Comparison of reactive oxygen species metabolism during grape berry development between ‘Kyoho’ and its early ripening bud mutant ‘Fengzao’

Enzymes and non-enzyme elements related to the metabolism of reactive oxygen species (ROS), such as catalase (CAT), superoxide dismutase (SOD), ascorbic acid (AsA), glutathione (GSH), NADPH oxidase (NOX), hydrogen peroxide (H2O2), superoxide anion (O2-), lipoxygenase (LOX) and malondialdehyde (MDA), were measured in ‘Kyoho’ and its early ripening bud mutant ‘Fengzao’ to compare ROS level changes and investigate the potential roles of ROS in grape berry development and the ripening process. In addition, the anthocyanin and sugar contents as well as berry diameter were also investigated at different berry development stages. The results showed that the H2O2 content and LOX activity exhibited obviously different trends between ‘Fengzao’ and ‘Kyoho’ during the berry development stages. Before berry softening, the SOD activity, LOX activity and H2O2 content were significant lower in ‘Fengzao’ than in ‘Kyoho’, but there were no significant differences in the production rate of O2-, ROS scavengers (CAT, AsA, GSH) and MDA content between them, which indicated that the higher oxidation status in ‘Fengzao’. It may promote the faster development of ‘Fengzao’ berry than ‘Kyoho’ before berry softening (EL31-33). The significant higher LOX and CAT activities at EL-34, as well as significant higher LOX activity and H2O2 content at EL-35 in ‘Fengzao’ than in ‘Kyoho’ indicated H2O2 was acted as the appropriate oxidative stress factor and the signal molecule to further accelerate the berry ripening of ‘Fengzao’. The increasing O2- and H2O2 after EL-35 in ‘Fengzao’ further promoted the ripening process. Furthermore, after the spraying of 300 μmol/L H2O2 solution on ‘Kyoho’ at EL-31 stage, the berries matured 15 days earlier than the untreated. Evidence in this study indicated that the overall oxidation status (ROS levels) in ‘Fengzao’ is higher than in ‘Kyoho’ and H2O2 could promote the early ripening of ‘Kyoho’ berry.