Partecipanti: Dott.ssa Alessandra Di Francesco; Dott.ssa Elena Baraldi
Volatile organic compounds efficacy in controlling postharvest diseases Alessandra Di Francesco1*, Michele Di Foggia2, Elena Baraldi1
e-mail*: alessand.difrancesc3@unibo.it
1 Università di Bologna, Dipartimento di Scienze e Tecnologie Agro-alimentari, Via Fanin 42, 40127 Bologna, Italia;
2 Università di Bologna, Dipartimento di Scienze Mediche e Chirurgiche, Via Belmeloro 8/2, 40126 Bologna, Italia;
Aureobasidium pullulans strains L1 and L8, effective against some fruit postharvest pathogens, were evaluated for VOCs production as a part of their modes of action towards different pathogens: Penicillium spp., Botritys cinerea, Colletotrichum acutatum, and Monilinia spp.. The VOCs were assayed with a double petri dish assay against conidia germination and mycelial growth and the obtained results showed that the VOCs generated by the antagonists inhibited significantly the conidia germination and the mycelial growth of all pathogens, in particular Penicillium spp. CFU growth (~ 100%) and M. fructigena mycelium growth (70% by L1 and 50% by L8) compared to the control. In in vivo tests, apples, oranges, and peaches were artificially inoculated with pathogens conidia and then biofumigated with VOCs emitted by both antagonists. The antagonistic treatment controlled significantly pathogens infection, confirming the results obtained in vitro. One of the best L1 and L8 VOCs activity was observed on apple inoculated with B. cinerea where the lesion diameter reduction observed was greater than the 88%. Regarding peach fruit, yeasts treatment displayed the best inhibiting action specially against M. laxa (100% by L1, 84% by L8). Moreover, the antagonistic activity was enhanced by the addition of asparagine (120 mg L-1) in the culture media composition. The compounds emitted by L1 and L8 strains were identified with the solid-phase microextraction (SPME)–gas chromatographic technique; their relative synthetic pure compounds were tested in vitro on pathogens mycelial, and conidia growth and their EC50 values were estimated. Through Infrared analysis, VOCs produced by both strains showed the capability to increase the fruit waxes complexity reducing the pathogens attack, playing an essential role in the antagonistic activity of both yeast strains and on fruit structural composition.