Relationships between polyamines, ethylene, osmoprotectants and antioxidant enzymes activities in wheat seedlings after short-term PEG- and NaCl-induced stresses

Abstract

Contents of ethylene, osmoprotectants, levels and forms of polyamines (PAs) and activities of antioxidant enzymes in the leaves and roots were investigated for five wheat cultivar seedlings (differing in drought tolerance) exposed to osmotic stress (-1.5 MPa). Stress was induced by 2-day-long treatment of plants with polyethylene glycol 6000 (PEG) or NaCl added to hydroponic cultures. Nawra, Parabola and Manu cv. (drought tolerant) showed a marked increase in osmoprotectors (proline and soluble carbohydrates, mainly glucose, saccharose and maltose), free PAs (putrescine Put, spermidine Spd and spermine Spm) and Spd-conjugated levels, in both leaves and roots, after PEGtreatments. Radunia and Raweta (drought sensitive) exhibited smaller changes in the content of these substances. The analysis of enzymes involved in proline metabolism revealed the glutamate as a precursor of proline synthesis in PEGinduced stress conditions. The increase in the activity of antioxidative enzymes, especially catalase and peroxidases, was characteristic for tolerant wheat plants, but for sensitive ones, a decrease in superoxide dismutase and an increase in mainly glutathione reductase activities were observed. After NaCl-treatment smaller changes of all biochemical parameters were registered in comparison with PEG-induced stress. Exceptions were the higher values of ethylene content and a significant increase in saccharose, raffinose and maltose levels (only in stress sensitive plants). The proline synthesis pathway was stimulated from both glutamate and ornithine precursors. These results suggest that the accumulation of inorganic ions in NaCl-stressed plants may be involved in protective mechanisms as an additional osmoregultor. Thus, a weaker stressogenic effect as determined as water deficit by leaf relative water content and relative dry weight increase rate and differences in metabolite synthesis in comparison with PEG stress was observed. Proline seems to be the most important osmo-protector in osmotic stress initiated by both PEG and NaCl. The synthesis of sugars and PAs may be stimulated in a stronger stress conditions (PEG).

Effects of exposure of callus cells of two wheat varieties to silver nanoparticles and silver salt (AgNO3)

“…The stress tolerance of these genotypes was confirmed in previous studies (Grzesiak et al 2013;Filek et al 2012). Embryos were sterilized in 70 % ethanol for 1 min, and then in 10 % solution of bleaching agent ''Domestos'' for 10 min.…”

“…Proline is one of the osmoprotectants synthesized in plants in response to stress conditions. So far, it has been shown that under such stresses as drought (Grzesiak et al 2013), salt (Kumar et al 2008), high and low temperatures (Babu and Devraj 2008), heavy metals (Theriappan et al 2011), mineral deficiency, UV (Saradhi et al 1995) and biotic stress (Haudecoeur et al 2009), the proline concentration increased often to values several times higher than that observed in control conditions. Independently of the osmoprotective role of proline, some studies have shown that this molecule can help maintain redox balance in cells (Mohammadkhani and Heidari 2008).…”

Adaptation of wheat cells to short-term ozone stress: the impact of α-tocopherol and gallic acid on natural and model membranes

“…The stimulation of synthesis of proline-the substance responsible for osmotic regulation in stressogenic conditions-is generally considered as an indicator of induction of defense mechanisms under the stressors (Aziz et al 1999;Munns and Tester 2008;Grzesiak et al 2013). In presented experiments no significant differences in proline content between objects grown on MS medium and on media supplemented with TOH and GA (control) can confirm that tested antioxidants did not act stressfully on calli cells.…”

Consequences of Seed Priming with Salicylic Acid and Hydro Priming on Smooth Vetch Seedling Growth under Water Deficiency

“…In this respect, Fernandez et al (2010) expressed that osmolytes along with osmotic homeostasis, are involved in maintaining of bio-membranes integrity and also ROS scavenging within plant cells. Accumulation of osmolytes has been reported as a main strategy adopted by plants to enhance osmotic stress tolerance (Grzesiak et al, 2013).…”