Overaccumulation of glycine betaine makes the function of the thylakoid membrane better in wheat under salt stress

Wheat(Triticum aestivum L.) lines T1, T4, and T6 were genetically modified to increase glycine betaine(GB) synthesis by introduction of the BADH(betaine aldehyde dehydrogenase, BADH)gene from mountain spinach(Atriplex hortensis L.). These transgenic lines and WT of wheat(T. aestivum L.) were used to study the effect of increased GB synthesis on wheat tolerance to salt stress. Salt stress due to 200 mmol L-1Na Cl impaired the photosynthesis of the four wheat lines, as indicated by declines in net photosynthetic rate(Pn), stomatal conductance(Gs),maximum photochemical efficiency of PSII(Fv/Fm), and actual photochemical efficiency of PSII(ФPSII) and an increase in intercellular CO2concentration(Ci). In comparison with WT, the effect of salinity on the three transgenic lines was mild. Salt stress caused disadvantageous changes in lipids and their fatty acid compositions in the thylakoid membrane of the transgenic lines and WT. Under salt stress, the three transgenic lines showed slightly higher chlorophyll and carotenoid contents and higher Hill reaction activities and Ca2+-ATPase activity than WT. All the results suggest that overaccumulation of GB resulting from introduction of the BADH gene can enhance the salt tolerance of transgenic plants, especially in the protection of the components and function of thylakoid membranes, thereby making photosynthesis better. Changes in lipids and fatty acid compositions in the thylakoid membrane may be involved in the increased salt stress tolerance of the transgenic lines.

Novel Zwitterionic Surfactants: Synthesis and Surface Active Properties of N-(3-Alkoxy-2-Hydroxypropyl)-N, N-Dimethyl glycine Betaines

Five new zwitterionic surfactants with long chain alkyl betaine structure incorporated with hydroxylpropyl group have been synthesized. Their structures were identified by elemental analysis, IR (HNMR)-H-1, and (CNMR)-C-13. Surface tension experiments showed that these surfactants have higher surface activity than those without hydroxypropyl group. The values of CMC and gamma(CMC) of these surfactants have been determined.

Exogenous Glycine Betaine Reduces Drought Damage by Mediating Osmotic Adjustment and Enhancing Antioxidant Defense in Phoebe hunanensis

Drought stress negatively impacts growth and physiological processes in plants.The foliar application of glycine betaine(GB)is an effective and low-cost approach to improve the drought tolerance of trees.This study examined the effect of exogenously applied GB on the cell membrane permeability,osmotic adjustment,and antioxidant enzyme activities of Phoebe hunanensis Hand.-Mazz under drought stress.Two levels(0 and 800 mL)of water irrigation were tested under different applied GB concentrations(0,50,100,and 200 mM).Drought stress decreased the relative water content by 58.5%while increased the electric conductivity,malondialdehyde,proline,soluble proteins,soluble sugars,and antioxidant enzyme activities(superoxide dismutase,catalase,peroxidase)by up to 62.9%,42.4%,87.0%,19.1%,60.5%,68.3%,71.7%,and 83.8%,respectively,on the 25^(th) day.The foliar application of GB,especially at 100 mM,increased the relative water content of P.hunanensis leaves under drought stress.The concentration of GB from 50 to 100 mM effectively alleviated the improvement of cell membrane permeability and inhibited the accumulation of membrane lipid peroxidation products.Under drought stress,the concentrations of proline,soluble proteins,and soluble sugars in the leaves of P.hunanensis increased as the applied GB concentration was increased and the water stress time was prolonged.Exogenously applied GB decreased oxidative stress and improved antioxidant enzyme activities as compared with treatments without GB application.Furthermore,the physiological and biochemical indexes of P.hunanensis showed a certain dose effect on exogenous GB concentration.These results suggest that GB helps maintain the drought tolerance of P.hunanensis.

Research Progress in Glycine Betaine Improving Plant Salty Stressful Tolerance

Many plants accumulate compatible solutes in response to the imposition of environmental stresses.Glycine betaine, which is one of compatible solutes in cell of plants,has been shown to have surviving ability for plant from salt stress.Effect of glycine betaine on improving plant salt resistance was discussed in plants under salt stress.The accumulation of glycine betaine protects plants against the damaging effects of stress.Strategies of glycine betaine against the damaging effects of stress were analyzed to clarify the roles of glycine betaine in salt stress tolerance of plants.

