Wheat blast, caused by the fungus Magnaporthe oryzae pathotype Triticum, was first identified in 1985 in South America, but has been seen in Bangladesh in recent years. The expansion of the disease is a great concern for regions of similar environmental conditions in South Asia, and other regions globally.
Although management of the disease using fungicide is possible, it is not completely effective for multiple reasons, including inefficiency during high disease pressure, resistance of the fungal populations to some classes of fungicides, and the affordability of fungicide to resource-poor farmers. Scientists see the development and deployment of wheat with genetic resistance to blast as the most sustainable and farmer-friendly approach to preventing devastating outbreaks around the world.
In an article published in Nature Scientific Reports, a team of scientists from the International Maize and Wheat Improvement Center (CIMMYT) and partners, led by CIMMYT associate scientist Philomin Juliana, conducted a large genome-wide association study to look for genomic regions that could also be associated with resistance to wheat blast.
Using data collected over the last two years on CIMMYT’s International Bread Wheat Screening Nurseries (IBWSNs) and Semi-Arid Wheat Screening Nurseries (SAWSNs) by collaborators at the Bangladesh Wheat and Maize Research Institute (BWMRI) and the Instituto Nacional de Innovación Agropecuaria y Forestal (INIAF) in Bolivia, Philomin and fellow scientists found 36 significant markers on chromosome 2AS, 3BL, 4AL and 7BL that appeared to be consistently associated with blast resistance across different environments. Among these, 20 markers were found to be in the position of the 2NS translocation, a chromosomal segment transferred to wheat from a wild relative, Aegilops ventricosa, that has very strong and effective resistance to wheat blast.
The team also gained excellent insights into the blast resistance of the globally-distributed CIMMYT germplasm by genomic fingerprinting a panel over 4000 wheat lines for the presence of the 2NS translocation, and found that it was present in 94.1% of lines from IBWSN and 93.7% of lines from SAWSN. Although it is reassuring that such a high percentage of CIMMYT wheat lines already have the 2NS translocation and implied blast resistance, finding other novel resistance genes will be instrumental in building widespread, global resilience to wheat blast outbreaks in the long-term.
Read the publication by Philomin Juliana, Xinyao He, Muhammad R. Kabir, Krishna K. Roy, Md. Babul Anwar, Felix Marza, Jesse Poland, Sandesh Shrestha, Ravi P. Singh, and Pawan K. Singh
This work was made possible by the generous support of the Delivering Genetic Gains in Wheat (DGGW) project funded by the Bill & Melinda Gates Foundation, the U.K. Foreign, Commonwealth & Development Office (FCDO) and managed by Cornell University, the U.S. Agency for International Development’s Feed the Future initiative, the CGIAR Research Program on Wheat (WHEAT), the Indian Council of Agricultural Research (ICAR), The Swedish Research Council (Vetenskapsråd), and the Australian Centre for International Agricultural Research (ACIAR), #CIM/2016/219.
Wheat blast, a fast-acting and devastating fungal disease, has been reported for the first time on the African continent, according to a new article published by scientists from the Zambian Agricultural Research Institute (ZARI), the International Maize and Wheat Improvement Center (CIMMYT) and the US Department of Agriculture – Foreign Disease Weed Science Research Unit (USDA-ARS) in the scientific journal PLoS One.
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.
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
“The first occurrence of the disease was very distressing. This happened at the spike stage, and caused significant losses,” said Tembo. “Nothing of this nature has happened before in Zambia.”
Researchers were initially confused when symptoms of the disease in the Mpika fields were first reported. 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 7 days, a whole field can be attacked,” said Tembo. Samples were collected and analyzed in the ZARI laboratory, and suspicions grew among researchers that this may be a new disease entirely.
A history of devastation
Wheat blast, caused by Magnaporthe oryzae pathotype Triticum (MoT), was initially discovered in Brazil in 1985, and within decades had affected around 3 million hectares of wheat in South America alone. The disease made its first intercontinental jump to Asia in 2016, causing a severe outbreak in Bangladesh, reducing yield on average by as much as 51% in the affected fields.
