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SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION
GENETICS
P46 - Study of the in vitro growth and pathogenicity of
a collection of Fusarium spp. and Microdochium
nivale obtained from the ear and the collar of wheat
collected in the central region of Algeria
H. Boureghda 1 , F. Djellialia 1
Département de Botanique- Ecole Nationale Supérieure Agronomique (ENSA) El Harrach-Algies-
Algeria
E-mail: hou.boureghda@gmail.com
The study of pathogenicity and in vitro growth of a collection of 22 isolates
belonging to different Fusarium species (F. graminearum, F. culmorum, F.
verticilliodes, F. avenaceum, F. lateritium, F. solani) and M. nivale obtained from
the ear and collar of wheat harvested in the central region of Algeria had been
made. The effect of temperature on the in vitro growth showed that the optimum
growth for species F. culmorum, F. graminearum, F. lateritium, and F. solani was
at 25 ° C, while F. verticilliodes, M. nivale and F. avenaceum exhibited optimum
growth at 20 ° C. In general, the growth of F. lateritium, F. culmorum, F.
graminearum and F. solani increased between 15 and 25 ° C and those of F.
avenaceum, F. verticiliiodes and M. nivale between 10 and 20 ° C. Pathogenicity
tests were carried out in vitro and in vivo. In vitro, pathogenicity test was carried
out by exanimating the effect of the pathogen species on the in vitro coleoptile
growth rate of wheat seedlings. The pathogenicity of the seven species in vitro
was evaluated at different temperatures 15 ° C, 20 ° C, 25 ° C and 30 ° C and
showed the aggressiveness of all the isolates tested. Regardless of the isolate
origin (collar or ear), species F. culmorum, F. graminearum and F. verticilliodes
showed the highest percentages of reduction of the coleoptile growth at 15 ° C (>
96% reduction), while M. nivale at 20 ° C (> 95%), and 30 ° C (> 98 %) for F.
solani compared to control seedlings. In vivo pathogenicity tests were carried out
by using two methods, ear infection and soil inoculation (to evaluate disease
severity on the collar and the root of wheat seedlings). Pathogenicity test on the
collar showed that all Fusarium spp. and M. nivale isolates induced symptoms on
the collar and root also those obtained from diseased ear. However F.
graminearum and F. culmorum isolates obtained from diseased collars caused
disease severity indices higher than the isolates obtained from ears. Also, it was
found in this study that isolates belonging to the genus Fusarium isolated from the
collar induced typical symptoms of Fusarium head blight on the ear and the
disease severity of isolates was independent of isolate origin (collar or ear).
Results obtained in this study showed that there is no correlation between the
pathogenicity of all Fusarium and M. nivale isolates on the collar and on the ear.
Keywords: Fusarium, Microdochium, In vitro growth, pathogenicity
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