Molecular characterization of the niaD and pyrG genes from Penicillium camemberti, and their use as transformation markers

Abstract

Genetic manipulation of the filamentous fungus Penicillium camemberti has been limited by a lack of suitable genetics tools for this fungus. In particular, there is no available homologous transformation system. In this study, the nitrate reductase (niaD) and orotidine-5'-monophosphate decarboxylase (pyrG) genes from Penicillium camemberti were characterized, and their suitability as metabolic molecular markers for transformation was evaluated. The genes were amplified using PCR-related techniques, and sequenced. The niaD gene is flanked by the nitrite reductase (niiA) gene in a divergent arrangement, being part of the putative nitrate assimilation cluster in P. camemberti. pyrG presents several polymorphisms compared with a previously sequenced pyrG gene from another P. camemberti strain, but almost all are silent mutations. Southern blot assays indicate that one copy of each gene is present in P. camemberti. Northern blot assays showed that the pyrG gene is expressed in minimal and r