Researchers at the University of California, Davis, led by Professor Jorge Dubcovsky, have recently discovered gene conferring resistance to the Ug99 strain of wheat stem rust that has caused significant losses in recent years in North Africa and Asia, becoming a world-wide threat.
Wheat is essential for feeding humanity, and is currently the second most important crop after rice. In the 1950s, epidemic of wheat stem rust caused significant losses in North America, destroying 40% of the wheat crop. Since then, scientists have created a variety of wheat cultivars resistant to this disease, but the disease appears to be able to make a comeback with the emergence of the Ug99 strain discovered in Uganda in 1999, which spreads rapidly across the region, covering almost all areas of Africa, crossing the Red Sea and reaching Yemen and Iran. At present, about 90% of wheat varieties are susceptible to infection by this strain.
Prof. Jorge Dubcovsky and his team managed to identify 3 forms of the Sr13 gene isolated from pasta wheat that confer resistance to Ug99 and several virulent strains from Yemen and Ethiopia. The results were recently published in the Proceedings of the National Academy of Sciences. In a previous study, Professor Dubcovsky and his team found the Sr35 gene, which also confers resistance to Ug99, and the team is now about to identify a third gene.
Prof. Dubcovsky’s findings allow the identified genes to be used for accelerated breeding with the help of DNA markers in order to pyramid genes conferring resistance to Ug99 in new varieties.
Wenjun Zhang, Shisheng Chen, Zewdie Abate, Jayaveeramuthu Nirmala, Matthew N. Rouse, and Jorge Dubcovsky. Identification and characterization of Sr13, a tetraploid wheat gene that confers resistance to the Ug99 stem rust race group. PNAS 2017 114: E9483-E9492