Levels Of Proline Accumulation Research Articles

Biomolecular evaluation of three contrasting rice cultivars (Oryza sativa L.) in salt stress response at seedling stage.

Salt contamination of soils due to climate change faces a severe environmental issue that affects crop production today. However, the response mechanism in plants to salt stress is not fully understood. The present study investigated molecular and biochemical changes under salt stress in rice seedlings of three rice cultivars, i.e., AGPPS114 (salt-tolerant), OM6967 (moderately tolerance), VD20 (salt-sensitive). Increasing salt concentration leads to a reduction in shoot/root length but different levels among the cultivars. In contrast, reactive oxygen species (ROS) accumulation and lipid peroxidation increased progressively with increasing salt concentration and time course treatment. However, at 250 ?M of NaCl, these parameters were more adversely affected in VD20 than AGPPS114 and OM6967. Using ICP showed that Na+ accumulation in rice root increased gradually with increasing NaCl concentrations in all cultivars under salt treatment but was low in salt-sensitive cultivar VD20 compared to other cultivars. Antioxidant enzyme activity analysis indicated catalase (CAT) and superoxide dismutase (SOD) were induced during salt treatment in all cultivars. The results also showed greater proline and glycine betaine accumulation in the AGPPS114 than OM6976 and VD20. qPCR indicated a significant difference in transcript levels of the Na+-transporter gene OsSOS1, OsNHX1 and OsHKT1s in AGPPS114 and OM6967 cultivars compared to VD20 cultivar. In summary, the active regulation of genes related to Na+ transport at the transcription level and with high glycine betaine and proline accumulation levels may be involved in salt tolerance mechanisms and thus might be useful for selecting tolerant plants.

Water relations composition among Egyptian cotton genotypes under water deficit

Background: water shortage is one of the major factor effects on growth characters and yield of most crops. Objective: this study was conducted to get to know the reactions of some Egyptian cotton genotypes to water deficit. Methods: The genetic materials used in this study included thirteen cotton genotypes belonging to Gossypium barbadense L., from the Cotton Research Institute (CRI), which was devoted to establishing the experimental materials for this investigation. Results: the ratio of GCA/SCA was less than unity for all studied indices, indicating predominance of non-additive gene action (dominance and epistasis), which is an important in exploitation of heterosis through hybrid breeding. Results: The data showed significant reduction in water relationship characters for all parental genotypes under stress conditions. The Egyptian variety Giza 68 gave high values for most water relationship characters. Data revealed that the greater the value of tolerance index is, the larger the yield reduction is under water deficit conditions and the higher the stress sensitivity is becoming. The parental genotypes Giza 96 showed the highest reduction in yield under water deficit conditions. At the same time, the cross combination Minufy x Australy showed higher values of yield reduction followed by the combinations Giza 67 x Australy. Of the male parents, the Russian genotype 10229 recorded the best GCA values for most water relationship characters. At the same time, the female parents, the old Egyptian genotype Giza 67 recorded the best values and exhibited good general combined for most water relationship characters. The cross combinations Giza 86 x Pima S6, Giza 77 x Pima S6, Giza 94 x Dandra and Giza 96 x Australy showed significant desirable SCA effect for most characters. Conclusion: relative water content %, osmotic pressure, chlorophyll and carotenoids content indicates better availability of water in the cell, which increases the photosynthetic rate. Also, the higher level of proline accumulation in the leaves which was recorded under deficit water suggests that the production of proline is probably a common response of plant under water deficit conditions.

Exploring the Potential of Nitric Oxide and Hydrogen Sulfide (NOSH)-Releasing Synthetic Compounds as Novel Priming Agents against Drought Stress in Medicago sativa Plants.

