By Mike Listman

Rapidly emerging and evolving races of wheat stem rust and stripe rust disease—the crop’s deadliest scourges worldwide—drove large-scale seed replacement by Ethiopia’s farmers during 2009-14, as the genetic resistance of widely-grown wheat varieties no longer proved effective against the novel pathogen strains, according to a new study by the International Maize and Wheat Improvement Center (CIMMYT).

Based on two surveys conducted by CIMMYT and the Ethiopian Institute of Agricultural Research (EIAR) and involving more than 2,000 Ethiopian wheat farmers, the study shows that farmers need access to a range of genetically diverse wheat varieties whose resistance is based on multiple genes.

After a severe outbreak in 2010-11 of a previously unseen stripe rust strain, 40 percent of the affected farm households quickly replaced popular but susceptible wheat varieties, according to Moti Jaleta, agricultural economist at CIMMYT and co-author of the publication.

“That epidemic hit about 600,000 hectares of wheat—30 percent of Ethiopia’s wheat lands—and farmers said it cut their yields in half,” Jaleta said. “In general, the rapid appearance and mutation of wheat rust races in Ethiopia has convinced farmers about the need to adopt newer, resistant varieties.”

The fourth most widely grown cereal after tef, maize, and sorghum, wheat in Ethiopia is produced largely by smallholder farmers under rainfed conditions. Wheat production and area under cultivation have increased significantly in the last decade and Ethiopia is among Africa’s top three wheat producers, but the country still imports on average 1.4 million tons of wheat per year to meet domestic demand.

National and international organizations such as EIAR, CIMMYT, and the International Centre for Agricultural Research in the Dry Areas (ICARDA) are working intensely to identify and incorporate new sources of disease resistance into improved wheat varieties and to support the multiplication of more seed to meet farmer demand.

New wheat varieties have provided bigger harvests and incomes for Ethiopia farmers in the last decade, but swiftly mutating and spreading disease strains are endangering wheat’s future, according to Dave Hodson, CIMMYT expert in geographic information and decision support systems, co-author of the new study.

“In addition to stripe rust, highly-virulent new races of stem rust are ruining wheat harvests in eastern Africa,” he explained. “These include the deadly Ug99 race group, which has spread beyond the region, and, more recently, the stem rust race TKTTF.”

As an example, he mentioned the case of the wheat variety Digalu, which is resistant to stripe rust and was quickly adopted by farmers after the 2010-11 epidemic. But Digalu has recently shown susceptibility to TKTTF stem rust and must now be replaced.

“In rust-prone Ethiopia, the risks of over-reliance on a widely-sown variety that is protected by a single, major resistance gene—Digalu, for example—are clearly apparent,” he added. “CIMMYT and partners are working hard to replace it with a new variety whose resistance is genetically more complex and durable.”

Hodson said as well that continuous monitoring of the rust populations in Ethiopia and the surrounding region is essential to detect and respond to emerging threats, as well as to ensure that the key pathogen races are used to screen for resistance in wheat breeding programs.

Hodson and partners at the John Innes Centre, UK, and EIAR are leading development of a handheld tool that allows rapid identification of disease strains in the field, instead of having to send them to a laboratory and lose precious time awaiting the results.

CIMMYT and partners are also applying molecular tools to study wheat varietal use in Ethiopia. “There are indications that yields reported by farmers were much lower than official statistics, and farmer recollections of varietal names and other information are not always exact,” Hodson explained. “We are analyzing results now of a follow-up study that uses DNA fingerprinting to better document varietal use and turnover.”

The authors would like to acknowledge the Standing Panel for Impact Assessment (SPIA) for financing, the Diffusion and Impacts of Improved Varieties in Africa (DIIVA) project that supported the first survey in 2011, and Cornell University, the Bill & Melinda Gates Foundation, and United Kingdom’s Department for International Development (DFID) through the Durable Rust Resistance in Wheat (DRRW, now called Delivering Genetic Gain in Wheat) project for support for the second survey in 2014.

By Laura Strugnell and Mike Listman

CIUDAD OBREGÓN, Mexico (CIMMYT) – As more than 200 wheat science and food specialists from 34 countries gathered in northwestern Mexico to address threats to global nutrition and food security, 9 outstanding young women wheat scientists among them showed that this effort will be strengthened by diversity.

Winners of the Jeanie Borlaug Laube Women in Triticum (WIT) Early Career Award joined an on-going wheat research training course organized by the International Maize and Wheat Improvement Center (CIMMYT), 21-23 March.

