Aetiology And Toxigenicity Of Fusarium Species, The Causal Agent Of Potato Tuber Dry Rot
Loading...
Date
2012-10
Authors
Mohamed Yahaya, Noor Fazila
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Fusarium dry rot is a worldwide reported disease infecting potato tubers. Thus, many studies have been conducted with a common aim to minimize losses incurred by the disease. The objectives of this study were to confirm the aetiology of Fusarium spp. isolated from potato dry rot and toxigenicity of selected isolates. A series of samplings were conducted in three states in northern Peninsular Malaysia namely Pulau Pinang, Kedah, and Perlis. A total of 56 samples of potato tubers with typical dry rot symptoms were collected. After the isolation on a semi-selective media, peptone pentachloronitrobenzene (PPA), 117 isolates of Fusarium spp. recovered were single-spored and identified morphologically into seven species, namely F. oxysporum (54 isolates; 46.2%), F. solani (52 isolates; 44.4%), F. proliferatum (3 isolates; 2.6%), F. semitectum (3 isolates; 2.6%), F. subglutinans (2 isolates; 1.7%), F. equiseti (2 isolates; 1.7%) and F. graminearum (1 isolate, 0.8%). Seventy isolates of Fusarium species were chosen for pathogenicity test for 21 days. From the test, three species of Fusarium i.e., F. oxysporum, F. solani and F. graminearum caused dry rot on artificially wounded potato tubers. Potato tubers inoculated with other species and those with sterile filter paper (control) did not show any disease symptoms. From 30 isolates of F. oxysporum, 29 isolates showed Scoring index of 4, which indicated severe infection of dry rot and soft rot and one with no symptom which indicated with Scoring index 1. From 29 isolates of F. solani, 28 isolates were pathogenic with 16 isolates showed severe infection with Scoring index 4, 10 isolates showed major dry rot symptoms with Scoring index 3, two isolates showed minor dry rot symptom with Scoring index 2 and one isolate showed no visible symptom with Scoring index 1. In addition, one isolate of F. graminearum showed Scoring index of 4 with severe infection. Analysis of FUMB1 and MON profiles was conducted on 25 isolates of F. oxysporum and 25 isolates of F. solani by inoculating sterilized rice and incubated for 28 days in the dark prior to extraction and filtration. Both FUMB1 and MON were analysed using Ultra Performance Liquid Chromatography (UPLC; Water® Associates, USA). Twenty isolates of F. oxysporum were able to produce FUMB1 ranged from 0.33 μg/g to 4.23 μg/g. Seven isolates of F. oxysporum (K7090P, K7304P, R7308P, R7417P, P7381P, P7424P, P7429P) were suspected to exceed the maximum limit practice for maize (~4.00 μg/g) by Food and Drug Association (FDA) and European Union (EU). None of the F. solani isolates was able to produce FUMB1. Twenty-four isolates of F. oxysporum also were able to produce MON ranged from 0.72 μg/g to 11.23 μg/g. Moreover, three isolates of F. solani (K7130P, R7145P, R7341P) were able to produce MON ranged from 0.49 μg/g to 1.34 μg/g. This study achieved all the objectives which were to confirm the aetiology of Fusarium spp. isolated from potato dry rot and toxigenicity of selected isolates This research is hoped to be beneficial to the authority involved in food industry and also to the throngs besides alert them on the existence of the disease and detrimental effects of mycotoxins when the contaminated potato tuber is used for cooking. This is the first report on aetiology and toxigenicity of Fusarium dry rot on potatoes in Malaysia.
Description
Keywords
Fusarium dry rot is a worldwide reported , disease infecting potato tubers