Posts Tagged ‘Pawan Singh’

Researchers in Zambia confirm: Wheat blast has made the intercontinental jump to Africa

Wheat blast in experimental plots (Photo: Batiseba Tembo, ZARI)

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.

Wheat blast in a farmer’s field in Mpika district, 2020 (Photo: Batiseba Tembo, ZARI)

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.”

Wheat blast observed in Mpika, Zambia  (Photo: Batiseba Tembo, ZARI)

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.”


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 (CIMMYT)

Batiseba Tembo, Wheat Breeder, Zambian Agricultural Research Institute (ZARI) batemfe@yahoo.com

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 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.

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 www.cimmyt.org.

University of Queensland honors student studies tan spot resistance in wheat at CIMMYT

This story, part of a series on the international agricultural research projects of recipients of the Crawford Fund’s International Agricultural Student Award, was originally posted on the Crawford Fund blog

In 2018, Tamaya Peressini, from The Queensland Alliance for Agriculture and Food Innovation (QAAFI), a research institute of the University of Queensland (UQ), travelled to CIMMYT in Mexico as part of her Honours thesis research focused on a disease called tan spot in wheat.

Tamaya performing disease evaluations 10 days post infection at CIMMYT’s glasshouse facilities

Tan spot is caused by the pathogen Pyrenophora triciti-repentis (Ptr), and her project aimed to evaluate the resistance of tan spot in wheat to global races to this pathogen.

“The germplasm I’m studying for my thesis carries what is known as adult plant resistance (or APR) to tan spot, which has demonstrated to be a durable source of resistance in other wheat pathosystems such as powdery mildew,” said Tamaya.

Symptoms of tan spot on wheat plants

Tan spot is prevalent worldwide, and in Australia causes the most yield loss out of the foliar wheat diseases. In Australia, there is only one identified pathogen race that is prevalent called Ptr Race 1. For Ptr Race 1, the susceptibility gene Tsn1 in wheat is the main factor that results in successful infection in Ptr strains that carry Toxin A. However, globally it is a more difficult problem, as there are seven other pathogen races that consist of different combinations of necrotrophic toxins. Hence, developing cultivars that are multi-race resistant to Ptr presents a significant challenge to breeders as multiple resistant genes would be required for resistance to other pathogens.

“At CIMMYT I evaluated the durability of APR I identified in plant material in Australia by inoculating with a local strain of Ptr and also with a pathogen that shares ToxA: Staganospora nodorum.”

“The benefit of studying this at CIMMYT was that I had access to different strains of the pathogen which carry different virulence factors of disease, I was exposed to international agricultural research, and importantly, I was able to create research collaborations that would allow the APR detected in this population to have the potential to reach developing countries to assist in developing durably resistant wheat cultivars for worldwide deployment,” explained Tamaya.

Recent work in Dr Lee Hickey’s laboratory in Queensland has identified several landraces from the Vavilov wheat collection that exhibited a novel resistance to tan spot known as adult plant resistance (APR). APR has proven to be a durable and broad-spectrum source of resistance in wheat crops; namely with the Lr34 gene which confers resistance to powdery mildew and leaf stem rust of wheat.

“My research is focussed on evaluating this type of resistance and identifying whether it is resistant to multiple pathogen species and other races of Ptr. This is important to the Queensland region, as the northern wheat belt is significantly affected by tan spot disease. Introducing durable resistance genes to varieties in this region would be an effective pre-breeding strategy because it would help develop crop varieties that would have enhanced resistance to tan spot should more strains reach Australia. Furthermore, it may provide durable resistance to other necrotrophic pathogens of wheat,” said Tamaya.

The plant material Tamaya studied in her honours thesis was a recombinant inbred line (RIL) population, with the parental lines being the APR landrace (carries Tsn1) and the susceptible Australian cultivar Banks (also carries Tsn1). To evaluate the durability of resistance in this population to other strains of Ptr, this material along with the parental lines of the population and additional land races from the Vavilov wheat collection were sent to CIMMYT for Tamaya to perform a disease assay.

“At CIMMYT I evaluated the durability of APR identified in plant material in Australia by inoculating with a local strain of Ptr and also with a pathogen that shares ToxA: Staganospora nodorum. After infection, my plant material was kept in 100 per cent humidity for 24 hours (12 hours light and 12 hours dark) and then transferred back to regular glasshouse conditions. At 10 days post infection I evaluated the resistance in the plant material.”

From the evaluation, the APR RIL line demonstrated significant resistance compared to the rest of the Australian plant material against both pathogens. The results are highly promising, as they demonstrate the durability of the APR for both pre-breeding and multi-pathogen resistance breeding. Furthermore, this plant material is now available for experimental purposes at CIMMYT where further trials can validate how durable the resistance is to other necrotrophic pathogens and also be deployed worldwide and be tested against even more strains of Ptr.
“During my visit at CIMMYT I was able to immerse myself in the Spanish language and take part in professional seminars, tours, lab work and field work around the site. A highlight for me was learning to prepare and perform toxin infiltrations for an experiment comparing the virulence of different strains of spot blotch.”

“I also formed valuable friendships and research partnerships from every corner of the globe and had valuable exposure to the important research underway at CIMMT and insight to the issues that are affecting maize and wheat growers globally. Of course, there was also the chance to travel on weekends; where I was able to experience the lively Mexican culture and historical sites – another fantastic highlight to the trip!”

Visiting the Sun and Moon temples of Teotihuacan

“I would like to thank CIMMYT and Dr Pawan Singh for hosting me and giving the opportunity to learn, grow and experience the fantastic research that is performed at CIMMYT and opportunities to experience parts of Mexico. The researchers and lab technicians were all so friendly and accommodating. I would also like to thank my supervisor Dr Lee Hickey for introducing this project collaboration with CIMMYT. Lastly, I would like to thank the Crawford Fund Queensland Committee for funding this visit; not only was I able to immerse myself in world class plant pathology research, I have been given valuable exposure to international agricultural research that will give my research career a boost in the right direction,” concluded Tamaya.