New article: New races of Puccinia striiformis found in Europe reveal race-specificity of long-term effective adult plant resistance in wheat

New races of Puccinia striiformis found in Europe reveal race-specificity of long-term effective adult plant resistance in wheat  / Chris K. Sørensen, Mogens S. Hovmøller, Marc Leconte, Françoise Dedryver, and Claude de Vallavieille-Pope

In: Phytopathology 2014 October 2014, Volume 104, Number 10, 1042-1051

doi: 10.1094/PHYTO-12-13-0337-R

Abstract

Resistance to Puccinia striiformis (Pst) was examined in nine wheat recombinant inbred lines (RILs) from a cross between Camp Rémy (resistant parent) and Récital (susceptible parent) using an isolate of a strain common to the NW-European population before 2011 (old) and two additional isolates, one representing an aggressive and high temperature adapted strain (PstS2) and another representing a virulence phenotype new to Europe since 2011 (new). The RILs carried different combinations of quantitative trait loci (QTL) for resistance to Pst. Under greenhouse conditions the three isolates gave highly contrasting results for infection type, latent period, lesion length and diseased leaf area. The PstS2 isolate revealed Yr-genes and QTL which conferred complete resistance in adult plants. Six QTL   had additive effects against the old isolate whereas the effects of these QTL were significantly lower for  the new isolate. Furthermore, the new isolate revealed previously undetected resistance in the susceptible parent. Disease severity under field conditions agreed with greenhouse results, except for  Camp Rémy being fully resistant to the new isolate and for two RILs being susceptible in the field.        These results stress the need of maintaining high genetic diversity for disease resistance in wheat and of using pathogen isolates of diverse origin in studies of host resistance genetics.