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In current study, we investigated the relationship between hydrogen sulfide (H2S) and nitric oxide (NO) in the regulation of ascorbate-glutathione (AsA-GSH) cycle in wheat seedlings by water stress. Findings showed that water stress significantly stimulated the production of H2S and NO, the transcript levels and activities of enzymes in AsA-GSH cycle, as well as malondialdehyde (MDA) production and electrolyte leakage, but significantly decreased AsA/DHA and GSH/GSSG. Meanwhile, water stress significantly decreased plant height and dry biomass. Except MDA and electrolyte leakage, above changes induced by water stress were reversed by H2S synthesis inhibitor aminooxyacetic acid (AOA) and NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME). However, AOA and L-NAME significantly enhanced MDA production and electrolyte leakage, which further decreased plant height and dry biomass of wheat seedlings under water stress. Application of exogenous H2S donor sodium hydrosulfide (NaHS) to AOA-treated plants and application of exogenous NO donor sodium nitroprusside (SNP) to L-NAME-treated plants reversed above effects of AOA and L-NAME, respectively. Application of L-NAME plus water stress significantly decreased NO production induced by water stress. However, application of L-NAME plus water stress had no obvious influence on H2S production induced by water stress, while application of AOA plus water stress significantly reduced the production of H2S and NO induced by water stress. Current findings suggested that H2S acted upstream of NO in the regulation of AsA-GSH cycle in wheat seedlings by water stress.

By pot experiment method, this study investigated the role of plant hormone abscisic acid (ABA) in the foliar application of 10 μM lanthanum nitrate (La(NO3)3)-regulated the biosynthesis, regeneration and degradation of vitamin C (Vc) and the content of Vc in the fruit of strawberry at different periods of growth and development. The results showed that La(NO3)3 significantly increased the content of Vc by increasingthe activities of recycling enzymes glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and biosynthetic enzyme L-galactono-1,4-lactone dehydrogenase (GalLDH), and decreasing the activities of recycling enzyme APX and degrading enzyme ascorbic acid oxidase (AAO). Compared with La(NO3)3 alone, applications of different ABA biosynthesis inhibitor sodium tungstate (Tu) all markedly decreased the activities of GR, MDHAR and GalLDH, and increased the activities of DHAR and APX, which resulted in the reduction in the content of Vc. Meanwhile, La(NO3)3 induced the production of ABA and Tu reversed the effect of La(NO3)3 on ABA content. Our results suggested that La(NO3)3-induced ABA participated in the regulation of Vc content in the fruit of strawberry.

This paper investigated the effects of LaCl3 on the ascorbate-glutathione (AsA-GSH) cycle in chloroplast of tomato seedlings under salt stress. Our findings displayed that salt stress significantly enhanced the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), and the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2), but significantly decreased AsA/DHA and GSH/GSSG, the net photosynthetic rate (PN), the contents of Chl and Car, plant height, stem diameter and dry weight, in contrast with the control. In contrast with salt stress alone, salt stress plus LaCl3 significantly increased the activities of above enzymes, AsA/DHA, GSH/GSSG, PN, Chl content and Car content, La accumulation, plant height, stem diameter and dry weight, and markedly cut down MDA content and H2O2 content in chloroplast. Meanwhile, pre-treatment with LaCl3 alone also markedly improved above indicators except MDA content and H2O2 content in chloroplast, in contrast with the control. These findings indicated that LaCl3 absorbed by plants up-regulated the antioxidant capacity in the chloroplast through AsA-GSH cycle, which improved the salt tolerance of tomato seedlings.

This paper investigated the roles of hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) and the possible relationship between them in regulating the AsA-GSH cycle in wheat leaves under drought stress (DS). Results showed that DS markedly increased the production of H2S and H2O2, the transcript levels and activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR); malondialdehyde (MDA) content; and electrolyte leakage (EL). Meanwhile, DS markedly reduced plant height and biomass. Above increases induced by drought stress except MDA content and EL were all suppressed by pretreatments with H2S synthesis inhibitor aminooxyaceticacid (AOA) and H2O2 synthesis inhibitor diphenylene iodonium (DPI). Besides, pretreatments with AOA and DPI further significantly increased MDA content and EL and significantly reduced plant height and biomass under DS. DPI reduced the production of H2O2 and H2S induced by DS. AOA also reduced the production of H2S and H2O2 induced by DS. Pretreatments with NaHS + AOA and H2O2 + DPI reversed above effects of AOA and DPI. Our results suggested that H2S and H2O2 all participated in the up-regulation of AsA-GSH cycle in wheat leaves by DS and possibly affected each other.

