Free Proline Research Articles

Peroxidación lipídica, contenido en prolina libre y azúcares solubles como indicadores de tolerancia al estrés oxidativo en algunas líneas avanzadas de trigo duro (Triticum durum Desf.).

Oxidative stress induced by glyphosate is a complex phenomenon caused by an imbalance between reactive oxygen species (ROS) and antioxidants in plants cells. The present research was carried out at the field crops institute, Agricultural Experimental Station of Setif (ITGC-AES), to assess the response of some durum wheat (Triticum Durum Desf.) lines exposed to oxidative stress induced by glyphosate herbicide. In the heading stage, a solution of 5 Mm of glyphosate was sprayed on flag leaves, and each measurement was taken 48 hours after the glyphosate application. Lipid peroxidation, free proline and soluble sugars were determined. The results indicated that oxidative stress increased the content of lipid peroxidation, proline, and soluble sugars in flag leaves. Analysis of variance revealed significant differences among the genotypes tested, the increase in the level of lipid peroxidation is much higher in advanced lines G5 and G3, in which lipid peroxidation and membrane damage are greater. Oxidative damage also increased the proline content in lines G3 and G4, and soluble sugars in line G5, which were showing a high tolerance to the oxidative stress induced.

Physiological Variables Influenced by 'Candidatus Liberibacter asiaticus' Infection in Two Citrus Species.

'Candidatus Liberibacter asiaticus' is the bacterium associated with the citrus disease known as huanglongbing (HLB). This study evaluated the influence of 'Ca. L. asiaticus' infection on a number of key plant physiological variables concerning photosynthesis, cell integrity, reactive oxygen species scavengers' activity, and osmoregulation of two different species of citrus-the pomelo Citrus maxima and the mandarin C. reticulata 'Tankan'-relative to their measured 'Ca. L. asiaticus' infection load. Results indicated that all measured physiological variables except soluble sugar were affected by increased 'Ca. L. asiaticus' infection titers, wherein the variety C. maxima proved overall more resistant than C. reticulata. 'Ca. L. asiaticus' infection was linked in both plants to decrease in chlorophyll concentration, cell membrane permeability, and malondialdehyde, as well as increased free proline and starch contents. Chlorophyll fluorescence measurements taken 9 months after grafting the mandarin C. reticulata with 'Ca. L. asiaticus' scions revealed a significant decrease in the photosynthesis variables maximum photochemical quantum yield of photosystem II (PSII), effective photochemical quantum yield of PSII, and coefficient of photochemical fluorescence quenching assuming interconnected PSII antennae, whereas nonphotochemical fluorescence quenching increased significantly; C. maxima plants, on the other hand, did not show significant differences until the 12th month from infection exposure. The variables superoxide dismutase, catalase, peroxidase, and soluble protein initially increased and later decreased. In addition, progression of 'Ca. L. asiaticus' replication in both citrus species was accompanied by rapid changes in three reactive oxygen species scavenging enzymes in C. maxima, while the pattern was different in C. reticulata. We hypothesize that the observed interspecific differences in physiological change are related to their relative resistance against 'Ca. L. asiaticus' infection. These results provide a scaffold for better describing the pathogenesis, selecting the most resistant breeds, or even validating pertaining omics research; ultimately, these detailed observations can facilitate the diagnosis of 'Ca. L. asiaticus' infection.

The influence of polyguanidin on the direction of biochemical processes in wheat (Triti- cum L.) plants.

