Modulation of polyamine levels in ginseng hairy root cultures subjected to salt stress

Modulation of differential gene expression and change of polyamine content by salt stress are analyzed for the first time in a well-known medicinal plant, Panax ginseng C.A. Meyer. Three ginseng genes (PgSPD, PgSAMDC, and PgADC) involved in polyamine biosynthesis showed differential up-regulation patterns after 1 and 7 days of salt treatments. The modulation of gene expression resulted in the elevation of total polyamine content with relatively high levels of spermidine and spermine, while putrescine level diminished depending on the salt concentration. Conversely, salt stress led to a significant increase in diamine oxidase and subsequent decline in polyamine oxidase. The proline content caused by salinity follows a similar pattern as the total polyamine content and exogenous spermidine also resulted in the alleviation of proline content under salinity. Further, polyamine biosynthesis inhibitors, such as cyclohexylamine and methylglyoxal bis-(guanylhydrazone) mediated down-regulation of PgSPD and PgSAMDC, and affected cellular polyamine levels. Thus, polyamines may enhance the ginseng plant tolerance in response to the salt stress by increasing the levels of endogenous polyamines.     

Inoculation with plant growth-promoting bacteria (PGPB) improves salt tolerance of maize seedling

Our objective was to evaluate the role of plant growth-promoting bacteria to protect maize (Zea mays L.) plants against salt damage. Bacillus aquimaris DY-3 based on their 16S rDNA sequences, the most tolerant to salinity and the synthesis of indole acetic acid was selected for further studies. Strain was inoculated on maize roots growing in sterilized sand under salt stress conditions (1% NaCl). After one week, plant growth was promoted by bacterial inoculation regardless of salt stress and non-salt stress. Chlorophyll content, leaf relative water content, accumulation of proline, soluble sugar and total phenolic compound, and activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase were enhanced, while lipid peroxidation levels and Na⁺ content were decreased. The results showed that B. aquimaris DY-3 alleviated the salt stress in maize, likely through the integration of the antioxidant enzymes and the non-antioxidant systems that improve the plant response. Hence, the application of indole acetic acid synthesizing plant growth-promoting bacteria may represent an important alternative approach to decrease the impact of salt stress on crops.     

Alternanthera bettzickiana (Regel) G. Nicholson,a potential halophytic ornamental plant: Growth and physiological adaptations

Exploration and cultivation of salt tolerant plants is a very effective strategy for utilization of salt affected soils. In this investigation, physiological traits that are conducive for salt tolerance of the ornamental plant Alternanthera bettzickiana, Amaranthaceae, were explored. A. bettzickiana was grown on soil substrate having six salinity levels (2.86, 10, 20, 30, 40 and 50 dS m⁻¹). It was observed that this plant can grow even at a salinity level of 40 dS m⁻¹. The survival rate of this plant was 75, 42 and 0% at salinity levels of 30, 40 and 50 dS m⁻¹, respectively. A. bettzickiana plants produced 30.3% less biomass than controls at the salinity level of 20 dS m⁻¹ and even less under still higher salt stress. Photosynthesis continued even at the salinity level of 40 dS m⁻¹, though its rate was reduced to 59% in plants exposed to such salinity relative to plants not affected by salinity. Total soluble proteins values in leaf and stem showed a gradual increase when plants were exposed to increasing salt stress. Plants growing at the high salinity level showed highest decrease in leaf nitrate reductase activity. A. bettzickiana plants accumulated less Na⁺ in shoot as compared to root when grown under salt stress. It can be characterized as a salt-tolerant glycophyte that could be used for greening of salt affected soils.     

Increase in unsaturated fatty acids in membrane lipids of Suaeda salsa L. enhances protection of photosystem II under high salinity

In order to examine the possible role of unsaturated fatty acids in photosynthesis of halophytes under high salinity, the effect of salinity on plant growth, chlorophyll (Chl) content, photochemical efficiency of PSII, membrane lipid content and fatty acids composition of a C₃ euhalophyte Suaeda salsa L. was investigated. Salt stress induced a slight increase of the maximal photochemical efficiency of PSII (F_v/F_m), actual PSII efficiency (Φ_PSII), Chl a content and Chl a/b ratio. The unsaturated fatty acid content also increased under salt stress. The proportion of MGDG, DGDG, SQDG, and PC decreased, while the proportion of PG increased from 10.9% to 26.9% under salt stress. These results suggest that S. salsa displays high resistance to photoinhibition under salt stress and that increased concentration of unsaturated fatty acids in membrane lipids of S. salsa enhances the tolerance of photosystem II to salt stress.     