The present study investigated the role of cerium nitrate (Ce(NO3)3) in regulating the ascorbate-glutathione (AsA-GSH) cycle, the relative water content (RWC), and the contents of malondialdehyde (MDA), hydrogen peroxide (H2O2), soluble sugar and proline in the petals, and the contents of chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoids (Car) in the leaves of Lilium longiflorum cut flowers. The findings showed that Ce(NO3)3 markedly improved the activities of ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR), the ratios of AsA/DHA and GSH/GSSG, RWC, and the contents of proline and soluble sugar in the petals, and markedly reduced the contents of MDA and H2O2 in the petals, compared with the control. Meanwhile, Ce(NO3)3 markedly improved the contents of Chl a, Chl b and Car in the leaves. Among different concentrations of Ce(NO3)3, 40 μM Ce(NO3)3 is the most effective treatment for the improvement of the vase life of Lilium longiflorum cut flowers. Above results indicated that Ce(NO3)3 improves the vase life of Lilium longiflorum cut flowers by enhancing the AsA-GSH cycle and water retaining capacity.

This study investigated the effects of lanthanum nitrate (La(NO3)3) on the activities and the transcript levels of enzymes in the biosynthesis, regeneration and degradation of vitamin C (Vc) and the content of Vc in the fruit of strawberry at different periods of growth and development, as well as the average weight of fruit at mature period. The results showed that low concentrations of La(NO3)3 significantly increased the content of Vc by increasing the activities and the transcript levels of recycling enzymes glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and biosynthetic enzyme l -galactono-1,4-lactone dehydrogenase (GalLDH), and decreasing the activity and the transcript level of degrading enzyme ascorbate oxidase (AO). However, high concentrations of La(NO3)3 significantly decreased the content of Vc by increasing the activities and the transcript levels of APX and AO, and decreasing the activities and the transcript levels of GR, DHAR, MDHAR and GalLDH. Meanwhile, our results also showed that low concentrations of La(NO3)3 significantly increased the average weight of fruit at mature period, compared with control and high concentrations of La(NO3)3. Our results suggested that low concentrations of La(NO3)3 could improve the content of Vc by regulating the activities and the transcript levels of enzymes in its biosynthesis, regeneration and degradation.

To study the role of cerium (Ce) in regulating the vase life of Rosa chinensis Jacq. cut flowers, the effects of cerium nitrate (Ce(NO3)3) on the activities of antioxidant enzymes, the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in the petals, and the contents of chlorophyll a, chlorophyll b and carotenoids in the calyces were investigated. The results showed that Ce(NO3)3 evidently enhanced the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST) and glutathione peroxidase (GPX), and evidently decreased the contents of MDA and H2O2 in the petals, compared with the control. Moreover, Ce(NO3)3 evidently increased the contents of chlorophyll a, chlorophyll b and carotenoids in the calyces. The results also showed that Ce(NO3)3 evidently increased the numbers of open flowers and decreased the numbers of wilted flowers. Our results suggest that Ce(NO3)3 extended the vase li...

In current study, we investigated the relationship between hydrogen sulfide (H

In this paper, the effect of exogenous hydrogen peroxide (H2O2) on the contents of ascorbate and glutathione in Vigna radiata (Linn.) Wilczek. leaves exposed to salt stress was determined. The findings showed that salt stress increased the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), gamma-glutamylcysteine synthetase (γ-ECS), electrolyte leakage (EL) and the contents of reduced ascorbate (AsA), reduced glutathione (GSH), total ascorbate, total glutathione and malondialdehyde (MDA). Exogenous H2O2 increased the contents of AsA, total ascorbate, GSH and total glutathione through APX, GR, DHAR and γ-ECS in leaves exposed to salt stress. Above increases were also induced by exogenous H2O2 alone, compared with control. Exogenous H2O2 had no effect on the activities of l-galactono-1,4-lactone dehydrogenase (GalLDH) and MDHAR and total ascorbate content. Exogenous H2O2 significantly reduced MDA content and EL induced by salt stress. Above results indicated that exogenous H2O2 could enhance the salt tolerance of V. radiata by regulating the ascorbate and glutathione metabolism.

