Competitive and colony layer formation ability as key mechanisms by yeasts for the control Botryosphaeria dothidea fruit rot of mango
2017
Terao, Daniel | de Lima Nechet, Kátia | Halfeld-Vieira, Bernardo de Almeida
Mango is an economically important fruit crop in Brazil and attacked by fungal diseases that require control. Currently, ensuring that fruit are free of pesticide residues before consumption is a key challenge in postharvest pathology. The fungus Botryosphaeria dothidea is the major pathogen and there is currently no efficient method for its control. This work aimed to evaluate the efficacy of yeast strains and the mechanisms involved in the biocontrol of mango rot caused by B. dothidea. The ability of seven yeast strains to control mango rot was compared to thiabendazole fungicide (485 g ai 100 L⁻¹). The modes of action involved in biocontrol were investigated by electron microscopy observations, as well bioassays for the production of inhibitory volatile compounds, chitinases, killer toxins and competition for nutrients and yeast colony layer interference. Strains of Candida membranifaciens and Meyerozyma guilliermondii reduced the severity of mango rot during 11-day storage period. Among them, C. membranifaciens (CMAA 1108) showed highest efficacy when compared to fungicide-treated fruit. No strains produced inhibitory substances against B. dothidea. Electron microscopy revealed an effective colonization by yeasts in the wounds. It is suggested that competition, as well as the establishment of a yeast colony layer after colonization, plays an important role in the reduction of mango fruit rot severity.
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