A multifaced approach sheds light on the molecular details underlaying the mechanism preventing enzymatic browning in ‘Majda’ apple cultivar (Malus domestica Borkh.)

Abstract

Fruit flesh browning is a natural oxidative phenomenon occurring after cutting or processing. This event, manifesting dark-brown coloration, can seriously limit the production and marketability of fresh cut fruit products. Antioxidant compounds can partially prevent this phenomenon, but in turn they can affect the quality and the organoleptic properties of fresh products. In this work we have investigated, through a multidisciplinary approach, the regulation of a natural non-browning phenotype of a particular apple cultivar ‘Majda’ in comparison with the browning reference apple cultivar ‘Golden Delicious’. The results highlight that the non-browning phenotype of ‘Majda’ was controlled by multiple mechanisms, particularly distinguished by a different concentration of chlorogenic acid and the expression of the polyphenol oxidase (MdPPO) gene. The metabolite assessment and gene expression profiling also disclosed the involvement of organic acids and glutathione in the prevention of oxidative browning phenomenon. The peculiar non-browning behavior of ‘Majda’ was also verified by a DPPH• kinetic approach that demonstrated the higher antioxidant activity of this apple cultivar. The results presented in this work proposed ‘Majda’ as a potential parental candidate to be considered for breeding activity oriented to select novel non-browning accessions addressed to ameliorate the sustainability of pre-cut fresh products.