LAUSR

BACKGROUND Mangoes are tropical fruits appreciated worldwide but are extremely perishable, susceptible to decay, pest infestation and fungal diseases. Using the flavorful and highly valued 'Manila' cultivar, we examined the effect of second-generation chitosan coatings on shelf-life, phenolic compound variation, phytohormones, pest infestation by fruit flies (Anastrepha obliqua) and anthracnose disease caused by the fungus Colletotrichum gloeosporioides. RESULTS We observed almost total annihilation of A. obliqua eggs with 10 and 20 g L-1 chitosan in diluted acetic acid and a 5- to 6-fold reduction in anthracnose damage. Treatment with 20 g L-1 chitosan also extended shelf-life. External (skin) and internal (pulp) discoloration process was were delayed. Fruit firmness was higher when compared with than control and acetic acid treatments, and total soluble solids (TSS) were lower in chitosan-treated fruit. Targeted and non-untargeted metabolomics analyses on chitosan-coated fruit identified some phenolic compounds related to the tannin pathway. In addition, abscisic acid (ABA) and jasmonic acid (JA) in the peel were down-regulated in chitosan coated mango peels. Both, phytohormones and phenolic content, may explain mangoes reduced susceptibility to anthracnose development and A. obliqua egg eclosion or larval development. CONCLUSION We conclude that chitosan coatings represent an effective postharvest treatment that significantly reduces anthracnose disease, inhibits A. obliqua egg eclosion, and significantly extends 'Manila' mango shelf-life, a key factor currently inhibiting large-scale commercialization of this precious fruit. This article is protected by copyright. All rights reserved.