This study investigated the effect of H2S on chloroplast antioxidant capacity and chlorophyll fluorescence of wheat seedlings under copper stress. The results showed that copper stress significantly increased the activities of ascorbate peroxidase (APX), glutathione reductase (GR), superoxide dismutase (SOD), glutathione peroxidase (GPX), and the contents of MDA and H2O2 in chloroplast and non-photochemical quenching (qN), compared with control. However, copper stress significantly reduced the values of maximum photochemical efficiency of PSII (Fv/Fm), photochemical quenching (qP), quantum efficiency of photochemistry (ΦPSII), and the net photosynthetic rate (Pn), compared with control. Meanwhile, copper stress significantly reduced the fresh and dry weight per plant. Compared with copper stress alone, pretreatment with different concentrations of NaHS plus copper stress enhanced the activities of the above enzymes in chloroplast; and the values of Fv/Fm, qP, qN, ΦPSII, and Pn, especially for copper plus 0.8 mM NaHS. Compared with copper stress alone, pretreatments with different concentrations of NaHS plus copper stress also reduced the contents of MDA and H2O2 in chloroplast and increased the fresh and dry weight per plant, especially for copper plus 0.8 mM NaHS. Our results suggested that H2S has important role for acquisition of copper tolerance by enhancing chloroplast antioxidant capacity and the function of photosynthetic apparatus of wheat.

This study investigated the effects of cerium on the regeneration and biosynthesis of ascorbate and glutathione in the leaves of turf grass Poa pratensis seedlings under copper (Cu) stress. The results showed that Cu stress increased the activities of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), glutathione reductase (GR), l-galactono-1,4-lactone dehydrogenase (GalLDH) and gamma-glutamylcysteine synthetase (γ-ECS), and the contents of reduced ascorbic acid (AsA), reduced glutathione (GSH), total ascorbate and total glutathione. However, Cu stress markedly increased the malondialdehyde content and electrolyte leakage and decreased the fresh and dry weights. Pretreatment with cerium (Ce(NO3)3) enhanced the activities of APX, GR, DHAR, GalLDH and γ-ECS, and the contents of AsA, GSH, total ascorbate and total glutathione under Cu stress. Meanwhile, pretreatment with Ce(NO3)3 decreased the malondialdehyde content and electrolyte leakage and increased the fresh and dry weights under Cu stress. Our results suggested that Ce(NO3)3 alleviated oxidative damage by regulating the metabolism of ascorbate and glutathione under Cu stress, and has important role in the acquisition of Cu tolerance in P. pratensis seedlings. Therefore, Ce(NO3)3 can be used as a regulator to improve the Cu tolerance of P. pratensis.

This study investigated the effects of lanthanum supplied as lanthanum (III) chloride (LaCl3) on the activities of antioxidant enzymes, the contents of non-enzymatic substances (reduced ascorbate (AsA) and reduced glutathione (GSH)), malondialdehyde (MDA), hydrogen peroxide (H2O2), osmoregulation substances (soluble protein, soluble sugar and proline) and the relative water content in the petals of Lilium longiflorum cut flowers. The results showed that LaCl3 significantly increased the activities of peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione peroxidase (GPX), the contents of AsA and GSH, and significantly decreased the contents of MDA and H2O2, compared to control. Meanwhile, LaCl3 significantly increased the contents of proline, soluble sugar and soluble protein, and the relative water content. Our results suggested that LaCl3 delayed the senescence of L. longiflorum cut flowers by improving antioxidant defense system and water retaining capacity.

