Changes of Proline Content,Activity,and Active Isoforms of Antioxidative Enzymes in Two Alfalfa Cultivars Under Salt Stress

The plants of two elfalfa （Medicago sativa L.） cultivars differing in salt tolerance were subjected to three salt treatments, 70, 140, and 210 mM NaCl for 7 days. Root, shoot, and leaf growths were inhibited by increased salt treatments in both cultivars, and at 140 and 210 mM salt treatments, Zhongmu 1 had significantly higher root, shoot, and leaf dry weights per plant than Deft. The malondialdehyde （MDA） accumulation in Deft was considerably greater than in Zhongmu 1, indicating a higher degree of lipid peroxidation at 140 and 210 mM salt treatments. The changes in the activity and active isoforms of antioxidant enzymes such as superoxide dismutase （SOD, EC 1.15.1.1）, catalase （CAT, EC 1.11.1.6）, peroxidase （POD, EC 1.11.1.7）, and ascorbate peroxidase （APOX, EC 1.11,1.11）, accumulation of free proline, and rate of lipid peroxidation in leaves of two alfalfa cultivars were also investigated. After stress, the activity and active isoforms of antioxidative enzymes were altered and the extent of alteration varied between the cultivar Deft and Zhongmu 1. The proline accumulation in Deft was considerably greater than in Zhongmu 1 at 210 mM salt treatment. This indicated that proline accumulation may be the result, instead of the cause, of salt tolerance.

Changes of Antioxidative Enzymes and Lipid Peroxidation in Leaves and Roots of Waterlogging-Tolerant and Waterlogging-Sensitive Maize Genotypes at Seedling Stage

To better understand the physiological and biochemical mechanisms of waterlogging tolerance, waterlogging effects on lipid peroxidation and the activity of antioxidative enzymes were investigated in leaves and roots of two maize genotypes, HZ32 （waterlogging-tolerant） and K12 （waterlogging-sensitive）. Potted maize plants were waterlogged at the second leaf stage under glasshouse conditions. Leaves and roots were harvested 1 d before and 2, 4, 6, 8 and 10 d after the start of waterlogging treatment. Through comparing the activities of superoxide dismutase （SOD）, ascorbate peroxidase （APX）, glutathione reductase （GR）, catalase （CAT） and guaiacol peroxidase （POD） between waterlogging-tolerant and waterloggingsensitive genotype, we deduced that CAT was the most important H2O2 scavenging enzyme in leaves, while APX seemed to play a key role in roots. POD, APX, GR and CAT activities in conjunction with SOD seem to play an essential protective role in the O2^- and H2O2 scavenging process. Lipid peroxidation was enhanced significantly only in K12 （P 〈 0.001） and there was no difference （P 〉 0.05） in HZ32 up to 6 d after waterlogging stress. These results indicated that oxidative stress may play an important role in waterlogging-stressed maize plants and that the greater protection of HZ32 leaves and roots from waterlogging-induced oxidative damage results, at least in part, through the maintenance of increased antioxidant enzyme activity.

Nickel accumulation and its effect on biomass,protein content and antioxidative enzymes in roots and leaves of watercress(Nasturtium officinale R.Br.)

In order to understand its response towards nickel stress, watercress （Nasturtium officinale R. Br.） was exposed to nickel （1-25 mg/L） for 1, 3, 5 and 7 days. The accumulation and translocation of nickel were determined and the influence of nickel on biomass, protein content and enzymatic antioxidants was examined for both roots and leaves. It was determined that N. o fficinale could accumulate appreciable amounts of Ni in both roots and leaves. Nickel accumulated particularly in the roots of plants. Biomass increased at low nickel concentrations but certain measurable change was not found at high concentrations. Under stress conditions the antioxidant enzymes were up-regulated compared to control. An increase in protein content and enzyme activities was observed at moderate exposure conditions followed by a decline at both roots and leaves. The maximum enzyme activities were observed at different exposure conditions. Our results showed that N. officinale had the capacity to overcome nickel-induced stress especially at moderate nickel exposure. Therefore, N. officinale may be used as a phytoremediator in moderately polluted aquatic ecosystems.

