Abstract
Pulsed light, as a postharvest technology, is an alternative to traditional fungicides, and can be used on a wide variety of fruit and vegetables for sanitization or pathogen control. In addition to these applications, other effects also are detected in vegetal cells, including changes in metabolism and secondary metabolite production, which directly affect disease control response mechanisms. This study aimed to evaluate pulsed ultraviolet light in controlling postharvest rot, caused by Fusarium pallidoroseum in ‘Spanish’ melon, in natura, and its implications in disease control as a function of metabolomic variation to fungicidal or fungistatic effects. The dose of pulsed light (PL) that inhibited F. pallidoroseum growth in melons (Cucumis melo var. Spanish) was 9 KJ m–2. Ultra-performance liquid chromatography (UPLC) coupled to a quadrupole-time-of-flight (QTOF) mass analyzer identified 12 compounds based on tandem mass spectrometry (MS/MS) fragmentation patterns. Chemometric analysis by Principal Components Analysis (PCA) and Orthogonal Partial Least Squared Discriminant Analysis (OPLS-DA) and corresponding S-Plot were used to evaluate the changes in fruit metabolism. PL technology provided protection against postharvest disease in melons, directly inhibiting the growth of F. pallidoroseum through the upregulation of specific fruit biomarkers such as pipecolic acid (11), saponarin (7), and orientin (3), which acted as major markers for the defense system against pathogens. PL can thus be proposed as a postharvest technology to prevent chemical fungicides and may be applied to reduce the decay of melon quality during its export and storage.
Highlights
Melon (Cucumis melo L.) is a widely produced fruit in different parts of the world and is an economically crucial part of Brazilian exports
A pulsed light (PL) dose of 9 KJ m–2 in melon inoculated with F. pallidoroseum controlled the disease promoted by this pathogen and induced metabolic variation in the fruit defense system
Pipecolic acid (11) and orientin (3) were the two possible biomarkers associated with postharvest disease control against F. pallidoroseum in infected melons treated with PL radiation
Summary
Melon (Cucumis melo L.) is a widely produced fruit in different parts of the world and is an economically crucial part of Brazilian exports. Fungal diseases from the genus Fusarium in fruit are traditionally controlled by the application of synthetic fungicides; this treatment leaves chemical residues, which could be harmful to the consumer and encourages the development of fungicide-resistant strains of fungal pathogens. To overcome these challenges, several alternative or integrative approaches, including physical methods, are imperative to develop fruit with increased natural defense responses through the resistance mechanisms induced by abiotic stress [3]
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