The disease has now become endemic to Bangladesh, and has potential to expand to similar warm, humid and wet environments in nearby India and Pakistan, as well as other regions of favorable disease conditions.
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.
Developing expert opinions
Tembo participated in the Basic Wheat Improvement Course at CIMMYT 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.
All experiments confirmed the presence of Magnaporthe oryzae pathotype Triticum (MoT).
“This is a disaster which needs immediate attention,” said Tembo. “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.”
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, such as an international course led by the Bangladesh Wheat and Maize Research Institute (BWMRI) in collaboration with CIMMYT, WHEAT and others, invite international participants to gain new technical skills in blast diagnostics and treatment and understand different strategies being developed to mitigate the wheat blast threat. WHEAT scientists and partners are also working quickly to study genetic factors that increase resistance to the disease and develop early warning systems, among other research interventions.
“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,” said Singh.
Tembo concluded, “It is imperative that the regional and global scientific community join hands to determine effective measures to halt further spread of this worrisome disease in Zambia and beyond.”
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 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).
About Accelerating Genetic Gains in Maize and Wheat for Improved Livelihoods
Accelerating Genetic Gains in Maize and Wheat for Improved Livelihoods (AGG) is a 5-year project that brings together partners in the global science community and in national agricultural research and extension systems to accelerate the development of higher-yielding varieties of maize and wheat — two of the world’s most important staple crops. Funded by the Bill & Melinda Gates Foundation, the UK Foreign, Commonwealth & Development Office (FCDO), the U.S. Agency for International Development (USAID) and the Foundation for Food and Agriculture Research (FFAR), AGG fuses innovative methods that improve breeding efficiency and precision to produce and deliver high-yielding varieties that are climate-resilient, pest- and disease-resistant, highly nutritious, and targeted to farmers’ specific needs.
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 www.cimmyt.org.
An ongoing projectwas praised for its swift progress in the
fight against wheat blast in Bangladesh and South Asia
a mid-term review event last month at the BRAC Learning Centre in Dinajpur,
Bangladesh, professionals from the Bangladesh Ministry of Agriculture, the
Bangladesh Wheat and Maize Research Institute (BWMRI), the Bangladesh
Agriculture Research Institute (BARI), the Department of Agriculture Extension
(DAE), the Krishi Gobeshona Foundation (KGF), the Bangladesh Agriculture
Development Corporation (BADC) and the International Maize and Wheat
Improvement Center (CIMMYT) discussed progress made in the battle against wheat
blast in Bangladesh and South Asia.
Wheat blast is a fast-acting and devastating fungal disease that threatens wheat production and food security in South America and South Asia. The disease, which originated in South America and first appeared in Bangladesh in 2016, can by dispersed by wind across large distances and spores can be seed borne. There is deep concern among scientists that the disease could spread further across South Asia. A 2018 ex-ante analysis found that in Bangladesh, India and Pakistan wheat blast could potentially cause losses of 0.89 – 1.77 million tons each year, with 7 million hectares of growing area at risk.
The project, funded by the Australian Centre for International Agricultural Research (ACIAR) addresses wheat blast in Bangladesh and South Asia through the identification of new sources of resistance genes for wheat blast and development of wheat blast resistant varieties. The germplasm, genes and markers, and genetic information developed through the project are shared with South Asian national wheat breeding programs and other researchers, finally ending up in farmers’ fields as resistant varieties.
review meeting was chaired by BWMRI Director General Israil Hossain, and
featured remarks by Bangladesh’s Additional Secretary of the Ministry of
Agriculture Kamala Ranjan Das.
project has over-delivered on its milestones,” said Eric Huttner, ACIAR
Research Program Manager and lead of the review. “It’s very likely that the
project will reduce the risk of blast on wheat production in Bangladesh.”
impacts in terms of research capacity and infrastructure are very clear:
The project-established precision phenotyping platform in Jashore
— the first of its kind in Bangladesh and the region — is running at full capacity, screening for
blast in wheat germplasm materials from as far away as China, the United States
and Europe. The facility currently has
the capacity to evaluate almost 5,000 wheat germplasm materials per season and
there are ongoing plans for expansion and improvement.
