GRRC annual report on wheat yellow rust 2018 released
This report presents results on Simple Sequence Repeat (SSR) genotyping of samples of Puccinia striiformis from wheat and triticale collected across four continents in 2018, with reference to 2017 results.
Key highlights 2018
Central Asia/East Africa: Pst11, first detected in Central Asia in 2012, became the most prevalent genetic group of yellow rust in East Africa in 2018, detected in Ethiopia, Kenya, Rwanda and Tanzania. The recent inter-continental spread into East Africa was confirmed by the presence of only a single race in group PstS11 irrespective of sample origin.
South America: PstS13 was completely dominating in both Argentina and Chile, in 2018 severely affecting both wheat and triticale cultivars. Only one race has been detected in this group, associated with severe rust epidemics on triticale in northern Europe and durum wheat in southern Europe.
Europe: PstS10, a.k.a. Warrior(-), was the most prevalent group consisting of one dominating genotype. The original Warrior group (PstS7) was less prevalent, but spreading to new areas. Additional groups were detected in many countries.
North Africa: A distinct race (and genotype) of PstS14, first detected in 2016, made up 100% of samples from Morocco, causing severe rust epidemics in 2017. A new unique genotype was observed in Egypt - not previously detected anywhere by GRRC.
Virulence to Yr5 and Yr15 was not detected.
Summary of SSR genotyping and race phenotyping results from GRRC (2008-2018) is available online (http://www.wheatrust.org/), including an updated table showing the relationship between races and genetic groups.
The testing of additional samples from 2018 is ongoing with emphasis on additional race testing of representative isolates from existing and new genetic groups.
Over the years, we have observed a strong link between genetic group and race. Race typing requires access to spore samples of alive, pure isolates and strict experimental conditions. In contrast, SSR genotyping was based on samples of rust infected plant material without prior recovery and spore multiplication. As opposed to virulence phenotyping, the SSR genotyping results reveals genetic diversity and relationships within and among genetic groups. Results from previous years are available as pdf files from the GRRC website, where the results are also available on maps and charts.