural officer in Tanzania’s Ministry of Agriculture, Food Security and Cooperatives.

After the success containing MLN, stakeholders suggested the need to stay alert on other transboundary pests and diseases such as the tar spot complex, which could be a major threat to Africa’s food security in case of an outbreak.

Study reveals diversity “blueprint” to help maize crops adapt to changing climates

Written by on . Posted in News.

EL BATAN, Mexico (CIMMYT) – Scientists have unlocked evolutionary secrets of landraces through an unprecedented study of allelic diversity, revealing more about the genetic basis of flowering time and how maize adapts to variable environments, according to new research published in Nature Genetics journal. The discovery opens up opportunities to explore and use landrace diversity in new ways to help breeders adapt crops to climate change and other emerging challenges to crop production.

Farmers worldwide have been ingeniously adapting landrace maize varieties to their local environments for thousands of years. In this landmark study, over 4,000 landraces from across the Americas were analyzed and their DNA characterized using recent advances in genomics.

A unique experimental strategy was developed to study and learn more about the genes underlying maize adaptation by researchers with the MasAgro Biodiversidad program and the Seeds of Discovery (SeeD) initiative.

Significantly, the study identified 100 genes, among the 40,000 that make up the maize genome, influencing adaptation to latitude, altitude, growing season and the point at which maize plants flower in the field.

Flowering time helps plants adapt to different environments. It is measured as the period between planting and the emergence of flowers, and is a basic mechanism through which plants integrate environmental information to balance when to make seeds instead of more leaves. The seeds form the next generation making flowering time a critically important feature in a plant’s life cycle.

Over the next century, increasingly erratic weather patterns and environmental changes projected to result from climate change mean that such crops as maize will need to adapt at an unprecedented rate to maintain stable production globally.

“This research offers a blueprint of how we can rapidly assess genetic resources for a highly variable crop species like maize, and identify, in landraces, those elements of the maize genome which may benefit breeders and farmers,” said molecular geneticist Sarah Hearne, who leads maize research within MAB/SeeD, a collaboration led by the International Maize and Wheat Improvement Center (CIMMYT) with strong scientific partnerships with Mexico’s research institute for agriculture, livestock and forests (INIFAP), the Antonio Narro Autonomous Agrarian University (UAAAN) in Mexico and Cornell University in the United States.

“This is the most extensive study, in terms of diversity, that has been conducted on maize flowering,” said Martha Willcox, maize landrace improvement coordinator at CIMMYT . “This was achieved using landraces, the evaluation of which is an extremely difficult and complex task.”

The groundbreaking study was supported by Mexico’s Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA) through the Sustainable Modernization of Traditional Agriculture (MasAgro) initiative. Additional support from the U.S. Department of Agriculture – Agricultural Research Service, Cornell University and the National Science Foundation facilitated the completion of vast quantities of data analysis.

“The knowledge we have gained from this work gives us something similar to a manual of ‘how to go on a successful treasure hunt;’ within the extensive genetic diversity that exists for maize. This knowledge can accelerate and broaden our work on developing resilient varieties, building upon millennia of natural and farmer selection in landraces,” Hearne said.

CORRECT CITATION:

Romero-Navarro, J. A., Willcox, M., Burgueño, J. Romay M. Swarts, K., Trachsel, S., Preciado, E., Terron, A., Vallejo Delgado, H., Vidal, V., Ortega, A., Espinoza Banda, A., Gómez Montiel, N.O., Ortiz-Monasterio, I., San Vicente, F., Guadarrama Espinoza, A., Atlin, G., Wenzl, P., Hearne, S.*, Buckler, E*. A study of allelic diversity underlying flowering time adaptation in maize landraces. Nature Genetics. http://www.nature.com/ng/journal/vaop/ncurrent/full/ng.3784.html
*Corresponding authors