Using the new reference map for wheat published by the International Wheat Genome Sequencing Consortium (IWGSC) in 2018, researchers from the International Maize and Wheat Improvement Center (CIMMYT) have shown that breeding by the Center and partners since 2003 has accumulated many favorable, yield-related genes in most wheat lines distributed through its International Wheat Improvement Network (IWIN), benefiting wheat farmers worldwide.
“These favorable alleles appear increasingly in wheat varieties released by national partners over the last decade,” said Philomin Juliana, associate scientist at CIMMYT who is facilitating the center’s efforts to use the new map. “This points to CIMMYT’s effectiveness in delivering high-quality wheat lines and serving countries unable to run their own full-fledged wheat breeding program.”
Wheat is the world’s most widely cultivated crop and contributes roughly one-fifth of the calories in human diets. Expert sources including the Food and Agriculture Organization (FAO) of the United Nations have projected a rise in the demand for wheat as high as 60 percent by mid-century, as the world population rapidly increases and moves to cities. 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.
Philomin and her colleagues have located key genomic regions associated with grain yield, tolerance to heat and drought stresses, disease resistance, and grain quality in CIMMYT wheat lines, along with cross-referencing those to matching regions in the new wheat genome map. CIMMYT has pioneered global research to leverage the new reference sequence.
Philomin Juliana, CIMMYT Wheat Breeder
“This sheds light on the relative positions of our markers, with respect to the genes, and on whether we have a novel ones or just the known ones, ultimately informing us how better to select for these traits.”
“Because our results are freely available, they represent a valuable resource for the global wheat research community and can accelerate genomics-assisted breeding for this crucial food crop.”
To enable this research using the new wheat genome, CIMMYT researchers fingerprinted more than 40,000 CIMMYT wheat breeding lines and dozens of wheat varieties worldwide, providing what Philomin calls “a quantum leap” in datasets for understanding the genetic bases of key traits in superior varieties.
Genomic assisted breeding: Wave of the future
The new genome map and related CIMMYT research will help the center's scientists to apply genomic information in choosing better parental combinations and selecting superior progenies through “genomic selection” that integrates the new wheat genome knowledge and constitutes a novel approach for wheat.
“The new map and CIMMYT studies provide insights into the genomic bases of trait ‘predictabilities’ and pinpoint chromosomal segments that contribute to the best lines,” Philomin said. “This can improve selection efficiency and get high-yielding, climate- and disease-resilient wheat varieties to farmers much faster.”
As documented in a 2017 article in the science journal Global Food Security, rapid breeding and varietal replacement are critical for adapting the developing world’s wheat and other cropping systems to the effects of climate change.
Philomin was a recipient of Monsanto’s Beachell-Borlaug International Scholars Program Award (2013) and the Jeanie Borlaug Laube Women in Triticum award (2015).
Funders of this work include the Cornell University-led Delivering Genetic Gain in Wheat (DGGW) project and USAID’s Feed the Future (FTF) Innovation Lab for Applied Wheat Genomics. Contributing to the research described are research teams engaged in wheat improvement at CIMMYT, and Jesse Poland, Associate Professor at Kansas State University and Director of the USAID Applied Wheat Genomics Innovation Lab.
Photo: Carolina Sansaloni, head of CIMMYT’s sequencing and genotyping lab, has supported research to understand the genetic bases of key traits for wheat breeding.
The wheat genome: A complex genetic treasure trove
The August 2018 edition of Science magazine published the newly completed and fully annotated reference genome for bread wheat by the IWGSC. The new wheat genome map includes a detailed analysis of genes among subgenomes as well as the organization of the chromosomes, the thread-like structures that carry the genes. A genome is the complete set of an organism’s DNA.
The bread wheat genome is a hybrid that comes from the natural crosses of genetically simpler Emmer wheat with a wild grass around 10,000 years ago and incorporates both genomes. The bread wheat genome is more than five times larger than the human genome. Its size and complexity made it hard for scientists to produce a high-quality reference sequence. The IWGSC has involved 2,400 members in 68 countries working together since 2005.
A BBC report on the new wheat genome map mentioned CIMMYT as a leader in the work to help meet the food demand of the 9.6 billion global population expected in 2050.
Credits:
See CIMMYT Annual Report 2018 for full credits.