Sixty-nine researchers and development professionals, including 9 women,
have benefited from the capacity development activities.
Molecular research is also making progress. Pawan Singh, project
leader and head of Wheat Pathology at CIMMYT, noted that the rapid response was
possible due to collective and collaborative action by research partners in
this project and beyond.
Meeting attendees emphasized the urgency and importance of
the project, which is set to conclude in 2021, in the battle against a
fast-moving and devastating disease.
As Huttner told attendees, “Now the resistant or tolerant
materials need to be efficiently deployed for breeding high-performance wheat
varieties that reach stakeholders as early as possible.”
New study finds that wheat farmers often do not accurately identify their varieties.
Despite the severe social and political unrest that constrain agriculture in Afghanistan, many farmers are growing high-yielding, disease resistant varieties developed through international, science-based breeding and made available to farmers as part of partnerships with national wheat experts and seed producers.
These and other findings have emerged from the first-ever large-scale use of DNA fingerprinting to assess Afghanistan farmers’ adoption of improved wheat varieties, which are replacing less productive local varieties and landraces, according to a paper published yesterday in the science journal BMC Genomics.
The study is part of an activity supported between 2003 and 2018 by the Australian Department of Foreign Affairs and Trade, through which the Agricultural Research Institute of Afghanistan and the International Maize and Wheat Improvement Center (CIMMYT) introduced, tested, and released improved wheat varieties.
“As part of our study, we established a ‘reference library’ of released varieties, elite breeding lines, and Afghan wheat landraces, confirming the genetic diversity of the landraces and their value as a genetic resource,” said Susanne Dreisigacker, wheat molecular breeder at CIMMYT and lead author of the new paper.
“We then compared wheat collected on farmers’ fields with the reference library. Of the 560 wheat samples collected in 4 provinces during 2015-16, farmers misidentified more than 40%, saying they were of a different variety from that which our DNA analyses later identified.”
Wheat is the most important staple crop in Afghanistan — more than 20 million of the country’s rural inhabitants depend on it — but wheat production is unstable and Afghanistan has been importing between 2 and 3 million tons of grain each year to meet demand.
Over half of the population lives below the poverty line, with high rates of malnutrition. A key development aim in Afghanistan is to foster improved agronomic practices and the use of high quality seed of improved wheat varieties, which together can raise yields by over 50%.
“Fungal diseases, particularly yellow rust and stem rust, pose grave threats to wheat in the country,” said Eric Huttner, research program manager for crops at the Australian Centre for International Agricultural Research (ACIAR) and co-author of the present paper. “It’s crucial to know which wheat varieties are being grown where, in order to replace the susceptible ones with high-performing, disease resistant varieties.”
Varietal adoption studies typically rely on questionnaires completed by breeders, extension services, seed producers, seed suppliers, and farmers, but such surveys are complicated, expensive, and often inaccurate.
“DNA fingerprinting resolves uncertainties regarding adoption and improves related socioeconomic research and farm policies,” Huttner explained, adding that for plant breeding this technology has been used mostly to protect intellectual property, such as registered breeding lines and varieties in more developed economies.
This new study was commissioned by ACIAR as a response to a request from the Government of Afghanistan for assistance in characterizing the Afghan wheat gene bank, according to Huttner.
“This provided the reference library against which farmers’ samples could be compared,” he explained. “Accurately identifying the varieties that farmers grow is key evidence on the impact of introducing improved varieties and will shape our future research
Joint research and development efforts involving CIMMYT, ACIAR, the Food and Agriculture Organization (FAO) of the United Nations, the International Centre of Agricultural Research in Dry Areas (ICARDA), French Cooperation, and Afghanistan’s Ministry of Agriculture, Irrigation and Livestock (MAIL) and Agricultural Research Institute (ARIA) have introduced more than 400 modern, disease-resistant wheat varieties over the last two decades. Nearly 75% of the wheat grown in the areas surveyed for this study comes from these improved varieties.
