Effects of Barium Stress in <i>Brassica juncea</i> and <i>Cakile maritima</i>: The Indicator Role of Some Antioxidant Enzymes and Secondary Metabolites

Soil contamination by toxic trace metal elements, like barium (Ba), may stimulate various undesirable changes in the metabolic activity of plants. The plant responses are fast and with, direct or indirect, generation of reactive oxygen species (ROS). To cope with the stress imposed by the ROS production, plants developed a dual cellular system composed of enzymatic and non-enzymatic players that convert ROS, and their by-products, into stable nontoxic molecules. To assess the Ba stress response of two Brassicaceae species (Brassica juncea, a glycophyte, and Cakile maritime, a halophyte), plants were exposure to different Ba concentrations (0, 100, 200, 300 and 500 μM). The plants response was evaluated through their morphology and development, the determination of plant leaves antioxidant enzymatic activities and by the production of plants secondary metabolites. Results indicated that the two Brassicaceae species have the ability to survive in an environment containing Ba (even at 500 μM). The biomass production of C. maritima was slightly affected whereas an increase in biomass B. juncea was noticed. The stress imposed by Ba activated the antioxidant defense system in the two species, noticed by the changes in the leaves activity of catalase (CAT), ascorbate peroxidase (APX) and guaicol peroxidase (GPX), and of the secondary metabolites, through the production of total phenols and flavonoids. The enzymatic response was not similar within the two plant species: CAT and APX seem to have a more important role against the oxidative stress in C. maritima while in B. juncea is GPX. Overall, total phenols and flavonoids production was more significant in the plants aerial part than in the roots, of the both species. Although the two Brassicaceae species response was different, in both plants catalytic and non-catalytic transformation of ROS occurs, and both were able to overcome the Ba toxicity and prevent the cell damage.     

Salt-Induced Changes in Physio-Biochemical and Antioxidant Defense System in Mustard Genotypes

Salinity stress is a major factor limiting plant growth and productivity of many crops including oilseed. The present study investigated the identification of salt tolerant mustard genotypes and better understanding the mechanism of salinity tolerance. Salt stresses significantly reduced relative water content (RWC), chlorophyll (Chl) content, K⁺ and K⁺ /Na⁺ ratio, photosynthetic rate (P_N), transpiration rate (Tr), stomatal conductance (gs), intercellular CO₂ concentration (Ci) and increased the levels of proline (Pro) and lipid peroxidation (MDA) contents, Na⁺ , superoxide (O₂^•− ) and hydrogen peroxide (H₂O₂) in both tolerant and sensitive mustard genotypes. The tolerant genotypes maintained higher Pro and lower MDA content than the salt sensitive genotypes under stress condition. The activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) were increased with increasing salinity in salt tolerant genotypes, BJ-1603, BARI Sarisha-11 and BARI Sarisha-16, but the activities were unchanged in salt sensitive genotype, BARI Sarisha-14. Besides, the increment of ascorbate peroxidase (APX) activity was higher in salt sensitive genotype as compared to tolerant ones. However, the activities of glutathione reductase (GR) and glutathione S-transferase (GST) were increased sharply at stress conditions in tolerant genotypes as compared to sensitive genotype. Higher accumulation of Pro along with improved physiological and biochemical parameters as well as reduced oxidative damage by up-regulation of antioxidant defense system are the mechanisms of salt tolerance in selected mustard genotypes, BJ-1603 and BARI Sarisha-16.     

<i>Azospirillum brasilense</i> and <i>Saccharomyces cerevisiae</i> as Alternative for Decrease the Effect of Salinity Stress in Tomato (<i>Lycopersicon esculentum</i>) Growth