Land plants are continuously exposed to multiple abiotic stress factors like drought, heat, and salinity. Nitric oxide (NO) and hydrogen sulfide (H2S) are two well-examined signaling molecules that act as priming agents, regulating the response of plants to stressful conditions. Several chemical donors exist that provide plants with NO and H2S separately. NOSH is a remarkable novel donor as it can donate NO and H2S simultaneously to plants, while NOSH-aspirin additionally provides the pharmaceutical molecule acetylsalicylic acid. The current study aimed to investigate the potential synergistic effect of these molecules in drought-stressed Medicago sativa L. plants by following a pharmacological approach. Plants were initially pre-treated with both donors (NOSH and NOSH-aspirin) via foliar spraying, and were then subsequently exposed to a moderate water deficit while NO and H2S inhibitors (cPTIO and HA, respectively) were also employed. Phenotypic and physiological data showed that pre-treatment with NOSH synthetic compounds induced acclimation to subsequent drought stress and improved the recovery following rewatering. This was accompanied by modified reactive-oxygen and nitrogen-species signaling and metabolism, as well as attenuation of cellular damage, as evidenced by altered lipid peroxidation and proline accumulation levels. Furthermore, real-time RT-qPCR analysis revealed the differential regulation of multiple defense-related transcripts, including antioxidant enzymes. Overall, the present study proposed a novel role for NOSH compounds as efficient plant priming agents against environmental constraints through the coordinated regulation of multiple defense components, thus opening new horizons in the field of chemical priming research toward the use of target-selected compounds for stress tolerance enhancement.

Adaptation reactions of common wheat (Triticum aestivum L.) and emmer (T. dicoccum Schrank ex Schübl.) seedlings under osmotic stress and treatment with metal nanoparticles

Aim. To study the adaptive reactions of common wheat (Triticum aestivum L.) and emmer (T. dicoccum Schrank ex Schübl.) seedlings using the parameters of oxidative homeostasis under polyethylene glycol (PEG)-induced osmotic stress and metal (Fe, Cu, Mn, Zn) mixture nanoparticles treatment. Methods. Biochemical assays: spectrophotometric measurements of the activity of antioxidant enzymes (SOD, CAT), the content of proline and products of lipid peroxidation; mathematical statistics. Results. The state of oxidative homeostasis of common wheat (cv. Favorytka, cv. Trypilska) and emmer (cv. Holikovska) seedlings under PEG-induced osmotic stress conditions was investigated and analyzed. The development of lipid peroxidation processes under stress conditions was observed only in the cv. Trypilska seedlings. It was established that proline content in common wheat seedlings of both cultivars under stress had signifi cant (10 : 1) predominance in roots, while in roots and shoots of emmer seedlings proline content increased equally. SOD activity in the leaves of the studied cultivars under stress conditions was not changed. At the same time, an increase of SOD activity by 30 % under osmotic stress was shown in the roots of common wheat of cv. Favorytka, while it decreased by 25 % in the roots of cv. Trypilska. It was established that CAT activity in the roots of both cultivars of common wheat decreased by 25 and 38 %, respectively, whereas in emmer of cv. Holikovska this parameter increased by 35 % under osmotic stress. Presowing treatment using a colloidal solution of a mixture of biogenic metal nanoparticles contributed to the induction of SOD activity in the roots of cv. Favorytka, CAT activity in the leaves of cv. Trypilska, and CAT activity in the roots and leaves of cv. Holikovska compared to non-treated plants. It should be noted that the treatment of plants with metal nanoparticles promoted the restoration of CAT activity in the roots under osmotic stress conditions to the level of the control plants in both wheat varieties. Conclusions. It was established that osmotic stress provoked the development of oxidative processes and inhibition of the activities of antioxidant enzymes, in particular, SOD and CAT, in the seedling roots of common wheat cultivars. It was shown that emmer wheat seedlings of cv. Holikovska can maintain redox homeostasis and avoid oxidative damage under osmotic stress conditions. It was found that the seedlings of common wheat and emmer demonstrated different strategies of osmotic regulation under osmotic stress, which is confi rmed, in particular, at the level of proline accumulation. It was shown that the application of colloidal solutions of metal nanoparticles induced an antioxidant protection system and reduced the oxidative processes, which are inevitable effects of drought. The obtained results indicate that common wheat cultivars are more susceptible to drought compared to emmer wheat of cv. Holikovska.

