Enzimi, acidi organici ed altri metaboliti coinvolti nella patogenesi di Penicillium spp

摘要: Blue mould caused by Penicillium expansum Link is one of the most destructive rot pome fruit in all growing areas (Snowdon, 1990; Jones and Aldwinckle, 1991; Tonini,1996) In past, rot has been controlled fungicide postharvest treatment mainly thiabendazole (TBZ) benomyl (Hardenburg Spalding, 1972), but their intense use produced appearance resistant strains with a great reduction activity The aims present study were to characterize isolates Pencillium sp causing blue mold on pear Italy physiological biochemical parameters. In particular differencing also behavior relationship sensitivity or resistance TBZ treatments. We have examined early stage infection relation enzyme activity, local modulation pH, production organic acids, secondary metabolism of pathogen. The results described here confirm that majority P. from pears packing houses are TBZ, Among TBZ-resistant scored this work, different (RR) showed higher percentage conidial germination TBZ-amended medium compared non amended medium. This may indicate a stimulatory effect conidial germination. Therefore treatments not only ineffective for controlling P. expansum, they increase severity fruits. In absence fungicide, showed significant difference infection severity, R RR characterized higher pathogenic fitness fruits, producing larger lesions than S isolates. These data supported with laboratory-induced isolates, which shows lack correlation between TBZ osmotic sensitivity, highlights association between TBZ resistance (Baraldi et al 2003). Enzymatic screening gave positive reaction esterase, urease, pectinase activity, in addition, pathogen able synthesize complex act degrade the main components cell wall especially pectin cellulose. Isolated sensitive good activity pectinase, especially from poligactoronase, which, as already reported several studies (D'hallewin al, 2004; Prusky 2004), basis degradative process of cell wall. Also, although measure was minor highlighted some activities of cellulase, even note kind cellulase hemicellulase P. Expansum targeted, studies found no other source information in this regard. Twenty expansum, tested vitro ad vivo acid production ability pH drop. We modulation acids extrusion influence to various parameter:  Initial pH: general, greatest observed isolates grown at 7, except four maintained medium close others significantly decreased ranging 5.5 4.1.. In extreme acid condition (pH 3,0) growth lower respect optimal 5,0). Also a greater adaptation environmental more S.  Time: acidification continues days, PH is strongest hours (48-72 hours)of inoculation process. Time affects the quality example an initial abundant succinc acid, followed important of galacturoinc acid.  Substrates: there many differences type vitro and vivo. Results abundant galacturonic, malic, citric unknown smaller concentrations. Secondary metabolite analysis revealed intra-specific differences, patulin was found and in samples. There concentration patulin, of infected fruits, sample lower rotten area the others, mycotoxin samples a higher lesion diameter area. Beyond detected presence of another metabolite, penitrem A.