Antioxidant System Differential Regulation is Involved in Coffee Ripening Time at Different Altitudes

Fruit ripening can be seen as an oxidative phenomenon that, depending on its intensity, may directly influence fruit quality. At relatively higher altitudes, coffee fruit ripening takes place through an extended period of time, which positively affects coffee quality. However, little is known about the oxidative processes and antioxidant metabolism of coffee fruits grown at these altitudes. Thus, this study aimed to characterise coffee fruit development from trees grown at two contrasting altitudes (965 m and 1310 m) through phenological analysis and antioxidant metabolism evaluation (Hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents; superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activity and gene expression). Phenological analysis showed that altitude extended coffee reproductive cycle by a month and promoted a higher ripening uniformity, with 100% of fruits at the ideal ripening stage for harvest (cherry stage) in the last evaluation time. H₂O₂ and malondialdehyde contents revealed that in both altitudes fruits went through oxidative damage, though in an early manner at the lower altitude. Although gene expression and enzyme activity did not well correlate, the delay in the oxidative damage in fruits of the higher altitude was probably a result of an increased efficiency in H₂O₂ neutralisation due to the higher activity levels of the APX and CAT enzymes, mainly in green fruits. Thus, a better removal of reactive oxygen species in coffee fruits from plants grown at higher altitudes is involved in the extension of the coffee reproductive cycle, contributing to the production of a higher cup quality coffee.