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  • Author or Editor: Lijian Liang x
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Nitric oxide (NO) is well known for its multifaceted physiological roles as a signaling molecule in plants. Previous studies have indicated that exogenous application of NO may be useful for alleviating chilling injury (CI) in fruits and vegetables. However, the potential role and mechanism of NO in mitigating chilling stress in anthurium (Anthurium andraeanum) remain unclear. In this study, physiological and biochemical analysis were performed to investigate the effects of exogenous NO in alleviating CI in anthurium. Anthurium seedling plants were treated with the NO donor sodium nitroprusside (SNP) at four concentrations (0, 0.2, 0.4, and 0.8 mm) and stored at 12/5 °C (day/night) for 15 day. The results showed that exogenous SNP mitigated the adverse effects of chilling on anthurium, and the most effective concentration was 0.2 mm. In addition, NO effectively improved the CI index, malondialdehyde (MDA) content, electrolyte leakage, photochemical efficiency (F v/F m), and chlorophyll loss of anthurium during low temperatures. Pretreatment with SNP also increased the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX); the content of antioxidants including glutathione (GSH), ascorbic acid (AsA), and phenolics; and reduced the accumulation of hydrogen peroxide and O2 . SNP pretreatment at 0.2 mm also significantly promoted the accumulation of proline, increased the activity of Δ1-pyrroline-5-carboxylate synthetase (P5CS), and reduced the activity of proline dehydrogenase (PDH), when compared with control (0 mm SNP→Chilling) under chilling stress. These results indicated that NO could enhance the chilling tolerance of anthurium by elicitation of an antioxidant response and proline accumulation for maintaining cell membrane integrity.

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Aquaporin (AQP) proteins can transport water and other small molecules through cellular membranes and are one of the first targets of stress-induced signaling in plants. A number of AQP genes have been identified from glycophytes, and their functions have been studied. However, the reports on AQPs from halophytes and their precise role in abiotic stress response are still rare. In this study, we have identified a PIP1 subgroup AQP gene, designated SbPIP1, from the euhalophyte Salicornia bigelovii and characterized it by overexpressing in tobacco plants. SbPIP1 transcript was induced by cold, but suppressed by NaCl and polyethylene glycol (PEG). Transient expression of GFP (green fluorescent protein)-SbPIP fusion protein indicated its localization in the plasma membrane. Overexpression of SbPIP1 in tobacco (Nicotiana tabacum) plants increased their drought tolerance. Leaf protoplasts from transgenic tobacco plants absorbed water more quickly than those from wild type (WT) plants when they were put into hypotonic solution. In addition, the transgenic tobacco plants possessed higher relative water content (RWC) and proline content, but lower levels of malondialdehyde (MDA) and less ion leakage (IL) when compared with WT under the treatment of the different concentrations of PEG. Taken together, our results demonstrate that heterologous expression of SbPIP1 in tobacco plants confers them drought stress tolerance by reducing membrane injury and increasing the ability to retain water.

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From a field experiment, the changes in morphophysiological characters and antioxidant enzyme activities were studied in two Lycoris species (Lycoris radiata and Lycoris aurea) subjected to 16 days of water deficit stress. With the increase of water deficit stress processing time, leaf relative water content (RWC), membrane stability index (MSI), net photosynthesis (Pn), stomatal conductance (g S), transpiration rate (E), and chlorophyll (Chl) content decreased in both studied species. The water use efficiency (WUE) showed an opposite tendency between the two species under water deficit stress, where WUE of L. aurea decreased moderately and WUE of L. aurea increased somehow. Intercellular CO2 concentration (C i) in L. aurea and L. radiata decreased in respond to water deficit stress at early stages of stress treatment, then increased throughout the rest of the stress period, and reached levels higher than those in well-watered plants at the end of the treatment. In addition, there was a significant increment in soluble sugar content and proline accumulation under water deficit stress in both species, and L. radiata showed a much more accumulation. The activity of superoxide dismutase (SOD), guaiacol peroxidase (POD), and ascorbate peroxidase (APX) increased in both plants subjected to water deficit stress while declined as the stress time increased. In L. aurea, catalase (CAT) showed a sustained increment, but it responded later and after a transient increase declined again in L. radiata under water deficit stress. In conclusion, L. radiata was more tolerant to water deficit stress than L. aurea as evidenced by its relatively higher water status, higher levels of proline, soluble sugar and pigments, and stronger photoprotection. Moreover, relatively higher antioxidant enzyme activities and lower levels of thiobarbituric acid reactive substances (TBARS) in L. radiata were also associated with its better protection against water deficit stress-induced oxidative damage.

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