The salinity stress is one of the most relevant abiotic stresses that affects the agricultural production. The present study was performed to study the improvement of the salt tolerance of tomato plants which is known for their susceptibility to salt stress. The present study aimed to assess to what extent strain Azospirillum brasilense (N040) and Saccharomyces cerevisiae improve the salt tolerance to tomato plants treated with different salt concentration. The inoculant strain A. brasilense (N040) was previously adapted to survive up to 7% NaCl in the basal media. A greenhouse experiment was conducted to evaluate the effect of this inoculation on growth parameter such as: plant height, root length, fresh and dry weight, fruits fresh weight, chlorophyll content, proline and total soluble sugar in tomato plants under salt stress condition. The results revealed that co-inoculation of Azospirillum brasilense (N040) and Saccharomyces cerevisiae significantly increased the level of proline (8.63 mg/g FW) and total soluble sugar (120 mg/g FW) of leaves under salinity condition comparing to non-inoculated plants (2.3 mg/g FW and 70 mg/g FW, respectively). Plants co-inoculated with adapted strain of A. brasilense and S. cerevisiae showed the highest significant (p < 0.01) increase in fruit yield (1166.6 g/plant), plant high (115 cm) and roots length (52.6) compared whit un-inoculated control plants (42 g/pant, 43.3 cm and 29.6 cm, respectively). In contrast, Na⁺ ion content was significantly decreased in the leaves of salt stressed plants treated with the A. brasilense (N040) and S. cerevisiae. Finally, the results showed that dual benefits provided by both A. brasilense (N040) and S. cerevisiae can provide a major way to improve tomato yields in saline soils.     

Ameliorative Role of Pre-Sowing Proline Treatment in <i>Coriandrum sativum</i> L. Seedlings under Mercury Toxicity

Heavy metal toxicity is one of the major ecosystem concerns globally in present time and is also responsible for significant threat to agronomic crops. The current work was conducted to investigate the possible ameliorative role of proline in Coriandrum sativum L. seedlings treated with mercury (Hg). The seedlings were exposed to different concentrations of Hg (0, 0.1, 0.3 and 0.5 mM) for 20 days. The effects of pre-sowing treatment with proline were studied on C. sativum seedlings in terms of pigment (chlorophylls, carotenoids and anthocyanins), malondialdehyde (MDA), antioxidant compound (glutathione, total phenolic compounds, ascorbic acid) and osmolytes (proline, glycine betaine). Additionally, activities of antioxidant enzymes, namely catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) were also studied. A strong decline of photosynthetic pigment concentrations was observed in leaves of C. sativum under Hg toxicity. Treatment of seeds with proline reduced the loss of photosynthetic pigments, counteract Hg-triggered oxidative stress, likely preserving the functionality of antioxidant apparatus under Hg stress. The increment of total polyphenols and glycine betaine also contributed in ameliorating Hg toxicity, suggesting the use of exogenous proline as a potential method to enhance the plant tolerance against heavy metal stress.     

A DESD-box helicase functions in salinity stress tolerance by improving photosynthesis and antioxidant machinery in rice (Oryza sativa L. cv. PB1)

The exact mechanism of helicase-mediated salinity tolerance is not yet understood. We have isolated a DESD-box containing cDNA from Pisum sativum (Pea) and named it as PDH45. It is a unique member of DEAD-box helicase family; containing DESD instead of DEAD/H. PDH45 overexpression driven by constitutive cauliflower mosaic virus-35S promoter in rice transgenic [Oryza sativa L. cv. Pusa Basmati 1 (PB1)] plants confers salinity tolerance by improving the photosynthesis and antioxidant machinery. The Na⁺ ion concentration and oxidative stress parameters in leaves of the NaCl (0, 100 or 200 mM) treated PDH45 overexpressing T₁ transgenic lines were lower as compared to wild type (WT) rice plants under similar conditions. The 200 mM NaCl significantly reduced the leaf area, plant dry mass, net photosynthetic rate (P_N), stomatal conductance (gs), intercellular CO₂ (Ci), chlorophyll (Chl) content in WT plants as compared to the transgenics. The T₁ transgenics exhibited higher glutathione (GSH) and ascorbate (AsA) contents under salinity stress. The activities of antioxidant enzymes viz. superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and glutathione reductase (GR) were significantly higher in transgenics; suggesting the existence of an efficient antioxidant defence system to cope with salinity induced-oxidative damage. Yeast two-hybrid assay indicated that the PDH45 protein interacts with Cu/Zn SOD, adenosine-5′-phosphosulfate-kinase, cysteine proteinase and eIF(4G), thus confirming the involvement of ROS scavenging machinery in the transgenic plants to provide salt tolerance. Furthermore, the T₂ transgenics were also able to grow, flower, and set viable seeds under continuous salinity stress of 200 mM NaCl. This study provides insights into the mechanism of PDH45 mediated salinity stress tolerance by controlling the generation of stress induced reactive oxygen species (ROS) and also by protecting the photosynthetic machinery through a strengthened antioxidant system.     

