Oxygen Radical Generation in Chilled Leaves of Cucumber (Cucumis sativus L.) Cultivars with Different Tolerances to Chilling Temperatures.
Year: 1999
Type: article
Abstract: The possible involvement of oxygen radical generation in chilled leaves in the different chilling tolerances of cucumber (Cucumis sativus L.) cultivars was investigated. Plants with their first expanded leaves were exposed to 3°C or 15°C in the dark for 24 hr ; they were warmed for another 24 hr at 28/22°C (day/night) with a 12-hr photoperiod. Chilled leaves subsequently developed chilling injury symptoms (marginal and inner necrosis) and accumulated malondialdehyde (MDA). Both chilling injury and rate of MDA accumulation were largest in 'Suyo', intermediate in 'Sharp I', and smallest in 'Jinchun No.3'. In leaves of chilling-sensitive 'Suyo'; NADPH-dependent superoxide and hydrogen peroxide-generating activities increased markedly during chilling. Hydroxyl radical-generating activities as indicated by methane sulfonic acid formation increased rapidly upon warming, with a concomitant decrease in activities of superoxide and hydrogen peroxide generation. The NADPH-dependent superoxide-generating activity increased again during the later warming period. In contrast, chilled leaves of chilling-tolerant 'Jinchun No.3' showed only a slight increase in the oxygen radical generation activities during both chilling and warming periods. In chilled leaves of 'Sharp I', activities of hydrogen peroxide and hydroxyl radical generation increased during the early warming period, whereas those of NADPH-dependent superoxide generation occurred later. The NADPH oxidase activity in chilled leaves changed with time similarly to the activity of NADPH-dependent superoxide generation in all cultivars examined. The results indicate that chilling injury of cucumber leaves is caused by the increased oxygen radical generation under chilling and subsequent warming conditions. This increase in oxygen radical generation may be triggered primarily by the increased NADPH oxidase activity, the rate of which determines the degree of chilling tolerance in cucumber cultivars.
DOI: 10.2503/jjshs.68.780
Authors: Wenyun Shen, Kazuyoshi Nada, Shoji Tachibana
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: diamond
OpenAlex ID: W2024933360