A putative methyltransferase, mtrA, contributes to development, spore viability, protein secretion and virulence in the entomopathogenic fungus Beauveria bassiana

Abstract

The filamentous fungus, Beauveria bassiana, is a ubiquitously distributed insect pathogen, currently used as an alternative to chemical pesticides for pest control. Conidiospores are the means by which the fungus disseminates in the environment, and these cells also represent the infectious agent most commonly used in field applications. Little, however, is known concerning the molecular basis for maintenance of spore viability, a critical feature for survival and persistence. Here, we report on the role of a putative methyltransferase, BbmtrA, in conidial viability, normal fungal growth and development, and virulence, via characterization of a targeted gene knockout strain. Loss of BbmtrA resulted in pleiotropic effects including reduced germination, growth and conidiation, with growing mycelia displaying greater branching than the WT parent. Conidial viability dramatically decreased over time, with ,5 % of the cells remaining viable after 30 days as compared with .80 % of the WT. Reduced production of extracellular proteins was also observed for the DBbmtrA mutant, including protease/peptidases, glycoside hydrolases and the hyd1 hydrophobin. The latter was further confirmed by hyd1 gene expression analysis. Insect bioassays using the greater wax moth, Galleria mellonella, further revealed that the DBbmtrA strain was attenuated in virulence and failed to sporulate on host cadavers. These data support a global role for mtrA in fungal physiological processes.

The Herbivore-Induced Plant Volatiles Methyl Salicylate and Menthol Positively affect Growth and Pathogenicity of Entomopathogenic Fungi

“…However, these EPFs encountered low pathogenicity, conidia viability and instability due to the effect of UVB irradiance, and as consequence, there are only few EPF products being used in the field3031. In this regards, to overcome these challenges, many methods of molecular biology3233, chemical biology343536, and biophysics3738 have been investigated to increase the use of EPFs under adverse field conditions and some studies look promising39. Therefore, our findings in this study are important for understanding the multi-trophic interactions in ecosystems as well as for developing new and easier means for increasing conidial production and improving the pathogenicity of EPFs.…”

Redesigning the regulatory pathway to enhance cellulase production in Penicillium oxalicum

“…Double-joint PCR was performed to construct knockout cassette with the bar cassette flanked by 1.5 kb upstream (CreA-F1 and Crebar-R) and 1.5 kb downstream (Crebar-F and CreA-R1) of the creA ORF. 1.038 kb of bar cassette was amplified from plasmid pUC-bar by using prime pair Bar-F and Bar-R [ 54 ]. The final deletion cassette fragment Δ creA :: bar was obtained by using the primer pair (Crenest-F + Crenest-R) with the three fragments above as a template for PCR.…”

Improving mycoinsecticides for insect biological control

“…Variations in temperature, humidity, and exposure to UV-irradiation are amongst some of the important abiotic factors that can significantly impact the efficacy of entomopathogenic fungi in field applications (Fernandes et al 2007;Le Grand and Cliquet 2013;Rangel et al 2005;Thompson et al 2006). Spore viability and persistence are also important considerations with some recent advances in our understanding of at least one molecular determinant involved, i.e., a putative fungal methyltransferase, reported by Qin et al (2014). Although not addressed in this review, while formulation, e.g., inclusion of UV-protectants (absorbers), heat/humidity stabilizers, etc., has a strong potential for addressing some of these problems, costs and unanticipated effects associated with formulation compounds can outweigh benefits (Behle et al 2009;Inglis et al 1995).…”