ARS | Publication request: Comparison of the Isoepoxydon Dehydrogenase Gene of the Patulin Metabolic Pathway in B. Nivea and Penicillium Species

Submitted to: American Society for Microbiology
Publication Type: Abstract
Publication Acceptance Date: February 17, 2006
Publication Date: May 21, 2006
Citation: Dombrink-Kurtzman, M.A. 2006. Comparison of the isoepoxydon dehydrogenase gene of the patulin metablolic pathway in B. nivea and penicillium species [abstract]. American Society for Microbiology. p. 445.

Technical Abstract: Penicillium expansum is the fungus most commonly associated with production of the mycotoxin patulin in apples and apple juice. The sequence of the isoepoxydon dehydrogenase (idh) gene, which codes for a key enzyme in the patulin biosynthetic pathway, was determined in 12 different Penicillium species and Byssochlamys nivea, all known to produce patulin. Byssochlamys nivea is unique among patulin-producers because of its ability to produce ascospores that survive pasteurization and cause spoilage of heat-processed fruit products worldwide. Primer pairs for DNA amplification by PCR and sequencing of the idh gene of Penicillium species were designed based on the P. griseofulvum idh gene deposited in GenBank. For determination of the B. nivea idh gene, it was necessary to construct GenomeWalker libraries because one of its introns was two- to three-fold larger than the introns in Penicillium species. The identity of all of the isolates was confirmed by sequencing rDNA (ITS1, 5.8 S, ITS2 and partial sequences of 28S rDNA). Maximum parsimony analysis showed trees based on idh and rDNA sequences to be congruent, suggesting that lateral gene transfer between the species examined had not occurred. There were numerous nucleotide substitutions in the idh gene of the Penicillium species and B. nivea, but the amino acid sequence was usually not affected because the nucleotide differences occurred in the third coding position. One significant amino acid difference among the fungi examined was the substitution of a conserved lysine residue by threonine. P. griseofulvum and closely related P. dipodomyicola were the only species containing lysine which is involved in binding the cofactor NADP+. It is anticipated that the genetic information presented will lead to a better understanding of the patulin biosynthetic pathway and will aid in synthesis of probes to identify these mycotoxigenic fungi.