The genome-wide association study leveraged data collected from sites in India, Kenya and Mexico to better understand the shared genetic basis of resistance to yellow rust, a tenacious and widespread fungal disease caused by a pathogen prevalent in more than 60 countries. An estimated 88% of the world’s wheat production is considered vulnerable, with up to 100% losses.
Philomin Juliana, Ph.D ’16, wheat breeder at International Maize and Wheat Improvement Center (CIMMYT), is lead author on the paper published July 2 in Nature’s Scientific Reports. The research was carried out by CIMMYT scientists with support from the Delivering Genetic Gain in Wheat (DGGW) project in the Department of Global Development.
Yellow rust, also known as stripe rust, is caused by the fungus Puccinia striiformis. A number of factors – including favorable weather conditions, the adaptation of existing varieties and emergence of new ones, and a changing climate – have caused a recent uptick in severe outbreaks. Farmers can use fungicides and farming management practices to battle the fungus, but sowing resistant seeds is widely considered as the most cost-effective, environmentally-safe and sustainable way to beat the disease.
“Rust diseases can destroy healthy and otherwise productive wheat fields in a matter of weeks,” said Maricelis Acevedo, associate director for science for DGGW and senior research associate in the College of Agriculture and Life Sciences’ Department of Global Development. “This study provides wheat breeders with new tools to take the fight to the yellow rust pathogen and help protect food security for people all over the globe.”
Using an extensive dataset of 43,706 observations on 23,346 wheat lines evaluated between 2013 and 2019, the scientists found more than 100 repeatable –that is, statistically significant in multiple datasets — genome-wide markers associated with yellow rust that aligned to the reference genome of wheat.
“These findings represent a significant advancement in our knowledge about the genetics of yellow rust resistance in bread wheat and provide exciting opportunities for designing future genomics-based breeding strategies for tackling yellow rust,” Juliana said.
The scientists also conducted “allelic fingerprinting” on the largest panel of wheat breeding lines to date — 52,067 lines, genomically characterizing them for yellow rust resistance. The resulting data creates opportunities using molecular markers to identify varieties with desired combinations of resistance genes.
“This information advances our knowledge on the genetics of yellow rust resistance in thousands of wheat lines, and has important implications for the future design of resistant crosses and varieties,” Juliana said.
Overall, the markers and fingerprints identified in this study are a valuable resource not only for CIMMYT breeders but also for the global wheat breeding community in its efforts to accelerate yellow rust resistance breeding.
DGGW is funded by the Bill & Melinda Gates Foundation and UK aid from the British people.
A version of this story appeared on the CGIAR Research Program on Wheat website.
