THE IN-PLANTA INDUCED ECP2 GENE OF THE TOMATO PATHOGEN CLADOSPORIUM-FULVUM IS NOT ESSENTIAL FOR PATHOGENICITY

During the colonization of tomato leaves, the fungal pathogen Cladospo rium fulvum excretes low-molecular-weight proteins in the intercellula r spaces of the host tissue. These proteins are encoded by the ecp gen es which are highly expressed in C. fulvum while growing in planta but are not, or are only weakly, expressed in C. fulvum grown in vitro. T o investigate the function of the putative pathogenicity gene ecp2, en coding the 17-kDa protein ECP2, we performed two successive disruption s of the gene. In the first of these, the ecp2 gene was interrupted by a hygromycin B resistance gene cassette. In the second gene disruptio n, the ecp2 gene was completely deleted from the genome, and replaced by a phleomycin resistance gene cassette. Both disruption mutants were still pathogenic on tomato seedlings, indicating that the C. fulvum e cp2 gene is not essential for pathogenicity in tomato.