Physiological and biochemical changes by nitric oxide and brassinosteroid in tomato (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis> Mill.) under drought stress

Drought stress produces many physiological and biochemical changes in plant affecting its life cycle and production. Oxidative damage and antioxidant defense responses are two components of plant to survive under drought stress. Nitric oxide (sodium nitroprusside, SNP) and brassinosteroid (24-epibrassinolide, EBL) were used in this experiment as single and combined application as foliar spray to study the mitigating effect of drought stress in two tomato genotypes EC-625652 (drought susceptible) and EC-620419 (drought tolerant). Drought stress produced harmful effect on number of leaves plant^?1, RWCL, fruit set percent, days to first fruit set, number of cluster plant^?1, lycopene content, fruit diameter and fruit yield. Plant produces reactive oxygen species (ROS), such as H₂O₂ in response to drought stress. Exogenous application of SNP and EBL, both in single and combined application, mitigated the deleterious effects of drought and improved drought tolerance by increasing SOD activity, fruit yield, and other physiological processes.     

Endophytic bacterium Bacillus subtilis (BERA 71) improves salt tolerance in chickpea plants by regulating the plant defense mechanisms

Plant growth-promoting endophytic bacteria can stimulate the growth, nutrient acquisition, symbiotic performance and stress tolerance of chickpea plants under saline soil conditions. The aim of this study was to investigate the stress-adaptive mechanisms of chickpea plants mediated by Bacillus subtilis (BERA 71) under saline conditions. Inoculation with BERA 71 enhanced plant biomass and the synthesis of photosynthetic pigments and reduced the levels of reactive oxygen species (ROS) and lipid peroxidation in plants under conditions of stress. Furthermore, the activities of ROS-scavenging antioxidant enzymes (superoxide dismutase, peroxidase, catalase and glutathione reductase), the levels of non-enzymatic antioxidants (ascorbic acid and glutathione) and the total phenol content were increased in stressed plants during bacterial association. The bacteria decreased sodium accumulation and enhanced the nitrogen, potassium, calcium and magnesium content in the plants. The suppression of ROS generation and of lipid peroxidation and the accumulation of proline in BERA-71-inoculated plants enhanced the membrane stability under salinity stress and non-stress conditions.     

OsSUV3 dual helicase functions in salinity stress tolerance by maintaining photosynthesis and antioxidant machinery in rice (Oryza sativa L. cv. IR64)

To overcome the salinity‐induced loss of crop yield, a salinity‐tolerant trait is required. The SUV3 helicase is involved in the regulation of RNA surveillance and turnover in mitochondria, but the helicase activity of plant SUV3 and its role in abiotic stress tolerance have not been reported so far. Here we report that the Oryza sativa (rice) SUV3 protein exhibits DNA and RNA helicase, and ATPase activities. Furthermore, we report that SUV3 is induced in rice seedlings in response to high levels of salt. Its expression, driven by a constitutive cauliflower mosaic virus 35S promoter in IR64 transgenic rice plants, confers salinity tolerance. The T₁ and T₂ sense transgenic lines showed tolerance to high salinity and fully matured without any loss in yields. The T₂ transgenic lines also showed tolerance to drought stress. These results suggest that the introduced trait is functional and stable in transgenic rice plants. The rice SUV3 sense transgenic lines showed lesser lipid peroxidation, electrolyte leakage and H₂O₂ production, along with higher activities of antioxidant enzymes under salinity stress, as compared with wild type, vector control and antisense transgenic lines. These results suggest the existence of an efficient antioxidant defence system to cope with salinity‐induced oxidative damage. Overall, this study reports that plant SUV3 exhibits DNA and RNA helicase and ATPase activities, and provides direct evidence of its function in imparting salinity stress tolerance without yield loss. The possible mechanism could be that OsSUV3 helicase functions in salinity stress tolerance by improving photosynthesis and antioxidant machinery in transgenic rice.     

