Cloning, sequencing and expression of a xylanase gene from the maize pathogen Helminthosporium turcicum

A gene encoding an endoxylanase from the phytopathogenic fungus Helminthosp orium turcicum Pass. was cloned and sequenced. The entire nucleotide sequen ce of a 1991 bp genomic fragment containing an endoxylanase gene was determ ined. The xylanase gene of 795 bp, interrupted by two introns of 52 and 62 bp, encoded a protein of 227 amino acids showing up to 95% amino acid homol ogy with other fungal xylanases. The precise splicing site of the introns w as identified by sequencing the corresponding cDNA. A northern blot showed that the gene is expressed when the fungus is grown in a medium containing xylan as a sole carbon source. The cloned xylanase gene was expressed in ma ize plants during infection.