Effect of Maturity Stage on the Gene Expression of Antioxidative Enzymes in Cucumber (Cucumis sativus L.) Fruits Under Chilling Stress

The gene expression pattems of antioxidative enzymes in cucumber （Cucumis sativus L.） fruits at four different maturity stages, immature （3-8 d after anthesis （DAA）, mature （9-16 DAA）, breaker （17-22 DAA）, and yellow （35-40 DAA）, were determined before and after cold storage at 2℃ for 9 d and after subsequent rewarming at 20℃ for 2 d. The electrolyte leakage and malondialdehyde content in cucumber fruits were increased after cold storage and subsequent rewarming. Increased expressions of peroxidase, ascorbate peroxidase （APX）, and monodehydroascorbate reductase after cold storage played an important role in cucumber fruits to cope with chilling injury. The elevated cyt-superoxide dismutase, catalase, APX and dehydroascorbate reductase after subsequent rewarming in cucumber fruits facilitated the recovery from chilling stress. The highest expression levels of all the seven antioxidative enzyme genes in yellow fruits might be responsible for the enhanced chilling tolerance. Cucumber fruits at earlier developmental stages was more susceptible to chilling stress than those at later stages. The relative higher gene expressions of antioxidative enzymes genes at earlier developmental stages may be the responses to the sever oxidative stress caused by chilling injury.

Effect of Low Light Stress on Photosynthetic Pigments and Antioxidative Enzymes in Field Grown Indian Mustard(Brassica juncea L.)Genotypes

Oilseed Brassicas have prominent place after soybean and groundnut.More than 90%of the area under oilseed Brassicas is occupied by the Indian mustard(Brassica juncea)because of its relative tolerance to biotic and abiotic stresses as compared to other oilseed Brassica species.Light plays key a role in net primary productivity and is necessary for plant growth,morphogenesis and several physiological processes.The present investigation aimed to assess the effect of low light stress on photosynthetic traits and antioxidative enzymes in Brassica juncea genotypes.Shading was imposed with nets from mid-December to mid-January which cut 25%-30%of natural sunlight.Shading period coincided with the onset of flowering.The results showed that chlorophyll b and antioxidant activities of superoxide dismutase(SOD),guaiacol-peroxidase(G-POD)and catalase(CAT)increased under low light stress at two stages of investigations(10 and 30 days after removal of nets).With shading treatment,soil plant analysis development(SPAD)chlorophyll meter values,chlorophyll a,total chlorophyll,chlorophyll a/b ratio,carotenoid and protein content decreased significantly while malondialdehyde content increased due to damages of plant cells.This study provides valuable information for further deciphering genetic mechanism and improving agronomic traits in Indian mustard cultivated under optimal light requirements.

Osmoprotectants and Antioxidative Enzymes as Screening Tools for Salinity Tolerance in Radish (Raphanus sativus)

The research addresses the identification of a screening methodology for salt stress tolerance in radish cultivars. In the first experiment, two different radish cultivars(long white and round red) were compared in their morphological and physiological responses to different salinity levels. Round red radish showed better morphological and physiological responses to incremental salinity in terms of yield and better adaptation of overall water relations. In the second experiment, the most tolerant genotype from the first experiment was used as a control against other seven round red radish genotypes ranked by their salinity tolerance according to morphological, physiological and biochemical indices. Salt stress did not significantly affect malondialdehyde(MDA) and hydrogen peroxide(H2O2) content, and ascorbate peroxidase(APX) activity in the studied cultivars. Nonetheless, the relatively salt tolerant cultivar SAXA2 showed higher ability to accumulate compatible solutes(e.g.proline and proteins) and maintain osmotic adjustment. In addition, cultivar SAXA2 also showed considerable increase in glutathione reductase(GR) activity. Our results supported that accumulation of proline and higher GR activity are associated with radish salt tolerance, whereas no relationship with salinity was observed in superoxide dismutase(SOD), MDA and H2O2 content.

