ISHS Acta Horticulturae 768: XXVII International Horticultural Congress - IHC2006: International Symposium on The Role of Postharvest Technology in the Globalisation of Horticulture
METABOLISM OF REACTIVE OXYGEN DYNAMIC CHANGES DURING TOMATO FRUIT RIPENING AND SENESCENCE |
| Authors: | Lin Shen, Ying Ruan, Kailang Liu, Jiping Sheng |
| Keywords: | reactive oxygen species, seed, hydrogen peroxide, antioxidant enzymes, postharvest physiology, fruit quality |
| DOI: | 10.17660/ActaHortic.2008.768.69 |
| Abstract:
Recently, reactive oxygen species (ROS) have been revealed to play an important role as signaling molecules in many processes, including hypersensitive response (HR) and senescence. Some studies have confirmed that ROS acts in concert with ethylene in HR and senescence. However, little is known about the source of ROS production and its metabolic dynamics in fruit ripening and senescence. In this study, tomato (Lycopersicon esculentum Mill.) pericarp and seed were used to investigate changes of ROS and activities of antioxidant enzymes during fruit ripening and senescence. Superoxide (O2-.) production rate and hydrogen peroxide (H2O2) content in seed were significantly higher than those in pericarp at all maturity stages, and the H2O2 content in the seed increased sharply after the pink stage. Higher activities of superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) occurred in seeds than that in the pericarp. At the beginning of fruit ripening, an increase of CAT activity followed the accumulation of H2O2, but its activity declined quickly by the end of ripening. These patterns of enzyme activity suggest that the AsA-GSH cycle might play an important role in scavenging H2O2. The maximum malondialdehyde (MDA) content appeared in seeds earlier than that in the pericarp, the maximum being 1.5 fold of that in the pericarp. High concentration of ROS in the seed is closely related with fruit ripening, and H2O2 might be an important factor in triggering senescence. | |
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