Genetic recipe for bread wheat resilience

New bread wheat traits set to thrive in hot dry cropping regions


Crops
ICARDA senior wheat breeder Wuletaw Tadesse takes a break from shopping for genetic crop diversity in Morocco, North Africa. PHOTO Clarisa Collis

ICARDA senior wheat breeder Wuletaw Tadesse takes a break from shopping for genetic crop diversity in Morocco, North Africa. PHOTO Clarisa Collis

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High yielding bread wheat germplasm shows improved tolerance to heat and drought.

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In the Marchouch commune area of Khémisset Province, near Morocco's capital Rabat, Wuletaw Tadesse, steps along narrow pathways set in dry vertosol soil, fissured with cracks, into a paddock under North Africa's hot midday sun.

A senior wheat breeder at the International Center for Agricultural Research in the Dry Areas (ICARDA), Dr Tadesse has the air of someone supermarket shopping as he treads between ripening wheat plants.

He has that demeanor because Dr Tadesse is, in fact, shopping for genetic crop diversity at ICARDA's Marchouch research station, spread across 150 hectares of semi-arid cropping country.

Dr Tadesse was browsing for new bread wheat genes from the dusty, earthen aisles defined by thousands of experimental trial plots when GroundCover™ visited the research station in Morocco this year.

High on his genetic shopping list are new plant traits that could thrive in hot, dry cropping regions prone to increased disease and insect pressure - regions that are predicted to expand around the world under the effects of climate change.

Plant genotypes containing these traits were the focus of GRDC-invested research to develop high yielding bread wheat germplasm that is more resilient to major abiotic (non-living) and biotic (living) stresses for Australian grain growers.

Thousands of experimental trial plots showcase genetic crop diversity at ICARDA's Marchouch research station spread across 150 hectares of semi-arid cropping country near Rabat, Morocco. PHOTO Clarisa Collis

Thousands of experimental trial plots showcase genetic crop diversity at ICARDA's Marchouch research station spread across 150 hectares of semi-arid cropping country near Rabat, Morocco. PHOTO Clarisa Collis

In particular, the research project from 2014 to 2018 aimed to secure genetic traits for improved tolerance to heat and drought, and better resistance to diseases, such as rusts and septoria tritici blotch.

Leading the project, Dr Tadesse says these new traits were sourced from bread wheat plants - wild crop relatives and old, locally-adapted farmer varieties (landraces) - collected from a vast geographic region.

Specifically, the Central West Asian and North Africa (CWANA) region stretching from Morocco's Atlas Mountains in the west to Kazakhstan's temperate, dry, northern areas in the east, encompassing Ethiopia's highland high-rainfall areas and Pakistan's fertile irrigated Indus Valley.

Plants containing the new traits were then strategically introgressed into adapted Australian cultivars and put to the test in ICARDA trials across the CWANA region at locations known for high pressure from abiotic and biotic stresses.

For instance, the ICARDA team examined the performance of traits for abiotic tolerance at five international trial sites linked to terminal heat stress. Trials providing these "pressure-cooker" heat stress conditions were located at Terbol, Lebanon; Kom Ombo, Egypt; Wad Madani, Sudan; and Marchouch, Morocco.

The genotoypes that graduated from this rigorous approach to trait testing for tolerance and resistance were annually delivered to Australian pre-breeders and breeders, in batches of 150 to 200, over the five-year term of the project.

"This has contributed to significant improvement in the wheat germplasm diversity available to Australian wheat breeders for pre-breeding purposes," Dr Tadesse says.

Dr Tadesse led research sourcing new genetic traits from bread wheat plants - wild crop relatives and old, locally-adapted farmer varieties (landraces) - across a vast geographic region. PHOTO Clarisa Collis

Dr Tadesse led research sourcing new genetic traits from bread wheat plants - wild crop relatives and old, locally-adapted farmer varieties (landraces) - across a vast geographic region. PHOTO Clarisa Collis

In other words, Australian wheat pre-breeders and breeders can introgress or integrate the new traits for abiotic tolerance and biotic resistance into the genetic profile of Australian bread wheat cultivars.

Facilitating the delivery of these resilient genotypes for use in Australian breeding programs each year was the CIMMYT Australia ICARDA Germplasm Evaluation (CAIGE) project, including its Australian breeding program.

"Some of the genotypes had a significant yield advantage over dominant Australian wheat varieties at multiple trial locations," he says.

"These genotypes have been used intensively for pre-breeding purposes by Australian wheat breeders," he says.

Dr Tadesse says the germplasm transfer into the genetic background of Australian bread wheat cultivars is also expected to provide cost-savings and environmental benefits for Australian growers.

"Use of the disease and insect-resistant traits in Australian breeding programs can help decrease expenditure on fungicides and insecticides, effectively reducing environmental impacts and wheat production costs."

Another indirect benefit of the germplasm developed for the Australian grains industry through the GRDC-invested research is the lift in bread wheat productivity and profitability it has provided in developing countries.

"More than 60 bread wheat varieties with origins in the ICARDA-led research have been released in CWANA and sub-Saharan African (SSA) countries, such as Afghanistan, Ethiopia, Morocco, Nigeria, Sudan and Uzbekistan, in the past five years," Dr Tadesse says.

Trials as part of ICARDA's bread wheat breeding program at Marchouch, Morocco. PHOTO Clarisa Collis

Trials as part of ICARDA's bread wheat breeding program at Marchouch, Morocco. PHOTO Clarisa Collis

ICARDA

Established in 1975, ICARDA is an international R&D organisation that aims to improve food, nutritional and water security, lift environmental health and reduce poverty in dry areas of the world facing climate challenges.

* Clarisa Collis travelled to Morocco in North Africa, with assistance from the Crawford Fund, as the 2018 winner of the Crawford Fund Food Security Journalism Award.

GRDC Research Code ICA00013

More information: Wuletaw Tadesse, ICARDA, w.tadesse@cgiar.org, www.icarda.org

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