Foliar application of zinc promotes cadmium absorption by increasing expression of cadmium transporter genes and activities of antioxidative enzymes in winter wheat

Cadmium(Cd)is a deleterious non-essential metal in plants.To elucidate the mechanisms by which zinc(Zn)application alleviates cadmium(Cd)toxicity in wheat,we characterized plant growth,antioxidant system,leaf cell ultrastructure,and Cd transporter gene expression in winter wheat under Cd exposure(50μmol L^(-1)Cd)with foliar Zn application in a hydroponic experiment.Results showed that Zn addition(Zn+Cd)or pretreatment(pre-Zn+Cd)at 2 g L^(-1)as Zn_(S)O_(4)·7H_(2)O significantly exacerbated Cd-induced growth inhibition and diminished root morphological parameters,root cell viability,and chlorophyll content.In addition,the Cd content increased in roots and shoots in the Zn+Cd and pre-Zn+Cd treatments,but the Cd translocation factor decreased,when compared to the treatment without Zn application.After Zn application,the Cd content increased in the root cell wall fraction but decreased in the soluble fraction.The activities of antioxidative enzymes(superoxide dismutase,peroxidase,and catalase)and the contents of non-enzymatic antioxidants(malondialdehyde,ascorbic acid,and glutathione)significantly increased in the roots and shoots of wheat after Cd exposure,particularly in the Zn+Cd and pre-Zn+Cd treatments.Gene expression analysis showed that five genes(TaHMA2,TRIAE5370,TCONS1113,TRIAE5770,TRIAE1060,and TCONS5200)participated in root absorption of Cd,whereas TCONS5200 and TRIAE5660 contributed to Cd transfer to shoots.Foliar application of Zn increased the number of chloroplasts,but the chloroplast structure was destroyed in the Zn+Cd treatment.These results indicated that 2 g L^(-1)ZnSO4·7H2O increased the toxicity of 50μmol L^(-1)Cd.Increased Cd uptake due to the upregulated expression of Cd transporter genes and increased reactive oxygen species accumulation may be the reasons why Zn application aggravated Cd toxicity.

Study on Antioxidant Enzyme Activity and Physiology and Biochemistry of Solanum nigrum L. under Glyphosate Stress

[Objectives] This study was conducted to investigate the scientific prevention and control of Solanum nigrum L. [Methods] Through experiments on S. nigrum from different sources, it was found that glyphosate stress had significant effects on antioxidant enzyme activity and oxidative damage of sensitive S. nigrum plants. [Results] Sensitive S. nigrum showed oxidative damage under glyphosate stress, while resistant S. nigrum responded to adversity damage by improving its antioxidant enzyme activity. The experimental results showed that the antioxidant enzymes and reduced glutathione of S. nigrum had certain metabolic detoxification effects under glyphosate stress. [Conclusions] This study provides a theoretical basis for scientific prevention and control of S. nigrum , and has a certain reference value for revealing the glyphosate resistance mechanism of S. nigrum .

Activity of Stress-related Antioxidative Enzymes in the Invasive Plant Crofton Weed(Eupatorium adenophorum)

Crofton weed is an invasive weed in southwestern China. The activities of several antioxidative enzymes involved in plant protection against oxidative stress were assayed to determine physiological aspects of the crofton weed that might render the plant vulnerable to environmental stress. Stresses imposed on crofton weed were heat （progressively increasing temperatures： 25 ℃, 30 ℃, 35 ℃, 38℃ and 42 ℃ at 24 h intervals）, cold （progressively decreasing temperatures： 25 ℃, 20 ℃, 15℃, 10 ℃ and 5℃ at 24h intervals）, and drought （without watering up to 4days）. The three stresses induced oxidative damage as evidenced by an increase in lipid peroxidation. The effect varied with the stress imposed and the length of exposure. The activity of superoxide dismutase （SOD） increased in response to all stresses but was not significantly different from the controls （P 〈 0.05） when exposed to cold stress. Catalase （CAT） activity decreased in response to heat and drought stress but increased when exposed to cold conditions. Guaiacol peroxidase （POD） and glutathione reductase （GR） activities increased in response to cold and drought but decreased in response to heat stress. The activity of ascorbata peroxidase （APX） responded differently to all three stresses. Monodehydroascorbate reductase （MDHAR） activity decreased in response to heat and drought, and slightly increased in response to the cold stress but was not significantly different from the controls （P 〈 0.05）. The activity of dehydroascorbata reductase （DHAR） increased in response to all three stresses. Taken together, the co-ordinate increase of the oxygen-detoxifying enzymes might be more effective to protect crofton weed from the accumulation of oxygen radicals at low temperatures rather than at high temperatures.

