Postharvest Biology and Technology 65 (2012) 22–32 Contents lists available at SciVerse ScienceDirect Postharvest Biology and Technology journa l h o me pa g e: www.elsevier.com/locate/postharvbio Climacteric level during fruit ripening influences lipid peroxidation and enzymatic and non-enzymatic antioxidative systems in Japanese plums (Prunus salicina Lindell) Sukhvinder Pal Singh a,1 , Zora Singh a,∗ , Ewald E. Swinny b a Department of Environment and Agriculture, School of Science, Faculty of Science and Engineering, Curtin University, GPO Box U1987, Perth, 6845 WA, Australia b ChemCentre, Resources and Chemistry Precinct, GPO Box 1250, Bentley, 6983 WA, Australia a r t i c l e i n f o Article history: Received 1 September 2011 Accepted 15 October 2011 Keywords: Ascorbate–glutathione cycle Ethylene Lipid peroxidation Oxidative stress Respiration Ripening a b s t r a c t Fruit of Japanese plum (Prunus salicina Lindell) cultivars show diversity in climacteric behaviour dur- ing ripening. Our objective was to study the influence of cultivar-specific climacteric behaviour on lipid peroxidation and antioxidative metabolism during fruit ripening in Japanese plums. Contrast- ing cultivars, ‘Blackamber’ (highly climacteric), ‘Amber Jewel’ (moderately climacteric), and ‘Angeleno’ (suppressed-climacteric), were harvested at commercial maturity and allowed to ripen at 21 ± 1 ◦ C for 8 d. The lipid peroxidation, indicated by the increase in activity of lipoxygenase (LOX) and con- centration of thiobarbituric acid reactive substances (TBARS), was lower in ‘Angeleno’ compared to ‘Blackamber’ and ‘Amber Jewel’ during the first 6 d of fruit ripening. Superoxide dismutase (SOD) activity showed an overall decrease during fruit ripening in all cultivars, but it remained lower in ‘Angeleno’ than in the other cultivars. In contrast, peroxidase (POD) activity was significantly higher in ‘Black- amber’ and ‘Amber Jewel’ than in ‘Angeleno’ during 4–8 d of fruit ripening. The advancement of fruit ripening caused oxidation of the redox buffers such as ascorbate (AA) and glutathione (GSH) resulting in increased concentrations of dehydroascorbate (DHA) and oxidized glutathione (GSSG) leading to a decline in the ratios of AA:DHA and GSH:GSSG, respectively. The activities of key enzymes involved in the ascorbate–glutathione cycle, ascorbate peroxidase (APX), monodehydroascorbate reductase (DHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were also determined. The data suggest that the climacteric-type cultivars, ‘Blackamber’ and ‘Amber Jewel’, showed a faster decline in the enzymatic and non-enzymatic antioxidative systems, parallel to the faster rate of ripening and senescence, as compared to the suppressed-climacteric cultivar, ‘Angeleno’. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Fruit ripening is a highly regulated and irreversible phe- nomenon involving a series of physiological, biochemical, and structural changes in fruit leading to an attractive, edible, and ripe fruit. The fruit are broadly classified into two categories – cli- macteric and non-climacteric (Biale, 1964). A typical climacteric fruit exhibits a peak in respiration and ethylene production dur- ing ripening, while this is lacking in non-climacteric fruit. There is another category of suppressed-climacteric fruit and/or cultivars ∗ Corresponding author. Tel.: +61 8 9266 3138; fax: +61 8 9266 3063. E-mail addresses: sukhvinder.pal.singh@gmail.com (S.P. Singh), Z.Singh@curtin.edu.au (Z. Singh). 1 Current address: National Agri-Food Biotechnology Institute (NABI), Mohali, Punjab 160071, India. that are unable to biosynthesize ethylene in sufficient quantity to induce a climacteric rise in respiration and ethylene production, which leads to delay and suppression of the climacteric (Abdi et al., 1998). Japanese plums are climacteric in nature, but a few culti- vars show suppressed-climacteric behaviour, and have a longer postharvest life (Abdi et al., 1998; Khan and Singh, 2007; Díaz-Mula et al., 2009). Fruit ripening is an aerobic metabolic process generating reac- tive oxygen species (ROS) that cause tissue damage (Brennan and Frenkel, 1977). ROS action has been known to initiate and enhance degenerative processes associated with fruit ripening and senes- cence (Brennan and Frenkel, 1977; Du and Bramlage, 1994; Lacan and Baccou, 1998; Rogiers et al., 1998). Fruit ripening is considered a protracted form of senescence that is characterized by mem- brane disintegration due to a change in membrane composition induced by lipoxygenase (LOX), among the other enzymes. Perox- idation of free polyunsaturated fatty acids (PUFA) by LOX causes 0925-5214/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.postharvbio.2011.10.007