Accumulation Of Betaine Research Articles

SDK completes expansion of capacity for titanium oxide nanoparticles

Salinity is an omnipresent stressor, depleting osmotic potential and affecting the vineyard development and productivity. It is indispensable to screen the grapevine genetic resources for possibilities to mitigate and adapt to the stress conditions. This paper describes the distinct response of the grapevine under progressive salt stress duration (0, 24, 48, and 72 h). Intriguingly, besides the adverse effect of salt stress on grapevine growth, the findings exhibit significant levels of stress responses to diminish the impact of salinity. Discerned are the accumulation of glycine betaine (GB) and trehalose, which can be supposed as distinct grapevine responses associated with the maintenance of high K+ level and, consequently, lower K+/Na+ ratios, with an excellent performance of cell water status and photosynthetic activity as compared to the controls. Moreover, an alleviated level of the oxidative stress marker (MDA) gives rise to superoxide radicals (O2−) and hydrogen peroxide (H2O2), while the antioxidative scavenging system is activated to counter the synthesis of reactive oxygen species (ROS). Principal component analysis (PCA) distinguished several salt prediction candidate markers based on physiological and transcriptional indexes in four different clusters. Current findings have elucidated new and fascinating responses of the grapevine to lengthy salt-stress period and provide a list of intended enzymatic targets for candidate gene selection to uplift the abiotic stress tolerance in horticultural crops.

Influence of the proline metabolism and glycine betaine on tolerance to salt stress in tomato (Solanum lycopersicum L.) commercial genotypes

Tomato is the crop with the greatest economic importance in the world and salinity stress causes a reduction in the quantity and quality of crop production. The objective of this work is to verify if the accumulation of proline and glycine betaine (GB) and their metabolisms improve tolerance to salt stress. Two commercial genotypes of Solanum Lycopersicum L., Grand Brix and Marmande RAF were used for this work. The analyzed parameters were growth parameters, proline concentration and its metabolism, GB and its above betaine aldehyde dehydrogenase (BADH) synthesis and some related amino acids. Saline stress reduced biomass and relative growth rate (RGR) in both genotypes, this effect being greater in Marmande RAF. These results, together with the proline accumulation indicate that Grand Brix is more tolerant to saline stress. The proline increase in Grand Brix came by the ornithine pathway, leaving the glutamate pathway repressed. On the other hand, it was found in both genotypes a BADH and GB decreases as a salinity tolerance mechanism. We propose that, unlike proline, GB synthesis can produce H2O2 thereby, GB not act as compatible solute and salt tolerance does not improve.

Differential responses of two Iranian rice cultivars to arsenite toxicity

Arsenic (As) is a toxic metalloid which is usually found in rice fields as a contamination and has negative effects on the plant growth and reduces the crop yield. Similar to heavy metals, the deleterious effects of As may be due to, at least in part, the amount of absorbed As and disturbance of the plant water status. In this connection, different varieties of the same species may show differential performances. Comparative responses to 75 µM AsIII were evaluated in two Iranian rice cultivars adapted to moderate-humid vs. very warm and dry climates (Hashemi and Amber, respectively). Although both cultivars absorbed AsIII, but its translocation factor was lower in Amber accompanied by accumulation of soluble sugars and glycine betaine and lower level of internal ABA. Moreover, adverse effect of AsIII onrelative water content and stomata closure was less prominent in Amber, compared to Hashemi. Results suggest that cultivars adapted to dry conditions are more capable to withstand against As and to control its entrance to human food chain.

Comparison of Distichlis spicata and Suaeda aegyptiaca in response to water salinity: Candidate halophytic species for saline soils remediation

