Sex in Penicillium series Roqueforti

Abstract

Various fungi were isolated during the course of a survey in a cold-store of apples in the Netherlands. One of these fungi belongs to the genus Penicillium and produces cleistothecia at 9 and 15 °C. A detailed study using a combination of phenotypic characters, sequences and extrolite patterns showed that these isolates belong to a new species within the series Roqueforti. The formation of cleistothecia at low temperatures and the inability to produce roquefortine C, together with a unique phylogenetic placement, make these isolates a novel entity in the Roqueforti series. The name Penicillium psychrosexualis sp. nov. (CBS 128137(T)) is proposed here for these isolates.

Keywords: P. carneum; P. paneum; Penicillium; phylogeny; roqueforti; taxonomy.

Fig. 1.

Bootstrap consensus tree from a maximum likelihood analysis of partial β-tubulin sequences. The bootstrap values from 1 000 replicates are shown at the nodes, the branches in bold have a bootstrap support higher than 95 %. The tree was rooted with Penicillium egyptiacum CBS 244.32^NT.

Fig. 2.

Bootstrap consensus tree from a maximum likelihood analysis of partial calmodulin sequences. The bootstrap values from 1 000 replicates are shown at the nodes, the branches in bold have a bootstrap support higher than 95 %. The tree was rooted with Penicillium egyptiacum CBS 244.32^NT.

Fig. 3.

Bootstrap consensus tree from a maximum likelihood analysis of ITS sequences. The bootstrap values from 1 000 replicates are shown at the nodes, the branches in bold have a bootstrap support higher than 95 %. The tree was rooted with Penicillium egyptiacum CBS 244.32^NT.

Fig. 4.

Penicillium psychrosexualis (CBS 128036 , ex wooden crate in cold-store of apples, the Netherlands). (A–C) Colonies grown at 25 °C for 7 d on (A) CYA, (B) MEA, and (C) YES; (D) cleistothecium; (E–F) ascospores; (G) conidiophores on DG18 with warted stipes; (H) conidiophore with smooth stipe; (I) conidia. Bar = 10 μm, except (F) = 1 μm.

Fig. 5.

Growth of Penicillium psychrosexualis CBS 128036 on oatmeal agar at various incubation temperatures. A–F: 9, 12, 18, 24, 27 and 33 °C.

Fig. 6.

Overview of growth rates of the members of Penicillium series Roqueforti on CYA at various temperatures. Row, top to bottom: 9, 12, 18, 24, 24 (reverse), 30 °C; columns, left to right: P. roqueforti DTO 81D6, P. paneum DTO 28G8, P. carneum DTO 128A9 and P. psychrosexualis CBS 128036.