“As my father used to say, you are the future,” said Jeanie Borlaug Laube, daughter of the late Nobel Peace Prize laureate, Dr. Norman E. Borlaug, and mentor of many young agricultural scientists. Speaking to the WIT recipients, she said, “You are ahead of the game compared to other scientists your age.”

Established in 2010 as part of the Delivering Genetic Gain in Wheat (DGGW) project led by Cornell University, the WIT program has provided professional development opportunities for 44 young women researchers in wheat from more than 20 countries.

The award is given annually to as many as five early science-career women, ranging from advanced undergraduates to recent doctoral graduates and postdoctoral fellows. Selection is based on a scientific abstract and statement of intent, along with evidence of commitment to agricultural development and leadership potential.

Women who will change their professions and the world

Weizhen Liu, a 2017 WIT recipient and postdoctoral researcher at Cornell University, is applying genome-wide association mapping and DNA marker technology to enhance genetic resistance in tetraploid and bread wheat to stripe rust, a major global disease of wheat that is quickly spreading and becoming more virulent.

“I am eager to join and devote myself to improving wheat yields by fighting wheat rusts,” said Liu, who received her bachelors in biotechnology from Nanjing Agricultural University, China, in 2011, and a doctorate from Washington State University in 2016. “Through WIT, I can share my research with other scientists, receive professional feedback, and build international collaboration.”

Mitaly Bansal, a 2016 WIT award winner, currently works as a Research Associate at Punjab Agricultural University, India. She did her PhD research in a collaborative project involving Punjab Agricultural University and the John Innes Centre, UK, to deploy stripe and leaf rust resistance genes from non-progenitor wild wheat in commercial cultivars.

“I would like to work someday in a position of public policy in India,” said Bansal, who received the Monsanto Beachell-Borlaug scholarship in 2013. “That is where I could have the influence to change things that needed changing.”

Networking in the cradle of wheat’s “Green Revolution”

In addition to joining CIMMYT training for a week, WIT recipients will attend the annual Borlaug Global Rust Initiative (BGRI) technical workshop, to be held this year in Marrakech, Morocco, from 14 to 17 April, and where the 2018 WIT winners will be announced.

The CIMMYT training sessions took place at the Norman Borlaug Experiment Station (CENEB), an irrigated desert location in Sonora State, northwestern Mexico, and coincided with CIMMYT’s 2018 “Visitors’ Week,” which took place from 19 to 23 March.

An annual gathering organized by the CIMMYT global wheat program at CENEB, Visitors’ Week typically draws hundreds of experts from the worldwide wheat research and development community. Participants share innovations and news on critical issues, such as the rising threat of the rust diseases or changing climates in key wheat farmlands.

Through her interaction with Visitors’ Week peers, Liu said she was impressed by the extensive partnering among experts from so many countries. “I realized that one of the most important things to fight world hunger is collaboration; no one can solve food insecurity, malnutrition, and climate change issues all by himself.”

A strong proponent and practitioner of collaboration, Norman E. Borlaug worked with Sonora farmers in the 1940-50s as part of a joint Rockefeller Foundation-Mexican government program that, among other outputs, generated high-yielding, disease-resistant wheat varieties. After bringing wheat self-sufficiency to Mexico, the varieties were adopted in South Asia and beyond in the 1960-70s, dramatically boosting yields and allowing famine-prone countries to feed their rapidly-expanding populations.

This became known as the Green Revolution and, in 1970, Borlaug received the Nobel Peace Prize in recognition of his contributions. Borlaug subsequently led CIMMYT wheat research until his retirement in 1979 and served afterwards as a special consultant to the Center.

When a new, highly virulent race of wheat stem rust, Ug99, emerged in eastern Africa in the early 2000s, Borlaug sounded the alarm and championed a global response that grew into the BGRI and associated initiatives such as DGGW.

“This is just a beginning for you, but it doesn’t end here,” said Maricelis Acevedo, a former WIT recipient who went on to become the leader of DGGW. Speaking during the training course, she observed that many WIT awardees come from settings where women often lack access to higher education or the freedom to pursue a career.

“Through WIT activities, including training courses like this and events such as Visitors’ Week and the BGRI workshop,” Acevedo added, “you’ll gain essential knowledge and skills but you’ll also learn leadership and the personal confidence to speak out, as well as the ability to interact one-on-one with leaders in your field and to ask the right questions.”

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 Research Programs on Maize and Wheat and the Excellence in Breeding Platform. The Center receives generous support from national governments, foundations, development banks and other public and private agencies.

Funded by the Bill & Melinda Gates Foundation and the UK’s Department for International Development (DFID) under UK aid, the DGGW project aims to strengthen the delivery pipeline for new, disease resistant, climate-resilient wheat varieties and to increase the yields of smallholder wheat farmers.