A Novel Penicillium sp. Causes Rot in Stored Sugar Beet Roots in Idaho.

Penicillium vulpinum along with a number of other fungi can lead to rot of stored sugar beet roots. However, Penicillium isolates associated with necrotic lesions on roots from a recent sugar beet storage study were determined to be different from P. vulpinum and other recognized Penicillium species. Phylogenies based on sequencing of the internal transcribed spacer (ITS)-5.8S, β-tubulin (BenA), and RNA polymerase II second largest subunit (RPB2) DNA regions indicate that these isolates are novel, but most closely related to the following Penicillium spp. in the section Fasiculata: P. aurantiogriseum, P. camemberti, and P. freii. Macro- and micromorphological data also support designating these isolates as a new species for which we propose the name, Penicillium cellarum sp. nov. Inoculation studies with the P. cellarum isolates on roots of the commercial sugar beet cultivar B-7 led to the formation of necrotic lesions 23 to 25 mm in diameter after 86 days in storage. These lesions were similar to those observed on sugar beet roots in commercial storage piles. These data indicate that P. cellarum is a pathogen which can cause root rot in stored sugar beet roots.