ABSTRACTDistichlis spicata and Suaeda aegyptiaca are two potential halophytic plant species for bioremediation of salt degraded soils, and development of saline agriculture. The physiological responses of the species to different levels of salinity (EC 0, 12, 24, 36, and 48 dS/m) in a controlled environment experiment were studied. Both species showed a high level of tolerance to elevated concentrations of salt in the irrigation water. The shoot fresh and dry weights in S. aegyptiaca increased till 36 dS/m and were sustained under 48 dS/m while in D. spicata, both parameters decreased as salinity increased. Glycine betaine accumulation did not change in D. spicata with increasing salinity, whereas proline content revealed a marked increase of 7.13 fold in 48 dS/m salinity compared to the control, which showed its critical osmoprotection role in the plant. In S. aegyptiaca, both osmolytes content significantly increased at high salinity levels (36 and 48 dS/m) up to 3.22 and 2.0 folds, respectively. Overall, S. aegyptiaca had a better potential of Na+ phytoremediation, and tolerated higher salinity compared to D. spicata. In contrast, the vigorous root and rhizome growth in D. spicata made it a proper solution for protecting the soils against further erosion under saline conditions.

Boron amendment improves water relations and performance of Pistacia vera under salt stress

Abstract Soils of arid and semi-arid environments are prone to salinization and boron toxicity. However, limited studies have been dedicated to investigating interactive effects of these stressors on plants. This study evaluates growth, water relations, and osmoregulation of 30-day-old Pistacia vera seedlings in response to combinations of different concentrations of NaCl (0, 800, 1600, and 2400 mg kg−1) and boron (0, 2.5, 5, and 10 mg kg−1) in soil under controlled environment conditions for 120 days. The treatments were arranged as a factorial experiment based on completely randomized design. Separate applications of 1600–2400 mg NaCl or 20 mg kg−1 soil reduced plant biomass and growth rate, due to development of water deficit, plasma membrane injuries, and decline of water use efficiency. Application of 10 mg kg−1 soil prevented plant growth inhibition under 800–1600 mg kg−1 soil. Under severe NaCl stress, however, 5 mg kg−1 soil was the best treatment for improving performance of the plants. The ameliorating effects of soil boron amendments on NaCl stress was due to improving osmoregulation via enhancement of glycine betaine accumulation, improvement of water availability to the plant, and reduced cell membrane injuries. On the other hand, boron toxicity pressure reduced under 800–1600 mg kg−1 soil treatments, which was mainly due to stomatal closure, limitation of transpiration rate, and reduced boron accumulation in shoot. These observations revealed that soil boron level largely influences plant responses to salt stress, and soil boron amendment can improve salt tolerance of P. vera.

Methyl jasmonate alleviates drought stress in young sugar beet (Beta vulgaris L.) plants

AbstractDrought is the major cause of yield and economic loss for the sugar beet crop. Mechanisms to reduce drought stress, however, are lacking as sugar beets are largely produced without irrigation and drought‐tolerant varieties are not available. As jasmonates are implicated in plant drought‐stress responses, research was conducted to determine whether methyl jasmonate (MeJA) could mitigate drought effects on sugar beet. Fourteen‐day‐old plants were treated with 0, 0.01, 0.1, 1 or 10 μM MeJA. Seven days later, half of the plants were drought‐stressed by withholding water, while control plants continued to receive water. Drought caused leaf relative water content (RWC), shoot fresh and dry weights, net photosynthetic rate (Pn), transpiration rate (EVAP), stomatal conductance (Gs), water‐use efficiency (WUE) and PSII quantum efficiency to decline and substomatal CO2 concentration (Ci) and proline and betaine concentrations to increase. MeJA, at 1 and 10 μM, reduced moderate and severe drought effects on RWC, Pn, Ci and WUE and altered drought‐induced changes in proline accumulation, but had no effect on Gs, EVAP or betaine accumulation. Results indicate that MeJA delayed plant dehydration and protected the photosynthetic apparatus from drought‐induced impairment. Exogenous application of MeJA, therefore, alleviates drought stress on young sugar beets and may provide a tool to reduce the economic loss caused by dry conditions during early crop production.

