Science

Scientists identify genome regions that lead to better yield, disease resistance in wheat

New Delhi | Updated on September 24, 2019 Published on September 24, 2019

An international team of scientists, including some from India, has found a way to breed wheat varieties that are of better quality and have a higher yield while also resisting diseases and the adverse effects of climate change. In a study published in the journal Nature Genetics on Monday, plant breeders led by Ravi Prakash Singh, a scientist at the Mexico-based International Maize and Wheat Improvement Center (CIMMYT), identified chromosomal regions in the wheat crop that confer favourable traits such as higher yields and disease resistance using the full wheat genome map published last year.

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, said Philomin Juliana, CIMMYT wheat scientist and first author of the new study.

The work is expected to help over 200 different wheat breeding programmes worldwide that are connected with CIMMYT’s global wheat breeding network and contribute to yield and other key traits in varieties sown on nearly half the world’s wheat fields, she said in a statement.

Worldwide staple

The staple food for more than 2.5 billion people globally, wheat provides 20 per cent 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-urbanising populations, and wheat epitomises the issues,” said Singh, who is the 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,” he said.

Many Indian-origin scientists working with CIMMYT participated in the study, apart from scientists from the New Delhi-based Borlaug Institute for South Asia.

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.

Effectiveness documented

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 favour 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 programme, 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.

Published on September 24, 2019
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