title: Increase of fumonisin b2 and ochratoxin a production by black Aspergillus species and oxidative stress in grape berries damaged by powdery mildew.
abstract: Powdery mildew (PM), caused by the fungus Erysiphe necator, is one of the most widespread fungal disease of grape and may cause extensive openings on the berry surface during the infection. We evaluated the effect of damage caused by PM in grape berries on the growth of and mycotoxin production by Aspergillus and on the oxidative stress in infected berries. Berries of Vitis vinifera L. cv. Negroamaro with sound skin (SS) and those naturally infected by PM were surface sterilized and inoculated with either fumonisin B2(FB2)-producing strains of Aspergillus niger or ochratoxin A (OTA)-producing strains of Aspergillus carbonarius and incubated at 20 and 30°C. The PM berries were significantly more susceptible to both Aspergillus colonization (5 to 15 times more susceptible) and OTA and FB2 contamination (2 to 9 times more susceptible) than were SS berries. The highest toxin concentration was detected in inoculated PM berries both for OTA (9 ng/g) at 20°C and for FB2 (687 ng/g) at 30°C. In inoculated SS and PM berries, although malondialdehyde and hydrogen peroxide concentrations did not increase, the two black Aspergillus species caused a significant decrease in ascorbate content, thus inducing a pro-oxidant effect. These results indicate that grape berries affected by PM are more susceptible to black Aspergillus growth and to production and/or accumulation of FB2 and OTA. Thus, preventive control of E. necator on grape berries could reduce the mycotoxicological risk from black Aspergillus infection.
authors.affiliation: Institute of Sciences of Food Production, National Research Council, via Amendola 122/0, 70126 Bari, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cozzi
authors.forename: Costantino
authors.initials: C
authors.lastname: Paciolla
authors.forename: Miriam
authors.initials: M
authors.lastname: Haidukowski
authors.forename: Silvana
authors.initials: S
authors.lastname: De Leonardis
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Mulè
authors.forename: Antonio
authors.initials: A
authors.lastname: Logrieco
mesh_terms: D001203:Ascomycota / Q000502:physiology*; D001230:Aspergillus / Q000254:growth & development / Q000378:metabolism*; D001234:Aspergillus niger / Q000254:growth & development / Q000378:metabolism; D060467:Disease Resistance; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D037341:Fumonisins / Q000032:analysis / Q000378:metabolism*; D009793:Ochratoxins / Q000032:analysis / Q000378:metabolism*; D018384:Oxidative Stress; D027843:Vitis / Q000382:microbiology*
chemical_list: D037341:Fumonisins; D009793:Ochratoxins; C056934:fumonisin B2; C025589:ochratoxin A