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Abstract :
[en] The use of plant-derived products in postharvest disease management may be a
valid alternative to conventional chemical treatments (Pane et al., 2016). Unfavorable
environmental conditions (such as salt and drought) increase production and accumulation of
reactive oxygen species (ROS). Consequently, extremophile plants have developed adaptive
responses including the synthesis of specific bioactive molecules used for medical and
nutritional purposes (Ksouri et al., 2012). In that context, the main objective of the present
study was the identification of effective plant extracts and essential oils from extremophile
plants against the most important plant pathogens in Europe (in term of loss, treatment
necessity and/or cost).
The study began with the selection of four endemic medicinal species suspected to be
antimicrobial due to their wealth of phenolic and terpene compounds, such as flavonoids,
phenolic acids, and coumarins (Ksouri et al., 2012). Each of the aerial plant materials was
grounded and macerated with solvent (methanol or chloroform) for 24 h. The solvent was
then eliminated along rotavapor. The yield of plant extract varied between 1.56 and 6.7%.
Kinetics of growth of the 3 pathogens cultivable in liquid medium was determined before
testing the impact of plant extracts and essential oils. Methanolic and chloroform plant
extracts (EM1, EM2, EC1 and EC2) and essential oils (EO1, EO2) were compared for their
antifungal potential. The chemical composition of the essential oils obtained by hydrodistillation
from the aerial parts was analyzed by GC/MS. Yield of essential oil varied
between 0.7 and 1.2%. Therefore, antifungal activity of plant extracts and essential oils was
evaluated using ELISA microplates with a blocked randomized design, as described
previously (Parisi et al., 2013).
The results obtained showed that EM2 at 7 mg/ml has a very high fungistatic activity
against Fusarium culmorum, F. oxysporum and Penicillium italicum. It was characterized
with a high amount of polyphenols, flavonoids and condensed tannins. Statistical analysis
showed that the efficiency of methanol extracts significantly differed from those of the
chloroform extracts. In addition, essential oils significantly reduced spores germination in a
dose-dependent manner. Their fungistatic activity reached 100% at 6000 ppm.
In conclusion, this work allowed us to open new perspectives on the application of
extremophile plant extracts as novel biocontrol strategy against plant pathogens.
