3.2 Compared to D. solani, D. dianthicolaexhibited a fitness advantage in potato plants
Plant assays were performed in the greenhouse to compare the severity of blackleg symptoms after inoculation by D. dianthicola or D. solani on non-wounded potato plants. Five D. dianthicola strains (RNS11-47-1-1A, CFBP1888, CFBP2982, CFBP2015, MIE34) and five D. solani strains (3337 = RNS08-23-3-1A, IPO2222, RNS05-1-2A, Ds0432.1, PPO9019) were used in these assays.
In a first assay, each strain was inoculated individually on 15 plants, and the number of asymptomatic and symptomatic plants (the two symptom classes) were counted. A Kruskal-Wallis test revealed differences between D. solani and D. dianthicola in terms of symptom severity (k=7; DF=1; p=8 x 10-3): D. dianthicola was found more aggressive than D. solani(percentages of symptomatic plants of 61% ± 10 versus 15% ± 11;