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Ten things you should know about maize and wheat

Can you imagine a world without maize and wheat? We can’t!

This article by Mike Listman and Rodrigo Ordóñez was originally posted on the website of the International Maize and Wheat Improvement Center.

As the calendar turns to October 16, it is time to celebrate World Food Day. At the International Maize and Wheat Improvement Center (CIMMYT), we are bringing you a few facts you should know about maize and wheat, two of the world’s most important crops.

1. Billions of people eat maize and wheat.

Wheat is eaten by 2.5 billion people in 89 countries. About 1 billion of them live on less than $1.90 a day and depend on wheat as their main food.

Maize is the preferred staple food for 900 million poor consumers and the most important food crop in sub-Saharan Africa.

According to 2017 figures, maize is grown on 197 million hectares. Wheat covers 218 million hectares, an area larger than France, Germany, Italy, Spain and the UK combined. The total annual harvest of these two crops amounts to about 1.9 billion tons of grain.

A little girl eats a freshly-made roti while the women of her family prepare more, at her home in the village of Chapor, in the district of Dinajpur, Bangladesh. (Photo: S. Mojumder/Drik/CIMMYT)
A little girl eats a freshly-made roti while the women of her family prepare more, at her home in the village of Chapor, in the district of Dinajpur, Bangladesh. (Photo: S. Mojumder/Drik/CIMMYT)

2. Of the 300,000 known edible plant species, only 3 account for around 60% of our calories and proteins: maize, wheat and rice.

About 300,000 of the plant species on Earth could be eaten, but humans eat a mere 200 species globally.

Approximately 75% of the world’s food is generated from only 12 plants and 5 animal species. In fact, more than half of our plant-sourced protein and calories come from just three species: maize, rice and wheat.

Farmers Kanchimaya Pakhrin and her neighbor Phulmaya Lobshan weed rice seedling bed sown by machine in Purnabas, Kanchanpur, Nepal. (Photo: P. Lowe/CIMMYT)
Farmers Kanchimaya Pakhrin and her neighbor Phulmaya Lobshan weed rice seedling bed sown by machine in Purnabas, Kanchanpur, Nepal. (Photo: P. Lowe/CIMMYT)

3. CIMMYT manages humankind’s most diverse maize and wheat collections.

The organization’s germplasm bank, also known as a seed bank, is at the center of its crop-breeding research. This remarkable, living catalog of genetic diversity is comprised of over 28,000 unique seed collections of maize and 150,000 of wheat.

From its breeding programs, CIMMYT sends half a million seed packages to 800 partners in 100 countries each year. With researchers and farmers, the center also develops and promotes more productive and precise maize and wheat farming methods and tools that save money and resources such as soil, water, and fertilizer.

Shelves filled with maize seed samples make up the maize active collection in the Wellhausen-Anderson Plant Genetic Resources Center at CIMMYT's global headquarters in Texcoco, Mexico. Disaster-proof features of the bank include thick concrete walls and back-up power systems. (Photo: Xochiquetzal Fonseca/CIMMYT)
Shelves filled with maize seed samples make up the maize active collection in the Wellhausen-Anderson Plant Genetic Resources Center at CIMMYT’s global headquarters in Texcoco, Mexico. Disaster-proof features of the bank include thick concrete walls and back-up power systems. (Photo: Xochiquetzal Fonseca/CIMMYT)

4. Maize and wheat are critical to a global food system makeover.

In 2010, agriculture accounted for about one-quarter of global greenhouse gas emissions.

High-yield and climate-resilient maize and wheat varieties, together with a more efficient use of resources, are a key component of the sustainable intensification of food production needed to transform the global food system.

