A green fluorescent protein-transformed Mycosphaerella fijiensis strain shows increased aggressiveness on banana

Abstract

The fungal pathogen Mycosphaerella fijiensis, causal agent of black leaf streak disease of bananas and plantains, was transformed with a green fluorescent protein-carrying construct by using a restriction enzyme-mediated integration methodology. A quantitative polymerase chain reaction was adapted to estimate transgene copy number and pathogenicity assays with three banana genotypes with dissimilar reactions to M. fijiensis infection were performed to characterize the transformants. Transgene insertion varied from one to five copies per genome among four random selected transformants. All M. fijiensis strains produced typical symptoms of the black leaf streak disease on the three banana genotypes assayed. Interestingly, the GFP-18 transformant showed increased aggressiveness on susceptible ‘Grande naine’ and resistant ‘Yangambi km5’ plants demonstrating that mutation events in M. fijiensis can increase virulence.