Phosphorylation of the zinc finger transcriptional regulator ZAT6 by MPK6 regulates Arabidopsis seed germination under salt and osmotic stress

C₂H₂-type zinc finger proteins (ZFPs) play diverse roles in plant response to abiotic stresses. ZAT6, an Arabidopsis C₂H₂-type ZFP, has been reported to regulate root development and nutrient stress responses. However, its roles in regulation of abiotic stress response are incompletely known. Here, we demonstrate that salt or osmotic stress triggers a strong increase in ZAT6 expression in leaves. Transgenic plants overexpressing ZAT6 showed improved seed germination under salt and osmotic stress. Intriguingly, ZAT6 interacts with a stress-responsive mitogen-activated protein kinase MPK6 in vitro and in planta. ZAT6 is phosphorylated by both recombinant and plant endogenous MPK6. Serine 8 and serine 223 in ZAT6 were identified as the sites phosphorylated by MPK6. In contrast to wild-type form of ZAT6, overexpression of phosphorylation mutant form did not display significantly enhanced salt and osmotic stress tolerance. Altogether, our results suggest that phosphorylation by MPK6 is required for the functional role of ZAT6 in seed germination under salt and osmotic stress.     

盐胁迫对杠柳幼苗中次生代谢产物积累的影响

摘要 为了探索盐胁迫对杠柳幼苗生长及次生代谢物的影响,初步了解杠柳盐耐受范围及盐胁迫对杠柳次生代谢产物的诱导作用。本试验以培养30 d的杠柳实生苗为材料,测定不同盐浓度（0（CK）、0.2 %、0.5 %、1.0 %、2.0 %）处理后,杠柳幼苗的生物量及总甾体成分、强心苷类成分（杠柳毒苷、杠柳次苷及杠柳苷元）、4-甲氧基水杨醛含量的变化特征。结果表明,杠柳幼苗在中低盐浓度盐胁迫下生长良好,且地上部分干鲜重及地下部分干重均有不同程度的增加,其干湿比也均随盐胁迫程度的增加逐渐升高;植株体内的主要有效成分如总甾体、强心苷类的含量在中等盐胁迫浓度作用下呈现明显上升趋势,而4-甲氧基水杨醛则在高盐胁迫下含量显著增加。研究发现,杠柳具有较高的耐盐性,且一定范围内的盐胁迫可显著提高杠柳幼苗根茎中主要药效成分含量。     

ACC deaminase-containing Arthrobacter protophormiae induces NaCl stress tolerance through reduced ACC oxidase activity and ethylene production resulting in improved nodulation and mycorrhization in Pisum sativum

Induction of stress ethylene production in the plant system is one of the consequences of salt stress which apart from being toxic to the plant also inhibits mycorrhizal colonization and rhizobial nodulation by oxidative damage. Tolerance to salinity in pea plants was assessed by reducing stress ethylene levels through ACC deaminase-containing rhizobacteria Arthrobacter protophormiae (SA3) and promoting plant growth through improved colonization of beneficial microbes like Rhizobium leguminosarum (R) and Glomus mosseae (G). The experiment comprised of treatments with combinations of SA3, G, and R under varying levels of salinity. The drop in plant biomass associated with salinity stress was significantly lesser in SA3 treated plants compared to non-treated plants. The triple interaction of SA3 + G + R performed synergistically to induce protective mechanism against salt stress and showed a new perspective of plant-microorganism interaction. This tripartite collaboration increased plant weight by 53%, reduced proline content, lipid peroxidation and increased pigment content under 200 mM salt condition. We detected that decreased ACC oxidase (ACO) activity induced by SA3 and reduced ACC synthase (ACS) activity in AMF (an observation not reported earlier as per our knowledge) inoculated plants simultaneously reduced the ACC content by 60% (responsible for generation of stress ethylene) in SA3 + G + R treated plants as compared to uninoculated control plants under 200 mM salt treatment. The results indicated that ACC deaminase-containing SA3 brought a putative protection mechanism (decrease in ACC content) under salt stress, apart from alleviating ethylene-induced damage, by enhancing nodulation and AMF colonization in the plants resulting in improved nutrient uptake and plant growth.     