Modern crop production requires a balance of high and sustainable productivity with maximum safety for the environment, consumers and agricultural workers. The well-known chemical compound polyguanidine, which was previously used as a disinfectant, surfactant and complexing agent, has recently become widely used as a plant growth and development stimulant. Despite the increasing use of polyguanidine preparations as a growth stimulant, there is no data in the literature on its mechanism of action on plants. There are many studies that try to determine whether the effect of biostimulants on plant productivity is a direct or indirect response, for example, through the soil or microbiome. In many cases, biostimulants are considered in terms of their effects on various plant regulatory and functional systems (signaling, metabolic, uptake and transport mechanisms, etc.). But, in general, these modes of action are very diverse and may include activation of nitrogen metabolism or release of phosphorus from soils, general stimulation of soil microbial activity, or stimulation of root growth and increased plant nutrition. The effect of polyguanidin on the physiological parameters of wheat plants was studied under vegetation and laboratory conditions. Seeds of winter wheat variety Bogdana were used for the study. For the determination of flavonoids, a spectrophotometric method based on the measurement of their absorption with aluminum chloride complex was used. It was proved that the treatment of wheat in the tillering and earing phases with polyguanidin had the greatest effect on the protein content in winter wheat grain, which ensured the formation of this indicator at the level of 11.0–13.4% compared to the control. The treatment of wheat seeds with a preparation based on polyguanidine increased the amount of chlorophyll a by almost two times, while the content of chlorophyll b and carotene increased somewhat less. Thus, the use of polyguanidine contributes to the efficient functioning of the photosynthetic apparatus of plants, which will increase their productivity. Since the energy basis of photosynthesis is the absorption of solar radiation by photosynthetic pigments, which are used to form organic matter, there is a direct link between chlorophyll content and plant productivity. Therefore, we decided to check the content of the main photosynthetic pigments in plants after treatment with polyguanidine. At the first stage of our research, plants at the early stages of ontogenesis were analyzed. Thus, we have shown that the treatment of wheat seeds with a polyguanidine-based preparation increases the amount of chlorophyll a almost twice. Evaluation of flavonoid content in wheat plants showed a decrease in their amount after treatment with polyguanidin. That is, after the treatment, the plants, on the contrary, reduced their adaptive potential, because at the biochemical stage it was believed that there were no unfavorable factors in the environment. The analysis of the free proline content showed an increase in its concentration after treatment with the test substance almost doubled both after the first and after the second treatment. Also, it should be noted that reducing the concentration of the drug to 0.15 liters per 200 liters of the working solution increases the level of proline after the first treatment. The increase in proline, in this case, can lead to an increase in stress resistance, which is provided by metabolic and physiological changes. Consequently, its accumulation and conversion into other amino acids due to changes in the activity of proline oxidase contributes to an increase in the protein content in the grain.

Transcriptomic analysis revealed the candidate metabolic pathways and genes associated with cold tolerance in a mutant without anthocyanin accumulation in common vetch (Vicia sativa L.)

Common vetch (Vicia sativa L.) is a leguminous crop used to feed livestock with vegetative organs or fertilize soils by returning to the field. Survival of fall-seeded plants is often affected by freezing damage during overwintering. This study aims to investigate the transcriptomic profiling in response to cold in a mutant with reduced accumulation of anthocyanins under normal growth and low-temperature conditions for understanding the underlying mechanisms. The mutant had increased cold a tolerance with higher survival rate and biomass during overwintering compared to the wild type, which led to increased forage production. Transcriptomic analysis in combination with qRT-PCR and physiological measurements revealed that reduced anthocyanins accumulation in the mutant resulted from reduced expression of serial genes involving in anthocyanin biosynthesis, which led to the altered metabolism, with an increased accumulation of free amino acids and polyamines. The higher levels of free amino acids and proline in the mutant under low temperature were associated with improved cold tolerance. The altered expression of some genes involved in ABA and GA signaling was also associated with increased cold tolerance in the mutant.

The ubiquitin-binding protein MdRAD23D1 mediates drought response by regulating degradation of the proline-rich protein MdPRP6 in apple (Malus domestica).

RAD23 (RADIATION SENSITIVE23) proteins are a group of UBL-UBA (ubiquitin-like-ubiquitin-associated) proteins that shuttle ubiquitylated proteins to the 26S proteasome for breakdown. Drought stress is a major environmental constraint that limits plant growth and production, but whether RAD23 proteins are involved in this process is unclear. Here, we demonstrated that a shuttle protein, MdRAD23D1, mediated drought response in apple plants (Malus domestica). MdRAD23D1 levels increased under drought stress, and its suppression resulted in decreased stress tolerance in apple plants. Through in vitro and in vivo assays, we demonstrated that MdRAD23D1 interacted with a proline-rich protein MdPRP6, resulting in the degradation of MdPRP6 by the 26S proteasome. And MdRAD23D1 accelerated the degradation of MdPRP6 under drought stress. Suppression of MdPRP6 resulted in enhanced drought tolerance in apple plants, mainly because the free proline accumulation is changed. And the free proline is also involved in MdRAD23D1-mediated drought response. Taken together, these findings demonstrated that MdRAD23D1 and MdPRP6 oppositely regulated drought response. MdRAD23D1 levels increased under drought, accelerating the degradation of MdPRP6. MdPRP6 negatively regulated drought response, probably by regulating proline accumulation. Thus, "MdRAD23D1-MdPRP6" conferred drought stress tolerance in apple plants.

