Studies of mycoparasite interactions with plant pathogenic Fusarium spp. and their mycotoxins
Date
2016-04-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
Sphaerodes mycoparasitica Vujan. SMCD 2220-01 is a mycoparasite that attacks major plant pathogenic Fusarium species such as F. avenaceum (Fr.) Sacc., F. oxysporum Schltdl., and F. graminearum Schwabe. The mycoparasite-host cell-to-cell replacement and interface changes in F. graminearum, as well as a decrease in production of mycotoxins in co-culture systems indicate a very complex fungus-fungus interrelationship in previous studies. The aim of this thesis is to investigate the interactions between the mycoparasite S. mycoparasitica and the host Fusarium spp., as well as the degradation of Fusarium mycotoxins by the mycoparasite. Host compatibility and adaptability of the mycoparasite with twelve Fusarium strains were examined using Fusarium filtrates through multiple paper disc assay and the results showed that the level of S. mycoparasitica adaptability strongly depends on types of Fusarium filtrates that indicate the degree of host compatibility ranging from biotrophic-attraction to antagonistic-inhibition relationships. The capacity of S. mycoparasitica to change the hydrophobicity of the host fungal surfaces during mycoparasitism was demonstrated by contact angles measurement using a dual culture assay. The results showed differential level of fungal surface hydrophobicity of S. mycoparasitica, F. proliferatum (Matsush.) Nirenberg SMCD 2246 (high hydrophobicity), and F. redolens Wollenw. SMCD 2401 (low hydrophobicity). They also change in hyphal surface hydrophobicity during mycoparasitism in different media. In terms of fungal surfaces, the isolates were assessed by atomic force microscopy (AFM). AFM results showed a shift in topography and physical properties of the hyphal surfaces affected by changes in nutrient and prolonged dry conditions. The potential for degradation of the mycotoxins by S. mycoparasitica and the metabolites were examined using thin layer chromatography and high performance liquid chromatography-electrospray ionization-high resolution mass spectrometry. The results showed a decrease in the mycotoxins such as zearalenone by 97%, 15-acetyl-deoxynivalenol by 72%, 3-acetyl-deoxynivalenol by 60%, and deoxynivalenol by 89%. Overall, S. mycoparasitica could be considered as a potential BCA specifically to reduce Fusarium-associated risks.
Description
Keywords
Biological control agent, Sphaerodes mycoparasite, Fusarium pathogens, Mycotoxins
Citation
Degree
Master of Science (M.Sc.)
Department
Food and Bioproduct Sciences
Program
Applied Microbiology