Miguel Ku Balam (left), from Mexico's Quintana Roo state, cultivates the traditional Mesoamerican milpa system. "My family name Ku Balam means 'Jaguar God'. I come from the Mayan culture," he explains. "We the Mayans cultivate the milpa for subsistence. We don't do it as a business, but rather as part of our culture — something we inherited from our parents." (Photo: Peter Lowe/CIMMYT)
Miguel Ku Balam (left), from Mexico’s Quintana Roo state, cultivates the traditional Mesoamerican milpa system. “My family name Ku Balam means ‘Jaguar God’. I come from the Mayan culture,” he explains. “We the Mayans cultivate the milpa for subsistence. We don’t do it as a business, but rather as part of our culture — something we inherited from our parents.” (Photo: Peter Lowe/CIMMYT)

5. We must increase maize and wheat yields to keep feeding the world.

By the year 2050, there will be some 9.7 billion people living on Earth. To meet the growing demand from an increasing population and changing diets, maize yields must go up at least 18% and wheat yields 15% by 2030, despite hotter climates and more erratic precipitation.

Farmers walk through a wheat field in Lemo district, Ethiopia. (Photo: P. Lowe/CIMMYT)
Farmers walk through a wheat field in Lemo district, Ethiopia. (Photo: P. Lowe/CIMMYT)

6. Climate-smart farming allows higher yields with fewer greenhouse gas emissions.

Decades of research and application by scientists, extension workers, machinery specialists, and farmers have perfected practices that conserve soil and water resources, improve yields under hotter and dryer conditions, and reduce the greenhouse gas emissions and pollution associated with maize and wheat farming in Africa, Asia, and Latin America.

Kumbirai Chimbadzwa (left) and Lilian Chimbadzwa stand on their field growing green manure cover crops. (Photo: Shiela Chikulo/CIMMYT)
Kumbirai Chimbadzwa (left) and Lilian Chimbadzwa stand on their field growing green manure cover crops. (Photo: Shiela Chikulo/CIMMYT)

7. Wholegrain wheat is good for your health.

An exhaustive review of research on cereal grains and health has shown that eating whole grains, such as whole-wheat bread and other exceptional sources of dietary fiber, is beneficial for human health and associated with a reduced risk of cancer and other non-communicable diseases.

According to this study, consumption of whole grains is associated with a lower risk of coronary disease, diabetes, hypertension, obesity and overall mortality. Eating whole and refined grains is beneficial for brain health and associated with reduced risk for diverse types of cancer. Evidence also shows that, for the general population, gluten- or wheat-free diets are not inherently healthier and may actually put individuals at risk of dietary deficiencies.

Whole wheat bread. (Photo: Rebecca Siegel/Flickr)
Whole wheat bread. (Photo: Rebecca Siegel/Flickr)

8. Biofortified maize and wheat are combating “hidden hunger.”

Hidden hunger” is a lack of vitamins and minerals. More than 2 billion people worldwide are too poor to afford diverse diets and cannot obtain enough critical nutrients from their staple foods.

Too help address this, CIMMYT — along with HarvestPlus and partners in 18 countries — is promoting more than 60 maize and wheat varieties whose grain contains more of the essential micronutrients zinc and provitamin A. These biofortified varieties are essential in the fight against “hidden hunger.”

A 2015 study published in The Journal of Nutrition found that vitamin A-biofortified orange maize significantly improves visual functions in children, like night vision. (Photo: Libby Edwards/HarvestPlus)
A 2015 study published in The Journal of Nutrition found that vitamin A-biofortified orange maize significantly improves visual functions in children, like night vision. (Photo: Libby Edwards/HarvestPlus)

9. 53 million people are benefiting from drought-tolerant maize.

Drought-tolerant maize developed by CIMMYT and partners using conventional breeding provides at least 25% more grain than conventional varieties in dry conditions in sub-Saharan Africa — this represents as much as 1 ton per hectare more grain on average.

These varieties are now grown on nearly 2.5 million hectares, benefiting an estimated 6 million households or 53 million people.

One study shows that drought-tolerant maize varieties can provide farming families in Zimbabwe an extra 9 months of food at no additional cost.

10. Quality protein maize is helping reduce child malnutrition.

Developed by CIMMYT during the 1970s and 1980s and honored by the 2000 World Food Prize, quality protein maize features enhanced levels of lysine and tryptophan, essential amino acids that can help reduce malnutrition in children whose diets rely heavily on maize.

Two girls eat biofortified maize in Mukushi, Zambia. (Photo: Silke Seco/DFID)
Two girls eat biofortified maize in Mukushi, Zambia. (Photo: Silke Seco/DFID)

Happy Rural Women’s Day!

