The relationship between secondary metabolism and infection in pathogenic fungi has remained largely elusive. The genus Penicillium comprises a group of plant pathogens with varying host specificities and with the ability to produce a wide array of secondary metabolites. The genomes of three Penicillium expansum strains, the main postharvest pathogen of pome fruit, and one Pencillium italicum strain, a postharvest pathogen of citrus fruit, were sequenced and compared with 24 other fungal species. A genomic analysis of gene clusters responsible for the production of secondary metabolites was performed. Putative virulence factors in P. expansum were identified by means of a transcriptomic analysis of apple fruits during the course of infection. Despite a major genome contraction, P. expansum is the Penicillium species with the largest potential for the production of secondary metabolites. Results using knockout mutants clearly demonstrated that neither patulin nor citrinin are required by P. expansum to successfully infect apples. Li et al. ( MPMI-12-14-0398-FI ) reported similar results and conclusions in their recently accepted paper.

Work at L. González-Candelas’ lab was partially supported by the Spanish Ministry of Economy and Innovation (Research Grants AGL-2008-04828-C03-02 and AGL2011-30519-C03-01) and by the Generalitat Valenciana, Spain(PROMETEO/2010/010 and PROMETEOII/2014/027). A.-R. Ballester is grateful to CSIC and the European Social Fund for her postdoctoral contract JAE-Doc. C. Selma-Lázaro is recipient of a FPI Predoctoral fellowship from the Spanish MICINN (BES-2012-054595). The T. Gabaldón group research is funded, in part, by a grant from the Spanish ministry of Economy and Competitiveness (BIO2012-37161), a Grant from the Qatar National Research Fund grant (NPRP 5-298-3-086), and a grant from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC (Grant Agreement n. ERC-2012- StG-310325).