Characterisation And Toxicity Studies Of Fusarium Isolates
| dc.contributor.author | Ismail, Nor Azliza | |
| dc.date.accessioned | 2017-02-07T08:24:08Z | |
| dc.date.available | 2017-02-07T08:24:08Z | |
| dc.date.issued | 2016-03 | |
| dc.description.abstract | Species in the genus Fusarium are pathogenic fungi to a wide variety of plants worldwide. Some species are able to produce fumonisin B1 (FB1), a mycotoxin that is harmful to humans and animals. The aims of this present study were to accurately identify and characterise Fusarium species associated with nine hosts in Malaysia, to determine the phylogenetic relationship between the species, to determine the ability of these species to produce FB1 and to test the toxicity of fungal crude extract containing FB1 on rice seedlings and mosquito larvae. In this study, 125 isolates of Fusarium species from nine hosts were identified as F. verticillioides (12 isolates), F. proliferatum (51 isolates), F. fujikuroi (24 isolates), F. andiyazi (six isolates) and F. oxysporum (32 isolates) using TEF-1α sequences. Maximum parsimony phylogenetic tree using TEF-1α and β-tubulin sequences resolved the species into five different clades of which the isolates from the same species were grouped in the same clade. Considerable genetic variation was observed for F. proliferatum and F. oxysporum isolates, supported by a number of sub-clades formed. FUM1 gene was detected in 96 out of 125 isolates but only 63 were positive for FB1 when tested with RIDA®QUICK FUMONISINS test strip, indicating that the presence of FUM1 gene was not necessarily associated with FB1 production. Based on UHPLC analysis, all 63 isolates produced FB1 with concentration levels ranging from 0.6 μg/g to 29.2 μg/g which were regarded as low FB1 producers, suggesting that the risk of FB1 contamination in Malaysia was also low. The crude extract of F. verticillioides (Q5566O) showed significant inhibitory effects on the root elongation at concentrations of 25, 50 and 100 μg/ml and the shoot elongation at 50 and 100 μg/ml, supporting the hypothesis that FB1 is phytotoxic to plant seedlings. The extract was also toxic to mosquito larvae with concentration resulting in 50% mortality (LC50) was very low, which was at 79.3 μg/ml. The results of this present study revealed that Fusarium isolates associated with various hosts in Malaysia were able to produce FB1 and demonstrated the toxicity effects on the tested seedlings and larvae. Although low levels of FB1 were produced, accumulation of the mycotoxin can occur under conditions that favour the fungal growth. The results also suggest a potential for FB1 contamination on agricultural crops in the field, implying the need to control of the fungal contamination at pre- and post-harvest stages. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/3690 | |
| dc.language.iso | en | en_US |
| dc.publisher | Universiti Sains Malaysia | en_US |
| dc.subject | Characterise Fusarium | en_US |
| dc.title | Characterisation And Toxicity Studies Of Fusarium Isolates | en_US |
| dc.type | Thesis | en_US |
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