2019 ASHS Annual Conference

Accumulating evidence indicates that the composition of the microbiota inhabiting an organism (both endo- and epiphytically) can have a profound effect on host physiology. New correlations between specific microbiota and human health are being reported at a rapid rate. While significant efforts have been made in characterizing the rhizosphere and epiphytic microbiome of plants, much less attention has been placed on developing and harvested fruit, despite the potential impact of the microbiome on fruit physiology, postharvest disease, and food safety. Currently, efforts are being made to determine a core (common) apple fruit microbiome, the impact of management practices on the microbiome, and the identification of microbial consortia that can be used to inhibit postharvest diseases. Thus far, our investigation has revealed spatial and temporal changes in microbial diversity with clear distinctions between the microbiota of peel, stem-end, calyx-end, and wounded tissues. In general, bacteria appear to be impacted more than fungal taxa by sanitation practices, especially the epiphytic microflora of peel tissues. Coating fruit with a commercial wax favored the survival of bacterial pathogens that had been applied prior to waxing. An effect of apple pedigree on the endophytic population of microbes was also documented, suggesting that apple hosts and their associated microbiome have co-evolved, as suggested by the holobiont hypothesis. Ongoing studies are analyzing the microbiome of ‘Royal Gala’ apple fruit at harvest from seven different countries (18 different orchards) to determine if a core microbiome can be identified.