A total of 48 endophytic bacteria were isolated from surface-sterilized tissues of the medicinal plant Lonicera japonica, which is grown in eastern China; six strains were selected for further study based on their potential ability to promote plant growth in vitro (siderophore and indoleacetic acid production). The bacteria were characterized by phylogenetically analyzing their 16S rRNA gene similarity, by examining their effect on the mycelial development of pathogenic fungi, by testing their potential plant growth-promoting characteristics, and by measuring wheat growth parameters after inoculation. Results showed that the number of endophytic bacteria in L. japonica varied among different tissues, but it remained relatively stable in the same tissues from four different plantation locations. Among the three endophytic strains, strains 122 and 124 both had high siderophore production, with the latter showing the highest phosphate solubilization activity (45.6 mg/L) and aminocyclopropane-1-carboxylic acid deaminase activity (47.3 nmol/mg/h). Strain 170 had the highest indoleacetic acid (IAA) production (49.2 mg/L) and cellulase and pectinase activities. After inoculation, most of the six selected isolates showed a strong capacity to promote wheat growth. Compared with the controls, the increase in the shoot length, root length, fresh weight, dry weight, and chlorophyll content was most remarkable in wheat seedlings inoculated with strain 130. The positive correlation between enzyme (cellulose and pectinase) activity and inhibition rate on Fusarium oxysporum, the IAA production, and the root length of wheat seedlings inoculated with each tested endophytic strain was significant in regression analysis. Deformity of pathogenic fungal mycelia was observed under a microscope after the interaction with the endophytic isolates. Such deformity may be directly related to the production of hydrolytic bacterial enzymes (cellulose and pectinase). The six endophytic bacterial strains were identified to be Paenibacillus and Bacillus strains based on the results of 16S rRNA gene sequencing analysis and their physiological and biochemical characteristics. Results indicate the promising application of endophytic bacteria to the biological control of pathogenic fungi and the improvement of wheat crop growth.

In this paper, we investigated whether nitric oxide (NO) participated in the regulation of the ascorbate-glutathione (AsA-GSH) cycle by exogenous jasmonic acid (JA) in the leaves of wheat seedlings under drought stress. The findings of our study showed that drought stress significantly enhanced the AsA-GSH cycle by upregulating the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR). Drought stress also markedly increased electrolyte leakage (EL), malondialdehyde (MDA) content, NO content, and significantly reduced the ratios of reduced ascorbate/dehydroascorbic acid (AsA/DHA) and reduced glutathione/oxidized glutathione (GSH/GSSG) compared with control. Exogenous JA significantly increased the above indicators, compared with drought stress alone. All these effects of JA were inhibited by pretreatment with NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). Meanwhile, exogenous JA markedly decreased MDA content and electrolyte leakage of wheat leaves under drought stress. Pretreatment with cPTIO reversed the above effects of exogenous JA. Our findings indicated that NO induced by exogenous JA upregulated the activity of the AsA-GSH cycle and had important role in drought tolerance.

This study investigated the effects of sodium selenite (Na2SeO3) on the antioxidant capacity and the fruit yield and quality of cadmium-stressed strawberry. The results showed that cadmium (Cd) stress notably decreased the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione synthetic enzyme gamma-glutamylcysteine synthetase (γ-ECS), plant height and plant biomass, and fruit yield and quality, improved the activities of ascorbate oxidase (AO), glutathione reductase (GR) and ascorbate synthetic enzyme L-galactono-1,4-lactone dehydrogenase (GalLDH), the ratios of AsA/DHA and GSH/GSSG and the contents of malondialdehyde (MDA), hydrogen peroxide (H2O2) and Cd, compared with control. Compared with Cd stress alone, 5 and 10 μM Na2SeO3 notably improved the activities of above enzymes except AO, the ratios of AsA/DHA and GSH/GSSG, plant height and biomass, Se contents in leaves and fruits, average fruit weight and the contents of Vc, soluble sugar and total soluble solid in fruits. 15 μM Na2SeO3 notably improved the activities of above enzymes except AO, the ratio of GSH/GSSG, plant height, Se contents in leaves and fruits, average fruit weight and Vc content in fruits. 20 μM Na2SeO3 only notably improved Se contents in leaves and fruits, average fruit weight and Vc content in fruits. Meanwhile, 5, 10 and 15 μM Na2SeO3 significantly reduced Cd stress-induced the contents of MDA, H2O2 and Cd, 20 μM Na2SeO3 only significantly reduced Cd stress-induced the contents of Cd in leaves and fruits, compared with Cd stress alone. Our findings indicated that only low concentrations of Se were effective in conferring Cd tolerance in strawberry plants by up-regulating their antioxidant capacity and reducing Cd accumulation, which further improved the fruit yield and quality of strawberry.

