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Fungitoxicity of organic extracts of Ocimum basilicum on growth and morphogenesis of Bipolaris species (teleomorph Cochliobolus)

Elsherbiny, E.A., Safwat, N.A., Elaasser, M.M.
Journal of applied microbiology 2017 v.123 no.4 pp. 841-852
Bipolaris cynodontis, Cochliobolus, Curvularia spicifera, Ocimum basilicum, asymmetry, butylated hydroxytoluene, chlorogenic acid, ethyl acetate, fungi, gas chromatography-mass spectrometry, germ tube, growth retardation, high performance liquid chromatography, methanol, morphogenesis, mycelium, pyrogallol, scanning electron microscopy, spore germination, teleomorphs
AIMS: This study aimed at evaluating the inhibitory effects of various organic extracts of Ocimum basilicum against some species of Bipolaris and Cochliobolus with GC‐MS and HPLC analysis. METHODS AND RESULTS: The ethyl acetate extract consisted of methyl cinnamate as the most abundant component, while butylated hydroxytoluene was the major component in the methanol extract. Pyrogallol and chlorogenic acid were major phenolic compounds in the ethyl acetate and methanol extracts, respectively. Complete growth inhibition of all fungi except Cochliobolus australiensis was observed by ethyl acetate extract, and on Bipolaris hawaiensis, Bipolaris spicifera and Cochliobolus cynodontis by methanol extract. Spore germination was completely inhibited for Bipolaris hawaiensis by ethyl acetate extract. Scanning electron microscopic observations revealed that the organic extracts cause considerable morphological changes of the fungal hyphae such as mycelial asymmetry, hyphal swelling, sunken, curling, distorted and broken hyphae. CONCLUSIONS: The ethyl acetate and methanol extracts of O. basilicum can result in an effective suppression of mycelial growth, spore germination and germ tube elongation of Bipolaris and Cochliobolus species. SIGNIFICANCE AND IMPACT OF THE STUDY: The organic extracts of O. basilicum are potential and promising natural tools for controlling Bipolaris and Cochliobolus species, economically important plant and human fungal pathogens.