Abstract:
This study was carried out in order to fight against the phytopathogenic fungus ""Fusarium"".
eight species from the genus Fusarium have been isolated from different organs of infected
plants. genus identification was conducted using morphological characters, while the
identification of species was performed by molecular pathway within the LMBA Laboratory
(Laboratory of Microbiology and Biomolecules Assets).
Indeed, according to affiliation results, the eight pathogenic strains belong to three Fusarium
species in the circumstances; Fusarium verticillioides, Fusarium solani and Fusarium
oxysporum.
Biological control against the phytopathogens is highlighted using seven strains from the
genus Trichoderma isolated from three Algerian agricultural soils.
The molecular identification of isolats conducted in the laboratory of LMBA has divided
the seven strains into five main species: Trichoderma album, Trichoderma harzianum,
Trichoderma virens, Trichoderma longibrachiatum, Trichoderma viride. Indeed, This study
showed a significant diversity of Trichoderma species in Algeria. However, to our
knowledge, there are no previous published studies on the isolation of Trichoderma album,
Trichoderma virens and Trichoderma longibrachiatum, from the Algerian soil.
The effect of the antagonist activity of Trichoderma strains against the eight isolated
Fusarium species was studied using two methods, direct and indirect confrontation. Direct
confrontation results show a percentage of inhibition ranging from 55% to 72% depending on
the tested pathogenic and antagonists species, while the results of the confrontation from
distance reveals low percentage of inhibition varied from 2% to 43%.
The seven tested Trichoderma strains show considerable capacity of resistance on the media
with a different pH from 2 to 9. Enzymatic activity test of antagonistic strains shows that the
seven tested strains represent very important sources of lytic enzymes namely chitinase,
cellulase, protease, lipase and laccase.
Both test for anti-Fusarium activity, and culture filtrates antagonistic strains show a low
inhibition of mycelial growth of pathogenic strains. Furthermore, this study showed a
remarkable change of color and appearance of the Fusarium strains due to antagonistic
metabolits.
chloroformic extract effect of the seven antagonistic strains, was tested by the BIOLOG
technic and by the technical soaked disks, both techniques show a good inhibitory activity of
the extracts, no matter what the concentration used is (50 mg / ml , 25 mg / ml and 1mg / ml)
