Effect of Chilling on Cyanide-resistant Respiration and Carbohydrate Status in Chilling-sensitive and -resistant Species

Abstract

The effect of chilling stress on induction of the cyanide-resistant pathway was investigated using roots of 3-day-old cucumber (Cucumis sativus L.) and 5-day-old pea (Pisum sativum L.) grown at 26°C, and then chilled at 2°C for 48 or 96 hours for cucumber, and 72 or 192 hours for pea. A 24-hour post-chilling treatment at 26°C was imposed on different sets of chilled roots from both crops. Carbohydrate status was determined by gas chromatography with an autosampler using a 12.5-m cross-linked methyl silicone capillary column (0.1 mm). Exposing seedlings to 2°C, as well as to a postchilling treatment, induced differential responses in the activity of the cyanide-resistant pathway. Cucumber seedling roots exhibited an accumulation of fructose, glucose and sucrose during chilling, with a rapid decline observed during the post-chilling treatment at 26°C. Pea seedling roots maintained a constant level of carbohydrates throughout the chilling period, and exhibited a slight decrease by the end of 192 hours at 2°C. There was an increase in carbohydrate levels during the post-chilling treatment. The involvement of the cyanide resistant pathway and carbohydrate changes will be discussed.