Abstract

The acclimation of plants to moderately high temperature plays an important role in inducing plant tolerance to subsequent lethal temperatures. This study was performed to investigate the effects of heat acclimation and sudden heat stress on the antioxidant and metabolic profile of lablab bean (Dolichos lablab). Following separate pretreatments with heat acclimation (35°C) and NaCl (100 mM), seedlings of lablab bean were exposed to heat stress at 45°C for 5 h and then recovered at 25°C for five days. Pre-treated seedlings performed better under heat stress than the control and it could be associated with the observed increased levels of sugars, proline, glutathione and ascorbate; and increased activities of Peroxidase (POX), glutathione reductase (GR) and ascorbate peroxidase (APX) than just heat shocked seedlings. Seedling growth was dramatically reduced under heat stress but heat acclimation and NaCl pre-treatment were effective in imparting thermoprotection against the lethal heat shock.

Key words: Acclimation, antioxidants, catalase, Dolichos lablab, glutathione reductase, heat stress, peroxidase, proline, sugar.

Abbreviation

Abbreviations: AMY, Amylase; ASC, ascorbate; APX, ascorbate peroxidase; CAT,catalase; GR, glutathione reductase; GSH, reduced glutathione; INV, invertase; POX,peroxidase; ROS, reactive oxygen species; RWC, relative water content; TBARS,thiobarbituric acid reactive species; TSS, total soluble sugars.