Delay of ripening and senescence in mango fruit by 6-benzylaminopurine is associated with inhibition of ethylene biosynthesis and membrane lipid catabolism

Abstract

6-Benzylaminopurine (6-BA), a synthetic cytokinin compound, plays a vital role in modulating diverse physiological processes in plants and is widely applied in agriculture. This study aims to investigate the effects of 6-BA on ripening and senescence and its possible mechanisms in harvested ‘Guifei’ mango fruit. The results exhibited that the application of 0.2 g L−1 6-BA to mango fruit inhibited the changes in firmness, flesh color, soluble solids content (SSC), titratable acidity (TA) and contents of carotenoid and chlorophyll, while retarded the climacteric process of respiration and ethylene. The delay of ethylene production due to 6-BA application was correlated with suppressed activities of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO) in mango fruit. 6-BA treatment also reduced the accumulation of reactive oxygen species (ROS) (·O2- and H2O2) and malonaldehyde (MDA) and maintained a lower membrane permeability. Moreover, 6-BA treatment inhibited the activities of phospholipase D (PLD) and lipoxygenase (LOX) and downregulated the relative expression of MiPLD and MiLOX, which resulted in reduced degradation of phosphatidylcholine (PC) to phosphatidic acid (PA) and limited lipid peroxidation. The results suggest that 6-BA could delay ripening and senescence in mango fruit through regulating ethylene biosynthesis, ROS production and membrane lipid metabolism.