“New gene sequencing technologies are increasingly affordable and their cost will continue to fall,” said Dreisigacker. “Expanded use of DNA fingerprinting can easily and accurately identify the wheat cultivars in farmers’ fields, thus helping to target breeding, agronomy, and development efforts for better food security and farmer livelihoods.”
For more information, or to arrange interviews with the researchers, please contact:
About CIMMYT The International Maize and Wheat 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 CGIAR and leads the CGIAR Research 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.
About ACIAR As Australia’s specialist international agricultural research for development agency, the Australian Centre for International Agricultural Research (ACIAR) brokers and funds research partnerships between Australian scientists and their counterparts in developing countries. Since 1982, ACIAR has supported research projects in eastern and southern Africa, East Asia, South and West Asia and the Pacific, focusing on crops, agribusiness, horticulture, forestry, livestock, fisheries, water and climate, social sciences, and soil and land management. ACIAR has commissioned and managed more than 1,500 research projects in 36 countries, partnering with 150 institutions along with more than 50 Australian research organizations.
About Afghanistan’s Ministry of Agriculture, Irrigation and Livestock The Ministry of Agriculture, Irrigation and Livestock (MAIL) of the Islamic Republic of Afghanistan works on the development and modernization of agriculture, livestock and horticulture. The ministry launches programs to support the farmers, manage natural resources, and strengthen agricultural economics. Its programs include the promotion and introduction of higher-value economic crops, strengthening traditional products, identifying and publishing farm-tailored land technologies, boosting cooperative programs, agricultural economics, and export with marketing.
To build resilience against the threat of wheat blast, training sessions were held in Bangladesh to increase the reach of research findings and possible solutions as well as to educate the stakeholders involved. Since 2017, hands-on training on disease screening and surveillance of wheat blast have been organized every year in Bangladesh, with participation of national and international scientists. The third of its kind was jointly organized by the International Maize and Wheat Improvement Center (CIMMYT), Wheat and Maize Research Institute (BWMRI), and the Department of Agricultural Extension (DAE) Bangladesh during 19-28 February, 2019 at Regional Agricultural Research Station, Jashore with financial support from the Australian Centre for International Agricultural Research (ACIAR), the CGIAR Research Program on Wheat (WHEAT), the Indian Council of Agricultural Research (ICAR), the Krishi Gobeshona Foundation (KGF) and the U.S. Agency for International Development (USAID). The objective of the training was to learn the basic techniques of pathogen identification and its culturing, field inoculation and disease scoring and share experiences regarding combating the disease and its progress among the participants from home and abroad. Thirty five wheat scientists from China, India and Nepal as well as from BWMRI, DAE and CIMMYT in Bangladesh participated in the training.
The training was inaugurated by Kamala Ranjan Das, Additional Secretary (Research), Ministry of Agriculture, Bangladesh. The Director General of BWMRI, Dr. Naresh C. D. Barma was the Chair and Dr. T. P. Tiwari, Country Representative, CIMMYT Bangladesh and Additional Director of Jashore region of DAE were the special guests in the inaugural session. In addition to Bangladeshi experts, Dr. José Maurício C. Fernandes from Brazil, Dr. Pawan K. Singh from CIMMYT, Mexico and Dr. Timothy J. Krupnik from CIMMYT, Bangladesh presented the updates on the techniques for mitigating the disease. Dr. M. Akhteruzzaman, Deputy Director of DAE, Meherpur, who has been working very closely with wheat blast research and extension, spoke on the history and present status of wheat blast in Bangladesh. It was a unique opportunity for the trainees to listen from grass root level experience based on the real situation in the farmers’ fields.
