Morphological and PCR characterisation of fungi isolated from tomato postharvest, and potential control of fruit spoilage by antifungal plant extracts
2019
Bate, P. N. N. | Tatsinkou, F. B. | Ngemenya, M. N. | Takam, G. H. F. | Mbah, J. A.
Fungal infection causes significant postharvest loss in tomato production. Few studies have evaluated natural products in vivo as alternative to unsafe synthetic chemical fungicides. Thepresent work evaluated three plants with known antifungal activity namely; Cymbopogon citratus (lemon grass), Ocimum gratissimum (African basil) and Thymus vulgaris (thyme), against fungi isolated from tomato postharvest in vitro. The most active extract was tested on healthy fruits for preliminary assessment of its effect. Fungi isolated from tomato postharvest in Buea, South West Cameroon, were characterised using morphological techniques followed by molecular identification using polymerase chain reaction. Four distinct fungal isolates were detected with Fusarium and Colletotrichum spp. being the predominant isolates. In antifungal disc diffusion and microdilution bioassays, the plant extracts exhibited moderateto high inhibition of fungal growth. The methylene chloride extract of T. vulgaris (TVC) was the most active with a minimum inhibitory concentration of 12.5 mg/mL. TVC suppressed artificial infection with F. oxysporum isolate and inhibited natural infection of fruits with 100% inhibition at 0.15 and 0.31% of TVC at 4°C after 30 days. T. vulgaris extract can potentially prevent postharvest infection and should be further investigated on tomato fruits as a suitablealternative to synthetic fungicides for extension of tomato shelf life postharvest.
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