Involvement of Polyamines in the Chilling Tolerance of Cucumber Cultivars

Abstract

The possible involvement of polyamines (PAs) in the chilling tolerance of cucumber (Cucumis sativus L. cv Jinchun No. 3 and cv Suyo) was investigated. Plants with the first expanded leaves were exposed to 3°C or 15°C in the dark for 24 h (chilling), and then transferred to 28°C/22°C under a 12-h photoperiod for another 24 h (rewarming). Chilling-tolerant cv Jinchun No. 3 showed a marked increase of free spermidine (Spd) in leaves, once during chilling and again during rewarming. Putrescine increased significantly during rewarming, but the increase of spermine was slight. Any of these PAs did not increase in chilling-sensitive cv Suyo during either period. PA-biosynthetic enzyme activities appear to mediate these differences between cultivars. Pretreatment of Spd to cv Suyo prevented chill-induced increases in the contents of hydrogen peroxide in leaves and activities of NADPH oxidases and NADPH-dependent superoxide generation in microsomes and alleviated chilling injury. Pretreatment of methylglyoxal-bis-(guanylhydrazone), a PA biosynthesis inhibitor, to chilled cv Jinchun No. 3 prevented Spd increase and enhanced microsomal NADPH oxidase activity and chilling injury. The results suggest that Spd plays important roles in chilling tolerance of cucumber, probably through prevention of chill-induced activation of NADPH oxidases in microsomes.

Polyamines: potent modulators of plant responses to stress

“…Activity of PA-biosynthetic enzymes appears to mediate these differences between cultivars. Moreover, pretreatment of cultivar 'Suyo' with Spd prevented chillinduced increase in the contents of H 2 O 2 in leaves and activities of NADPH oxidases and NADPH-dependent superoxide generation in microsomes and alleviated chilling injury (Shen et al 2000). These results suggest that Spd plays an important role in chilling tolerance of cucumber, probably through prevention of chill-induced activation of NADPH oxidases in microsomes.…”

“…Wang (1987) reported that seedlings of Cucumis sativus L. cultivar 'Victory' induced a twofold increase in Spd level when exposed to chilling at 58C. Similarly, Shen et al (2000) found that in chilling-tolerant cucumber cultivar 'Jinchun No. 3,' content of Spd increased markedly in response to chilling which was closely related to a lower rate of ROS generation but there was little effect on Put and Spm during chilling stress.…”

Change in Free Polyamine Contents and Expression Profiles of Two Polyamine Biosynthetic Genes in Citrus Embryogenic Callus under Abiotic Stresses

“…Another explanation for the increase is associated with the polyamines' protective functions against the stress which can help the stressed tissues or cells to resist the stress-activated physiological damage like reactive oxygen species and lipid peroxidation. therefore, high accumulation of free PAs in callus exposed to stresses can be considered to directly participate in stress defense via membrane rigidification or free radical scavenging (6,14). it has to be pointed out that an indirect role is also possible via activation of some antioxidant systems, as it has been shown elsewhere (16,17).…”

Polyamines and their ability to provide environmental stress tolerance to plants

“…Since an increase in Put due to potassium deficiency was reported decades ago, changes in polyamines have been extensively investigated when plants are exposed to single or combined stresses (Rowland-Bamford et al 1989;Tiburcio et al 1994;Scalet et al 1995;Nam et al 1997; Santa-Cruz et al 1997b; Shen et al 2000; Mo and Pua 2002;Urano et al 2003;Kuthanová et al 2004;Camacho-Cristóbal et al 2004;Liu et al 2006b). In many cases, stress led to an accumulation of free or conjugated polyamines, indicating that polyamine biosynthesis might serve as an integral component of plant response to stress (Bouchereau et al 1999).…”