Respostas bioquímicas em manga ‘Kent’ cultivada no semiárido brasileiro sob diferentes doses de triacontanol

ABSTRACT The management adopted for the mango crop requires that, at a certain stage, the irrigation depth should be reduced to promote a more uniform flowering. In regard to that, it is necessary to introduce new alternatives that mitigate the harmful effects of abiotic stress and that promote greater fruit yield. Therefore, the present study aimed to evaluate the influence of triacontanol on the levels of organic solutes, antioxidant enzymatic activity, and production of ‘Kent’ mango under Brazilian semi-arid conditions. The experiment was carried out for two consecutive years, 2018 and 2019, in a commercial orchard located at the DAN Farm, Petrolina-PE. The experimental design used was randomized blocks, with five treatments and four replications, evaluating four plants per plot. The treatments consisted of triacontanol doses: 0 (control treatment), 3.75; 7.50; 11.25, and 15.00 ppb per plant. Two consecutive harvests (2018 and 2019) were evaluated during the stages of branch maturation (2019 only), floral induction, full flowering, and initial fruiting. Foliar application of triacontanol positively favored the contents of total amino acids, free proline, total proteins, and activity of the enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). There was an increase in production of 50.85% (dose - 11.25 ppb) and 64.95% (dose - 10.50 ppb) in the 2018 and 2019 crop years, respectively.

Oxidative Damages of Two Neonicotinoid Pesticides to Arthrospira platensis (Gomont)

In this study, chlorophyll-a amount, OD 560 and antioxidant parameters (total SOD, APX, GR, MDA, H2O2 and Proline) were determined in order to understand the effects of Thiacloprid and Imidacloprid on Arthrospira platensis Gomont. Both Imidacloprid and Thiacloprid applications showed significant reductions in growth rate and chlorophyll-a content of A. platensis cultures with dose-dependent manner when the days and concentrations were compared each other. SOD activity significantly decreased in the Imidacloprid application while Thiacloprid caused a significant increase only at 75 µg mL-1 concentration. APX activity significantly increased in the Imidacloprid and Thiacloprid applications at 50 µg mL-1 and 35 µg mL-1 concentrations, respectively. Imidacloprid treatment increased GR activity at 20 and 30 µg mL-1 concentrations while GR activity increased at 15, 25 and 35 µg mL-1 Thiacloprid concentrations. The MDA content of A. platensis cultures did not change with Imidacloprid or Thiacloprid applications. The H2O2 content did not change at all different Imidacloprid concentrations. However, the H2O2 content decreased at 15 µg mL-1 and increased at 45 and 75 µg mL-1 Thiacloprid concentrations. Free proline content increased in the Imidacloprid and Thiacloprid applications at 100 µg mL-1 and 75 µg mL-1 concentrations, respectively. These neonicotinoid pesticides cause oxidative stress in A. platensis cells.

Effect of Selenium on Growth, Physio-Biochemical and Yield Traits of Lettuce under Limited Water Regimes

