Sequence tag analysis of gene expression during pathogenic growth and microsclerotia development in the vascular wilt pathogen Verticillium dahliae

Two cDNA libraries were constructed from cultures of the vascular wilt fungus Verticillium dahliae, grown either in simulated xylem fluid medium (SXM) or under conditions that induce near-synchronous development of microsclerotia. Expressed sequence tags (ESTs) were obtained for over 1000 clones from each library. Most sequences in the two EST collections were unique; nearly 55% of the translated ESTs had strong similarity to protein sequences in the NCBI nonredundant database. ESTs corresponding to melanin biosynthetic enzymes were exclusive to the developing microsclerotia (DMS) collection, and sequences corresponding to extracellular hydrolases (plant cell wall degrading enzymes) were more abundant in that collection. ESTs corresponding to proteins involved in transport and cell growth were more abundant in the SXM collection. The results of this preliminary analysis suggest that the in vitro growth conditions used here provide useful model systems that will facilitate studies of pathogenesis and microsclerotia development in V. dahliae.