PROBIEN   20416
INSTITUTO DE INVESTIGACION Y DESARROLLO EN INGENIERIA DE PROCESOS, BIOTECNOLOGIA Y ENERGIAS ALTERNATIVAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Yeast for biological control of postharvest pears pathogens in Patagonia, Argentina
Autor/es:
LUTZ M.C.; LOPES C.A.; SOSA M.C.; SANGORRÍN M.P.
Lugar:
Guadalajara
Reunión:
Simposio; 29th International Specialised Symposium on Yeast; 2011
Institución organizadora:
International Commission on Yeasts
Resumen:
Introduction. The main pear growing area inArgentina is situated in Northpatagonian region.During postharvest storage in cold (-1/0°C), importanteconomical losses occur because of the developmentof blue and grey molds caused by Penicilliumexpansum and Botrytis cinerea. In that condition,selected criotolerant yeasts are promising biocontrolagents as they grow and colonize rapidly the surfaceand microwounds.The objectives of this work were to obtain yeasts withantagonistic activity against postharvest pathogensfrom pear stored at low temperature, by means of anew improved isolation and selection methodology.Methods. Yeasts and pathogens were isolated frompear fruits from two different managed (organic andtransition) packinghouses, during 2007/2008 seasons.Pathogens were identified and selected (resistance tofungicides and virulence) as described Robiglio et al.,2011.Washings from healthy wounds and surfaces of pearsafter 7 months of cold storage were used in a first invivo assay against P. expansum. Reduction inincidence and severity of decays were used asbiocontrol evaluation. Those washings showing thehighest biocontrol activity were used for yeastisolation. Individual yeasts, identified by ITS-RFLP andsequences (Lutz et al., 2011), were then used in asecond in vivo assay. Finally, the most promisingisolates were tested in a third bioassay both P.expansum and B. cinerea.In order to assess the possible yeast antagonisticmechanism, yeasts were characterized by productionof (in vitro, -1/0º C - 30 days): killer toxins, lyticenzymes, siderophores, volatile compounds andbiofilms. Also the germination inhibition of conidia wasevaluated in pears broth. The capacity for colonizationof the wounds was performed in vivo at -1 /0° C.Results and discussion. A total of 116 washingswere recovered from healthy wounds (64.7%) andpear surfaces (35.3%) after 7 months of storage fromboth packinghouses. 27 washings (23%), showedgood antagonist activity against P. expansum. Most ofthem were obtained from healthy wounds. From thesewashings, 55 yeast isolates were obtained andidentified as mainly belonging to Aureobasidium andCryptococcus genus. 26 isolates representative ofeach different yeast species were evaluated in vivoagainst P. expansum to -1/0°C. All isolates controlled100% of blue mold incidence after 100 days, whereasonly 38% did so after 200 days. Against B. cinerea,these isolates were less effective. Cryptococcusalbidus NPCC 1248, Pichia membranifaciens NPCC1250, Cryptococcus victoriae NPCC 1259 and NPCC1263, and Cryptococcus weringae NPCC 1268 werethe most promising isolates.All selected yeasts showed glucanase activity and C.weringae also showed protease activity. The twoisolates of C. victoriae formed biofilms. C. weringaeand C. victoriae showed killer activity againstpathogens. No isolate presented chitinase andpectinase activity, production of volatile compoundsand siderophores. The germination inhibition washigher against P. expansum that B. cinerea, whereNPCC 1268 showed the percentages better.Colonization assays demonstrated that the 5 yeastsachieved rapid and effective establishment in thewounds of pear, with farther performance isolatesNPCC 1248, 1250 and 1263.Conclusions. Three of the five indigenous criotolerantyeasts showing good biocontrol activity against P.expansum and B. cinerea in postharvest pears at lowtemperature. Potential control antagonist mechanismswere elucidated.References.1. Robiglio A. Sosa M, C, Lutz M.C, Lopes C. A. andSangorrín M. P, 2011, Yeast biocontrol of fungal spoilageof pears stored at low temperature. International Journal ofFood Microbiol. 147: 211–216.2. Lutz M. C., Robiglio A., Sosa M.C., Lopes C. A. andSangorrín M.P., 2011, Two Selection Strategies of EpiphyticNative Yeasts with Potential Biocontrol Capacity againstPostharvest Pear Pathogens in Patagonia. Acta Horticult.