甘蓝型油菜苗期生长阶段对NaCl胁迫的生理响应

以甘蓝型油菜自交系2205(强耐盐型)、487(中耐盐型)和1423(敏盐型)为材料,采用土培+水培方法于五叶期研究了0(无盐胁迫,CK)、60 mmol·L-1(低盐)、120 mmol·L-1(中低盐)、180 mmol·L-1(中盐)、240mmol·L-1(高盐)NaCl胁迫后的叶片MDA、可溶性糖、甜菜碱和叶绿素含量的变化特征,为油菜耐盐性评价提供理论依据。结果显示:(1)叶片MDA含量在低盐和中低盐胁迫下降低且显著低于CK,在中盐和高盐胁迫下显著升高,并以品系2205含量最低且升幅最小,品系1423最高且升幅最大。(2)叶片可溶性糖含量在低盐和中低盐胁迫下减少(但2205在中低盐胁迫下显著高于CK),在中盐和高盐胁迫下升高且显著高于CK,并以品系2205含量最高增幅最大且显著高于品系487和1423,品系1423含量最低且增幅最小。(3)叶片甜菜碱含量随NaCl浓度升高增加,品系2205和487在中低以上盐浓度胁迫下显著升高,品系1423仅在高盐胁迫下显著升高,并以品系2205含量最高且增幅最大,1423含量最低且增幅最小。(4)叶片叶绿素含量在低盐和中低盐胁迫下显著增加,且以2205叶片叶绿素含量最高且增幅最大,但在中盐和高盐胁迫下显著减少,并以品系1423含量最低且降幅最高。研究表明,120mmol·L-1以下NaCl胁迫对油菜苗期生长可能有促进作用,180mmol·L-1以上NaCl胁迫则有明显抑制作用,且NaCl浓度越高油菜受伤害越重;油菜苗期生长阶段,NaCl胁迫浓度在120~180mmol·L-1时各生理指标发生显著变化,可能是鉴定耐盐性强弱的适宜浓度;综合分析认为,品系2205具有强的耐盐性,品系1423耐盐性最差,这与之前萌芽期和幼苗期鉴定结果一致。     

Analysis of fatty acid composition of PGPR <Emphasis Type="Italic">Klebsiella</Emphasis> sp. SBP-8 and its role in ameliorating salt stress in wheat

A halotolerant plant-growth-promoting rhizobacteria (PGPR) can ameliorate salt stress in associated plants by various mechanisms. Therefore, the present study aimed to characterize a PGPR Klebsiella sp. SBP-8 for its ability to tolerate salt stress and to study the mechanism of PGPR-mediated mitigation of salt stress in the wheat plant. The abiotic stressors result in multiple changes in the fatty acid composition of Klebsiella sp. SBP-8, helping the membrane to keep its integrity, fluidity, and function for its growth under salt (NaCl) stress conditions. The changes in fatty acid composition of test organism were analyzed by fatty acid methyl ester (FAME) analysis under varying saline conditions. The spectroscopy (GC-MS) profile of cell extract at different salt concentrations was comprised of hydrocarbons, and fatty alcohols with varying carbon chain length. Inoculation of Klebsiella sp. SBP-8 to wheat seedling showed increase in proline, total soluble sugar, and total protein content of treated plants. Bacterial inoculation also decreased the concentration of salinity-induced malondialdehyde (MDA) content. In addition, bacterial inoculation also increased the various antioxidative enzymes like superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) in treated plants. It is likely that bacterial inoculation alleviated the salt stress to wheat plant by co-ordination of antioxidative machinery, and improvement in osmolyte contents. Therefore, the present study suggests that bacterial-inoculated wheat plants were able to cope better with salt stress than uninoculated control, therefore it can serve as a promising bio-inoculant for enhancing the growth of wheat like cereal crops under saline stress.     

Overexpression of osmotin gene confers tolerance to salt and drought stresses in transgenic tomato (Solanum lycopersicum L.)

