Estudo de proteases degradadoras de cutícula produzidas por Beauveria bassiana

AUTOR(ES)

Ariane Coelho Donatti

DATA DE PUBLICAÇÃO

2007

RESUMO

The entomopathogenic fungus Beauveria bassiana is considered a promising agent of microbial control of insects considered pests of agriculture, such as, the grasshopper Rhammatocerus schistocercoides. This grasshopper attacks economically important plantations in the center-west Brazil. B. bassiana is capable to penetrate through cuticle of the host by apressorium formation and production of cuticle-degrading enzymes, such as proteases, that are considered virulence factors. The isolate CG425 of B. bassiana presents virulence against R. schistocercoides. The production of extracellular proteases, subtilisin-like (Pr1) and trypsin-like (Pr2) by isolate CG425 was analyzed after growth in medium supplemented with R. schistocercoides cuticle and non-cuticular substrate. The production of proteases Pr1 and Pr2 was higher in presence of cuticle, suggesting that these proteases-types are induced for components of the cuticle. The higher values of Pr1 compared to that of Pr2 suggests that the regulation system of these enzymes is distinct. The regulation of proteases production (Pr1 and Pr2) by CG425 was also analyzed in cultures contained different amino acids. Of tested amino acids, only the methionine, that is an amino acid few found in cuticle of some grasshoppers species, seems to have a role in the expression of these proteoteases. Transformants of B. bassiana obtained by the employment of Agrobacterium tumefaciens-mediated transformation had been analyzed concerning alterations conidia production, due to the fact that the production of conidia by entomopathogenic fungus is an important feature in the context of microbial control of pests. Of the 179 transformants analyzed, 14 had presented alterations in production of conidia, compared to that of the wild-type strain. One of the transformants with such alteration was submitted to the TAIL-PCR analysis aiming at the identification of genomic DNA sequences spanning the insertion junction of the T-DNA.

ASSUNTO(S)

pragas agrícolas - controle biológico. enzimas proteolíticas beauveria bassiana proteolytic enzymes agricultural pests - biological control.

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