The effect of time and type of stress moderators on yield and yield components of cotton on conventional and double‑cropping systems under saline conditions

Background:Today,stress moderators are employed to mitigate crop loss due to the adverse effects of environmental stress.The current research aimed to investigate the impacts of time and stress moderator types on agro-physiological responses of cotton on conventional and double-cropping systems during 2017 and 2018 under saline conditions.A split-plot factorial experiment was carried out in a randomized complete block design with three replications.Cultivation system[conventional(recommended planting date)and double-cropping systems(sowing after harvest of wheat)]were considered as the main plots,and stress moderator type at four levels[water control,2 mmol·L^(-1) Salicylic acid(SA),100 mmol·L^(-1) Glycine betaine(GB),and 100μmol·L^(-1) sodium nitroprusside(SNP)]and application time(flowering and flowering+bolling stages)were regarded as subplots.Results:Plant height,reproductive branch number,the number of bolls,10-boll weight,1000-seed weight,biological yield,seed cotton yield,lint yield,chlorophyll a,chlorophyll b,carotenoids,total chlorophyll,sodium,potassium,and proline content were less in double-cropping system comparing with conventional system.Spraying with the stress moderators alleviated soil salinity effects on yield,yield components,and biochemical traits of cotton.SNP spraying led to maximum plant height,branch number,the number of bolls per plant,10-boll weight and seed cotton yield.SA spraying yielded the highest 1000-seed weight,biological yield,lint percentage and lint yield.The highest chlorophyll a,chlorophyll b,carotenoids,and total chlorophyll content resulted from SNP spraying.Yield,yield components,and biochemical traits did not respond to the stress moderator types in double-cropping system.However,the highest chlorophyll a,carotenoids,proline content,the number of bolls per plant,and seed cotton yield resulted from SNP spraying in conventional system.No statistically significant differences were observed between spraying with SNP and SA in most studied traits.Conclusions:The results suggest that the optimum cotton planting time and SNP spraying could be recommended for producing the most suitable yield under saline conditions.Highlights:External application of stress modulators increases salinity stress tolerance.Spraying with sodium nitroprusside has more moderating effect.Agro-physiological response of cotton to moderators is stronger in early sowing.Maximum seed cotton yield was achieved at early sowing and spraying sodium nitroprusside.Delayed cultivation reduces cotton yield.

In Vitro Propagation, Isolation and Expression Studies of Suaeda edulis Genes Involved in the Osmoprotectants Biosynthesis

Halophytes are an excellent choice for the study of genes conferring salt tolerance to salt-sensitive plants and,they are suitable for reclamation and remediation of saline soil.We develop an in vitro plant propagation protocol and studies of genes involved with GB and Pro biosynthesis in Suaeda edulis.Axillary buds were used as explants and cultured in different treatments on Murashige and Skoog(MS)medium supplemented with different concentrations and combinations of plant growth regulators.The highest number of multiple shoots was on MS medium containing 1 mg/L Benzyladenine(BA)and/or 2 g/L activated carbon with 5.5±06 shoots per explant.The identification and expression analysis of genes involved in glycine betaine(GB)biosynthesis were S-adenosyl-methionine synthetase(SAMS),choline monooxygenase(CMO)and betaine alde-hyde dehydrogenase(BADH),and for proline(Pro)was pyrroline 5-carboxylate synthetase(P5CS).These sequences shared 90–95%of identity with others plant homologous in public databases.The amino acids sequence analysis showed that all these peptides contain some of the conserved motifs of those kinds of enzymes.The qRT-PCR analysis revealed a higher expression of SeBADH,SeCMO,and,SeP5CS genes in the roots and leaves from plants collected in the field in contrast with from in vitro plants.However,the expression level of SeSAMS was higher only in the leaves of plants collected in the field when com-pared to those cultivated in vitro.

Transgenic Brassica chinensis plants expressing a bacterial codA gene exhibit enhanced tolerance to extreme temperature and high salinity

Transgenic Brassica compestris L.spp.chinensis plants expressing a choline oxidase(codA) gene from Arthrobacter globiformis were obtained through Agrobacterium tumefaciens-mediated transformation.In the transgenic plants,codA gene expression and its product transportation to chloroplasts were detected by the enzyme-linked immunosorbent assay(ELISA) examination,immunogold localization,and 1 H-nuclear magnetic resonance( 1 H-NMR) . Stress tolerance was evaluated in the T3 plants under extreme temperature and salinity conditions.The plants of transgenic line 1(L1) showed significantly higher net photosynthetic rate(Pn) and Pn recovery rate under high(45°C,4 h) and low temperature(1°C,48 h) treatments,and higher photosynthetic rate under high salinity conditions(100,200,and 300 mmol/L NaCl,respectively) than the wild-type plants.The enhanced tolerance to high temperature and high salinity stresses in transgenic plants is associated with the accumulation of betaine,which is not found in the wild-type plants.Our results indicate that the introduction of codA gene from Arthrobacter globiformis into Brassica compestris L.spp.chinensis could be a potential strategy for improving the plant tolerance to multiple stresses.