Transcriptomic analysis by RNA-seq of Escherichia coli O157:H7 response to prolonged cold stress

The adaptability of Escherichia coli O157:H7 to different environmental stresses, including prolonged cold stress, poses a threat to food safety. In order to elucidate the prolonged cold response in E. coli O157:H7, genes related to prolonged coldresistance and their expression changes in E. coli O157:H7 ATCC35150 were screened and identified by analyzing their transcriptomedifferences between normal (37 °C) and low temperature storage (4 °C or −20 °C, 10 d), using RNA-sequencing. According to our results, 425 differentially expressed genes (DGEs) were identified responding to cold stresses in this study. Gene rpoS was significantly up-regulated (more than two fold; p < 0.05) and was referred to be the critical switch for the whole regulation in the response to prolonged cold stress. Moreover, cold shock genes played an important role only in the acclimation phase of E. coli O157:H7 in the early stage of cold stress, and were down-regulated in the adaptation stage. Specifically, E. coli O157:H7 would promote its resistance to prolonged cold stress mainly by increasing the expression of genes involved in the synthesis of unsaturated fatty acids and the accumulation of trehalose and betaine.

Exogenously applied zinc and copper mitigate salinity effect in maize (Zea mays L.) by improving key physiological and biochemical attributes

Zinc or copper deficiency and salinity are known soil problems and often occur simultaneously in agriculture soils. Plants undergo various changes in physiological and biochemical processes to respond to high salt in the growing medium. There is lack of information on the relation of exogenous application of Zn and Cu with important salinity tolerance mechanisms in plants. Therefore, the present study was conducted to determine the effect of foliar Zn and Cu on two maize cultivars (salt-tolerant cv. Yousafwala Hybrid and salt-sensitive cv. Hybrid 1898). Salinity caused a significant reduction in water and turgor potentials, stomatal conductance, and transpiration and photosynthetic rate, while increase in glycine betaine, proline, total soluble sugars, and total free amino acids was evident in plants under saline regimes. Furthermore, there was significant decline in P, N, Ca, K, Mn, Fe, Zn, and Cu and increase in Na and Cl contents in plants fed with NaCl salinity. Nitrate reductase activity was lower in salt-stressed plants. However, foliar application of Zn and Cu circumvented salinity effect on water relations, photosynthesis, and nutrition and this was attributed to the better antioxidant system and enhanced accumulation of glycine betaine, proline, total free amino acids, and sugars. The results of the present study suggested that Zn application was superior to Cu for mediating plant defense responses under salinity.

Glycine betaine accumulation in Avicennia germinans propagules and seedlings as a function of abiotic stress

The black mangrove (Avicennia germinans) is native to the subtropical coasts of Florida and can tolerate moderate to high salinity environments. Propagules, germinated seeds that remain attached to the maternal plants until mature, are dispersed in shallow waters and transported through currents until washing ashore, and establishing roots on an appropriate substrate to initiate growth. Recently, the poleward expansion of A. germinans has been observed. The literature and findings in our laboratory suggest that A. germinans gains its salt and temperature tolerance in part by the modified amino acid, glycine betaine (GB). We sought to investigate the expression of GB in A. germinans as a function of abiotic stressors: high saline and low temperatures. The role of endogenous GB accumulation as a function of substrate condition and temperature was investigated in propagules. The accumulation of exogenous GB was measured in seedlings exposed to various saline and temperature environments. Propagules exposed to colder temperatures accumulated more GB (100–200 ug/umol) than moderate temperatures (50 ug/umol). Propagules exposed to 18 ppt saline accumulated more GB than those exposed to 36 ppt at 0°C. Propagules exposed to saline environments accumulated more GB at 0°C compared to sand and air samples. Significantly more propagules treated at 36 ppt developed into seedlings and demonstrated faster growth rates. Additionally, an exogenous application of 10 μM GB improved seedling survival after exposure to −2°C and high saline stress (60 ppt and 100 ppt). Preliminary findings demonstrate that APX and SOD enzymes are both present in the leaf samples after these stressors. These results further characterize the role GB contributes to the ability of A. germinans to acclimate following environmental stressors. Propagules express endogenous GB in response to abiotic stress, while exogenous application of GB may confer additional protection from continued stress. Subsequent investigations will further elucidate the roles APX and SOD may influence in the GB mechanism. The significance of these findings further characterize the mechanisms by which A. germinans survive high saline environments and colder temperatures.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Parental Drought-Priming Enhances Tolerance to Post-anthesis Drought in Offspring of Wheat.