Silicon and Nitric Oxide-Mediated Regulation of Growth Attributes,Metabolites and Antioxidant Defense System of Radish (<i>Raphanus sativus</i> L.) under Arsenic Stress

Arsenic (As) contaminated food chains have emerged as a serious public concern for humans and animals and are known to affect the cultivation of edible crops throughout the world. Therefore, the present study was designed to investigate the individual as well as the combined effects of exogenous silicon (Si) and sodium nitroprusside (SNP), a nitric oxide (NO) donor, on plant growth, metabolites, and antioxidant defense systems of radish (Raphanus sativus L.) plants under three different concentrations of As stress, i.e., 0.3, 0.5, and 0.7 mM in a pot experiment. The results showed that As stress reduced the growth parameters of radish plants by increasing the level of oxidative stress markers, i.e., malondialdehyde and hydrogen peroxide. However, foliar application of Si (2 mM) and pretreatment with SNP (100 µM) alone as well as in combination with Si improved the plant growth parameters, i.e., root length, fresh and dry weight of plants under As stress. Furthermore, As stress also reduced protein, and metabolites contents (flavonoids, phenolic and anthocyanin). Activities of antioxidative enzymes such as catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POD), and polyphenol oxidase (PPO), as well as the content of non-enzymatic antioxidants (glutathione and ascorbic acid) decreased under As stress. In most of the parameters in radish, As III concentration showed maximum reduction, as compared to As I and II concentrations. However, the individual and combined application of Si and NO significantly alleviated the As-mediated oxidative stress in radish plants by increasing the protein, and metabolites content. Enhancement in the activities of CAT, APX, POD and PPO enzymes were recorded. Contents of glutathione and ascorbic acid were also enhanced in response to co-application of Si and NO under As stress. Results obtained were more pronounced when Si and NO were applied in combination under As stress, as compared to their individual application. In short, the current study highlights that Si and NO synergistically regulate plant growth through lowering the As-mediated oxidative stress by upregulating the metabolites content, activity of antioxidative enzymes and non-enzymatic antioxidants in radish plants.

     

Brassinosteroids alleviate chilling-induced oxidative damage by enhancing antioxidant defense system in suspension cultured cells of <Emphasis Type="Italic">Chorispora bungeana</Emphasis>

Brassinosteroids (BRs), a class of plant steroid hormones, play a significant role in the amelioration of various biotic and abiotic stresses. In order to further explore and elaborate their roles in plants subjected to chilling stress, suspension cultured cells of Chorispora bungeana with or without 24-epibrassinolide (EBR) application were exposed to 4 and 0°C for 5 days. The EBR treated cells exhibited higher viability after exposure to low temperatures compared with the control. Under chilling stress, reactive oxygen species (ROS) levels and lipid peroxidation were increased in the cultured cells, which were significantly inhibited by EBR application. The activities of antioxidative enzymes such as ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) were increased during chilling treatments, and these increases were more significant in the EBR applied suspension cells. The EBR treatment also greatly enhanced contents of ascorbic acid (AsA) and reduced glutathione (GSH) under chilling stress. From these results, it can be concluded that EBR could play the positive roles in the alleviation of oxidative damage caused by ROS overproduction through enhancing antioxidant defense system, resulting in improving the tolerance of C. bungeana suspension cultures to chilling stress.     

Allantoin Alleviates Seed Germination Thermoinhibition in <i>Arabidopsis</i>

Allantoin as the metabolite of purine catabolism can store and remobilize nitrogen for plant growth and development. However, emerging evidence suggests it also contributes to plant tolerance to stress response through altering abscisic acid (ABA) and reducing reactive oxygen species (ROS) level. 1-CYS PEROXIREDOXIN (PER1) is a seed-specific antioxidant that enhances seed longevity through scavenging ROS over-accumulation. High temperature (HT) suppresses seed germination and induces seed secondary dormancy, called as seed germination thermoinhibition. However, the mechanism that allantoin and PER1 regulate seed germination thermoinhibition remains unknown. In this study, we reported that allantoin treatment enhances seed germination under HT stress. Consistently, the aln mutants displayed higher seed germination, as well as more accumulation of endogenous allantoin, than that of wild-type control. Further biochemical and genetic analyses showed that allantoin reduces ABA content under HT, and allantoin targets PER1 to efficiently scavenge HT-induced ROS accumulation, meanwhile, the function of allantoin requires PER1 during seed gemination thermotolerance. Collectively, our finding proposes a novel function of allantoin in enhancing seed germination tolerance to HT, and uncovers the underlying mechanism by which allantoin regulates seed germination through altering ABA metabolism and PER1-mediated ROS level under HT stress.     