Abiotic stresses, especially salinity and drought, are major limiting factors for plant growth and crop productivity. In an attempt to develop salt and drought tolerant tomato, a DNA cassette containing tobacco osmotin gene driven by a cauliflower mosaic virus 35S promoter was transferred to tomato (Solanum lycopersicum) via Agrobacterium-mediated transformation. Putative T0 transgenic plants were screened by PCR analysis. The selected transformants were evaluated for salt and drought stress tolerance by physiological analysis at T1 and T2 generations. Integration of the osmotin gene in transgenic T1 plants was verified by Southern blot hybridization. Transgenic expression of the osmotin gene was verified by RT-PCR and northern blotting in T1 plants. T1 progenies from both transformed and untransformed plants were tested for salt and drought tolerance by subjecting them to different levels of NaCl stress and by withholding water supply, respectively. Results from different physiological tests demonstrated enhanced tolerance to salt and drought stresses in transgenic plants harboring the osmotin gene as compared to the wild-type plants. The transgenic lines showed significantly higher relative water content, chlorophyll content, proline content, and leaf expansion than the wild-type plants under stress conditions. The present investigation clearly shows that overexpression of osmotin gene enhances salt and drought stress tolerance in transgenic tomato plants.     

Effect of NaCl stress on dihaploid tobacco lines tolerant to Potato virus Y

Salinity is an important abiotic factor that limits plant growth and development. The influence of salt stress induced by sodium chloride on plant growth, proline content, level of lipid peroxidation and activities of antioxidative enzymes was studied in F1 hybrid DH10 and four dihaploid lines (207B, 238C, 239K, 244B) of tobacco (Nicotiana tabacum L.). Dihaploids were obtained from anther-derived haploids of hybrid DH10 and were previously proved to be tolerant to Potato virus Y (PVY). In our study, plants were grown in vitro and exposed to NaCl (100 and 200 mM) for 33 days. All dihaploids and hybrid DH10 showed reduced growth after NaCl treatment. They accumulated significant amounts of sodium and proline in response to salt stress as have already been observed in tobacco and other plant species. In tobacco exposed to NaCl the lipid peroxidation level did not increase and activities of superoxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate peroxidase and catalase (CAT) mostly did not change significantly. The exception was line 239K where salt induced higher activities of SOD, CAT and POD. Two (238C and 244B) out of four dihaploids appeared more susceptible to salt stress as they showed weak growth in correlation with high proline and sodium content. Therefore, it seems that salt tolerance is not associated with tolerance to PVY. Variations in malondialdehyde and proline content as well as in enzymes activities observed among tobacco lines imply that dihaploids have different genetic properties which might result in different sensitivity to NaCl.     

Garden-waste-vermicompost leachate alleviates salinity stress in tomato seedlings by mobilizing salt tolerance mechanisms

The incidence of salinity-induced plant stress as a result of natural and anthropogenic factors in arid and semi-arid agricultural lands is great. In South Africa alone, 9 % of irrigated agricultural land is salt-affected. Commercial fertilizers used for improving soil nutrient levels are costly and affect the quality, lifespan and sustainability of soil and water resources. Organic farming practices are based on cost-effective and environmentally-aware management systems. Vermicompost leachate (VCL) is a vermicompost-derived liquid product that has become recognised as a suitable soil amendment product. Commercial tomato (Lycopersicon esculentum Mill var. Heinz-1370) seedlings were subjected to sodium chloride (NaCl) concentrations of 0, 25, 50 and 100 mM and were treated with 1:10 (v/v) WizzardWorms VCL prepared in Hoagland’s nutrient solution under greenhouse conditions. Morphological characters of VCL-treated tomato seedlings showed improved root growth and stimulated overall aboveground growth with significantly higher numbers of leaves, greater stem thickness and increased leaf area, even at a high NaCl-tested concentration (100 mM). The accumulation of compatible solutes such as proline and total soluble sugars indicate an induced salt tolerance or adaptive mechanism in VCL-treated tomato seedlings. The current investigation demonstrates the potential of an organic liquid to maximise tomato productivity by improving seedling growth performance under salt stress conditions.     