Drought is the major abiotic stress that decreases plant water status, inhibits photosynthesis, induces oxidative stress, restricts growth and finally lead to the reduction of wheat yield. It has been proven that drought priming during vegetative growth stage could enhance tolerance to drought stress at grain filling in wheat. However, whether drought priming imposed at grain filling in parental plants could induce drought tolerance in the offspring is not known. In this study, drought priming was successively applied in the first, the second and the third generation of wheat to obtain the plants of T1 (primed for one generation), T2 (primed for two generations), T3 (primed for three generations). The differently primed plants were then subjected to drought stress during grain filling in the fourth generation. Under drought stress, the parentally primed (T1D, T2D, T3D) plants, disregarding the number of generations, showed higher grain yield, leaf photosynthetic rate and antioxidant capacity as well as lower release rate and contents of H2O2 and MDA than the non-primed (T0D) plants, suggesting that drought priming induced the transgenerational stress tolerance to drought stress. Moreover, the parentally primed plants showed higher leaf water status, which may result from the higher contents of proline and glycine betaine, and higher activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS) and betaine aldehyde dehydrogenase (BADH), compared with the non-primed plants under drought stress. In addition, there was no significant difference among three generations under drought, and the drought priming in parental generations did not affect the grain yield of the offspring plants under control condition. Collectively, the enhanced accumulation of proline and glycine betaine in the parentally primed plants could have played critical roles in parental priming induced tolerance to drought stress. This research provided a potential approach to improve drought tolerance of offspring plants by priming parental plants.

Effects of Salinity on Growth Physiology, Accumulation of Osmo-Protectant and Autophagy-Dependent Cell Death of Two Maize Variety

Maize is moderately sensitive to salt stress; therefore, soil salinity is a serious threat to its production worldwide. Here, two maize variety Kharif Shaktiman-1 and Pioneer 30 v92 were screened to understand the maize response to salt stress and its tolerance mechanisms. Difference in relative water content, membrane stability index, stomatal conductance, shoot and root fresh/dry weight has been analyzed under salinity. The effect of osmotic stress was also analyzed on the basis of accumulation of osmoprotentant like proline, glycine betaine and soluble sugar content. The gas exchange characteristics and autophagy-dependent cell death were used to analyses the physiological effects of osmotic stress at about 15 days after salt stress in maize. The results of relative water content, membrane stability index, stomatal conductance, accumulation of osomoprotectant was higher in Kharif Shaktiman-1, the autophagy-dependent cell death was less in Pioneer 30 v92, indicate that Kharif Shaktiman-1 has more salt tolerant ability than the Pioneer 30 v92. But the result of autophagy-dependent cell death showed an opposite trend, as it was higher in Kharif Shaktiman-1, indicate more cell damage in it under salinity. So molecular technique or marker based on autophagy-dependent cell death for the screening of stress tolerant trait in desired crop may act as method of choice.

Compatible solutes and metabolites accumulation does not explain partial desiccation tolerance in Hymenoglossum cruentum and Hymenophyllum dentatum (Hymenophyllaceae) two filmy ferns with contrasting vertical distribution

Hymenoglossum cruentum (Cav.) Presl. and Hymenophyllum dentatum (Cav.) are poikilohydric partial desiccation tolerant (PDT) epiphytic filmy ferns with contrasting vertical distributions. H. cruentum is restricted to trunk base (ground to 1 m), and H. dentatum is more generalist growing from the ground up to 9 m in the host. Vertical distribution has been related to interspecific differences to cope with greater desiccating conditions such as low humidity and high irradiance. PDT plants exhibit a series of mechanisms that allow them to better tolerate severe dehydration that include the accumulation of compatible solutes, and the de novo synthesis of proteins and free sugars that are thought to protect cellular structure during cycles of desiccation-rehydration. Therefore, interspecific differences in the capacity to accumulate compatible solutes and metabolites during desiccation-rehydration may explain differences in vertical distribution between these two “filmy fern” species. The contents of proline, glycine betaine, soluble sugars, total proteins, and pigments of the photosynthetic system were evaluated during a cycle of desiccation-rehydration in H. cruentum and H. dentatum. The latter exhibited a more rapid desiccation-rehydration cycle in contrast to the former. Soluble sugars, proline, and pigment contents decreased in the dehydrated state. The two filmy ferns did not exhibit a major accumulation of proline (lower than 8 μmol g−1 DW) or glycine betaine (lower than 4 mg g−1 DW) which contrasts with other higher plants exposed to water deficit. Both species exhibited an elevated sugar concentration in the hydrated state, which decreased during desiccation by approximately 2.5-fold. These results differ from previous studies on other desiccation tolerant higher-plants but agree with results from bryophytes. We concluded that accumulation of conventional compatible solutes of higher plants is not part of the dehydration induced mechanisms conferring desiccation tolerance in filmy ferns, and do not explain interspecific differences in vertical distribution of the two species. Therefore, partial desiccation tolerance of filmy ferns probably relies on preformed structural rather than induced biochemical mechanisms, suggesting similarities of Hymenophyllaceae (primitive ferns) with bryophytes.