Climate change has become one of the most complicated challenges of the twenty-first century. Water scarcity is a significant threat to food security, and climate change has adversely affected the likelihood of extreme events such as drought. Selenium (Se) has been reported to mitigate abiotic stress effects, such as drought, on various plant species. The purpose of the current study was to observe the effects of foliar-applied Se to minimize the detrimental effects of water-deficient conditions. Therefore, this study was designed to evaluate the exogenous application of Se at various levels (0, 3, 6 and 9 mg L−1) on the growth, physio-biochemical attributes and antioxidant defense system of lettuce plants growing under an irrigation water deficit from 85 ± 5% (control) to 35 ± 5% (drought stress). The results revealed that increasing water deficit stress linearly reduced plant growth and biomass by reducing relative water content (19.49%) and chlorophyll contents (23.95%) through increased electrolyte leakage (20.67%). However, foliar-applied Se significantly increased fresh and dry biomass under control and water-stressed conditions. Under drought stress, Se supply increased free proline content and the activities of SOD, POD and CAT in leaf tissues. The exogenous application of Se partly alleviated the effects of drought on lettuce by the upregulation of the antioxidant system and leaf soluble sugars and a simultaneous decrease in electrolyte leakage. This study further suggests that the upregulation of antioxidants and osmoprotectants is positively associated with the drought tolerance of lettuce. In conclusion, the exogenous application of Se (6 mg L−1) has more potential to improve lettuce growth, physiological attributes and modulation of enzymatic antioxidant potential, which can be recommended for use to maximize lettuce productivity and quality in a dry environment. This research provides a promising, technically feasible strategy for mitigating drought stress in order to achieve the Sustainable Development Goals (SDGs) of good health and zero hunger.

Integrated strength of osmotic potential and phosphorus to achieve grain yield of rice under water deficit by arbuscular mycorrhiza fungi

Arbuscular mycorrhizal ecosystem provides sustainability to plant integrity under drought situations. However, host plants that survive in drought frequently lose yield. The potential of Funneliformis mosseae (F), Claroideoglomus etunicatum (C), and Acaulospora fovaeta (A) was assessed to evaluate in indica rice cv. Leum Pua during booting stage under 21-day water withholding. The effects of three inoculation types; (i) F, (ii) F + C (FC), and (iii) F + C + A (FCA), on physiological, biochemical, and yield traits were investigated. The three types showed an induced total chlorophyll content in the host as compared to uninoculated plants. Total soluble sugars and free proline were less regulated by FC and FCA inoculated plants than by F inoculated plants under water deficit conditions. However, the FC and FCA inoculations increased phosphorus content, particularly in the shoots of water-stressed plants. In the three inoculations, the FCA dramatically improved plant osmotic potential adaptability under water deficit stress. Furthermore, even when exposed to the water deficit condition, panicle weight, grain number, and grain maturity were maintained in FCA inoculated plants. According to the findings, the increased osmotic potential and phosphorus content of the FCA-inoculated rice plant provide a protection sign against drought stress and will benefit food security in the future.

Leaf extract of neem (Azadirachta indica Adr. Juss.) modulates morphological and biochemical characteristics in maize (Zea mays L.) under water deficit stress

Foliar spray of neem (Azadirachta indica Adr. Juss.) leaf extract was exogenously applied at pre-flowering stage to examine the changes in growth and physio-biochemical characteristics of two maize cultivars (Sultan and Sadaf) under different water regimes (100%, 75% and 60% field capacity). Water deficit conditions significantly reduced shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), root dry weight (RDW), shoot length, root length, chlorophyll b, total soluble proteins and free proline, but it significantly increased ascorbic acid (AsA) and total phenolics in both maize cultivars. Foliar-applied leaf neem extract significantly improved SFW, SDW, RFW, RDW, shoot length, chlorophyll b and ascorbic acid concentrations, but it significantly minimized hydrogen peroxide (H2O2) contents. Application of 1.0% neem extract was effective in improving chlorophyll b and AsA contents, whereas 2.0% neem extract was beneficial for total soluble proteins and MDA contents. Of both maize cultivars, cv. Sultan was found to be drought sensitive and cv. Sadaf as drought tolerant. Exogenous application of leaf neem extract was suggested to be effective in enhancing drought stress tolerance in maize by improving plant growth and oxidative defense system.

