Genotypic Variation in Plant Disease Resistance--Physiological Resistance in Relation to Field Disease Transmission

Cloned genotypes of Silene alba differed in the percentage of plants that became diseased following floral and bud inoculation with six isolates of the fungus Ustilago violacea. The three flower and bud inoculation methods used in the study had little effect on the resistance ranking of the genotypes. No differences in virulence were found among the six fungal isolates. Multiple regression analyses revealed that the percentage of diseased plants following inoculation was an important predictor of disease levels of the same genotypes in a field experiment with natural disease transmission. This result validates the use of inoculation methods for large-scale resistance testing in this system (..)