Exogenous application of allelopathic water extracts helps improving tolerance against terminal heat and drought stresses in bread wheat (Triticum aestivum L. Em. Thell.)

AbstractThe allelopathic water extracts (AWEs) may help improve the tolerance of crop plants against abiotic stresses owing to the presence of the secondary metabolites (i.e., allelochemicals). We conducted four independent experiments to evaluate the influence of exogenous application of AWEs (applied through seed priming or foliage spray) in improving the terminal heat and drought tolerance in bread wheat. In all the experiments, two wheat cultivars, viz. Mairaj‐2008 (drought and heat tolerant) and Faisalabad‐2008 (drought and heat sensitive), were raised in pots. Both wheat cultivars were raised under ambient conditions in the wire house till leaf boot stage (booting) by maintaining the pots at 75% water‐holding capacity (WHC). Then, managed drought and heat stresses were imposed by maintaining the pots at 35% WHC, or shifting the pots inside the glass canopies (at 75% WHC), at booting, anthesis and the grain filling stages. Drought stress reduced the grain yield of wheat by 39%–49%. Foliar application of AWEs improved the grain yield of wheat by 26%–31%, while seed priming with AWEs improved the grain yield by 18%–26%, respectively, than drought stress. Terminal heat stress reduced the grain yield of wheat by 38%. Seed priming with AWEs improved the grain yield by 21%–27%; while foliar application of AWEs improved the grain yield by 25%–29% than the heat stress treatment. In conclusion, the exogenous application of AWEs improved the stay green, accumulation of proline, soluble phenolics and glycine betaine, which helped to stabilize the biological membranes and improved the tolerance against terminal drought and heat stresses.

Physiological adjustments of wheat to drought stress as influenced by osmoprotectants and cytokinins

Glycine betaine (GB), Trehalose (Tre) and proline function as compatible solutes and are up regulated in plants under drought stress. In physiological responses, these play an osmoprotective role enabling the plants to better tolerate the adverse conditions of growth. In the present study, the effect of exogenous application of GB and Tre along with cytokinins (Kn, BA) applied during vegetative and anthesis stages to wheat cultivars (HD2967, PBW660 and WH1105) has been investigated. Proline content significantly increased under drought stress in all the three cultivars. Application of Tre along with both Kn and BA reduced the accumulation of proline in leaves at vegetative and anthesis stage. Drought stress conditions favoured accumulation of GB and choline in leaves of wheat cultivars and percent increase was more in PBW660. GB and Tre further improved accumulation of endogenous glycine betaine and choline. This advantageous effect of the osmoprotectants in combination with cytokinins alleviated growth inhibition during drought and improved the number of productive tillers and grains.

