New races caused epidemics of yellow rust in Europe, East Africa and Central Asia in 2016
Two significant new races having unique yellow rust genotypes were detected across wide areas in Europe/North Africa and East Africa/Central Asia, respectively. One new race was detected in Morocco, Italy and countries in Northern Europe. Another new race of a unique genotype was prevalent in epidemics in Ethiopia, Uzbekistan and Afghanistan.
New races detected in 2016
Two important new races having unique molecular genotypes were detected across wide areas in Europe/North Africa and East Africa/Central Asia, respectively (Table 3 and Table 4). One of the races, temporarily designated “Pst(new)” was detected in Morocco, Italy and northern Europe, where sampling was done systematically in 2016. The race was most prevalent in Morocco, a non-epidemic situation during the drought in winter and spring in that area, and on Sicily in a severe epidemic situation, where yellow rust until recent years was considered insignificant. Isolates of this new race in Sicily and Morocco had a 100% genotype match. The same race was detected at low frequency in four countries in Northern Europe and all these isolates diverged by a single marker from the genotype detected in Sicily/Morocco.
Another race was detected for the first time in East Africa in the autumn of 2016, after being first detected in Afghanistan in 2012 and 2013 (temporarily designated “AF2012”). The race was prevalent in epidemics in Ethiopia, where a series of varieties became severely affected by yellow rust. All Isolates of the race shared molecular genotype, including isolates collected in Afghanistan and Uzbekistan in 2016, where yellow rust epidemics were widespread.
Other prevalent races in 2016
The PstS5 lineage with a complex virulence profile was prevalent in Central Asia, including Uzbekistan, which is in accordance with results from previous years, and the aggressive PstS2 with virulence to Yr27 was again detected across wide areas (Walter et al., 2016). The PstS6 race, which has previously been prevalent in East Africa, was in 2016 also detected in Afghanistan.
In Europe, Warrior(-) was by far the most prevalent race, now being detected in several countries in East Europe and West Asia along with the original Warrior race (Tables 3 and 4) (Hovmøller et al., 2016). A new variant of Warrior(-) with additional virulence to variety ‘Ambition’ was detected in several countries, i.e., regular race typing cannot distinguish this new variant from isolates of the original Warrior race, emphasizing the advantage of integrating SSR genotyping and race typing activities. The triticale races, Triticale2006 and Triticale2015, which in general do not infect European winter wheat varieties, were detected on triticale and spring wheat in several countries. Both races have caused up to 100% yield loss in susceptible triticale varieties grown under organic conditions.
Race analyses were conducted according to Thach et al. (2015) and Sørensen et al. (2016)
Tables, maps and charts and full report
See the race analysis results here
See the genotype analysis results here
Find Yellow Rust Tools - Maps and charts here
Read the full report here
Prof. Mogens S. Hovmøller,
GRRC, Aarhus University
Hovmøller MS, Walter S, Bayles R, Hubbard A, Flath K, Sommerfeldt N, Leconte M, Rodriguez-Algaba J, Hansen JG, Lassen P, Justesen AF, Ali S, de Vallavieille-Pope C. 2016. Replacement of the european wheat yellow rust population by new races from the centre of diversity in the near-himalayan region. Plant Pathology 65: 402-411.
Sørensen, CK, Thach T, and Hovmøller MS. 2016. Evaluation of spray and point inoculation methods for the phenotyping of Puccinia striiformis on wheat. Plant Disease 100:1064-1070.
Thach T, Ali S, Rodriguez-Algaba J, Justesen AF, Hovmøller MS. 2015. Recovery and virulence phenotyping of the historic ‘Stubbs collection’ of the yellow rust fungus Puccinia striiformis from wheat. Ann Appl Biol, 167: 314–326.
Walter S, Ali S, Kemen E, Nazari K, Bahri B, Enjalbert, Hansen, JG, Brown JK, Sicheritz-Pontén T, Jones J, de Vallvieille-Pope C, Hovmøller MS, Justesen AF. 2016. Molecular markers for tracking the origin and worldwide distribution of invasive strains of Puccinia striiformis. Ecol Evol, 6: 2790–2804.