Women and girls play a crucial role in ensuring the sustainability of rural households and communities, improving rural livelihoods and overall wellbeing. Globally, one in three employed women works in agriculture

However, women farmers are less able to access land, credit, agricultural inputs and markets to receive the best prices for their crops. Structural barriers and discriminatory social norms also constrain rural women’s decision-making power and community participation.

This International Day of Rural Women, we honor women working in wheat and highlight ways to meet their needs. Click the thumbnails below to explore these stories of amazing women working in wheat.

UK Aid and Bill & Melinda Gates Foundation join to support research to protect crops from pests and disease and increase climate-resilience 

Visit between Bill Gates and DFID head Alok Sharma featured demonstration of MARPLE  mobile rust-testing  lab

The MARPLE mobile lab in Ethiopia. Credit: JIC

New £38 million funding from the Department for International Development (DFID, or UK aid), with additional funding from the Bill & Melinda Gates Foundation, will allow scientists to research cutting-edge technology to protect crops from pests and diseases and produce new varieties that are climate-resilient.

The joint funding, which was announced on Monday October 7, will directly contribute to securing global food security against pest and disease threats, climate change and natural resource scarcity. It will also reduce poverty in sub-Saharan Africa and South Asia by improving agricultural productivity of smallholder farmers.

The partnership will support  biotechnologies to enable crops to convert sunlight and carbon dioxide more efficiently to promote higher yields,  tools and methods to reduce the impact of root crop diseases in West Africa, and work  to harness naturally occurring biological nitrogen fixation processes to improve crops’ nitrogen uptake and increase yields while reducing fertilizer use among smallholder farmers in Africa.

At a visit to the Sainsbury Lab at the University of Cambridge on Monday, UK International Development Secretary Alok Sharma and Bill Gates participated in a demonstration of Mobile and Real-time PLant disEase) (MARPLE) Diagnostics, a mobile rust-testing lab developed by the John Innes Centre, the International Maize and Wheat Improvement Center (CIMMYT), and the Ethiopian Institute of Agricultural Research. The suitcase sized mobile lab can identify strains of wheat rust disease in just 48 hours – a process that normally takes months.

 Early last year DFID also announced funding for CGIAR to help scientists identify specific genes in crops related to improved nutrition, faster growth and disease and climate-resilience. Their work will help up to 100 million African farmers and their families lift themselves out of poverty.

The full press release by the Department for International Development and The Rt Hon Alok Sharma MP is available on the GOV.UK website.

Borlaug Fellowship highlights longterm Washington State University-CIMMYT collaboration

The Norman Borlaug International Agricultural Science and Technology Fellowship Program at Washington State University, sponsored by the U.S. Department of Agriculture, facilitates international collaboration to fight soil borne pathogens

Cereal cyst nematodes

Soil borne pathogens (SBPs) are microorganisms that thrive in the soil and attack cereal crops, notably wheat. They cause high yield losses and reduce grain quality and quantity. SBPs include nematodes, a kind of round worm — including the Heterodera species of cereal cyst nematode and Pratylenchus species of root lesion nematodes — and crown rot caused by the Fusarium species, all of which attack roots of cereal crops.  Drought and monoculture farming exacerbate this damage.

Although chemical, biological and other options can be used to keep pathogen population levels low, the most environmentally friendly and biologically effective method of control is through a resistant crop variety.  However, up to now, only a few resistance genes have been identified against the cereal cyst nematode, Heterodera filipjevi, and this resistance is not yet present in high yielding cultivars.  

For nearly 20 years, research to fight these pathogens has benefited from a productive collaboration between the International Maize and Wheat Improvement Program (CIMMYT) in Turkey and Washington State University (WSU) and the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) in the United States through a fellowship program named after CIMMYT founder and Green Revolution pioneer Norman Borlaug. CIMMYT wheat breeders in Turkey have been working with breeders in Pullman, Washington to find stronger resistance genes to cereal cyst nematodes identify pathotypes, and other research areas that strengthen both CIMMYT and WSU wheat breeding programs.

