Comparative genomic study of the Penicillium genus elucidates a diverse pangenome and 15 lateral gene transfer events.

The Penicillia are known to produce a wide range natural products-some with devastating outcome for the agricultural industry and others with unexploited potential in different applications. However, a large-scale overview of the biosynthetic potential of different species has been lacking. In this study, we sequenced 93 Penicillium isolates and, together with eleven published genomes that hold similar assembly characteristics, we established a species phylogeny as well as defining a Penicillium pangenome. A total of 5612 genes were shared between ≥ 98 isolates corresponding to approximately half of the average number of genes a Penicillium genome holds. We further identified 15 lateral gene transfer events that have occurred in this collection of Penicillium isolates, which might have played an important role, such as niche adaption, in the evolution of these fungi. The comprehensive characterization of the genomic diversity in the Penicillium genus supersedes single-reference genomes, which do not necessarily capture the entire genetic variation.

Regulation of a novel Fusarium cytokinin in Fusarium pseudograminearum.

Fusarium pseudograminearum is an agronomically important fungus, which infects many crop plants, including wheat, where it causes Fusarium crown rot. Like many other fungi, the Fusarium genus produces a wide range of secondary metabolites of which only few have been characterized. Recently a novel gene cluster was discovered in F. pseudograminearum, which encodes production of cytokinin-like metabolites collectively named Fusarium cytokinins. They are structurally similar to plant cytokinins and can activate cytokinin signalling in vitro and in planta. Here, the regulation of Fusarium cytokinin production was analysed in vitro. This revealed that, similar to deoxynivalenol (DON) production in Fusariumgraminearum, cytokinin production can be induced in vitro by specific nitrogen sources in a pH-dependent manner. DON production was also induced in both F. graminearum and F. pseudograminearum in cytokinin-inducing conditions. In addition, microscopic analyses of wheat seedlings infected with a F. pseudograminearum cytokinin reporter strain showed that the fungus specifically induces its cytokinin production in hyphae, which are in close association with the plant, suggestive of a function of Fusarium cytokinins during infection.