Partial Resistance of Near-Isogenic Wheat Lines Compatible withErysiphe graminisf. sp.tritici

Publisher Website
Google Scholar
Abstract
Six near-isogenic lines of ''Chancellor'' winter wheat, differing in known powdery mildew resistance genes (Pmx), were evaluated relative to ''Chancellor'' for partial resistance to compatible isolates of E. graminis f. sp. tritici collected in central Pennsylvania [USA]. The variability due to the host always exceeded that due to the isolates for the parasitic fitness attributes that were investigated: latent period (LP), cumulative sporulation (CSP) per colony, and corrected infection efficiency (CIE). Fitness genes other than virulence genes, or multiple alleles of the virulence genes, caused significant differences in certain fitness attributes for different isolates of the same race when compared on the same host. In certain instances, lines carrying a particular) Pmx gene were more susceptible than ''Chancellor''. Significant isolate .times. host interactions and significant differences in isolate ranking were demonstrated for several near-isogenic lines, indicating the potential for erosion of partial resistance over time. Pooled data over all isolates indicated partial resistance for several near-isogenic lines carrying known Pmx genes relative to ''Chancellor'': ''CI14122'' with Pm3c (LP); ''CI14123'' with Pm4 (CSP); and ''CI14122'' with Pm3c, ''CI14123'' with Pm4, and ''CI14033'' with Pmx gene from cultivar Michigan Amber (CIE).