<Emphasis Type="Italic">Dunaliella salina</Emphasis> exopolysaccharides: a promising biostimulant for salt stress tolerance in tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis>)

Microalgal exopolysaccharides represent a potential sustainable alternative for the enhancement and protection of agricultural crops including management of both biotic and abiotic stress. In the present study, we investigated the potential of Dunaliella salina exopolysaccharides (PS) to attenuate the effect of salt stress on growth of Solanum lycopersicum, which was grown under different salinity levels (3 and 6 g L^?1 NaCl). The effects of PS treatment on plant growth, osmoprotectant molecules, protein content, and antioxidant enzymes activities of tomato plants under salt stress were analyzed. A metabolomics study showed that the exopolysaccharides released by D. salina contained sulfated moiety along with carbohydrates and uronic acids. The application of sulfated exopolysaccharides on tomato plants alleviated the salt stress and mitigated the decrease in length and dry weight of the plant’s shoot and root systems, as well as that of potassium (K⁺), and K⁺/Na⁺ ratio. Furthermore, the increase in proline, phenolic compounds, Na⁺, and antioxidant enzymes (CAT, POD, SOD) activities caused by salt stress were attenuated after the exopolysaccharide treatment. GC-MS metabolomics analysis showed that PS treatment allowed the activation and/or inhibition of various metabolic pathways involved in the plant’s tolerance to stress such as jasmonic acid-dependent pathways. This study shows the potential of microalgal exopolysaccharides for enhancing tomato tolerance to salt stress and highlights the possibility of their use as plant growth biostimulants under harsh environmental conditions.     

Boron and calcium increasePisum sativum seed germination and seedling development under salt stress

A beneficial effect of B and Ca application on symbiotic interaction between legume and rhizobia under saline conditions has recently been shown, suggesting conventional agricultural practices to increase crop salt tolerance. However, nothing is known about application of both nutrients on early events of legume development under salt stress, prior to the establishment of a symbiotic interaction. Therefore, the effects of different levels of B (from 9.3 to 93μM B) and Ca (from 0.68 to 5.44 mM Ca) on seed germination, root elongation, plant development, and mineral composition of pea (Pisum sativum L. cv. Argona) grown under 0 to 150 mM NaCl, were analysed. Development of plants previously germinated in the presence of salt was more impaired than that of plants put under salt stress once seeds were germinated. A NaCl concentration of 75 mM and 150 mM inhibited pea seed germination and seedling growth. The addition of either extra B or extra Ca to the germination solution prevented the reduction caused by 75 mM NaCl but not that of 150 mM NaCl. However, root elongation and plant development under salt stress (75 mM NaCl) was enhanced only by addition of both B and Ca. When plants were cultivated in the absence of external N, N content in roots and shoots originating from seeds was diminished by salt and enhanced by B and Ca, suggesting a role of these nutrients in remobilisation of seed nutrient stores. Salinity also led to an extremely high concentration of Na⁺ ions, and to a decrease of B and Ca concentrations. This can be overcome by addition of both nutrients, increasing salt tolerance of developing pea plants. The necessity of nutritional studies to increase crop production in saline soils is discussed and proposed.     

Responses of Nipa palm (Nypa fruticans) seedlings,a mangrove species,to salt stress in pot culture

Nipa palm (Nypa fruticans) is the only palm that grows in mangrove vegetation. We investigated the effect of salt stress on the growth and physiology of 6-month-old seedlings of Nipa palm exposed to different degrees of salt stress (as NaCl) in pot culture. The overall growth performance of Nipa palm was unaffected by mild salt stress (8.9−16.6 dS m⁻¹), whereas seedlings grown under severe salt stress (EC = 57.2 dS m⁻¹) had lower chlorophyll content and fluorescence, reduced net photosynthesis and transpiration, which resulted in reduced growth of the plants. Na⁺ contents in leaf, petiole, and root tissues increased considerably under salt stress, depending upon the NaCl levels in the soil solution. Under salt-stress K⁺ content declined, whereas Ca²⁺ content increased somewhat, in parallel to Na⁺. Free proline accumulated in plants growing under high salt stress (EC = 57.2 dS m⁻¹). In contrast, soluble sugars were enriched under intermediate levels of salt stress (EC = 16.6 dS m⁻¹). The results obtained in the present study suggest that, based on ecophysiological data, N. fruticans is a species best adapted to grow in mangrove coastal areas with moderate only salt load, and circumscribing quite well the actual areas of occurrence of this palm in the gradient from seawater habitats to inland sites. © 2014 Elsevier GmbH     