Selenium nanoparticles induce growth and physiological tolerance of wastewater‑stressed carrot plants

Climate changes have a direct impact on agricultural lands through their impact on the rate of water levels in the oceans and seas, which leads to a decrease in the amount of water used in agriculture, and therefore the use of alternative sources of irrigation such as wastewater and overcoming its harmful effect on plants was one of the solutions to face this problem. In the present study, the impacts of the synthesized selenium nanoparticles (Se NPs) alone or in combination with glycine betaine and proline treatments on the growth, physiological, and yield attributes of wastewater irrigated carrot plants are investigated. Furthermore, to evaluate heavy metals uptake and accumulation in edible plant parts. The usage of wastewater to carrot plants significantly increased free proline contents, total phenols, superoxide dismutase, catalase, peroxidase, polyphenol oxidase, Malondialdehyde (MDA), and hydrogen peroxide (H2O2) throughout the two growth stages. While total soluble carbohydrate and soluble protein content in carrot shoots and roots were significantly reduced. Moreover, the concentrations of nickel (Ni), cadmium (Cd), lead (Pb), and cobalt (Co) in carrot plants were considerably higher than the recommended limits set by international organizations. Application of selenium nanoparticles alone or in combination with glycine betaine and proline reduced the contents of Ni, Cd, Pb, and Co; free proline; total phenols; superoxide dismutase; catalase; peroxidase; polyphenol oxidase; Malondialdehyde (MDA) and Hydrogen peroxide (H2O2) in carrot plants. However, morphological aspects, photosynthetic pigments, soluble carbohydrates, soluble protein, total phenol, and β-Carotene were enhanced in response to Se NPs application. As an outcome, this research revealed that Se NPs combined with glycine betaine and proline can be used as a strategy to minimize heavy metal stress caused by wastewater irrigation in carrot plants, consequently enhancing crop productivity and growth.

Exogenous Calcium Reinforces Photosynthetic Pigment Content and Osmolyte, Enzymatic, and Non-Enzymatic Antioxidants Abundance and Alleviates Salt Stress in Bread Wheat.

One of the main environmental stresses that hinder crop development as well as yield is salt stress, while the use of signal molecules such as calcium (Ca) has a substantial impact on reducing the detrimental effects of salt on different crop types. Therefore, a factorial pot experiment in a completely randomized design was conducted to examine the beneficial role of Ca (0, 2.5, and 5 mM) in promoting the physiological, biochemical, and growth traits of the wheat plant under three salt conditions viz. 0, 30, and 60 mM NaCl. Foliar application of Ca increased the growth of salt-stressed wheat plants through increasing photosynthetic pigments, IAA, proline, and total soluble sugars contents and improving antioxidant enzymes in addition to non-enzymatic antioxidants glutathione, phenol and flavonoids, β-carotene, and lycopene contents, thus causing decreases in the over-accumulation of free radicals (ROS). The application of Ca increased the activity of antioxidant enzymes in wheat plants such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), which scavenge reactive oxygen species (ROS) and relieved salt stress. An additional salt tolerance mechanism by Ca increases the non-antioxidant activity of plants by accumulating osmolytes such as free amino acids, proline, and total soluble sugar, which maintain the osmotic adjustment of plants under salinity stress. Exogenous Ca application is a successful method for increasing wheat plants' ability to withstand salt stress, and it has a considerable impact on the growth of wheat under salt stress.

Bioadsorption – To Clean Match Industry Effluent Toxicity

This study investigates the possibility of applying an adsorption process using seaweed dry powder natural seaweeds the adsorbents were used to treat real match industry effluent. Bioadsorption is an effective low-cost tool for cleaning polluted environment. In the present study the seedlings of Vigna mungo (L) Hepper were treated with various concentrations of match industry effluent and their impact on the growth, biochemical and enzyme characters were studied. After fourteen days treatment with different concentration of match industry effluent (20%, 40%, 60%, 80% and 100%) the growth parameter such as,shoot and root lengths, leaf area, fresh weight and dry weight were decreased than the control. Biochemical parameters such as chlorophyll, carotenoids, soluble sugar, protein content and nitrate reductase activity also decreased with the increase in the concentration of cobalt chloride. But the content of free amino acid, proline, phenol and leaf nitrate content were increased with the increase in the concentration of cobalt chloride. The activities of enzyme such as catalase, peroxidase and polyphenol oxidase were found to be increased with the increase in the concentration of match industry effluent. Application of seaweed (Sargassum wightii) in different concentrations (2gm/L, 4gm/L and 6gm/L) on 60% efluent treated plants has shown the stress relieving effect caused by the toxins of match industry effluent. It is good low cost bioadsorbant for match industry effluent pollution.