CIMMYT pathologist and Turkey Country Representative Abdelfattah Dababat has been working with WSU and USDA-ARS since 2010. Dababat, who joined CIMMYT as a postdoctoral student studying soil borne pathogens (SBPs) in 2009, recently spent two months in Pullman as a Norman Borlaug International Agricultural Science and Technology Fellow, sponsored by the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS). There he was able to share CIMMYT work with members of the WSU Department of Plant Pathology, USDA-ARS, exchange ideas with well-known pathologists, and even travel to Cleveland, Ohio to attend the meeting of the American Phytopathological Society.

“My experience at WSU has been productive and inspiring.” said Dababat. “I have learned from some of the best minds in plant pathology, and worked on SBP issues that plague farmers both in my region and theirs.

“I would like to thank CIMMYT, especially Dr. Hans Braun, for the opportunity to obtain this great fellowship visit to WSU.”

The CIMMYT-WSU relationship was strengthened when the two institutions collaborated on a proposal for an Ethiopian PhD student at the University of Ankara, Turkey to work on SBPs. Through the sponsorship of a Borlaug Leadership Enhancement in Agriculture Program (LEAP) scholarship, Elfinesh Shikur Gebremariam spent four months at WSU in 2013-14 to learn about molecular aspects related to crown rot diseases. She published three peer-reviewed papers in high impact factor journals.

From left to right: Abdelfattah Dababat, Timothy Paulitz and WSU wheat breeding postdoctoral student Nuan Wen during a survey for cereal cyst nematodes in Pullman, Washington

Timothy Paulitz, a research plant pathologist with USDA-ARS and an adjunct professor in WSU’s Department of Plant Pathology has also been an active member in this collaboration, contributing to two master classes on soil borne pathogens in cereals at CIMMYT’s Turkey research station.

“Dr. Paulitz has made tremendous impact in our region,” said Dababat. “He trained more than 50 young scientists who are now in a high scientific and or managerial positions and are contributing not only to their own food security but also to international food security.”

SBP resistance progress and challenges

CIMMYT screens hundreds of wheat germplasm lines each year against SBPs at its research station in Eskisehir, Turkey, in collaboration with the Grain Research Development Corporation of Australia. Using association mapping, CIMMYT researchers have been able to identify new sources of resistance to cereal cyst nematodes, and many new lines have been approved as moderately resistant to resistant compared known varieties.  As a result, hundreds of lines of winter and spring wheat germplasm moderately resistant to SBPs are available.

Cereal cyst nematodes (CCN) are a persistent problem, however. Among the most damaging nematode pests to small grain cereal production, CCN are common from the Middle East, North Africa and Central Asia to the Pacific Northwest of the U.S. These nematodes alone are estimated to reduce production of crops by 10% globally.  Breeding for resistance is difficult because breeders must use live nematodes to phenotype, or measure, the lines, and there are few molecular markers linked to the resistance genes against the major CCN species to help identify them.

However, CIMMYT research — involving targeted genetic exploitations, classical selection breeding of resistant genotypes discovery of quantitative trait loci (QTLs) associated with resistance genes, as well as recent genome-wide association studies (GWAS) to associate nematode resistance or susceptibility with particular regions of the genome — has seen some success. One important source for disease-resistance genes is found in wheat’s wild relatives.  So far, 11 resistance genes have been reported. Nine of these were transferred into common wheat from its wild relatives (like Aegilops or goat grass, and other Triticum species) to enhance resistance against the H. avenae species of nematode.

Dababat and Wen in the lab while extracting DNA from wheat lines at the WSU laboratories.

Recently, CIMMYT and the University of Bonn, Germany performed GWAS on 161 winter wheat accessions and identified 11 QTL associated with resistance against the H. filipjevi species of nematode. These QTLs were intercrossed into susceptible winter wheat germplasm and the first generation material (F1) along with the parents were sent to WSU as part of the Borlaug fellowship.  CIMMYT and WSU also conducted several surveys in countries including Azerbaijan and Kazakhstan to detect SBPs in cereals.

This joint research will help both institutes to find stronger resistance genes to the cereal cyst nematodes.

The Washington State-based part of Dababat’s Borlaug fellowship is drawing to a close, but the collaboration and relationship between the two institutions remains. In June of next year, Paulitz will visit him in Turkey to follow up on his research progress.

