Activity and Siderophores Production by Rhodotorula spp. Isolates, Potential Antagonists of Botrytis Storage Rot

Document Type : Original Article


 GREY MOULD, caused by Botrytis cinerea Pers. (ex Fr.), is one of the most severe postharvest disease of fruit and vegetables. The use of fungicides is restricted in most countries, and there are problems due to the negative effects they may have on the human and environmental health, and on the selection of fungicide-resistant strains of the pathogen. The use of naturally occurring antagonists to control storage decay and increase product quality represents a practicable alternative to chemical fungicides. However, the mechanisms of action for most of the antagonists investigated have not yet been fully elucidated, because of the difficulties due to the complex interactions between host, pathogen, antagonist, and others microorganisms occurring in the site of interaction. Among the desirable characteristics of microbial antagonists is included the ability for siderophores production. Several phyllosphere yeasts species are known to produce hydroxamate-type siderophores, iron-binding compounds in response to Fe-stress conditions. In this research, more than 100 red yeasts were isolated from the surface of organically and conventionally trained grape berries and leaves, orange fruits, and olive drupes. The ability to produce siderophores was scored qualitatively, and the most active isolates were selected for further biocontrol activity tests against Botrytis storage rot on apple fruits. On the whole, results indicated that isolates R50 and R51, identified as Rhodotorula spp., were the most effective in reducing Botrytis storage rot on apple fruits, although with an intermediate hydroxamate-type siderophores production.