Molecular characterization of a benzoquinone reductase gene in the fungus Beauveria bassiana

N. PEDRINI; M.P. JUÁREZ

Puerto Madryn

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular; 2010

Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular

Tribolium castaneum, a major pest of stored and processed grains, is the most tolerant beetle to the entomopathogenic fungus Beauveria bassiana. Glandular alkyl-1,4-benzoquinones (BQ) are the major components of the defensive secretions of T. castaneum. In this work we characterized a 1,4-benzoquinone reductase (BQR) gene of B. bassiana, and discussed its function on BQ degradation. We also studied the potential antifungal properties of beetle secretions, in order to elucidate their role in the scarce susceptibility of T. castaneum to entomopathogenic fungi. The cDNA of BQR consisted of 947 nucleotides and encoded a deduced protein containing 201 amino acids. Neither glycosylation sites nor signal peptide cleavage sites were found, and PSORT analysis suggested a cytosolic localization. Reduced germination and a significant inhibition on B. bassiana growth were detected after fungal incubation in culture media containing T. castaneum gland extracts or synthetic BQ. Below minimal inhibitory concentration, the BQR gene expression was significantly induced in BQ-exposed fungi. The largest fold induction was obtained after 1-day incubation; with 50-fold and 12-fold induction for 1 and 0.5 ug/ul BQ, respectively. Additional studies on BQR would be needed to understand the effect of these toxic compounds, in order to help develop a fungus-based biological control of these beetles.