Transgenic peanut overexpressing <Emphasis Type="Italic">mtlD</Emphasis> gene confers enhanced salinity stress tolerance via mannitol accumulation and differential antioxidative responses

Globally, peanut is an important oilseed crop, which is cultivated under different agro-climatic zones. Soil salinity is one of the major constraints in peanut cultivation. Therefore, to understand the physio-biochemical mechanisms imparting salinity stress, four transgenic peanut lines (cv. GG20) already developed and confirmed by our lab, having bacterial mannitol dehydrogenase gene (mtlD), were subjected to different levels of salinity stresses (1, 2 and 3 dS m^?1) in pots under containment facility. Further, these lines were also characterized for various physio-biochemical parameters at flowering, pegging and pod formation stages. All the transgenic lines recorded significantly higher mannitol dehydrogenase (MTD) activity and mannitol accumulation than the wild type (WT). Under salinity stress, significantly higher levels of superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase, glutathione reductase activities, while significantly lower levels of H₂O₂ and malondialdehyde contents, were recorded in the transgenics compared to WT. Similarly, significantly higher ascorbic acid and relative water content (RWC) were recorded in transgenic lines. The MTD activity showed positive correlation with various antioxidant enzymes, growth parameters and RWC, while negative correlation was recorded with H₂O₂ and malondialdehyde content at most of the plant growth stages. The mtlD transgenic peanut lines under pot conditions were found maintaining lower oxidative injuries, indicating amelioration of salinity-induced oxidative stress by enhanced protection mechanisms via mannitol accumulation and antioxidative responses. The best lines identified (MTD1 and MTD4) may be used further as pre-breeding source for imparting salinity stress tolerance in peanut. Besides, these lines may also be tested under open-field trials for release as salt-tolerant variety.     

Salicylic Acid Application Mitigates Oxidative Damage and Improves the Growth Performance of Barley under Drought Stress

Drought is a severe environmental constraint, causing a significant reduction in crop productivity across the world. Salicylic acid (SA) is an important plant growth regulator that helps plants cope with the adverse effects induced by various abiotic stresses. The current study investigated the potential effects of SA on drought tolerance efficacy in two barley (Hordeum vulgare) genotypes, namely BARI barley 5 and BARI barley 7. Ten-day-old barley seedlings were exposed to drought stress by maintaining 7.5% soil moisture content in the absence or presence of 0.5, 1.0 and 1.5 mM SA. Drought exposure led to severe damage to both genotypes, as indicated by phenotypic aberrations and reduction of dry biomass. On the other hand, the application of SA to drought-stressed plants protected both barley genotypes from the adverse effects of drought, which was reflected in the improvement of phenotypes and biomass production. SA supplementation improved relative water content and proline levels in drought-stressed barley genotypes, indicating the osmotic adjustment functions of SA under water-deficit conditions. Drought stress induced the accumulation of reactive oxygen species (ROS), such as hydrogen peroxide (H₂O₂) and superoxide (O₂ ^•− ), and the lipid peroxidation product malondialdehyde (MDA) in the leaves of barley plants. Exogenous supply of SA reduced oxidative damage by restricting the accumulation of ROS through the stimulation of the activities of key antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX). Among the three-applied concentrations of SA, 0.5 mM SA exhibited better mitigating effects against drought stress considering the phenotypic performance and biochemical data. Furthermore, BARI barley 5 showed better performance under drought stress than BARI barley 7 in the presence of SA application. Collectively, our results suggest that SA played a crucial role in improving water status and antioxidant defense strategy to protect barley plants from the deleterious effects of water deficiency.     

Improvement of Selected Morphological,Physiological, and Biochemical Parameters of Banana (<i>Musa acuminata</i> L.) Using Potassium Silicate under Drought Stress Condition Grown <i>in vitro</i>

Drought stress has become more common in recent years as a result of climate change impacts on the production of banana crops and other fruit trees. The growth and productivity of Musa spp are severely impacted by the gradual degradation of water resources and the erratic distribution pattern of annual precipitation amount. The aim of the work includes increased drought tolerance in light of water scarcity in the world as a result of the bananas’ being gluttonous for water needs. This investigation was carried out from 2019 to 2020 to study the effect of potassium silicate on morphological growth and biochemical parameters of Musa acuminata L under drought stress by PEG. As a result, drought stress reduced the morphological characteristics such as shoots number, shoot length, roots number, and survival percentage and biochemical characteristics such as chlorophyll a, b, carotenoids, stomatal status, and RWC. While proline content increased in the leaf of M. acuminata L. Media complemented with K₂SiO₃ (2 to 6 mM) either individually or in combination with PEG led to an improvement in all morphological and biochemical characteristics. The activities of CAT, POD, and PPO enzymes increased signifi- cantly compared to control. Furthermore, the lowest PPO, CAT, and POD activity were achieved. Additionally, K₂SiO₃ treatments under drought stress successfully enhanced the leaf stomatal behavior. Our results suggest that K₂SiO₃ can help to maintain plant integrity in the tested cultivar under drought stress.     