“The international collaboration between CIMMYT and WSU shows how much progress we can make when we work together,” said Dababat. “I look forwarding to continuing our partnership to help farmers around the world find resistance to SBPs.”

Large-scale genomics will improve the yield, climate-resilience, and quality of bread wheat, new study shows

Scientists identified significant new chromosomal regions for wheat yield and disease resistance, which will speed up global breeding efforts.

This story by Mike Listman was originally posted on CIMMYT.org

Bread wheat improvement using genomic tools will be critical to accelerate genetic gains in the crop's yield, disease resistance, and climate resilience. (Photo: Apollo Habtamu/CIMMYT)
Bread wheat improvement using genomic tools will be critical to accelerate genetic gains in the crop’s yield, disease resistance, and climate resilience. (Photo: Apollo Habtamu/CIMMYT)

Using the full wheat genome map published in 2018, combined with data from field testing of wheat breeding lines in multiple countries, an international team of scientists has identified significant new chromosomal regions for wheat yield and disease resistance and created a freely-available collection of genetic information and markers for more than 40,000 wheat lines.

Reported today in Nature Genetics, the results will speed up global efforts to breed more productive and climate-resilient varieties of bread wheat, a critical crop for world food security that is under threat from rising temperatures, rapidly-evolving fungal pathogens, and more frequent droughts, according to Philomin Juliana, wheat scientist at the International Maize and Wheat Improvement Center (CIMMYT) and first author of the new study.

“This work directly connects the wheat genome reference map with wheat lines and extensive field data from CIMMYT’s global wheat breeding network,” said Juliana. “That network in turn links to over 200 breeding programs and research centers worldwide and contributes to yield and other key traits in varieties sown on nearly half the world’s wheat lands.”

The staple food for more than 2.5 billion people, wheat provides 20% of human dietary calories and protein worldwide and is critical for the nutrition and food security of hundreds of millions of poor persons in regions such as North Africa and South Asia.

“Farmers and societies today face new challenges to feed rising and rapidly-urbanizing populations, and wheat epitomizes the issues,” said Ravi Singh, CIMMYT wheat breeder and corresponding author of the study. “Higher temperatures are holding back yields in major wheat-growing areas, extreme weather events are common, crop diseases are spreading and becoming more virulent, and soil and water are being depleted.”

Juliana said the study results help pave the way to apply genomic selection, an approach that has transformed dairy cow husbandry, for more efficient wheat breeding.

“Molecular markers are getting cheaper to use; meanwhile, it’s very costly to do field testing and selection involving many thousands of wheat plants over successive generations,” Juliana said. “Genome-wide marker-based selection can help breeders to precisely identify good lines in early breeding generations and to test plantlets in greenhouses, thereby complementing and streamlining field testing.”

The new study found that genomic selection could be particularly effective in breeding for wheat end-use quality and for resistance to stem rust disease, whose causal pathogen has been evolving and spreading in the form of highly-virulent new races.

The new study also documents the effectiveness of the global public breeding efforts by CIMMYT and partners, showing that improved wheat varieties from this work have accumulated multiple gene variants that favor higher yields, according to Hans-Joachim Braun, director of CIMMYT’s global wheat program.

“This international collaboration, which is the world’s largest publicly-funded wheat breeding program, benefits farmers worldwide and offers high-quality wheat lines that are released directly to farmers in countries, such as Afghanistan, that are unable to run a full-fledged wheat breeding program,” Braun explained.

The study results are expected to support future gene discovery, molecular breeding, and gene editing in wheat, Braun said.

Together with more resource-efficient cropping systems, high-yielding and climate-resilient wheat varieties will constitute a key component of the sustainable intensification of food production described in Strategy 3 of the recent EAT-Lancet Commission recommendations to transform the global food system. Large-scale genomics will play a key role in developing these varieties and staying ahead of climate- and disease-related threats to food security.

Funders of this work include USAID’s Feed the Future Innovation Lab for Applied Wheat Genomics. Contributing to the research described are research teams engaged in wheat improvement at CIMMYT, and the lab of Jesse Poland, Associate Professor at Kansas State University and Director of the USAID Applied Wheat Genomics Innovation Lab.

