Molecular identification of Penicillium species associated with blue mold on grapes in German vineyards

Abstract

Species of 788 Penicillium strains from grape bunches affected by blue mold in German wine growing regions were identified by PCR based molecular methods. P. expansum was the most common species (n = 733) on the grapes and could be identified by species specific PCR of the polygalacturonase gene certainly (Marek et al., 2003). Eleven further species, P. minoluteum, P. crustosum, P. commune, P. purpurogenum, P. solitum, P. spinulosum, P. brevicompactum, P. chrysogenum (on flower residues only), P. aurantiogriseum, P. thomii/P. purpurescens, and P. janthinellum/P. griseovulvum, could be identified by different molecular methods. However, the identification of these species and the discrimination of closely related species by ITS sequencing was time consuming and not possible in each case. Therefore, a new molecular method based on an amplification of a cytochrome oxidase gene (cox1) sequence by PCR followed by a single restriction with HpyF3I or triple digestion with HpyF3I, BspT1, and BsmI was established. This method allows a fast and reliable distinction of the most common Penicillium species occurring on affected grape bunches in German wine growing regions, and allowed a discrimination of closely related species such as P. crustosum and P. commune, respectively.