Relationships between fungal spore morphologies and surface properties for entomopathogenic members of the general Beauveria, Metarhizium, Paecilomyces,Tolypocladium, and Verticillium

Abstract

The surface properties of aerial conidia (AC) from 24 strains of entomopathogenic fungi were studied and compared using the salt-mediated aggregation and sedimentation (SAS) assay, electron microscopy, FITC-labelled lectins, and spore dimensions. Spores with rugose surfaces were hydrophobic, whereas hydrophilic spores had smooth surfaces. Correlation analysis found no link between spore dimensions and either hydrophobicity or surface carbohydrates. However, there was a strong positive correlation between spore hydrophobicity and surface carbohydrates. The three spore types of Beauveria bassiana were all shown to possess discrete surface hydrophobicities, which were also strongly linked to surface carbohydrate profiles. Various chemical treatments had pronounced effects on spore surface properties, with sodium dodecyl sulfate (SDS) and formic acid (FA) reducing both lectin binding and surface hydrophobicity. When FA-protein extracts were separated and analysed using SDS-PAGE, only the hydrophobic spores had low molecular weight hydrophobin-like peptides that were unglycosylated and contained disulfide bonds. The strains with hydrophilic AC had much lower levels of FA-extractable protein per spore dry weight compared to their more hydrophobic counterparts. Moreover, extracts of the more hydrophobic spores tended to have greater protein:carbohydrate ratios.Key words: fungi, spores, hydrophobicity, lectins, morphology, microbial insecticides, protein.

Isolation and Physical Characterization of Hydrophobin-Like Proteins (HLP) from Aerial Conidia of <i>Metarhizium Anisopliae</i> Var. <i>Anisopliae</i>

“…This non-specific hydrophobic attachment of the conidia to the host cuticle is also found to involve the mediation of the Hydrophobin-Like Proteins (HLP) from the conidia onto the hydrophobic surfaces of the cuticle (Boucias et al, 1988). The formic-acid extractable proteins have been proved as HLP in the conidia of Beauveria bassiana (Jeffs et al, 1999). The hydrophobin gene ssga of M. anisopliae has also been studied in the molecular basis (Bidochka et al, 2001).…”

Identification of novel genes associated with conidiation inBeauveria bassianawith suppression subtractive hybridization

“…B. bassiana produce three single cell forms, aerial conidia, in vitro blastospores and submerged conidia in different conditions (Jeffs et al 1999). Aerial conidia are produced on the surface of solid medium by a process of hyphal extension, formation of phialides (rachis) and spore production.…”

EST analysis of cDNA libraries from the entomopathogenic fungus Beauveria (Cordyceps) bassiana. I. Evidence for stage-specific gene expression in aerial conidia, in vitro blastospores and submerged conidia

“…bassiana produces at least three single cell infectious propagules, known as aerial conidia, in vitro blastospores and submerged conidia, which display different morphological and biochemical properties (Bidochka et al, 1987;Jeffs et al, 1999;Thomas et al, 1987). Aerial conidia are relatively resistant to varying environmental conditions and represent the most commonly used cell form in biological control applications.…”