Analysis of Expressed Sequence Tags from the Fungal Banana Pathogen Mycosphaerella fijiensis

Abstract

Mycosphaerella fijiensis is a fungal pathogen causing black leaf streak disease in banana plants. In order to de-velop our understanding of the molecular mechanisms of host infection by M. fijiensis, we initiated a first step towards large-scale gene discovery through the generation and analysis of expressed sequence tags (ESTs). Three cDNA libraries representing different culture conditions were constructed. A subset of clones was sequenced at the 5' end and a total of 3,771 ESTs were generated. These ESTs were clustered into a set of 1,945 unique sequences. BLASTX analysis indicated that 410 of the unisequences showed homology to genes with known function, including those related to pathogenicity and virulence. Meanwhile, 66% and 89% of the ESTs matched to the predicted transcripts and genome sequences of M. fi-jiensis, respectively. The diversity of the EST collection developed in this study will facilitate genome annotation as well as identification and characterization of genes involved in host infection and fungal development through a comparative and functional genomics approach.