Tag: students

Irrigated wheat field. (Photo: S. Sukumaran/CIMMYT)

CIMMYT trains next generation of scientists to tackle soil-borne pathogens

Written by Alison Doody on December 14, 2021. Posted in News.

Two new students have graduated from the International Maize and Wheat Improvement Center’s (CIMMYT’s) Soil-Borne Pathogens program. The two new graduates, Khawla Mehalaine and Salah-Eddine Laasli, were supervised by CIMMYT senior scientist Abdelfattah Dababat.

He leads the Soil-Borne Pathogens program, which focuses on identifying the main soil-borne pathogens associated with cereals and developing an integrated pest management approach to combat them. The research team is particularly interested in finding novel sources of resistance against these pathogens.

Over the last two decades, CIMMYT scientists leading the Soil-Borne Pathogens program have trained tens of students which constitute the next generation of top researchers on this topic. Through this program, CIMMYT has also organized workshops and courses in North Africa, including a symposium on cereal nematodes held in Agadir, Morocco, in 2017.

Since soil-borne pathogens are exacerbated by water stress conditions, researchers have identified the Central and West Asia and North Africa regions as priority areas, due to their vulnerability to drought.

On March 1, 2021, Syngenta, in collaboration with CIMMYT and other partners, led the first One Earth Soil and Root Health Forum, an event which examined the importance of root and soil health to food security, climate resilience and livelihoods. The event also created a community for action on root and soil health.

Khawla Mehalaine celebrates graduating from her PhD. (Photo: handout)

Nematodes in Algeria

Mehalaine holds an engineering degree in agronomy and a master’s degree in plant protection from the Higher National School of Agronomy (ENSA) in Algeria. She successfully defended her PhD dissertation “Studies of cereal cyst nematodes of the genus Heterodera in the regions of northern Algeria” in June 2021, graduating from ENSA with honors.

She studied the behavior of four durum wheat varieties against cereal cyst nematodes through field surveys, molecular identification at species levels, and by evaluating the yield components of these wheat varieties.

She was promoted by ENSA professor Hammach M. and supervised by Dababat from CIMMYT, and professors Mustafa Imren and Göksel Özer from Abant Izzet Baysal University in Turkey.

“Completing my doctorate was a truly enriching experience and a challenging but rewarding journey,” Mehalaine said. “It was a collective effort and I am extremely grateful to Dr Abdelfattah Dababat for sharing his scientific skills, for his patience and support, and for all the opportunities I was given to further my research. Thanks to him, I got to know the world of nematodes. Special thanks to CIMMYT for funding the molecular study part.”

Salah-Eddine Laasli on his graduation day. (Photo: handout)

Root-lesion nematode and crown rot fungi

Laasli graduated with an International Master of Agronomic and Environmental Nematology (IMANEMA) from Ghent University, in collaboration with CIMMYT, the National Institute of Agricultural Research in Morocco and the Faculty of Agriculture at Abant Izzet Baysal University in Turkey.

His master thesis, entitled “Interaction of Root-Lesion Nematode (Pratylenchus thornei) and Crown Rot fungi (Fusarium culmorum) associated with wheat resistance under simulated field conditions,” was promoted by Wim Bert, a professor at the University of Ghent, and Dababat. The project was also supervised by Imren and Özer.

Laasli evaluated the host status of 150 spring wheat lines to both P. thornei and F. culmorum, and estimated the damage caused by the disease complex involving both pathogens at different infection scenarios. He found several lines that possessed multiple resistance to both diseases tested — which could be powerful sources of resistance for breeding program worldwide.

Cover photo: Irrigated wheat field. (Photo: S. Sukumaran/CIMMYT)

Researcher Tamaya Peressini performs disease evaluations 10 days post infection at CIMMYT’s glasshouse facilities.

University of Queensland student researches tan spot resistance in wheat at CIMMYT

Written by on January 21, 2019. Posted in Features.

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.

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,” Peressini said.

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,” Peressini explained.

“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.”

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 focused 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,” Peressini said.

The plant material Peressini studied in her honors 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,” Peressini said.

Peressini had a chance to visit the pyramids of Teotihuacán and other Mexican landmarks. — *During her stay in Mexico, Peressini had a chance to visit the pyramids of Teotihuacán and other cultural landmarks.*

“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!”

“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,” Peressini concluded.

Student reflection: my visit to CIMMYT-Hyderabad, India

Written by on November 6, 2013. Posted in Blogs.

Alex Renaud is a third-year graduate student pursuing a doctorate degree in plant breeding and genetics from Purdue University in West Lafayette, Indiana, USA.

When given the opportunity to travel to India to work on heat tolerance in maize, I leaped at the prospect. I was excited by the potential for professional development and the chance to experience a different culture. My visit was part of the Heat Tolerant Maize for Asia (HTMA) collaborative project, funded by the United States Agency for International Development Feed the Future Initiative. The project supports graduate students in plant breeding to learn about and contribute to completing initiative objectives. HTMA is a public-private partnership (PPP) led by CIMMYT-Asia. Partners include Purdue University, Pioneer Hi-Bred and other seed companies and public sector maize programs in South Asia.

CIMMYT-Asia in Hyderabad, India, provides an ideal environment to evaluate or phenotype maize genotypes for heat stress tolerance. Temperatures regularly reach 40°C or higher and the relative humidity is usually below 30 percent during the reproductive development of maize planted during spring season. Additionally, the CIMMYT facilities in Hyderabad provided an excellent laboratory environment for testing hypotheses concerning the basis of heat stress tolerance in maize.

Having never been to India, I really enjoyed my stay in Hyderabad, from both research and cultural standpoints. I enjoyed getting to know the research scientists and technicians involved in the research project and had ample opportunities to learn in workshops, trainings, field visits and over dinner. My stay, which was longer than two months, provided me with the opportunity to build both personal and professional relationships. Anyone who has visited Hyderabad in May will understand just how hot it can be. It took time for me to adapt to the heat. As I was leaving the U.S. for India, my hometown received 300 millimeters of snow in 24 hours. During my first week in Hyderabad, the temperatures exceeded 40°C. It was quite a change.

Alex Renaud (middle) with CIMMYT-Hyderabad field staff. Photo: By Alex Renaud

In addition to taking advantage of research opportunities, I visited several interesting cultural sites, including the Taj Mahal. My favorite memories include sampling many different types of food, from Hyderabadi biryani to India’s version of Kentucky Fried Chicken; I never tried anything I did not like! As an aspiring plant breeder, this was a great experience, and I hope to continue my involvement with the PPP as it develops heat-stress-tolerant maize for South Asia.

I would like to sincerely thank Mitch Tuinstra, professor of plant breeding at Purdue University for providing me with this opportunity as well as P.H. Zaidi, senior maize physiologist at CIMMYT-Hyderabad and project leader of HTMA, and his wonderful team for everything that made my two-month stay professionally productive and personally memorable.