Nitrogen (N) and Potassium (K) Supplementation to Improve Salt Tolerance in Brassica (Brassica juncea, cv: Agati sarheen)

To observe the mitigating effects of nitrogen and potassium under salinity on Brassica juncea (cv. Agati sarheen), N and K was supplemented at different stages of growth. The studies were conducted under control condition (gravel culture). Salinity (12 dS/m) was imposed by NaCl salt after three weeks of germination through irrigation (1/4th Hoagland solution). Nitrogen and Potassium was applied exogenously in the form of KNO3 @ (T1. 30mM and T2 60mM) at vegetative and flowering stage. There was decrease in growth and yield under salinity. However; the relative reduction in plant height, slique length, grain wt/ 5 slique and grain yield/ 15 plants was comparatively low due foliar application of N and K as compared to non applicated plants. The overall accumulation of organic solutes (proline and glycine betaine) was significantly high under salinity. The response of N and K application was almost nil in case of proline accumulation. On the other hand application of KNO3 @ 30mM showed increased accumulation of glycine betaine. The uptake of Na under salinity was less in plant having KNO3 application @ 30mM (T1). Potassium content under saline condition was high in KNO3 @ 60mM (i.e. T2 treatment), resulting in high K/Na ratio. The application of KNO3 also found to increase in nitrogen content in brassica. It is therefore concluded that better performance of brassica genotype under salinity might be due to low Na uptake and high K/ Na ratio especially under T1 treatment (i.e KNO3 @ 30mM).

Modulation of Glycine Betaine Accumulation with Oxidative Stress Induced by Aluminium Toxicity in Rice

The present study addresses the sensitivity of rice species to varying concentrations of Al toxicity. Aluminium salt for plants was used in increasing order (240, 360, 480 µM) during short period to decipher the impact of metal stress on metabolic status with reference to oxidative damages. Interestingly, plants responded well with increase in linear root growth. In a dose dependent manner of metal concentration, plants suffered more from developed ROS (both O2− and H2O2) in root cortex. The histochemical detection of tissue lysis as detected by Evans blue and Hematoxylin was in proportionate to the aluminium concentration over control. In response to peroxide radical accumulated in the tissues, plants were characterized in a variable manner for APX, CAT and GR activities. Still, on protein polymorphism of these genes, the plants responded well with a distinct expression varied over control. In support of decreased activity, a single band expression was key feature to characterize the plants under Al toxicity. Plants though maintained a stable proportion of non-thiol content but a steeper up regulation of GR activity at highest concentration of Al was indicating for more GSH recruitment in oxidative stress. Banding patterns of APX, CAT and GR through Al concentrations appeared as bio-indices under metal reactivity in rice species. Betaine aldehyde dehydrogenase was also in proportionate manner to support the synthesis of osmolyte under metal toxicity. This is more relevant with protein expression of aldehyde dehydrogenase activity and distinct bands favor the gene expression under modulation of metal stress.

Antioxidant defense system in chickpea against drought stress at pre- and post- flowering stages

Ten wilt resistant and three wilt susceptible chickpea genotypes were subjected to drought stress at pre and post flowering stages along with four drought tolerant and three drought susceptible checks by withholding irrigation. The three wilt resistant chickpea genotypes viz., GJG 0922, JG 24 and JG 2001-4 recorded significant increase in proline and glycine betaine accumulation and SOD, APX, GPX, CAT activities under water-deficit stress at preflowering stage. The mean leaf proline content of the control genotypes was 23.72 µmol g−1 DW and increased to 56.73 µmol g−1 DW under drought stress at preflowering stage. Based on the level of osmolyte accumulation, induction of antioxidative enzymes, five chickpea genotypes viz., JG 552476, GJG 0922, JG 24, JG 2001-4 and GJG 0919 could be categorized as drought tolerant. Chickpea genotype PBG 5 which recorded 26.8% wilt incidence and exhibited higher induction of antioxidative enzymes was rolerant to drought stress at preflowering stage while the three wilt resistant genotypes viz., BCP 2010-1, GJG 0904 and IPC 1048 appeared to be drought susceptible.