Endophytic Bacteria Promote the Growth of Suaeda glauca in Saline-Alkali Stress:Regulation of Osmotic Pressure and Antioxidative Defense System

Endophytic bacteria are promising bacterial fertilizers to improve plant growth under adverse environment.For ecological remediation of coastal wetlands,it was necessary to investigate the effect and interaction of endophytes on halophytes under saline-alkali stress.In this study,an endophytic bacterium strain HK1 isolated from halophytes was selected to infect Suaeda glauca under pH(7 and 8)and salinity gradient(150,300 and 450mmolL^(-1)).Strain HK1 was identified as Pantoea ananatis and it had ability to fix nitrogen,dissolve inorganic phosphorus and produce indole-3-aceticacid(IAA).The results showed that strain HK1 could promote the growth of S.glauca seedings when the salinity was less than 300mmolL^(-1),in view of longer shoot length and heavier fresh weight.The infected plants could produce more proline to decrease the permeability of cells,which content increased by 26.2%–61.1%compared to the non-infected group.Moreover,the oxidative stress of infected plants was relieved with the malondialdehyde(MDA)content decreased by 16.8%–32.9%,and the peroxidase(POD)activity and catalase(CAT)activity increased by 100%–500%and 6.2%–71.4%,respectively.Statistical analysis revealed that increasing proline content and enhancing CAT and POD activities were the main pathways to alleviate saline-alkali stress by strain HK1 infection,and the latter might be more important.This study illustrated that endophytic bacteria could promote the growth of halophytes by regulation of osmotic substances and strengthening antioxidant activities.This finding would be helpful for the bioremediation of coastal soil.

Effect of powdery mildew on interleaf microbial communities and leaf antioxidant enzyme systems

Chinese peony(Paeonia lactiflora Pall.)is both medicinally and aesthetically beneficial.Powdery mildew is a common fungal disease that seriously jeopardizes the value of numerous species,including peonies as a crop.In order to provide a basis for the prevention and treatment of peony powdery mildew,we examined the microbial diversity,the malondialdehyde(MDA)concentrations and antioxidant enzyme activities of peony leaves infected with three levels of powdery mildew to determine any modifications to the leaf's antioxidant enzyme systems and microbial community structure following the onset of disease.The results show that the MDA content rose as the degree of infection became worse.Antioxidant enzyme activity rose and then declined.Following the initiation of powdery mildew,fungal community diversity decreased,whereas there was not any appreciable change in bacterial communities according to microbial diversity sequencing.The relative abundance of more than half of fungal species decreased,with the bacterial genera displaying both abundant and diminished communities with less pronounced alterations in their community structure after the disease spread.Significant different taxa that were critical to the organization of each microbiome were found.Correlation analysis showed that the relative abundance of powdery mildew pathogenic fungal genus Erysiphe was correlated with those of 11 fungal genera and one bacterial genus.Among them,Aureobasidium,Neosetophoma and Sclerostagonospora showed significant positive correlations with Erysiphe and MDA.

Osmotic Regulation,Antioxidant Enzyme Activities and Photosynthetic Characteristics of Tree Peony(Paeonia suffruticosa Andr.)in Response to High-Temperature Stress

Tree peony(Paeonia suffruticosa Andr.)is a traditional Chinese flower,which prefers cool weather.However,high temperature in summer in the middle and lower reaches of the Yangtze River restricts its growth and development.In this study,osmotic regulation,antioxidant enzyme activities,and photosynthetic characteristics of tree peony in response to high-temperature stress were investigated.The results showed that high-temperature stress had destroyed the cell membrane,manifested as the increased relative electrical conductivity and malondialdehyde content.Moreover,high-temperature stress led to excessive accumulation of reactive oxygen species,thereby,activating antioxidant enzyme activities.Also,photosynthetic parameters and chlorophyll fluorescence parameters directly reflected the damage to the photosystem II reflection center under high-temperature stress.In addition,high-temperature stress led to stomatal closure and chloroplast damage.This study revealed the physiological responses of tree peony to high-temperature stress,laying a foundation for the promotion of tree peony in high-temperature areas and the improvement of high-temperature resistance.

