Effect of the conditioned medium of mesenchymal stem cells on the expression levels of P2X4 and P2X7 purinergic receptors in the spinal cord of rats with neuropathic pain

Purinergic Signalling - Recent studies have shown that mesenchymal stem cells (MSCs) and their conditioned medium (CM) have potential therapeutic effects in animal models of neuropathic pain (NP)....     

Influence of exogenously applied paclobutrazol on some physiological traits and growth of Stevia rebaudiana under in vitro drought stress

This investigation was carried on to find out the changes occurred in Stevia rebaudiana in response to paclobutrazol (PBZ; 0–4 mg L^?1) treatment and drought stress. Polyethylene glycol (PEG; 0–6 % w/v) was used to stimulate drought stress. Drought stress reduced fresh and dry weight, water content, chlorophylls, carotenoids, anthocyanins, water soluble carbohydrates, reducing sugar and proline amounts. Electrolyte leakage, MDA, α-tocopherol and glycine betaine contents increased in drought-stressed plants. The activity of P5CS and PDH enzymes and protein content showed no significant changes under drought stress. PBZ (with or without PEG) treatments decreased fresh and dry weight and water content. In PBZ-treated plants, less pigments was damaged by drought stress. PBZ treatment reduced the negative effect of drought stress on lipid peroxidation which resulted in lower electrolyte leakage and MDA content, compared to the same PEG level without PBZ. PBZ (with or without PEG) treatments increased glycine betaine, α-tocopherol, proline and protein contents. The amount of water soluble carbohydrates, reducing sugar and activity of P5CS and PDH were not affected by PBZ treatments. SDS-PAGE analysis revealed that drought stress increased a 25 kD protein with a critical function in plant development under stresses. According to the results, PEG provoked a severe drought stress in S. rebaudiana that could partly be restored by PBZ treatment.     

Physiological,biochemical, antioxidant and growth characterizations of gibberellin and paclobutrazol-treated sweet leaf (<Emphasis Type="Italic">Stevia rebaudiana</Emphasis> B.) herb

A greenhouse experiment was designed to study the responses of Stevia rebaudiana herb to paclobutrazol (PBZ) and gibberellin (GA) treatments. GA and PBZ treatments caused no significant impact on photosynthesis pigments while they increased carbohydrates, amino acids and protein metabolites. Stevia showed a potent antioxidant activity through scavenging DPPH, NO^·; O ₂ ^·? and OH^· radicals which was highlighted in GA and PBZ treatments. The enzymatic and non-enzymatic antioxidant system of Stevia plant showed a significant increase in response to PBZ and GA treatments. PBZ treatment decreased plant growth while GA treatment had no significant effect on it. Collectively, both GA and PBZ treatments effectively increased metabolites and antioxidant property of Stevia herb.     

Characterization of Exogenous Nitric Oxide Effect on Crocus sativus Response to Different Irrigation Regimes

Journal of Plant Growth Regulation - Water scarcity is one of the main factors limiting crop production worldwide. The study on response of saffron to irrigation regime showed that one-time...     

Effect of paclobutrazol on wheat salt tolerance at pollination stage

The effects of paclobutrazol (PBZ) (0, 30, 60, and 90 ppm) and NaCl (0, 75, 150, and 225 mM) treatments on a salt-tolerant (Karchia-65) cultivar of wheat (Triticum aestivum L.) at the pollination stage were studied. Salt stress decreased plant height, the length and area of the flag leaf, fresh and dry weights of the shoot, roots, and flag leaf, and water content. On the background of salinity, PBZ treatment further suppressed plant height. Although plants growth was suppressed in PBZ-treated plants, PBZ treatment moderated the negative effect of salinity on some growth parameters. Under PBZ treatments, plants tissues accumulated more watersoluble carbohydrates and reducing sugars than control plants, with the exception of water-soluble carbohydrates in the roots. The Na⁺ content in roots significantly (p ≤ 0.05) increased at 150 and 225 mM NaCl, but PBZ treatment moderated the harmful effect of the highest levels of salinity. Salinity with or without PBZ treatment improved the K⁺, P, and N contents in plants. It is reasonably to suggest that the protection and increasing salt tolerance caused by PBZ was due to the mechanism nearly similar to the salt-tolerant cultivar physiological systems. These observations suggest that PBZ treatment has the potential to increase salt tolerance with a limiting damage caused by salt stress even in salt-tolerant plants. This text was submitted by the authors in English. Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 2, pp. 278–284.     

