title: Genetic structure and natural variation associated with host of origin in Penicillium expansum strains causing blue mould.
abstract: Blue mould, caused by Penicillium expansum, is one of the most economically damaging postharvest diseases of pome fruits, although it may affect a wider host range, including sweet cherries and table grapes. Several reports on the role of mycotoxins in plant pathogenesis have been published, but few focussed on the influence of mycotoxins on the variation in host preference amongst producing fungi. In the present study the influence of the host on P. expansum pathogenicity/virulence was investigated, focussing mainly on the relationship with patulin production. Three P. expansum strain groups, originating from apples, sweet cherries, and table grapes (7 strains per host) were grown on their hosts of isolation and on artificial media derived from them. Strains within each P. expansum group proved to be more aggressive and produced more patulin than the other two groups under evaluation when grown on the host from which they originated. Table grape strains were the most aggressive (81% disease incidence) and strongest patulin producers (up to 554μg/g). The difference in aggressiveness amongst strains was appreciable only in the presence of a living host, suggesting that the complex pathogen-host interaction significantly influenced the ability of P. expansum to cause the disease. Incidence/severity of the disease and patulin production proved to be positively correlated, supporting the role of patulin as virulence/pathogenicity factor. The existence of genetic variation amongst isolates was confirmed by the High Resolution Melting method that was set up herein, which permitted discrimination of P. expansum from other species (P. chrysogenum and P. crustosum) and, within the same species, amongst the host of origin. Host effect on toxin production appeared to be exerted at a transcriptional level.
authors.affiliation: Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, Via G. Amendola 165/A, 70126 Bari, Italy. simonamarianna.sanzani@uniba.it
authors.forename: S M
authors.initials: SM
authors.lastname: Sanzani
authors.forename: C
authors.initials: C
authors.lastname: Montemurro
authors.forename: V
authors.initials: V
authors.lastname: Di Rienzo
authors.forename: M
authors.initials: M
authors.lastname: Solfrizzo
authors.forename: A
authors.initials: A
authors.lastname: Ippolito
mesh_terms: D005516:Food Microbiology; D005638:Fruit / Q000382:microbiology*; D014644:Genetic Variation; D054884:Host-Pathogen Interactions / Q000502:physiology*; D009183:Mycotoxins / Q000032:analysis / Q000096:biosynthesis; D010365:Patulin / Q000032:analysis / Q000096:biosynthesis; D010407:Penicillium / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D009183:Mycotoxins; D010365:Patulin