Ellagic Acid Enhances Antioxidant System Activity and Maintains the Quality of Strawberry Fruit during Storage

Ellagic acid(EA)is a natural antioxidant,widely present in a lot of forms’soft fruits,nuts,and other plant tissues,and helpful for promoting human health;however,its protective effect on postharvest fruit and improving the quality index of postharvest fruit have rarely been studied.In this experiment,the strawberries were soaked in 0,100,200,300,400,and 500 mg L^(−1) EA,respectively,and the influential EA on fruit quality and the antioxidant system of strawberries were studied.Compared with the control,EA treatment can reduce the browning degree and rotting rate of strawberry fruit during storage and augment the soluble solid content(SSC).EA treatment can also increase the content of related stuff and enzyme activity in antioxidant systems;the gene expression level of polyphenol oxidase(PPO)in strawberries treated with EA was always down-regulated,correspondingly,the expression of other antioxidant enzyme genes was enhanced.Among the strawberry fruits treated with EA of different concentrations,300 mg L^(−1) EA had the best effect in the process of strawberry preservation.The results suggested that the proper concentration of exogenous EA at 300 mg L−1 could maintain strawberries’quality and enhance the antioxidant system by improving the activities of antioxidative enzymes and the ascorbateglutathione(AsA-GSH)cycle during storage.

Microalgae(Chlorella vulgaris Beijerinck)alleviates drought stress of broccoli plants by improving nutrient uptake,secondary metabolites,and antioxidative defense system

Microalgae,such as Chlorella vulgaris Beijerinck(green algae),are beneficial microscopic organisms that may help plants to improve nutrient uptake,growth,and abiotic tolerance to stressors.The current study was performed to investigate the effectiveness of algae(Chlorella vulgaris Beijerinck)foliar applications[1%,3%,or 5%(v/v)]on mitigation of drought stress in broccoli plants subjected to water deficit at 25%of field capacity.The results showed that the broccoli plants grown under drought stress alone exhibited severe disturbance in growth with considerable reductions in the shoot length,and fresh and dry weights,leaf area,relative water content,leaf water potential,and photosynthetic pigment contents and elevated levels of the lipid peroxidation product malondialdehyde in the leaves.Additionally,the foliar application of microalgae mitigated the detrimental effects of drought,leading to better growth performance(increase of 9%–132%)when compared with the drought-stressed plants that had not received an application of microalgae.Microalgae-mediated beneficial effects were particularly evident in the enhancement of the photosynthetic pigment contents,including chlorophyll-a(6%–60%),chlorophyll-b(19%–55%),and total carotenoids(26%–114%).Exogenous microalgae also contributed to the reduction of membrane damage,as proven by significantly decreased levels of malondialdehyde(10%–39%)in the leaves of the broccoli plants exposed to drought stress.The application of microalgae increased the total flavonoid and phenolic contents,and nutrition uptake.Furthermore,the activities of enzymatic antioxidants like ascorbate peroxidase,catalase,glutathione reductase,and superoxide dismutase increased in response to mediation,resulting in significant alleviation of drought-induced oxidative damage.The most effective application concentration of microalgae was determined as 5%.Overall investigations revealed that the foliar application of microalgae could be recommended as a sustainable strategy to improve the defense system of drought-stressed broccoli plants.

Grafting Enhances Copper Tolerance of Cucumber Through Regulating Nutrient Uptake and Antioxidative System

An experiment was carried out to determine plant growth, mineral uptake, lipid peroxidation, antioxidative enzymes, and antioxidant of cucumber plants （Cucumis sativus L. cv. Xintaimici） under copper stress, either ungrafted or grafted onto the rootstock （Cucurbitaficifolia）. Excess Cu inhibited growth, photosynthesis, and pigment synthesis of grafted and ungrafted cucumber seedlings and significantly increased accumulation of Cu in roots besides reducing mineral uptake. Cu concentration in roots of grafted cucumber plants was significantly higher than that of ungrafted plants and obviously lower in leaves. The accumulation of reactive oxygen species （ROS） significantly increased in cucumber leaves under Cu stress and resulted in lipid peroxidation, and the levels of ROS and lipid peroxidation were greatly decreased by grafting. Activities of protective enzymes （superoxide dismutase, SOD; peroxidase, POD; catalase, CAT; ascorbate peroxidase, APX; dehydroascorbate reductase, DHAR; glutathione reductase, GR） and the contents of ascorbate and glutathione in leaves of grafted plants were significantly higher than those of ungrafted plants under Cu stress. Better performance of grafted cucumber plants were attributed to the higher ability of Cu accumulation in their roots, better nutrient status, and the effective scavenging system of ROS.