二色补血草的耐盐性研究

通过NaCl胁迫发芽试验、盆栽浇灌NaCl盐水试验、不同含盐量土壤的种植试验,研究二色补血草（Limoniumbicolor）3个时期的耐盐能力。结果表明：高浓度NaCl对二色补血草种子的萌发有明显的抑制作用,种子的发芽率与盐浓度之间呈显著的负相关,种子萌发时盐胁迫的适宜值、临界值、极限值分别是0.49%、1.30%、2.11%;盆栽试验结果表明,二色补血草在2.0%以下的NaCl盐水胁迫下没有表现明显的盐害症状,只表现高浓度NaCl胁迫下,生长量低于低浓度处理的,当处理浓度达到2.4%时,多数植株濒临死亡;不同含盐量土壤的种植试验结果表明,在自然条件下,二色补血草成株耐盐临界值为1.7%～1.8%。试验结果说明二色补血草具有较强的耐盐能力,适合在滩涂盐碱地推广种植。     

Knock-out of Arabidopsis AtNHX4 gene enhances tolerance to salt stress

AtNHX4 belongs to the monovalent cation:proton antiporter-1 (CPA1) family in Arabidopsis. Several members of this family have been shown to be critical for plant responses to abiotic stress, but little is known on the biological functions of AtNHX4. Here, we provide the evidence that AtNHX4 plays important roles in Arabidopsis responses to salt stress. Expression of AtNHX4 was responsive to salt stress and abscisic acid. Experiments with CFP-AtNHX4 fusion protein indicated that AtNHX4 is vacuolar localized. The nhx4 mutant showed enhanced tolerance to salt stress, and lower Na⁺ content under high NaCl stress compared with wild-type plants. Furthermore, heterologous expression of AtNHX4 in Escherichia coli BL21 rendered the transformants hypersensitive to NaCl. Deletion of the hydrophilic C-terminus of AtNHX4 dramatically increased the hypersensitivity of transformants, indicating that AtNHX4 may function in Na⁺ homeostasis in plant cell, and its C-terminus plays a role in regulating the AtNHX4 activity.     

二色补血草的耐盐性研究

通过NaCl胁迫发芽试验、盆栽浇灌NaCl盐水试验、不同含盐量土壤的种植试验,研究二色补血草(Limonium bicolor)3个时期的耐盐能力。结果表明:高浓度NaCl对二色补血草种子的萌发有明显的抑制作用,种子的发芽率与盐浓度之间呈显著的负相关,种子萌发时盐胁迫的适宜值、临界值、极限值分别是0.49%、1.30%、2.11%;盆栽试验结果表明,二色补血草在2.0%以下的NaCl盐水胁迫下没有表现明显的盐害症状,只表现高浓度NaCl胁迫下,生长量低于低浓度处理的,当处理浓度达到2.4%时,多数植株濒临死亡;不同含盐量土壤的种植试验结果表明,在自然条件下,二色补血草成株耐盐临界值为1.7%~1.8%。试验结果说明二色补血草具有较强的耐盐能力,适合在滩涂盐碱地推广种植。     

Effect of salinity and waterlogging on growth,anatomical and antioxidative responses in <Emphasis Type="Italic">Mentha aquatica</Emphasis> L.

Salinity and waterlogging are two stresses which in nature often occur simultaneously. In this work, effects of combined waterlogging and salinity stresses are studied on the anatomical alteration, changes of enzymatic antioxidant system and lipid peroxidation in Mentha aquatica L. plants. Seedlings were cultured in half-strength Hoagland medium 50 days after sowing, and were treated under combination of three waterlogging levels (well drained, moderately drained and waterlogging) and NaCl (0, 50, 100, 150 mM) for 30 days. Moderately drained and waterlogging conditions induced differently aerenchyma formation in roots of M. aquatica salt-treated and untreated plants. Moreover, stele diameter and endodermis layer were also affected by salt stress and waterlogging. Salt stress significantly decreased growth, relative water content (RWC), protein level, catalase (CAT) and polyphenol oxidase (PPO) activities, and increased proline content, MDA content, H₂O₂ level and activities of superoxide dismutase (SOD), peroxidase (POX), and ascorbate peroxidase (APX). Waterlogging in salt-untreated plants increased significantly growth parameters, RWC, protein content, antioxidant enzyme activity, and decreased proline content, H₂O₂ and MDA levels. In salt-treated plant, waterlogging caused strong induction of antioxidant enzymes activities especially at severe stress condition. These results suggest M. aquatica is a waterlogging tolerant plant due to significant increase of antioxidant activity, membrane stability and growth under water stress. High antioxidant capacity under waterlogging can be a protective strategy against oxidative damage, and help to salt stress alleviation.