title: Contrasting Genomic Diversity in Two Closely Related Postharvest Pathogens: Penicillium digitatum and Penicillium expansum.
abstract: Penicillium digitatum and Penicillium expansum are two closely related fungal plant pathogens causing green and blue mold in harvested fruit, respectively. The two species differ in their host specificity, being P. digitatum restricted to citrus fruits and P. expansum able to infect a wide range of fruits after harvest. Although host-specific Penicillium species have been found to have a smaller gene content, it is so far unclear whether these different host specificities impact genome variation at the intraspecific level. Here we assessed genome variation across four P. digitatum and seven P. expansum isolates from geographically distant regions. Our results show very high similarity (average 0.06 SNPs [single nucleotide polymorphism] per kb) between globally distributed isolates of P. digitatum pointing to a recent expansion of a single lineage. This low level of genetic variation found in our samples contrasts with the higher genetic variability observed in the similarly distributed P. expansum isolates (2.44 SNPs per kb). Patterns of polymorphism in P. expansum indicate that recombination exists between genetically diverged strains. Consistent with the existence of sexual recombination and heterothallism, which was unknown for this species, we identified the two alternative mating types in different P. expansum isolates. Patterns of polymorphism in P. digitatum indicate a recent clonal population expansion of a single lineage that has reached worldwide distribution. We suggest that the contrasting patterns of genomic variation between the two species reflect underlying differences in population dynamics related with host specificities and related agricultural practices. It should be noted, however, that this results should be confirmed with a larger sampling of strains, as new strains may broaden the diversity so far found in P. digitatum.
authors.affiliation: Bioinformatics and Genomics Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain Universitat Autònoma De Barcelona, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Julca
authors.affiliation: Department of Postharvest Science, ARO, the Volcani Center, Bet Dagan, Israel.
authors.forename: Samir
authors.initials: S
authors.lastname: Droby
authors.affiliation: Department of Plant Pathology and Weed Research, The Volcani Center, Bet Dagan, Israel.
authors.forename: Noa
authors.initials: N
authors.lastname: Sela
authors.affiliation: Bioinformatics and Genomics Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Marcet-Houben
authors.affiliation: Bioinformatics and Genomics Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain Institució Catalana De Recerca I Estudis Avançats (ICREA), Barcelona, Spain toni.gabaldon@crg.es.
authors.forename: Toni
authors.initials: T
authors.lastname: Gabaldón
mesh_terms: D017753:Ecosystem; D049810:Genetic Speciation; D016681:Genome, Fungal; D010407:Penicillium / Q000235:genetics* / Q000302:isolation & purification; D020641:Polymorphism, Single Nucleotide
keywords: Penicillium; genome variation; genomics