Genetic diversity and biocontrol activity of Aureobasidium pullulans isolates against postharvest rots

Aureobasidium pullulans, a cosmopolitan yeast-like fungus, colonises leaf surfaces and is a potential biocontrol agent for plant pathogens. Forty-one isolates of the fungus from the surface of several fruits and vegetables cultivated in Southern Italy were compared by molecular analysis and biocontrol activity. Characterisation of the isolates by using arbitrarily primed PCR (ap-PCR) confirmed the presence of a high genetic variability within the species. All the isolates were evaluated for their ability to control postharvest grey mold of apples, and two of them (SL250 and SL236), plus a proven antagonist (isolate L47), were able to control Penicillium digitatum on grapefruit, Botrytis cinerea, Rhizopus stolonifer and Aspergillus niger on table grape and B. cinerea and R. stolonifer on cherry tomato. Furthermore, preharvest application of isolate L47 on table grape resulted in a significant reduction of grey mold ranging from 27.1 to 49.5% compared to the untreated control. Random amplified polymorphic DNA technique (RAPD) was a useful method for the identification and evaluation of the survival rate of the applied antagonist. (C) 1999 Elsevier Science B.V. All rights reserved.