Оцінка функціонального стану деревних насаджень парків міста Дніпро за показниками інтенсивності вільнорадикального окиснення та вмісту проліну

<p>We studied the accumulation of the malondialdehyde and free proline in the leaves of woody plants which growing in the city parks of Dnipro in zones with different anthropogenic pollution. We registered the significant increase of free radical oxidation in the leaves of all tree species and at all monitored plots. The reactions of free radical oxidation were more intense in zones with heavy pollution and vice versa. The most intensive accumulation of products of free radical oxidation were observed in the assimilative organs of <em>Tilia cordata</em> Mill. and <em>Acer platanoides</em> L. In <em>Robinia pseudoacacia</em> L. and <em>Biota orientalis</em> Endl. the accumulated products were registered in slightly less but still significant amounts. The quantities of proline in trees of the city parks located in different functional areas exceeded the corresponding control values. The highest concentration of amino acid and malonic dialdehyde were registered in the assimilative organs of the trees from urban parks with heavy level of pollution while the lowest concentration of amino acid was registered in the trees of park located far from industrial zones. On average, amino acid content ranges between 122.61 and 585.77% from the control values. The high level of proline accumulation was observed in the leaves of <em>Robinia pseudoacacia</em> L., since this species is the most environment-resistant. The levels of proline accumulation attributable to anthropogenic pollution of the leaves of <em>Tilia cordata </em>Mill. and <em>Robinia pseudoacacia</em> L. were almost identical.</p>

Proline Accumulation Is Not Correlated with Saline‐Alkaline Stress Tolerance in Rice Seedlings

Proline accumulation is a common physiological response of plants to various environmental stresses. However, the physiological importance of proline accumulation in stress tolerance remains controversial. Here, we examined whether proline accumulation in rice (Oryza sativa L.) seedlings is correlated with tolerance to saline–alkaline stress factors, namely, salt, alkaline and osmotic stresses, by using 25 japonica cultivars. The tolerance of seedlings to each stress treatment varied significantly among the cultivars as evaluated by membership degree (MD) of fuzzy set theory on the basis of changes in shoot length (SL), total root length (TRL), total root surface area (RSA), average root diameter (RD), total root volume (RV), and root numbers (RN), after 6 d of stress treatment. The proline levels in all the japonica cultivars increased significantly in response to the investigated stresses. However, partial correlation analysis showed no significant correlations between the basal or elevated proline levels and tolerance to any of the investigated stress factors. These findings suggest that proline accumulation levels do not serve as reliable parameters for assessing saline–alkaline stress tolerance in rice. On the other hand, several root growth indices of rice seedlings, namely TRL, RSA, RD, RV, and RN, showed good correlations with the investigated stress tolerance, and therefore, represent a useful set of growth parameters for assessing saline‐alkaline stress tolerance in rice.

Salt-Stress Induced Physiological and Proteomic Changes in Tomato (Solanum lycopersicum) Seedlings

Soil salinity is one of the major abiotic stress limiting crop productivity and the geographical distribution of many important crops worldwide. To gain a better understanding of the salinity stress responses at physiological and molecular level in cultivated tomato (Solanum lycopersicum. cv. Supermarmande), we carried out a comparative physiological and proteomic analysis. The tomato seedlings were cultivated using a hydroponic system in the controlled environment growth chamber. The salt stress (NaCl) was applied (0, 50, 100, 150 and 200 mM), and maintained for 14 days. Salt treatment induced a plant growth reduction estimated as fresh-dry weight. Photosynthetic pigments (chlorophyll a, b) content of NaCl-treated tomato plants was significantly decreased as the salinity level increased. Proline accumulation levels in leaf and root tissues increased significantly with increasing NaCl concentration. Relative electrolyte leakage known as an indicator of membrane damage caused by salt stress was increased proportionally according to the NaCl concentrations. Roots of control and salt-stressed plants were also sampled for phenol protein extraction. Proteins were separated by two-dimensional gel electrophoresis (2-DGE). Several proteins showed up- and downregulation during salt stress. MALDI-TOF/MS analysis and database searching of some of the identified proteins indicated that the proteins are known to be in a wide range of physiological processes, that is, energy metabolism, ROS (reactive oxygen species) scavenging and detoxification, protein translation, processing and degradation, signal transduction, hormone and amino acid metabolism, and cell wall modifications. All proteins might work cooperatively to reestablish cellular homeostasis under salt stress, water deficiency, and ionic toxicity.