Meet Lucia Nevescanin Moreno, first PhD recipient of the HeDWIC fellowship

The International Maize and Wheat Improvement Center (CIMMYT’s) own Lucia Nevescanin Moreno is the first recipient of a new scholarship sponsored by the Heat and Drought Wheat Improvement Consortium (HeDWIC) for its doctoral training program.

The HeDWIC Doctoral Training Program evolved out of the MasAgro-Trigo project, thanks to funding from the Mexican Secretariat of Agriculture and Rural Development (SADER) and National Council for Science and Technology (Consejo Nacional de Ciencia y Tecnología, CONACYT). The idea of the initiative is to provide young scientists from climate or food security vulnerable regions with opportunities to conduct research at advanced institutes internationally, to boost heat and drought tolerance of wheat in their home country. The program is expected to expand to other climate vulnerable regions through similar efforts to train talented young scientists who wish to be involved in improving the climate resilience of crops.

Lucia, who is currently working as an assistant research associate with CIMMYT, will be pursuing a PhD on wheat root function under abiotic stress under the supervision of University of Nottingham professor of Plant Sciences Malcom Bennett starting in October.

We asked Lucia a few questions about her research and the importance of heat and drought resilience.

How did you hear about CIMMYT?

A professor from my master’s program told me about it. I was doing a master’s in Natural Resources in the Instituto Tecnologico de Sonora, working specifically on tropical dry forest in Northwest Mexico but I always wanted to do science in a more applied way. I wanted to work on something that could help other people. Food security is something that people need to pay a lot of attention to. I started working for CIMMYT in February 2018 as an assistant research associate in the Global Wheat Program, conducting experiments in different conditions and I really learned a lot and am still learning a lot.

How did you hear about HeDWIC?

I was working with [CIMMYT Remote Sensing Specialist] Francisco Pinto on wheat root research here at CIMMYT and he asked me if I wanted to continue with my studies. I told him that I wanted to do a PhD and he showed me this opportunity with HeDWIC and the University of Nottingham. So I applied and I got it. Actually, I was very surprised to learn that I am the first PhD recipient of the HeDWIC scholarship. It’s a lot of pressure!

What will you be working on?

I will be studying wheat root function under abiotic stress under the supervision of Malcom Bennett at the University of Nottingham. I will be doing field-based phenotyping at Yaqui Valley in Mexico to determine what root characteristics are underlying plant performance under a range of environments including heat stress and water stress conditions. I will be using techniques like x-ray and laser ablation tomography in controlled conditions at the University of Nottingham to measure the physiology and anatomy of the wheat roots. I will also be working with Francisco Pinto and Matthew Reynolds from CIMMYT, Darren Wells and Craig Sturrock from the University of Nottingham and Jonathan Lynch from Penn State University.

Why do you think a consortium like HeDWIC is important for food security?

With climate change occurring at such a rapid pace, we really need to adapt to these new conditions. The population is also growing and so the demand for food needs serious attention. In HeDWIC they are working with external conditions like drought and heat and they are looking at how crops can adapt to these conditions. I think that just looking at how to increase yield is not enough, we need to look at how the crop will respond in the different environmental conditions we will go through.

What advice would you give to young women interested in a career in science?

I think it’s more difficult for women to adapt to this environment of work but we just need to be brave and show that we can do it! I was really interested in working in science because I wanted to know how things work and why. Maybe with my research and with research in general we can help people in power to make important decisions that can help other people. I think that should be the principle purpose of science.

Lucia’s PhD is supported by the CONACYT-Government of Mexico, SADER’s MasAgro Trigo and the University of Nottingham.

Smarter deployment of disease-resistance genes critical for safeguarding world’s food supplies

This story by Matt Hayes was originally posted on the Borlaug Global Rust Initiative website.

Maricelis Acevedo inspects wheat samples with Murugasamy Sivasamy at the Indian Agricultural Research Institute, Regional station, Wellington. Photo: Matt Hayes / Cornell

In the worst years of the rust disease epidemic that decimated North American wheat fields in the 1950s, fungal spores riding wind currents across the continent reached into the sextillions — that’s a number with 21 zeros.