Aβ-Carotene Ketolase Gene NfcrtO from Subaerial Cyanobacteria Confers Drought Tolerance in Rice

Nostoc flagelliforme is a terrestrial cyanobacterium that can resist many types of stressors,including drought,ultraviolet radiation,and extreme temperatures.In this study,we identified the drought tolerance gene NfcrtO,which encodes aβ-carotene ketolase,through screening the transcriptome of N.flagelliforme under water loss stress.Prokaryotic expression of NfcrtO under 0.6 mol/L sorbitol or under 0.3 mol/L NaCl stress significantly increased the growth rate of Escherichia coli.When NfcrtO was heterologously expressed in rice,the seedling height and root length of NfcrtO-overexpressing rice plants were significantly higher than those of the wild type(WT)plants grown on½Murashige and Skoog solid medium with 120 mmol/L mannitol at the seedling stage.Transcriptome analysis revealed that NfcrtO was involved in osmotic stress,antioxidant,and other stress-related pathways.Additionally,the survival rate of the NfcrtO-overexpression lines was significantly higher than that of the WT line under both hydroponic stress(24%PEG and 100 mmol/L H_(2)O_(2))and soil drought treatment at the seedling stage.Physiological traits,including the activity levels of superoxide dismutase,peroxidase,catalase,total antioxidant capacity,and the contents of proline,trehalose,and soluble sugar,were significantly improved in the NfcrtO-overexpression lines relative to those in the WT line under 20%PEG treatment.Furthermore,when water was withheld at the booting stage,the grain yield per plant of NfcrtO-overexpression lines was significantly higher than that of the WT line.Yeast two-hybrid analysis identified interactions between NfcrtO and Dna J protein,E3 ubiquitin-protein ligase,and pyrophosphate-energized vacuolar membrane proton pump.Thus,heterologous expression of NfcrtO in rice could significantly improve the tolerance of rice to osmotic stress,potentially facilitating the development of new rice varieties.

Melatonin mitigates cold-induced damage to pepper seedlings by promoting redox homeostasis and regulating antioxidant profiling

This study assessed the influence of exogenous ME in the mitigation of cold damage in pepper seedlings. Melatonin(ME) is a dynamic molecule that helps plants cope with stress in several ways. Cold stress(CS) is one of the most important environmental factors that restrict plant growth and yield. Pepper(Capsicum annuum L.) is a valuable commercial crop, highly sensitive to CS. Thus, identifying an efficient strategy to mitigate cold damage is critical for long-term pepper production. For this purpose, the roots of pepper seedlings were pretreated with ME(5 μmol · L^(-1)) and exposed to CS for 7 d. The results indicated that CS suppressed pepper growth, hampered photosynthetic capacity, and damaged root architecture in pepper plants. In contrast, the production of reactive oxygen species(ROS), malondialdehyde(MDA), electrolyte leakage(EL), proline, and soluble sugars were enhanced in plants under CS. ME(5 μmol · L^(-1)) pretreatment reduced the negative effects of CS by recovering plant growth, root traits, gas exchange elements, and pigment molecules compared to CS control treatment. Furthermore, ME application efficiently reduced oxidative stress markers [hydrogen peroxide(H_(2)O_(2)), superoxide ion(O_(2)^(·-)), EL, and MDA] while increasing proline and soluble sugar content in pepper leaves. ME application combined with CS further increased antioxidant enzymes and related gene expression. Collectively, our results confirmed the mitigating potential of ME supplementation for CS by maintaining pepper seedling growth,improving the photosynthesis apparatus, regulating pigments, and osmolyte content.