Accumulation of Proline under Salinity and Heavy metal stress in Cauliflower seedlings

Salinity and heavy metals affect the growth and development of higher plants and also their productivity. In the present study, Cauliflower (Brassica oleracea var botrytis) seeds were allowed to germinate andgrow in the absence (control) and presence of different concentrations (50, 100, 250, 500, 750 and 1000 ìM) of NaCl, CdCl2, HgCl2 and ZnCl2. Seed germination and growth parameters of seedlings of cauliflower were observed after 5, 10 and 15 days of exposure to salinity and heavy metals. In case of salinity, maximum inhibition of seedling growth was observed at 250 ìM of NaCl which resulted into 66%, 67%, 61%, 56% and 25% inhibition in seed germination, shoot length, root length, fresh weight and dry weight, respectively after 5 days of germination. NaCl at500-ìM concentration and above completely inhibited seed germination. In case of heavy metals, HgCl2 was found to be the most toxic one with 94% inhibition in seed germination at 250 ìM concentrations. Shoot length, root length, fresh weight and dry weights were inhibited by 69%, 88%, 66% and 71% respectively, after 5 days of growth in presence of HgCl2 (250 ìM). On the other hand, only 66% and 55% inhibition in seed germination was observed with as high concentration as 1000 ìM of both CdCl2 and ZnCl2 respectively, after 5 days of seed growth. Further, the extent of reduction in shoot length, root length, fresh weight and dry weight in presence of both CdCl2 and ZnCl2 was found to be less than HgCl2. In general development of root system was severely inhibited in presence of NaCl,CdCl2, ZnCl2 and HgCl2 at all the concentration tested as evidenced by decrease in root length. Increase in the level of proline accumulation was observed in presence of all heavy metals studied and sodium chloride.

Effect of NaCl in the irrigation water on growth, anti-oxidant enzyme activities, and nutrient uptake in five citrus rootstocks

SummarySeven–month-old, uniform-sized seedlings of five citrus rootstocks [sour orange (Citrus aurantiam), Attani-2 (C. rugulosa), Troyer citrange (C. sinensis × Poncirus trifoliata), billikhichlli (C. reshni), and RLC-6 (C. jambhiri)] were irrigated to 70% of field capacity with water containing 0, 50, 100, or 200 mM NaCl for 180 d. Growth, in terms of plant heights and the numbers of leaves, decreased with increasing levels of salinity in all five rootstocks. The decrease in plant height was greatest in the salt-susceptible Troyer citrange and billikhichlli at higher levels of salinity. However, in the salt-tolerant sour orange and Attani-2, NaCl caused only a slight decrease in plant height. Defoliation was maximum in the salt-susceptible Troyer citrange and billikhichlli. The maximum increases in superoxide dismutase (SOD) and peroxidase (POD) activities were found in the salt-susceptible Troyer citrange at higher levels of salinity. Leaf proline contents increased most in Attani-2, sour orange, and RLC-6 at higher levels of salinity.The concentration of Na+ ions in leaf tissues increased to a maximum in Attani-2; while, in root tissues, RLC-6 and Troyer had the highest Na+ ion contents. The maximum increase in leaf Cl– ion levels occurred in Troyer citrange, and the minimum was in RLC-6, at 200 mM NaCl. These data suggest that higher levels of proline accumulation and leaf abscission could be used as indicators for screening citrus rootstocks for resistance to NaCl stress. Sour orange and Attani-2 were able to exclude Cl– ions, whereas Troyer citrange appeared to exclude Na+ ions at lower levels of NaCl. Further studies are required to observe the translocation of harmful and beneficial mineral elements to scion cultivars grafted onto sour orange and Attani-2 and grown under NaCl stress. Overall, salt-tolerance increased in the following order: Troyer ì billikhichlli ì RLC-6 ì Attani-2 ì sour orange.

