Expressão de genes potencialmente envolvidos na patogenicidade de Aspergillus niger ao sisal

Abstract

Sisal (Agave sisalana) is one the few plants able to survive the conditions of the Brazilian Semi-arid Northeast region. This crop allows thousands of people to obtain minimal wages. However, there is a decline of the crop caused by the fungus Aspergillus niger. The objective of this work was to study the expression of five A. niger genes putatively involved in the pathogenicity to sisal through quantitative real time PCR (qPCR). These genes comprise four hydrolytic enzymes (cellulase, cutinase, protease and lipase) and the mycotoxin ocrhratoxin A. The dissertation is composed of one literature review and 2 chapters. The literature review contains information about sisal, the bole rot disease, hydrolytic enzymes and ochratoxin A. In the first chapter the expression of genes potentially involved in the pathogenicity of A. niger to sisal were studied in an in vitro simulated interaction. Primers for hydrolytic enzymes and ocrhratoxin A were designed and optimized for qPCR. Higher expression of all genes was observed in medium supplemented with sisal extract than in the minimal medium. In the second chapter an attempt to study the expression of genes putatively involved in pathogenicity of A. niger and in the defense of sisal plants against the fungus in in vivo conditions. However, it was not possible to amplify the target genes due to primer inefficiency or lack of fungal DNA. Other studies will be carried out in the future to optimize the extraction of RNA from the interaction. These data are the first to focus on the mechanisms of pathogenicity of A. niger to sisal.