3.5 Dickeya solani exhibited a fitness advantage overD. dianthicola in hyacinths.
The symptom incidence and competition were further evaluated in
hyacinths, that represent important hosts as they constitute a reservoir
or/and primary or intermediate host of D. solani. We expected a
higher symptom incidence and growth advantage of D. solani on
hyacinth host as compared to D. dianthicola . The five D.
dianthicola and five D. solani bacterial strains were inoculated
separately on eight plants per strain and the number of symptomatic and
asymptomatic plants were counted. At 61 dpi, a Kruskal-Wallis test
revealed differences between D. solani and D. dianthicolain terms of symptom incidence (k=3.03; DF=1; p=0.08): D. solaniwas found more virulent than D. dianthicola ; means ± SE of the
percentage of symptomatic plants reached 43% ± 17 and 23% ± 9,
respectively (Figure S5a) .
In co-inoculation assays with species mixtures (Figure S5b ),
the qPCR quantification of the pathogens in five symptomatic tissues
showed that the calculated CI were different from one (Kruskal-Wallis
test: k=7.8; DF=1; p= 5 x 10-3). The CI median value
of 4 x 109 indicated a high competitive advantage ofD. solani over D. dianthicola in rotted tissues of
hyacinths. Bulb plants thus appeared promoting competitive exclusion ofD. dianthicola by D. solani , which would lead to an
enrichment in D. solani in the bulb plant agrosystems.