Nitric Oxide Effect on Growth,Physiological and Biochemical Processes,Flowering, and Postharvest Performance of Narcissus tazzeta

Journal of Plant Growth Regulation - Narcissus tazetta is an appreciated ornamental plant worldwide with a unique sensory value. Therefore, every new insight into the behavioral aspects is crucial...     

Antioxidant potential in <Emphasis Type="Italic">Stevia rebaudiana</Emphasis> callus in response to polyethylene glycol,paclobutrazol and gibberellin treatments

The study on Stevia callus has the potential to advance the knowledge of antioxidant mechanisms involved in unorganized cells response to drought stress. The effects of polyethylene glycol (PEG; 0 and 4% w/v) in combination with paclobutrazol (PBZ; 0 and 2 mg l^?1) and gibberellin (GA; 0 and 2 mg l^?1) were studied on Stevia rebaudiana callus. PEG treatment led to an oxidative stress, as indicated by increased H₂O₂ content whose accumulation was prevented with PBZ and GA treatments. All treatments of PEG, PBZ and GA increased the total antioxidant capacity, with the highest antioxidant power in PBZ and GA treatments without PEG. The activity of superoxide dismutase, catalase and ascorbate peroxidase significantly increased in PEG treatment alone or in combination with PBZ and GA. All treatments of PEG, PBZ and GA significantly increased proteins, amino acids and proline contents, with the highest increase in presence of PBZ in medium culture. In contrary to proline, the activity of pyrroline-5-carboxylate synthetase and proline dehydrogenase did not change in response to any of the treatments. Collectively, our results demonstrated that PBZ and GA increased reactive oxygen species scavenging and osmolytes in PEG-treated calli more than PEG treatment alone to alleviate negative effects of PEG on Stevia calli. These findings will enable us to design effective genetic engineering strategies in callus culture to generate some somaclonal variation that may be useful in enhancing drought resistance in Stevia.     

The effect of polyethylene glycol-induced drought stress on photosynthesis,carbohydrates and cell membrane in <Emphasis Type="Italic">Stevia rebaudiana</Emphasis> grown in greenhouse

Drought stress is one of the major environmental stresses that limit crop production in arid regions. A greenhouse culture experiment was conducted to evaluate the response of an agronomically and economically important sweet medical herb (Stevia rebaudiana) to polyethylene glycol (PEG 6000)-induced drought stress (5, 10, and 15% (w/v) PEG, equivalent to leaf water potentials of ??0.49, ??1.40 and ??2.93 MPa, respectively) for 1 month. Plant mass, a major determinant of Stevia yield, showed a reduction after PEG treatments. PEG-reduced photosynthesis traits included the maximal quantum yield of photosystem II (F_v/F_m), efficiency of photosystems I and II (PI_abs), intercellular CO₂, net photosynthesis, chlorophylls, carotenoids and water use efficiency, followed by the reduction of carbohydrates. Under PEG treatment, the reactive oxygen species (ROS) accumulation occurred and plants exhibited an increase in H₂O₂ generation. Consequently, an increase in malondialdehyde and electrolyte leakage was evident in PEG treatment, indicating membrane lipid peroxidation. In PEG-treated plants, the ROS accumulation was accompanied by an increase in activity of some enzymatic and non-enzymatic antioxidants. Leaf extracts of PEG-treated plants showed lower superoxide anion, hydroxyl and nitric oxide radical scavenging activity than control plants. Drought stress also caused the accumulation of the compatible solutes proline and glycine betaine. Collectively, the results demonstrated that PEG-induced oxidative stress, due to insufficient antioxidant mechanisms, provoked damages to cell membrane and photosynthetic apparatus, with consequently reduced carbohydrates and plant growth. These results are of basic importance as vegetative growth is the major determining criterion for Stevia crops and adequate irrigation is crucial for obtaining higher yield.