Estimation of Drought Tolerance Indices in Upland Cotton under Water Deficit Conditions

Cotton is a precious commodity that offers raw material to the textile industry. This crop is grown in tropical and sub-tropical regions of the world. Abiotic stresses exerts negative impact on cotton production, but water scarcity has the worst impact. It is rising due to current situation, in which global warming is producing a decrease in precipitation while an increase in evapo-transpiration is causing an agricultural drought. Thus, it is a difficult task for cotton breeders to identify cotton lines that can respond to areas with limited water supplies without lowering yields and might be utilized as suitable parents in a breeding program to produce drought-tolerant indices. The primary objective of this research was the estimation of drought tolerance indices in upland cotton under water deficit conditions. For this purpose, fifty accessions of upland cotton were assessed for their ability to tolerate the water stress under three conditions, namely control, 50% FC, and 75% FC. These genotypes showed significant variations based on morpho-physiological and biochemical characteristics. At control conditions, these genotypes exhibited enhanced growth and better performance. Whereas, the behavior of some indices under 75% FC showed less growth as compared to control, while under the 50% FC highly significant reductions were observed among genotypes. The genotypes that are resistant to drought and those that are susceptible were found using the K-means cluster and biplot analysis. In terms of performance, the genotypes namely Cyto-515, CIM-595, FH-142, and IR-3701 exhibited relatively better in all the treatments and low excised leaf water loss, high relative water contents, chlorophyll contents, free proline contents, and peroxidase activity were observed to be useful selection criteria for drought resistance. These identified genotypes namely, Cyto-515, CIM-595, FH-142, and IR-3701 may be grown in water deficit areas of the country to assess their potential, could be used in breeding programs for development of germplasm suitable for water stress conditions.

Sodium hydrosulfide-mediated upregulation of nitrogen metabolism improves drought stress tolerance in pepper plants

Although hydrogen sulfide (H2S) has been proven to promote plant tolerance to abiotic stress (including drought), the specific mechanism by which H2S mediates this process remains uncertain. The aim of the study was to fill this knowledge gap by investigating the potential of sodium hydrosulfide (NaHS) to improve drought tolerance in pepper plants through upregulating nitrogen metabolism-related enzymes and to gain insights into plant responses to drought stress. Pepper (Capsicum annuum) plants were grown at 80% and 40% of full field capacity. Reduced water availability led to a drastic decline in plant dry weight, leaf water potential (ΨI), relative water content (RWC), PSII operation efficiency (chlorophyll fluorescence Fv/Fm ratio), and chlorophyll content. Soluble protein and leaf and root nitrogen (N) levels were also lowered. Simultaneously, drought has significantly increased the levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA), and resulted in increased content of nitrate (NO3-) and ammonium (NH4+). Also increased were the amount of free amino acid, soluble sugars, glycine betaine and free proline. The activities of peroxidase (POD), glutathione S-transferase (GST), and catalase (CAT) were elevated, as were those of endogenous hydrogen sulfide (H2S), L-cysteine desulfhydrase (L-DES), and methylglyoxal (MG). When 0.2 mM sodium dihydrosulfide (NaHS, a H2S donor) was sprayed on drought-affected plants, oxidative stress markers were reduced, as well as NO3-, NH4+ and free amino acid levels. Furthermore, NaHS improved endogenous H2S without changing L-DES activity. At the same time, NaHS activated nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthetase (GOGAT) and glutamine dehydrogenase (GDH) activities, as well as enzymes related to the glyoxalase system (Gly I and Gly II) thus improving nitrogen metabolism. This resulted in an increased plant growth, photosynthetic attributes, and N content. To demonstrate the causal role of H2S in drought tolerance, plants were administered an H2S scavenger, hypotaurine (HT), along with NaHS. HT treatment negated beneficial effects of NaHS by lowering H2S content without changing L-DES activity. Thus, exogenous application of NaHS could offer a simple and economical alternative for crop productivity in environments with restricted water supply.

Mediating Effect of Bio-Organic Fertilizer on the Physiological Characteristics of “Qi-Nan” Agarwood from Aquilaria sinensis (Lour.)