Effects of Potassium-Solubilizing Bacteria on Growth, Antioxidant Activity and Expression of Related Genes in Fritillaria taipaiensis P. Y. Li

This study aimed to examine the effects of inoculating Fritillaria taipaiensis P.Y.Li leaves with different strains ofpotassium-solubilizing bacteria (KSB), or combinations thereof, focusing on aspects of photosynthesis and physiologicaland biochemical characteristics. At present, some studies have only studied the rhizosphere microbialcommunity characteristics of F. taipaiensis and have not discussed the effects of different microbial species on thegrowth promotion of F. taipaiensis. This paper will start from the perspective of potassium-solubilizing bacteria toconduct an in-depth study. Seed cultivation commenced at the base with three different KSBs in early October2022. The growth of F. taipaiensis leaves was observed after different treatments. Both single-plant and compoundinoculations were executed. A total of eight treatment groups were established, with aseptic fertilizer and sterilizedsoil functioning as the control group. The results reveal that intercellular CO_(2) concentration (Ci), stomatal conductance(Gs), and transpiration rate (Tr) were at their apex in the S7 group. Most treatment groups exhibited anincrease in leaf area, photosynthetic pigment content, soluble sugar, soluble protein, Superoxide Dismutase(SOD), Peroxidase (POD), Catalase (CAT) activities, and proline content. The expression levels of POD, SOD,and CAT genes were evaluated, following inoculation with different KSB. The highest was the S7 group. Theinoculation with various KSB, or combinations thereof, appears to bolster the growth and development of F. taipaiensis.The composite inoculation group S7, comprising Bacillus cereus, Burkholderia cepacia, and Bacillus subtilis,manifested the most favorable impact on the diverse indices of F. taipaiensis, thereby furnishing valuableinsights for the selection of bacterial fertilizer in the artificial cultivation of F. taipaiensis.

Salt Stress Induced Modulations in Growth, Compatible Solutes and Antioxidant Enzymes Response in Two Cultivars of Safflower (Carthamus tinctorius L. Cultivar TSF1 and Cultivar SM) Differing in Salt Tolerance

Safflower is an important, traditional, multipurpose oil crop. This was to investigate the effect of different salinity levels on morphological, physiological, biochemical and antioxidant response of two safflower cultivars (Carthamus tinctorius L. cultivar TSF1 and cultivar SM) differing in salt tolerance. Salinity stress (0.0%, 1.0%, 1.5% and 2.0% of NaCl) was induced to safflower plants after 19 days of vegetative growth. After 12 days of stress impositions, plants were harvested and analysed for various parameters. The results revealed that cultivar TSF1 showed maximum growth, dry weight, cell membrane stability and more water content in both root and leaf tissues at higher salinity levels than cultivar SM. Salt stress resulted an accumulation of more soluble sugars, amino acids, proline and glycine betaine at high salinity level confers the tolerance potential of cultivar TSF1 over cultivar SM. Salt stress induces more increase in the enzyme activity of superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase and catalase in tolerant cultivar than sensitive one. The results indicate that each cultivar adopt specific strategy at distinct salinity level for resistance against salinity. The possible conclusion is that improved tolerance in cultivar TSF1 to salinity may be accomplished by better management of growth, physiological attributes and antioxidative defence mechanisms.

Effects of Exogenous H_(2)O_(2) on ROS Metabolism in Nitraria tangutorum Bobr. Leaves Under Salt Stress

Salt stress is a major abiotic stress limiting plant growth and yield. In the present study, the effects of exogenous H_(2)O_(2) on the reactive oxygen species(ROS) metabolism and the antioxidant system in leaves of Nitralia tangutorum Bobr. under salt stress were studied. N. tangutorum seedlings were subjected to 200 mmol·L^(-1) NaCl treatment with or without the exogenous application of H_(2)O_(2) for 7 days. The results showed that NaCl stress significantly increased the relative conductivity, the contents of thiobarbituric acid reactive substances(TBARS) and ROS(H_(2)O_(2) and O_(2)^(·-)), as well as promoted the activities of antioxidant enzymes including superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and ascorbate peroxidase(APX) in N. tangutorum leaves. In addition, exogenous H_(2)O_(2) decreased the relative conductivity, the contents of TBARS, H_(2)O_(2) and O_(2)^(·-), while further enhanced the activities of antioxidant enzymes. These results indicated that H_(2)O_(2) effectively alleviated the adverse effects of NaCl stress on N. tangutorum through the regulation of ROS metabolism.