Two Selection Strategies of Epiphytic Native Yeasts with Potential Biocontrol Capacity against Postharvest Pear Pathogens in Patagonia

LUTZ M.C.; ROBIGLIO A.; SOSA M.C.; LOPES C.A.; SANGORRÍN M.P.

ACTA HORTICULTURAE

International Society for Horticultural Science

Año: 2011

0567-7572

To reduce the use of fungicides, biological control with yeasts has been proposedworldwide in recent years. In order to find antagonistic yeasts adapted to pearstorage conditions (-1/0 ºC for 7 months), two isolation strategies were explored. In2007 (strategy A), the yeasts were isolated from the surface of healthy fruits.Aliquots of the obtained suspensions were seeded on GPY agar and incubated at 26ºC. In 2008 (strategy B), washes from healthy wounds after 150 days at 0 ºC wereused to inoculate fresh pear wounds with Penicillium expansum. Yeasts were isolatedfrom healthy wounds after 50 days of incubation in cold. From both A and Bisolation strategies, one isolate from each yeast species was tested for antagonisticactivity against P. expansum and Botrytis cinerea by in vivo (pear wounds at 0 ºC)and in vitro (dual cultures at 20 ºC) assays. By means of strategy A, six yeast specieswere identified. Among them, the best antagonists were A. pullulans and R.mucilaginosa, which reduced only P. expansum disease incidence (33%). Fromstrategy B, five of six species obtained, Cryptococcus weringae, C. victoriae,Cystofilobasidium infirmominiatum, Rhodotorula laryngis and A. pullulans, showedthe highest antagonistic activity against P. expansum; they completely controlleddisease incidence at 100 days. Only Cryptococcus weringae and C. victoriae reducedincidence of B. cinerea (80%) at 100 days. Differences between in vivo and in vitrobiocontrol assays were observed. In in vitro assays, all yeasts produced a greatergrowth inhibition of P. expansum than of B. cinerea. Strategy B was the mosteffective strategy for the selection of antagonistic yeasts for postharvest diseasecontrol.