Yeasts for biological control of postharvest pears pathogens in Patagonia, Argentina

LUTZ, MARIA CECILIA; LOPES CHRISTIAN; SOSA, MARIA CRISTINA; MARCELA PAULA SANGORRIN

Guadalajara

Congreso; 29th. International Specialized Symposium on Yeasts; 2011

A total of 116 washings were recovered from healthy wounds (64.7%) and pear surfaces (35.3%) after 7 months of storage from both packinghouses. 27 washings (23%), showed good antagonist activity against P. expansum. Most of them were obtained from healthy wounds. From these washings, 55 yeast isolates were obtained and identified as mainly belonging to Aureobasidium and Cryptococcus genus. 26 isolates representative of each different yeast species were evaluated in vivo against P. expansum to -1/0°C. All isolates controlled 100% of blue mold incidence after 100 days, whereas only 38% did so after 200 days. Against B. cinerea, these isolates were less effective. Cryptococcus albidus NPCC 1248, Pichia membranifaciens NPCC 1250, Cryptococcus victoriae NPCC 1259 and NPCC 1263, and Cryptococcus wieringae NPCC 1268 were the most promising isolates. All selected yeasts showed glucanase activity and C.wieringae also showed protease activity. The two isolates of C. victoriae formed biofilms. C. wieringae and C. victoriae showed killer activity against pathogens. No isolate presented chitinase and pectinase activity, production of volatile compounds and siderophores. The germination inhibition was higher against P. expansum that B. cinerea, where NPCC 1268 showed the percentages better. Colonization assays demonstrated that the 5 yeasts achieved rapid and effective establishment in the wounds of pear, with farther performance isolates NPCC 1248, 1250 and 1263. Conclusions. Three of the five indigenous criotolerant yeasts showing good biocontrol activity against P. expansum and B. cinerea in postharvest pears at low temperature. Potential control antagonist mechanisms were elucidated.