A genetic transformation method via secondary somatic embryogenesis was developed for alfalfa (Medicago sativa L.). Mature somatic embryos of alfalfa were infected by Agrobacterium strain GV3101 containing the binary vector pCAMBIA2301. pCAMBIA2301 harbors the uidA Gus reporter gene and npt II acts as the selectable marker gene. Infected primary embryos were placed on SH2K medium containing plant growth regulators to induce cell dedifferentiation and embryogenesis under 75 mg/L kanamycin selection. The induced calli were transferred to plant medium free of plant growth regulators for embryo formation while maintaining selection. Somatic embryos germinated normally upon transfer to a germination medium. Plants were recovered and grown in a tissue culture room before transfer to a greenhouse. Histochemical analysis showed high levels of GUS activity in secondary somatic embryos and in different organs of plants recovered from secondary somatic embryos. The presence and stable integration of transgenes in recovered plants were confirmed by polymerase chain reaction using transgene-specific primers and Southern blot hybridization using the npt II gene probe. The average transformation efficiency achieved via secondary somatic embryogenesis was 15.2%. The selection for transformation throughout the cell dedifferentiation and embryogenic callus induction phases was very effective, and no regenerated plants escaped the selection procedure. Alfalfa transformation is usually achieved through somatic embryogenesis using different organs of developed plants. Use of somatic embryos as explants for transformation can avoid the plant development phase, providing a faster procedure for introduction of new traits and facilitates further engineering of previously transformed lines.

This study investigated the regulation of ascorbate and glutathione metabolism by jasmonic acid (JA) in Agropyron cristatum leaves under water stress induced by 10% PEG 6000. The results showed that JA level, the transcript levels and activities of APX, GR, MDHAR, DHAR, GalLDH and g-ECS, and the contents of AsA, GSH, total ascorbate and total glutathione were increased by water stress. Above increases except for total glutathione content and the transcript level and activity of g-ECS were suppressed by application of JA biosynthesis inhibitor ibuprofen (IBU), a lipoxygenase inhibitor, for 12 h before water stress treatment. Application of JA to IBU-inhibited plants prevented the reduction in the transcript levels and activities of GalLDH, APX, GR, DHAR and MDHAR, and the contents of AsA, GSH, total ascorbate induced by IBU under water stress. Meanwhile, pretreatment with IBU increased the malondialdehyde content and electrolyte leakage of plants and these increases were suppressed by application of JA under water stress. Our results suggested that water stress-induced JA is a signal that leads to the regulation of ascorbate and glutathione metabolism and has important role for acquisition of water stress tolerance in A. cristatum.

With locust (Robinia pseudoacacia), the main tree species in afforestation, as test material, this paper studied the characteristics of its water physiological ecology and productivity under four habitats, i. e. , sunny, shady, semi-sunny and semi-shady hillsides, in the North Shaanxi gully areas of Loess Plateau. The mean water content in 0 - 500 cm soil layer was 8.87% (shady), 8.06% (semi-shady), 7.62% (semi-sunny), and 6.96% (sunny), respectively. There was a significant discrepancy between shady, semi-shady, semi-sunny and sunnyhilisides (a 0.01), and the difference between shady, semi-shady and semi-sunny, as well as between semi-sunny and sunny hillsides was also significant (a 0.05) . Remarkable relationships were found between leaf RWC, locus WSD and soil water content (SWC) . The leaf RWC and locust water potential under sunny hillside were lower, but those under shady hillside were higher. The daily mean transpiration was in order of shady (4.07 microg x cm(-2) x s(-1))semi-shady (3.89 microg x cm(-2) x s(-1))semi-sunny (3.05 microg x cm(-2) x s(-1))sunny (2.70 microg x cm(-2)s(-1)) hillside. The remarkable difference of transpiration appeared at 11:00 and 13:00, and there existed a remarkable relationship between transpiration and light intensity, RH and soil water content. All of these resulted in a diversity of locust biomass under different habitats, the highest under shady hillside, and the lowest under sunny hillside, and the differences between different habitats were all significant. It could be concluded that soil water content was the main factor affecting locust growth.