Relationship between virulence and enzymatic profiles in the cuticle of Tenebrio molitor by 2-deoxy-d-glucose-resistant mutants of Beauveria bassiana (Bals.) Vuill

Abstract

The secretion of hydrolases by Beauveria bassiana is a main factor in the degradation of cuticle, while in filamentous fungi the resistance to 2-deoxy-Dglucose (2DG) is related to enzymatic deregulation. A series of 2DG-resistant B. bassiana strains were classified according to the phenotypes of germination (G) and radial growth rate (U r ), in addition to their virulence parameters on Tenebrio molitor. This analysis allowed distinction between mutants with greater (881.2) and lesser (884.5) G and U r values, relative to the wild-type strain (88), which correlated with virulence parameters including maximal mortality (M) and time to reach 50% mortality (LT 50 ). Subsequently, using the cuticle of T. molitor as the substrate for these strains, an enzymatic analysis (total proteases, Pr1, chitinases and b-N-acetylglucosaminidase) showed that the contrasting virulence traits were associated with different deregulation patterns: higher specific activities (up to 100%) for the more virulent mutant 881.2 and lower enzymatic levels for mutant 884.5, specifically chitinases (33% reduction), relative to the wild-type strain (88) for both mutants. The differences in cuticle-degrading enzymes were consistent with the appearance of hyphal bodies within infected insects. This is the first study describing the altered enzymatic profiles in 2DG-resistant mutants of B. bassiana with practical implications in the selection of improved strains for biological control.

Reactive oxygen species production, induced by atmospheric modification, alter conidial quality ofBeauveria bassiana

“…Similarly, Montesinos‐Matías et al . () found differences in those infectivity parameters using several B. bassiana mutant strains resistant to 2‐deoxy‐ d‐ glucose. There is a differentiated response related to EF, since a hyperoxidant state improved infectivity in two strains of I. fumosorosea (Miranda‐Hernández et al .…”

“…Additionally, conidial adhesion to the insect cuticle is an important step in the infective cycle of EF, and occurs through unspecific interactions attributed to hydrophobin-like proteins. Thus, it is important to determine quality parameters of any process to produce conidia (Jeffs et al 1999;W€ osten 2001;Montesinos-Mat ıas et al 2011).…”

Molecular characterization and virulence of Beauveria bassiana and Metarhizium anisopliae against Galleria mellonella (Lepidoptera: Pyralidae) and Tenebrio molitor (Coleoptera: Tenebrionidae) larvae

“…The IPA148 was the most genetically distant in regarding to the other ones, at less than 40% similarity. G. mellonella and T. molitor are known to be susceptible to B. bassiana and M. anisopliae, for this reason they have been used as baits for isolation of entomopathogenic fungi from the soil (Zimmerman, 1986;Bidochka et al, 2002;Montesinos et al, 2011) or, as a probe to pathogenicity of other insect species (Bharadwaj et al, 2011). Mortality and concentrations were considered parameters in the study of the best strains behavior once indicating the pathogen colonization capacity, surpassing all competitor agents present in the insect (Neves, 1998).…”

An alternative inoculation technique of Colletotrichum gloeosporioides on mango for early anthracnose tolerance screening

“…Monosporic strains Gro, Col, Oax, Sin and Tux were isolated from infected mango tissue; Gro and Sin showed the higher growth rate, sporulation density and germination (Table 1). These factors correlated with virulence (Estrada-Valencia et al, 1997;Montesinos-Matías et al, 2011). It was observed that Gro and Sin isolates induced the highest incidence and severity in detached leaves (Table 2) (p<0.05).…”