Metabolism of reactive oxygen: dynamic changes during tomato fruit ripening and senescence
Jiping Sheng, Ying Ruan, Kailang Liu and Lin Shen
Abstracts of 27th International Horticultural Congress & Exhibition (IHC 2006), August 13-19, 2006, COEX (Convention & Exhibition), Seoul, Korea. 494 pages.
2006
บทคัดย่อ
Recently, reactive oxygen species (ROS) have been shown to play an important role as signaling molecules in many processes, including hypersensitive responses (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 during fruit ripening and senescence.Tomato (Lycopersicom esculentum Mill.) pericarp and seed were used to investigate the changes of ROS and activities of antioxidant enzymes during fruit ripening and senescence.Superoxide (O2) production rate and hydrogen peroxide (H2O2) content in seeds were significantly higher than those in the pericarp at all maturity stages, and the H2O2 content in seeds increased sharply after the pink stage.Higher activities of SOD, CAT and GR occurred in seeds than that in the pericarp.At the beginning of fruit ripening, an increase of CAT activity followed accumulation of H2O2, but 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 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 seed is closely related with fruit ripening, and H2O2 might be an important factor in triggering senescence.