Functional screening for salinity tolerant genes from <Emphasis Type="Italic">Acanthus ebracteatus</Emphasis> Vahl using <Emphasis Type="Italic">Escherichia coli</Emphasis> as a host

Salinity reduces plant growth and crop production globally. The discovery of genes in salinity tolerant plants will provide the basis for effective genetic engineering strategies, leading to greater stress tolerance in economically important crops. In this study, we have identified and isolated 107 salinity tolerant candidate genes from a mangrove plant, Acanthus ebracteatus Vahl by using bacterial functional assay. Sequence analysis of these putative salinity tolerant cDNA candidates revealed that 65% of them have not been reported to be stress related and may have great potential for the elucidation of unique salinity tolerant mechanisms in mangrove. Among the genes identified were also genes that had previously been linked to stress response including salinity tolerance, verifying the reliability of this method in isolating salinity tolerant genes by using E. coli as a host.     

Overexpression of the Arabidopsis photorespiratory pathway gene, serine: glyoxylate aminotransferase (AtAGT1), leads to salt stress tolerance in transgenic duckweed (Lemna minor)

Salt stress has attracted increasing attention due to its toxic ability to restrict plant growth, and the photorespiration pathway has been shown to develop improved plant tolerance to abiotic stress. In this study, an Arabidopsis photorespiratory pathway gene serine: glyoxylate aminotransferase (SGAT), named as AtAGT1, was successfully overexpressed in duckweed (Lemna minor) to investigate the salinity defense capability in three transgenic overexpressed (OE) lines. Increased SGAT activity and decreased endogenous serine levels in these transgenic plant lines under salt stress resulted in enhanced protection against root abscission, higher maximum quantum yield of photosystem II (Fv/Fm), increased defense from cell damage as a result of improved cell membrane integrity, a decrease of reactive oxygen species (ROS) accumulation, and a strengthened antioxidant system. The salt tolerance in these transgenic OE lines indicates that the improvement of photorespiration stimulated the antioxidant system to scavenge ROS. The change of serine level also suggests the role of serine during salt stress. This transgenic engineering in duckweed not only introduced salt tolerance to this aquatic plant but also reveals a significant role of photorespiration during salinity stress.     

植物抗盐分子机制及作物遗传改良耐盐性的研究进展

盐胁迫是全球农业生产上的一个主要逆境因子。解析耐盐分子机制有助于培育耐盐能力提高的作物新品种。我们综述了植物对盐胁迫的感应及信号传导、主要Na^＋运输体、盐胁迫下的解毒途径以及耐盐途径中涉及到的表观遗传研究。此外,我们还讨论了利用遗传改良手段提高作物耐盐性的研究进展。     

<i>In vitro</i> Evaluation of Seed Germination in Twelve Alfalfa Cultivars under Salt Stress

Alfalfa (Medicago sativa L.), when exposed to abiotic stress such as salinity, suffers significant losses in yield and productivity. The present study evaluated the salinity tolerance of 12 alfalfa cultivars in vitro using five concentrations of sodium chloride (NaCl), ranging from 0 to 250 mmol L⁻¹ . The results obtained in the current study revealed that the Saudi cultivars, Kasimi and Hassawi, and the German cultivar (Berlin) had the highest salinity tolerance in terms of germination percentage (GP), corrected germination rate index (CGRI), days to reach 50% germination (GT50), and ability to form cotyledonary and true leaves. Under mmol L⁻¹ NaCl, the Saudi cultivar Kasimi cultivar showed GP, CGRI, and GT50 of 55.20%, 123.15, and 3.77 days, respectively. Similarly, the German cultivar (Berlin) showed GP, CGRI, and GT50 of 50.06%, 86.61, and 5.17 days, respectively. These findings might reveal a pivotal aspect in salt tolerance in alfalfa. Our results will help to select salt-tolerant alfalfa cultivars that could thrive in arid and semi-arid areas with salinity problems.