Work will pave way for production of wheat varieties better adapted to climate challenges, with improved yields, nutritional quality and sustainability.

August 17, 2018

4 Min Read
Detailed bread wheat genome published
Credit: Isabelle Caugant

The International Wheat Genome Sequencing Consortium (IWGSC) published in the international journal Science a detailed description of the genome of bread wheat, the world’s most widely cultivated crop.

This work will pave the way for the production of wheat varieties better adapted to climate challenges, with higher yields, enhanced nutritional quality and improved sustainability, IWGSC said.

The research article — authored by more than 200 scientists from 73 research institutions in 20 countries — presents the reference genome of the bread wheat variety Chinese Spring. The DNA sequence ordered along the 21 wheat chromosomes is the highest-quality genome sequence produced to date for wheat, the consortium said. It is the result of 13 years of collaborative international research.

As a key crop for food security, wheat is the staple food of more than a third of the global human population and accounts for almost 20% of the total calories and protein consumed by humans worldwide, more than any other single food source. It also serves as an important source of vitamins and minerals.

To meet future demands of a projected world population of 9.6 billion by 2050, wheat productivity needs to increase by 1.6% each year. In order to preserve biodiversity, water and nutrient resources, the majority of this increase has to be achieved via crop and trait improvement on land currently cultivated rather than committing new land to cultivation, IWGSC explained.

With the reference genome sequence now completed, breeders have at their disposal new tools to address these challenges. They will be able to identify more rapidly genes and regulatory elements underlying complex agronomic traits — such as yield, grain quality, resistance to fungal diseases and tolerance to abiotic stress — and produce hardier wheat varieties.

“The wheat genome sequence lets us look inside the wheat engine,” said Rudi Appels, a professor at Australia's University of Melbourne and Murdoch University and AgriBio research fellow. “What we see is beautifully put together to allow for variation and adaptation to different environments through selection, as well as sufficient stability to maintain basic structures for survival under various climatic conditions.”

It is expected that the availability of a high-quality reference genome sequence will boost wheat improvement over the coming decades, with benefits similar to those observed with maize and rice after their reference sequences were produced, IWGSC said.

“How do you thank a team of scientists who persevered and succeeded in sequencing the wheat genome and changed wheat breeding forever? Perhaps it is not with the words of a scientist but with the smiles of well-nourished children and their families whose lives have been changed for the better,” said Stephen Baenziger, University of Nebraska-Lincoln professor and Nebraska Wheat Growers presidential chair.

Sequencing the bread wheat genome was long considered an impossible task due to its enormous size — five times larger than the human genome — and complexity — bread wheat has three sub-genomes, and more than 85% of the genome is composed of repeated elements, IWGSC said.

“The publication of the wheat reference genome is the culmination of the work of many individuals who came together under the banner of the IWGSC to do what was considered impossible,” IWGSC executive director Kellye Eversole explained. “The method of producing the reference sequence and the principles and policies of the consortium provide a model for sequencing large, complex plant genomes and reaffirms the importance of international collaborations for advancing food security.”

The impact of the wheat reference sequence has already been significant in the scientific community, as exemplified by the publication on the same date of six additional publications describing and using the reference sequence resource: one appearing in the same issue of Science, one in Science Advances and four in Genome Biology. Moreover, more than 100 publications referencing the reference sequence have been published since the resource was made available to the scientific community in January 2017.

“The publication has so many implications not only in science but in countries facing food insecurity all over the world,” said Hikmet Budak, the Winifred Asbjornson plant sciences chair in the Montana State University College of Agriculture. “This could lead to higher incomes for farmers, better nutrition for world populations and new wheat varieties. The research also offers immense potential for the scientific world to create new discoveries when it comes to agricultural food production and security.”

In addition to the sequence of the 21 chromosomes, the Science article also presents the precise location of 107,891 genes and more than 4 million molecular markers, as well as sequence information between the genes and markers containing the regulatory elements influencing the expression of genes, IWGSC noted.

IWGSC achieved this result by combining the resources it generated over the last 13 years using classic physical mapping methods and the most recent DNA sequencing technologies; the sequence data were assembled and ordered along the 21 chromosomes using highly efficient algorithms, and genes were identified with dedicated software programs.

All IWGSC reference sequence resources are publicly available at the IWGSC data repository at URGI-INRA Versailles and at other international scientific databases such as GrainGenes and Ensembl Plant.

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