This study examines the impact of bio-organic fertilizers on the physiological characteristics and leaf nutrient content of “Qi-Nan” agarwood seedlings. The aim is to provide a theoretical foundation for the efficient cultivation of “Qi-Nan”. The experiment was conducted under field conditions using a Randomized complete block design. The control group received no fertilization, while the three fertilizer-treated groups received vermicompost, sheep manure, or microbial organic fertilizer. The results indicate that the application of bio-organic fertilizer significantly promoted the growth of plant height and diameter, increased the contents of soluble proteins, soluble sugar, chlorophyll, and leaf nutrients; and decreased the contents of free proline, peroxidase, malondialdehyde, and other stress indices. Redundancy analysis showed that the main factors affecting the seedlings height and diameter were free proline, chlorophyll, total nitrogen, and total potassium. Principal component analysis and membership function analysis revealed significant variations in growth, physiological characteristics, and nutrient content among the three fertilizer groups and the control group, with vermicompost > microbial organic fertilizer > sheep manure > no fertilization. In conclusion, biological organic fertilizer significantly promotes the growth of “Qi-Nan” seedlings, and vermicompost is the most effective fertilizer in this experiment.

Effects of Cd treatment on morphology, chlorophyll content and antioxidant enzyme activity of Elymus nutans Griseb., a native plant in Qinghai-Tibet Plateau

ABSTRACT Cd pollution is a global environmental problem. However, the response mechanism of the alpine plant Pelagia under Cd stress remains unclear. Therefore, in this study, a native plant(Elymus nutans Griseb.) of the Qinghai-Tibet Plateau was used as the material to quantify plant height, leaf number, length of leaf, crown width, root number, biomass, Dry weight malondialdehyde (MDA), free proline, superoxide dismutase (SOD), ascorbate enzyme (APX), catalase (CAT) and chlorophyll contents under different Cd concentrations. The results showed that the growth of Elymus nutans Griseb. was a phenomenon of “low concentration promotes growth, high concentration inhibited growth” under Cd treatment. It meant that 10 mg·L−1 Cd promoted the growth of leaf number, plant height, crown width and tiller number, while 40 mg·L−1 Cd inhibited the growth of root number and biomass of Elymus nutans Griseb. compare with the control. The MDA content, free proline content, SOD activity, APX activity and CAT activity of Elymus nutans Griseb. was increased with the increase of Cd treatment concentration to resist the oxidative damage caused by Cd to the body. At the same time, the accumulation of chlorophyll A, chlorophyll B and chlorophyll AB was decreased with the increase of Cd stress concentration. In addition, the carotenoid content did not change much between the control group and the treatment group, indicating that Cd treatment had little effect on it. The results could provide a reference for the mechanism of heavy metal resistance and the selection and improvement of Cd -resistant varieties of Elymus nutans Griseb.

Physiological, Biochemical, Anatomical, and Agronomic Responses of Sesame to Exogenously Applied Polyamines under Different Irrigation Regimes

Polyamines (PAs) are plant growth regulators that attenuate the destructive impacts of water deficit on sesame plants, particularly in arid regions under abrupt climate change. Limited information is available on the physiological, biochemical, anatomical, and agronomic responses of sesame to exogenous application of PAs under water deficit under field conditions. Thus, a two-season field trial was carried out to assess the impact of exogenously sprayed spermine (Spm), spermidine (Spd), and putrescine (Put) on physio-biochemical and anatomical parameters and their influences on agronomic performance and crop water productivity of sesame plants. The sesame plants were assessed under three irrigation regimes; full irrigation (100% ETc), mild drought (75% ETc), and severe drought (50% ETc) conditions. Drought stress displayed negative impacts on all evaluated parameters. However, exogenously applied Pas, especially Put, restricted the destructive effects of water deficit. The application of PAs exhibited highly significant enhancement in photosynthetic pigments (chlorophyll a, b, and carotenoids), gas exchange (net photosynthetic rate, stomatal conductance, and rate of transpiration), water relations (relative water content, membrane stability index, excised leaf water retention), and plant nutrient content (N, P, and K) compared to untreated plants, particularly under severe drought stress. Moreover, PA application displayed highly significant amelioration in osmoprotectants (free proline, soluble sugars, α-Tocopherol, ascorbate, and glutathione), and antioxidant enzyme activities (catalase, peroxidase, superoxide dismutase, ascorbate peroxidase, and glutathione reductase). In addition, foliar nourishing with PAs exhibited a highly significant reduction in oxidative stress markers (malondialdehyde, electrolyte leakage, superoxide, and hydrogen peroxide). These positive impacts of PA application under drought stress were reflected in highly significant improvement in anatomical characteristics (midrib length and width, vascular bundle length and width, thickness of phloem, xylem and collenchyma, vessel diameter, and number of xylem rows in midvein bundle), and yield-related traits (plant height, leaf area, number of capsules per plant, 1000-seed weight, seed yield, and oil content). Consequently, exogenous application of PAs (in particular, Put) could be exploited to enhance the crop water productivity and yield traits of sesame plants under low water availability in arid regions.

