In Vitro Antifungal Activity of 'Desmodium Intortum' and 'D. Uncinatum' Root Extracts against Growth of Toxigenic 'Fusarium Verticillioides' and 'Aspergillus Flavus'

Abstract

Maize grown under push-pull cropping system has been reported to contain lower concentrations of fumonisin and aflatoxin than maize monocrop. This study determined the inhibitory effect of desmodium root extracts on spore germination and radial growth of toxigenic 'Aspergillus flavus and Fusarium verticillioides'. 'Aspergillus flavus and F. verticillioides' were isolated from maize and soil and tested for ability to produce aflatoxin and fumonisin by inoculation on mycotoxin-free maize. Aflatoxin and fuminisin were detected and quantified by direct competitive ELISA. Desmodium roots were dried, ground to fine powder and extracted with methanol and dichloromethane and evaluated for anti-fungal activity by inhibition of spores of 'A. flavus and F. verticillioides' potato dextrose agar (PDA) medium. Isolates of F. verticillioides produced up to 599,741 mug/kg fumonisin while isolates of 'A. flavus' produced up to 199,184 mug/kg aflatoxin. Desmodium root extracts reduced germination of 'A. flavus spores and F. verticillioides' by 9.6% and 43.8%, respectively and reduced their respective colony radial growth by 15% and 57%. The results suggested that desmodium roots contain chemical compounds that inhibit growth of 'A. flavus and F. verticillioides'. This may explain the reduction in infection of maize with mycotoxin-producing fungi before harvest in push-pull cropping systems by reducing the pathogen inoculum in the soils. Determination of the active compounds in the root exudates is recommended.

Description

Article

Keywords

In vitro antifungal activity, Desmodium intortum, Desmodium uncinatum, Root extracts, Fusarium verticillioides, Aspergillus flavus, Toxigenic fungi, Antifungal properties, Plant extracts, Biocontrol

Citation

Njeru, N. K., Midega, C. A. O., Muthomi, J. W., Wagacha, J. M., & Khan, Z. R. (2020). In vitro antifungal activity of'Desmodium intortum'and'D. uncinatum'root extracts against growth of toxigenic'Fusarium verticillioides' and'Aspergillus flavus'. Australian Journal of Crop Science, 14(12), 1942-1948.

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