INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
A 1,4-benzoquinone reductase of the entomopathogenic fungus Beauveria bassiana is involved in the degradation of Tribolium castaneum defensive secretions.
Autor/es:
PEDRINI N.; JUÁREZ M. PATRICIA; KEYHANI NEMAT O
Reunión:
Congreso; 45th Annual Meeting of the Soc. Vertebrate Pathology; 2012
Resumen:
Tribolium castaneum, a major pest of stored and processed grains, is a poor host for the entomopathogenic fungus Beauveria bassiana, rendering biological control efforts at using the fungus against the beetle problematic. Glandular alkyl-1,4-benzoquinones (BQs) are the major components of the defensive secretions produced by T. castaneum. In this work, a 1,4-benzoquinone reductase (bqr) gene from B. bassiana was characterized, and its function in relation to BQ degradation probed. A cDNA clone corresponding to bqr was isolated and characterized. The ORF consisted of 947 nucleotides and encoded a deduced protein of 201 amino acids. Reduced germination, and a significant inhibition on B. bassiana growth were observed when the fungus was incubated in culture media containing T. castaneum gland extracts or synthetic BQs. Below the minimal inhibitory concentration, bqr expression was significantly induced in BQ-exposed fungi, suggesting a role for the protein in detoxifying BQs. The largest gene induction and enzyme activity were observed using 2 and 1 mg/ml of BQ, respectively. A bqr targeted gene disruption mutant of B. bassiana was constructed and a bqr overexpressing strain was obtained. The targeted gene knockout strain lacking bqr displayed a slightly decreased virulent phenotype against T. castaneum, whereas B. bassiana overexpressing the bqr gene resulted in significantly higher mortality rates (> 2-fold) as compared to the wild-type parent strain. These results shed light on the interaction between entomopathogenic fungi and tenebrionid defensive secretions, suggesting a novel function for a fungal quinone reductase as a specific virulence factor against quinone-secreting tenebrionids.