Characterization and in vitro expression patterns of an exopolygalacturonase encoding gene from Fusarium oxysporum f.sp radicis lycopersici

Aims: In this work, we report the isolation, characterization and expression pattern in in vitro cultures of an EXOPG encoding gene (pgx2), a novel EXOPG encoding gene of Fusarium oxysporum f.sp. radicis lycopersici , responsible for foot crown and root rot disease in tomato plants. The gene was compared with other fungal polygalacturonases (PGs) previously reported. Methods and Results: Partial sequences of the purified EXOPG native protein were used to design primers that amplified a genomic fragment by PCR. The amplified genomic fragment was used as a probe to screen a genomic library. One isolated clone was analysed. The complete genomic, cDNA and the deduced amino acid sequences were compared with other fungal EXOPGs and ENDOPGs. Regulation of pgx2 expression was analysed by Northern blot in in vitro cultures supplemented with different carbon sources. Conclusions: Pgx2 was present as single copy in the haploid genome of several Fusarium species. PGX2 showed the conserved amino acid motifs typical of PGs and those reported for fungal EXOPGs. Pgx2 was regulated at transcriptional level showing similar expression pattern to other EXOPG encoding gene (pgx1) when the fungus was cultured on different carbon sources suggesting a coordinate expression of both genes. This similarity would be supported by the presence of common putative regulatory motifs in the upstream regions of both genes. Significance and Impact of the Study: This study reports the analysis of a novel EXOPG gene of the tomato pathogen F. oxysporum f.sp. radicis lycopersici , a contribution to the understanding of the role of cell-wall-degrading enzymes produced by fungi during pathogenesis.