Exogenous glycinebetaine affects growth and proline accumulation and retards senescence in two rice cultivars under NaCl stress

The ability of exogenously applied glycinebetaine (GB) for the alleviation of growth inhibition and senescence resulting from NaCl stress was investigated in view of growth parameters, net PS-II efficiency, photosynthetic pigments, protein and proline contents in two rice ( Oryza sativa L.) cultivars differing in salt tolerance (salt-tolerant Pokkali, and salt-sensitive IR-28). Shoot fresh weight (FW) of Pokkali and shoot and root dry weight of IR-28 showed a decrease under salinity but an increase with exogenous GB application. NaCl treatment caused no serious decrease in F V/ F M ratio of Pokkali whereas F V/ F M ratio of IR-28 showed a remarkable decline throughout the experiment. Exogenous GB application partially preserved net PS-II efficiency of IR-28 from salt-stress. While Chl-b and carotenoid contents of IR-28 decreased, photosynthetic pigment contents of Pokkali showed no notable change under salinity. GB treatment did not show protective effect on photosynthetic pigment contents of IR-28 decreased under-salinity. Proline content significantly increased in Pokkali and IR-28 under salt-stress with a higher rate of increase in the former. When compared to NaCl-exposed groups alone, GB treatment caused an increase and a decrease in the level of proline accumulation in Pokkali and IR-28, respectively. While protein content of Pokkali enhanced with salinity, GB pre-application decreased it to control levels. Protein content of IR-28 showed a decrease under salinity but an increase with GB application. Therefore, we conclude that GB can reduce the impact of salt-stress on growth and senescence, enhance the photosynthetic efficiency of PS-II and increase the protein content of rice seedlings.

Relationship between salt tolerance and proline accumulation in Australian acacia species

The effects of salinity on the seedlings of five acacia species, Acacia ampliceps, A. salicina, A. ligulata, A. holosericea, and A. mangium were studied with respect to mortality, growth, and proline accumulation. There was marked variation among the species in their response to salinity. A. ampliceps showed the highest level of salt tolerance among the five acacia species. In contrast, A. holosericea and A. mangium were classified as the least tolerant. The concentration which caused 100% mortality in 2-week-old seedlings during 1 week of treatment was 2.5% (w/v) and 1.5% NaCl for A. ampliceps and A. holosericea, respectively. The dry weights of whole plant of two acacia species decreased markedly under the above salt stress conditions. Proline accumulation was found in leaves and roots after NaCl treatment. The maximum level of proline accumulation in A. holosericea was about twice as great as that in A. ampliceps throughout the stress period. Thus, the level of proline accumulation was not related to the degree of salt tolerance in these acacia species, although a positive correlation between the extent of salt stress and the accumulation of proline was found.

Does proline accumulation play an active role in stress-induced growth reduction?

An interesting observation, reported for transgenic plants that have been engineered to overproduce osmolytes, is that they often exhibit impaired growth in the absence of stress. As growth reduction and accumulation of osmolytes both typically result from adaptation, we hypothesized that growth reduction may actually result from osmolyte accumulation. To examine this possibility more closely, intracellular proline level was manipulated by expressing mutated derivatives of tomPRO2 (a Delta(1)-pyrroline-5-carboxylate synthetase, P5CS, from tomato) in Saccharomyces cerevisiae. This was done in the presence and absence of a functional proline oxidase, followed by selection and screening for increased accumulation of proline in the absence of any stress. Here we show, in support of our hypothesis, that the level of proline accumulation and the amount of growth are inversely correlated in cells grown under normal osmotic conditions. In addition, the intracellular concentration of proline also resulted in increases in ploidy level, vacuolation and altered accumulation of several different transcripts related to cell division and gene expression control. Because these cellular modifications are common responses to salt stress in both yeast and plants, we propose that proline and other osmolytes may act as a signaling/regulatory molecule able to activate multiple responses that are part of the adaptation process. As in previous studies with transgenic plants that overaccumulate osmolytes, we observed some increase in relative growth of proline-overaccumulating cells in mild hyperosmotic stress.

Biology and ecophysiology ofTrianthema portulacastrum L. (Molluginaceae) in arid ecosystem

Attempts have been made to reveal the survival strategies of the two forms ofTrianthema portulacastrum. These morphs, vizrubra andflava, do not show any remarkable difference in their morphology, phenology and water relations. Metabolically,rubra form is more hardy thanflava form, because of lesser water loss, higher water retention capacity, high protein content and higher levels of proline accumulation at different stages of plant growth. Seed germination studies revealed the presence of hard seed coatedness in both morphs, being more in theflava form.