Wheat is especially susceptible to blast infection during warm and humid weather conditions. While the fungus infects all above ground parts of the crop, infection in spikes is most critical and responsible for yield loss. Hence, to determine whether blast is endemic to the specific region and also to assess the epidemic potential in unaffected regions, Dr. Fernandes developed a wheat blast forecasting model with support from CIMMYT Bangladesh. To collect data on the presence of wheat blast spores in the air, CIMMYT, in collaboration with BWMRI, installed four spore traps in four different wheat fields in Meherpur, Faridpur, Rajshahi and Dinajpur districts of Bangladesh. The results from these spore traps and weather parameters will help validate the wheat blast forecasting model. After final validation, the recommendation message will be sent to farmers and DAE personnel through mobile app. This will help farmers decide the perfect time for spraying fungicide to control blast effectively.
During the training participants received the hands-on experience of activities in the precision phenotypic platform (PPP) for wheat blast, where 4500 germplasm from different countries of the world and CIMMYT Mexico are being tested under artificial inoculated conditions. To keep the environment sufficiently humid, the trial is kept under mist irrigation to facilitate proper disease development. Trainees learned identification of leaf and spike symptoms of wheat blast, identification and isolation of conidia under microscope, inoculum preparation, tagging selected plants in the fields for inoculation, field inoculation of germplasms being tested at the PPP and more.
According to the United States Department of Agriculture (USDA), wheat consumption in Bangladesh is 7.7 million tons as of 2018 while only 1.25 million tons are supplied domestically. Since the majority of wheat is imported, it will adversely affect the economy if the comparatively smaller amount the country produces decreases due to blast. So the impact of wheat blast is not limited to food production but affects the economy as a whole, and steps to help mitigate the disease are crucial in ensuring healthy growth of wheat yield.
Wheat blast, caused by Magnaporthe oryzae pathotype Triticum (MoT), was first discovered in Brazil in 1985 and then surprisingly appeared in the wheat fields of Bangladesh in 2016, causing 25-30% yield loss in 15,000 ha. As an immediate response to this crisis, CIMMYT and the government of Bangladesh have worked together to mitigate the disease, most notably by distributing factsheets to farmers, conducting routine follow-ups followed by the development and rapid release of blast resistant wheat variety BARI Gom 33 and tolerant varieties (BARI Gom 30 and 32) and strengthening research on blast.
The grain in this blast-blighted wheat head has been turned to chaff (Photo: CKnight/ DGGW/ Cornell University)
EL BATAN, Mexico (July 1, 2017) — The urgent global response to wheat blast, a little understood fungal disease that appeared suddenly and blighted wheat crops in Bangladesh in 2016, has received a big boost from the Australian Centre for International Agricultural Research (ACIAR), which is funding an initial four-year research project to breed blast resistant wheat varieties.
The wheat blast pathogen, which can move on air currents or ride infected grain, is likely to spread soon throughout South Asia, a region where rice-wheat cropping rotations cover 13 million hectares and nearly a billion inhabitants eat wheat.
Under the initiative led by the Mexico-based International Maize and Wheat Improvement Center (CIMMYT), researchers from nearly a dozen institutions worldwide will join forces to develop high-yielding varieties with resistance to blast, reducing the risk of catastrophic crop losses.
“This research project aims to identify sources of resistance, characterize the resistance genes, and develop DNA markers to create resistant, locally-adapted wheat varieties and make them available to farmers,” said Pawan Singh, head of wheat pathology at CIMMYT, an organization whose breeding lines are used by public research programs and seed companies in over 100 countries. “The work could not be more critical, given the likelihood of blast’s spread and its deadly virulence for wheat varieties worldwide.”
Caused by the fungus Magnaporthe oryzae pathotype Triticum (MoT), wheat blast was first identified in Brazil in 1985 and has threatened and constrained wheat farming in South America for decades.
Fungicides offer only partial control of blast, according to N.C.D. Barma, director at Bangladesh’s Wheat Research Centre (WRC). “Under the right conditions, the fungus can develop with lightning speed, blanching and withering the grain,” Barma said. “By that time the farmer’s losses are near total.”
Wheat experts and government officials in Bangladesh, in collaboration with CIMMYT, sounded the alarm last year, when a surprise blast outbreak struck 15,000 hectares of wheat fields near the country’s border with India.