Severe wheat disease epidemics produce staggering numbers of spores containing incredible genetic diversity — and incalculable risks to global food supplies. If fungal spores encounter even a single susceptible wheat variety, natural selection positions the pathogen to take hold and proliferate, releasing more rounds of spores and spreading its own virulence genes across entire populations.  

Wheat breeders face a daunting task trying to defend against such a relentless barrage of evolving pathogens. In the battle, scientific ingenuity confronts biological innovation: wheat varieties that contain single disease-resistant genes can be easily overrun by rapidly evolving spores.

To safeguard food supplies and ensure durable disease resistance in wheat, scientists must embrace a globally integrated strategy that deploys resistant genes in a coordinated way, according to Maricelis Acevedo, associate director of science for the Delivering Genetic Gain in Wheat (DGGW) project.

“We need to be smart about gene deployment,” Acevedo said at the All India Wheat and Barley meeting Aug. 25 in Indore, Madhya Pradesh.

“If we don’t change our mentality, we risk reliving the worst horrors of the past and the widespread hunger that results when rust diseases wipe out the wheat supply,” she said.

Acevedo cautioned that the release of susceptible or vulnerable varieties at a national level weakens wheat resistance on a global scale. Varieties with only one major effective resistance gene, which may appear adequate to withstand disease pressure in a field trial, are at increased risk to disease pressure when released into circulation. Varieties with only a single resistance gene risk tainting an otherwise effective gene for everybody and imperiling the wheat crop around the world.

Varieties with five to six disease-resistance genes make it mathematically unlikely that spores will have the genetic ability to defeat the resistance. Minnesota scientists in 1985 calculated that the probability a pathogen contains virulence to all six major genes is more than four times greater than the number of spores released in a single year in the US under stem rust epidemic levels. 

To reduce the chances of selection in pathogen populations, often caused by major genes, breeders exploit combinations of genes that may provide partial resistance to a broader number of races.

Ravi Singh gives his presentation at the All India Wheat and Barley meeting in Indore. Photo: Matt Hayes / Cornell

While only releasing varieties with stacked genes is the most prudent breeding strategy, there are factors that incentivize shortcuts, according to Acevedo. Plant breeders in some countries are often promoted based on the numbers of varieties released — not for their long-term usefulness. And, in some countries, there are political incentives to provide farmers with new varieties year after year rather than release fewer, but more durable varieties.

Teams of plant breeders employed by National Agricultural Research Systems in countries around the world develop improved crop varieties. Many wheat breeders receive lines from CIMMYT, the International Maize and Wheat Improvement Center, which national scientists then cross with local varieties to adapt to local conditions. National scientists also breed their own from existing local varieties. The process to develop and release any new variety can take up to ten years and up to 15 years to make it to farmers fields.

 “A way to make varieties more durable for resistance to rusts is to use marker-assisted introgression of multiple resistance genes using speed breeding in recent varieties or promising varietal candidates, which also possess some of the known durable adult-plant resistance genes,” said Ravi Singh, distinguished scientist and head of Global Wheat Improvement at CIMMYT. The All India Wheat and Barley meeting was co-sponsored by CIMMYT and the International Center for Agricultural Research in the Dry Areas (ICARDA).

The Borlaug Global Rust Initiative (BGRI) was established at Cornell to reduce the world’s vulnerability to stem, yellow and leaf rusts of wheat. Acevedo said the BGRI’s main impacts have resulted from scientific collaboration, commitment to pathogen monitoring, and development and deployment of rust resistant varieties. The BGRI established a Gene Stewardship Award in 2012 to encourage the release of varieties with complex and diverse disease resistance.

In 2018, the Indian Council of Agricultural Research (ICAR), in New Delhi, India, and associated institutions, received the BGRI Gene Stewardship Award in part for replacing susceptible wheat varieties with resistant varieties.

Those efforts have proven successful: on Aug. 24, in a reported delivered at the All India Wheat and Barley meeting, ICAR announced that India for the first time produced more than 100 million tons of wheat in a year.

DGGW is funded by the Bill & Melinda Gates Foundation and UK Aid by the British people.