ISOLATION AND ANTIFUNGAL SUSCEPTIBILITIES OF PHYTOPATHOGENIC FUNGI FROM YAM LEAVES (Dioscorea rotundata and cayenesis) IN ZARIA, NIGERIA
ISOLATION AND ANTIFUNGAL SUSCEPTIBILITIES OF PHYTOPATHOGENIC FUNGI FROM YAM LEAVES (Dioscorea rotundata and cayenesis) IN ZARIA, NIGERIA
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Date
2012-12
Authors
Mu’azu Jodi, Sa’adatu
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Abstract
Fungal attack of yams leaves has been reported to substantially result in low yam tuber
yield. This study was designed to isolate phytopathogenic fungi from yam leaves in
Zaria, Nigeria and to evaluate their susceptibilities Minimum Inhibitory Concentration
(MIC) and Minimun Inhibitory Concentration (MFC) to some antifungal agents
(Terbinafine; Fluconazole; Flucytosine; Benomyl and Sodium propionate). The
fungistatic activities of these chemical compounds alone and in combinations at varying
pH, temperature and different water sources used as diluents were investigated.
Fourteen fungi species namely Aspergillus niger, Cladosporium sp, Aspergillus
ostianus, Scopolarium sp, Aspergillus flavus, Rhizopus sp, Penicillium citrinum,
Aspergillus wentii, Penicillium oxalicum, Aspergillus cervinus, Penicillium sp,
Aspergillus fumigatus, Aspergillus oryzae and Rhizopus stolonifer were isolated from
infected yam leaves in eleven farms in Zaria, Nigeria. The MIC values varied
significantly from one organism to another. Generally, Aspergillus niger, Penicillium
citrinum, Aspergillus cervinus, and Rhizopus stolonifer were the most resistant to the
test anti-fungal agents. The order of fungi-static activity (MIC) of the test anti-fungal
agents against resistant Rhizopus stolonifer spores was Flucytosine (200.00μg/ml) >
Terbinafine HCl (250.00μg/ml) > Benomyl (500.00μg/ml) > Fluconazole (1000.
00μg/ml) > Sodium propionate (2500. 00μg/ml). However the lethal activity profile was
not the same with the fungi-static activity and the order of lethal activity (MFC) was
Terbinafine HCl (500.00μg/ml) > Flucytosine (1600.00μg/ml) > Benomyl
(2000.00μg/ml) = Fluconazole (2000. 00μg/ml) > Sodium propionate (5000. 00μg/ml).
The effect of fungicidal concentration of the test antifungal agent against viable test
fungal spores at different time interval showed rapid sporicidal effects. The cmbination
of either Terbinafine HCl or Fluconazole or Benomyl with Sodium propionate displayed
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synergistic anti-fungal activity with FICs of 0.098 to 0.140 against resistant Rhizomes
stolonifer spores. The anti-fungal effects of the test anti-fungal agent and their
combinations were shown to be more active at temperature of 450C. Combinations of
the anti-fungal agents’ were effective at neutral pH with the exception of Terbinafine
HCl and Sodium propionate that were only active at alkaline pH. The anti-fungal
activities of the combined test anti-fungal agents were reduced when unboiled water
sources were used as diluent. The in-vino anti fungal activity of the potential fungicides
combination such as Benomyl/Fluconazole (1000/5,000μg/ml), Benomyl/Terbinafine
HCl (1000/200μg/ml) and Benomyl/Sodium propionate (1000/15,000μg/ml) were
observed to protect yam leaves from resistant Aspergillus Niger spores (2.0x108cfu/ml)
on the farm in Zaria, Nigeria.
Description
Department of Pharmaceutics and Pharmaceutical
Microbiology, Faculty of Pharmaceutical Sciences, Ahmadu
Bello University, Zaria.
Keywords
ISOLATION,, ANTIFUNGAL,, SUSCEPTIBILITIES,, PHYTOPATHOGENIC,, FUNGI,, YAM,, LEAVES,, Dioscorea rotundata., cayenesis,, ZARIA,, NIGERIA.