Lipopeptides from Bacillus mojavensis I4 confer induced tolerance toward Rhizoctonia solani in potato (Solanum tuberosum)
2022
Ghazala, Imen | Charfeddine, Mariam | Charfeddine, Safa | Haddar, Anissa | Ellouz-Chaabouni, Semia | Gargouri-Bouzid, Radhia
Bacterial lipopeptides are known for their protective activity against plant pathogens. The antifungal activity of I4 lipopeptide was confirmed in vitro by a growth inhibition assay. In fact, the mycelium growth inhibition of R. solani in the presence of 5 mg/ml of I4 biosurfactants was about 76%. In this study, the protective effect of lipopeptides from Bacillus mojavensis I4 was tested in vitro against Rhizoctonia solani in potato plants. The treatment of potato plants with I4 lipopeptides (5 mg/ml), previously inoculated with 10² CFU/ml of R. solani was carried out for 15 days. Different physiological parameters such as plant morphology and growth, plant elongation, and chlorophyll content were higher in the inoculated and treated plants (IT) than in the inoculated untreated ones (IUT). Indeed, after 10 days of treatment, the application of I4 lipopeptide under biotic stress enhanced plant elongation and chlorophyll content by 75% and 65%, respectively, compared to the inoculated untreated plants (IUT). Moreover, the application of I4 lipopeptide biosurfactant under biotic stress caused a decrease in hydrogen peroxide (H₂O₂), malondialdehyde content (MDA) and enzymatic antioxidants activities (SOD, CAT and GPX) compared to untreated plants under the same conditions. Besides, The I4 lipopeptide treatment induced the expression of PR (pathogenesis-related) genes under control and biotic stress conditions and reduced plant diseases. Considered together, the data presented in this study demonstrated that biosurfactants produced by B. mojavensis I4 can be used to improve the biological control of potato pathogens.
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