Qualitative and relative abundance analysis of Alternaria alternata metabolites in pomegranate (Punica granatum L.) cultivars affected by Heart Rot using UHPLC-Q-TOF-MS

Abstract

Secondary metabolites of Alternaria alternata in juice extracted from fruit of pomegranate ( Punica granatum ) ‘Acco’ and ‘Wonderful’ affected by heart rot were identified using the UHPLC-Q-TOF-MS analytical method. Juice from healthy and infected fruit was analyzed comparatively with particular focus on mycotoxin content. Overall, 22 metabolites were detected, including the mycotoxins tenuazonic acid, alternariol, alternariol monomethyl ether (AME) and altenuene (ALT). Multivariate analyses, including Principal Component Analysis and Random Forest models, clearly separated the metabolic profiles of healthy and infected fruit. Symptomatic fruits, especially those of ‘Wonderful’, exhibited markedly higher levels of mycotoxins, such as alternarlactone A and altertoxin, suggesting that these metabolites are potential biomarkers for early detection of heart rot. In contrast, they were characterized by a substantial lower level of punicic acid, indicating heart rot infection affected negatively the nutraceutical value of juice due to the depletion of the content in this omega−5 fatty acid. This study provides better insights into the effects of A. alternata infection on the quality of pomegranate juice as well as new evidences in favour of a regulation of the mycotoxin level in pomegranate juice. • Identification of Alternaria mycotoxins in pomegranate juice using UHPLC-Q-TOF-MS. • Juice from heart rot affected fruit showed high levels of tenuazonic acid and alternariol. • Heart rot infection depleted the content in punicic acid, an omega-5 fatty acid, in juice. • Multivariate analysis identified biomarkers for early detection of Alternaria infections. • Heart rot incited by Alternaria alternata impact the quality of pomegranate juice.

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