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

Due to low rainfall at early autumn, smooth vetch seedling growth in rain-fed lands often is limited by water deficit stress yet the data regarding the reactions of smooth vetch to water deficit at early growth stages are pretty rare. The objective of current study was to examine possibility of using priming treatments (hydro priming and priming salicylic acid) to alleviate the inhibitory effect of water deficiency during early growth of Smooth Vetch. In this respect, seeds were soaked in distilled water (hydro priming) or 0.5 mM solution of SA for 36 h at 10 °C then dried back to original moisture content. Pots were irrigated for 25 days at four levels of available water containing field capacity (FC), 75% FC, 50% FC and 25% FC. In general, seedling emergence and early growth were markedly limited by increasing water deficiency. However, priming treatments particularly with SA caused considerable improvement in either emergence or growth of seedlings (dry weight, length). The obtained results showed that primed samples exhibited higher accumulation of proline, glycine betaine (GB) under all levels of available water except 100% FC and also higher total soluble sugars (TSS) and trehalose under severe water deficit (25% FC). SA primed samples had higher relative water content especially under higher levels of water deficiency. The more balanced water status within SA primed samples also was accompanied with higher accumulation of proline and glycine betaine. There were significant differences between two priming treatments in terms of proline and GB content within seedlings and SA priming considerably increased proline and GB accumulation. In contrast to proline and GB, TSS and trehalose content wasn’t influenced by SA treatment and both hydro and SA primed samples showed statistically similar quantities.

Betaine in the Brain: Characterization of Betaine Uptake, its Influence on Other Osmolytes and its Potential Role in Neuroprotection from Osmotic Stress.

Betaine (N-trimethylglycine), a common osmolyte, has received attention because of the number of clinical reports associating betaine supplementation with improved cognition, neuroprotection and exercise physiology. However, tissue analyses report little accumulation of betaine in brain tissue despite the presence of betaine/GABA transporters (BGT1) at the blood brain barrier and in nervous tissue, calling into question whether betaine influences neuronal function directly or indirectly. Therefore, the focus of this study was to determine what capacity nervous tissue has to accumulate betaine, specifically in the hippocampus, a region of the brain associated with learning and memory and one that is particularly susceptible to damage (e.g., seizure activity). Here we report that hippocampal slices actively accumulate betaine in a time, dose and osmolality dependent manner, resulting in peak intracellular concentrations four times extracellular concentrations within 8h. Our data also indicate that betaine uptake differentially influences the accumulation of other osmolytes. Under isosmotic conditions, betaine uptake minimally impacted some osmolytes (e.g., glycerylphosphorylcholine and glutamate) while significantly reducing others (taurine, creatine, and myo-inositol). Under osmotic stress (hyperosmotic) conditions, we observed dramatic changes in osmolytes like glycine and glutamine-key players in inhibitory neurotransmission-and little change in osmolytes such as taurine, creatine and myo-inositol when betaine was available. These data suggest that betaine may influence pathways of inhibitory neurotransmitter production/recycling in addition to serving as an osmolyte and metabolic intermediate. In sum, our data provide detailed characterization of betaine uptake in the hippocampus that implicates betaine in the modulation of hippocampal neurophysiology and neuroprotection.

Diverse salinity responses in Crithmum maritimum tissues at different salinities over time

Crithmum maritimum (sea fennel) withstands high salinity, and to better understand how different protective mechanisms against salinity are activated, young seedlings were exposed to increasing concentrations of NaCl (0 to 512 mM) over six weeks. Plant survival and chlorophyll content were reduced at >85 mM NaCl and growth was affected at > 341 mM NaCl. Relative water content fell and Na+ accumulated more in leaves than in roots. Induction of Na+/H+ antiporter expression reached a maximum at 427 mM NaCl in both tissues. Salinity induced the accumulation of proline, soluble sugars and glycine betaine. All three accumulated to higher levels in leaves than roots and greatest accumulation was after 6 weeks and the highest salt concentrations. Hydrogen peroxide levels fell with increasing salinity in leaves, while ascorbic acid and catalase activity rose. Overall, the most dramatic changes occurred after six weeks of saline stress but different mechanisms were activated at different salinity thresholds and in the two tissues. Key salinity thresholds in the response of Crithmum maritimum to salinity stress are identified activating different mechanisms. At 85 mM NaCl roots reach osmotic adjustment, at 171 mM further osmolyte protection mechanisms are activated, at 256 mM NaCl leaves reach osmotic adjustment, at 341 mM plant growth is affected and at the highest salinity tested, 512 mM, protective mechanisms are affected in leaves but not in roots.