RESUMO
The postharvest application of high degree of polymerization agave fructans (HDPAF) was tested, evaluating anthracnose disease, defense-related enzyme activities, and quality attributes in avocado fruit. Application of a 20% HDPAF solution showed a reduction in anthracnose severity (60%) and incidence (34%) compared to the other concentrations evaluated and the water-treated control. Polyphenoloxidase activity increased 4.6 times more 24 h after treatment. In addition, peroxidase and phenylalanine ammonia-lyase enzyme activity was 4.34 and 1.7 times higher than the control at 0.5 h after treatment. HDPAF retrieves the deceleration of both firmness loss and physiological weight loss compared to the control. Regarding quality parameters such as color, pH, total soluble solids, and titratable acidity, no significant differences were observed between treatments compared to the control; therefore, these parameters were not negatively affected by HDPAF treatments, but a positive effect on the induction of the defense system is shown.
RESUMO
In the present study, the antifungal activity of metabolites produced by Bacillus atrophaeus B5 and a new Brevibacterium strain against Alternaria alternata was evaluated. Assays in vitro and in vivo on tomato fruit during postharvest were made. Based on the 16S rDNA gene sequence analysis, the new strain (strain B7) was identified as Brevibacterium frigoritolerans. Metabolites produced by both bacterial strains reduced the spore germination of A. alternata in vitro and decreased the severity of the alternaria rot disease on tomato fruit during postharvest. This is the first report that demonstrates the potential of B. frigoritolerans B7 as a biocontrol agent against this fungal phytopathogen. The use of metabolites produced by B. atrophaeus B5 and B. frigoritolerans B7 represents a new approach to reduce the use of chemical pesticides and control fungal decay during the postharvest stage.