Trehalose and NO work together to alleviate Cd toxicity in pepper (Capsicum annuum L.) plants by regulating cadmium sequestration and distribution within cells and the antioxidant defense system

The response of plants to trehalose (TR) and nitric oxide (NO) has been tested in different stressful conditions, but the contribution of endogenous TR to plant tolerance to cadmium stress (Cd-S) induced by NO is still unclear. Ten days after germination, among the pepper seedlings, half were immersed for 12 h in a solution containing 15.0 mM TR or 0.6 mM sodium citrate (SC), an inhibitor of trehalose-6-phosphate phosphatase (TPP). Then, the plants were exposed to control (no addition of Cd) or Cd-S (0.1 mM CdCl2) up to two additional weeks. Throughout the stress period, both treatments were combined with sodium nitroprusside (SNP; 0.1 mM), a NO donor, supplied through the nutrient solution. Plants exposed to Cd-S experienced a substantial reduction in plant growth, photosynthesis, and leaf water relation parameters, but an increase in oxidative stress parameters, free proline, phytochelatins (PCs), and the activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), and ascorbate peroxidase (APX). The detrimental effects of Cd-S on the afore-mentioned traits were reversed by the supplementation of SNP, which in turn significantly increased the endogenous NO and TR levels, and leaf calcium (Ca2+) and potassium (K+), and reduced the leaf H2O2, MDA, and Cd contents as well as membrane leakage. SNP raised the amounts of GSH and PCs in Cd-S- plants, thereby modulating Cd sequestration to render it nontoxic. The treatment of SNP encouraged Cd build-up in the cell walls of root and leaf in order to prevent Cd from being transported to other vital cell organelles to safeguard them from metal toxicity. The supplementation of SC, a scavenger of TPP, eliminated TR content, thereby reversing the positive effect of SNP on Cd-S plants. Exogenous application of TR together with SNP+SC reversed the negative effect of SC. This suggests that TR is necessary for NO to be effective in improving the pepper plant Cd-S tolerance.

Phytomitigation potential and adaptive responses of helophyte Typha latifolia L. to copper smelter-influenced heavily multi-metal contamination.

The present study of phytomitigation potential and adaptive physiological and biochemical responses of helophyte Typha latifolia L. growing in water bodies at different distances from the century-old copper smelter (JSC "Karabashmed" Chelyabinsk Region, Russia) was conducted for the first time. This enterprise is one of the most dominant sources of multi-metal contamination for water and land ecosystems. The aim of the research was to assess the heavy metal (Cu, Ni, Zn, Pb, Cd, Mn, and Fe) accumulation, the photosynthetic pigment complex, and some redox reactions in T. latifolia from six differently technogenic impacted sites. In addition, the quantity of mesophilic aerobic and facultative anaerobic microorganisms (QMAFAnM) in rhizosphere sediments, as well as some plant growth-promoting (PGP) attributes of 50 isolates from each site, were determined. The water and sediment metal concentrations in highly contaminated sites exceeded the permissible/critical limits and were found much higher than that previously reported by other researchers while studying this helophyte. Both the degree of contamination and geoaccumulation indexes further elucidated extremely high contamination due to prolonged activity of copper smelter. T. latifolia accumulated significantly higher concentrations of the most of studied metals in its roost and rhizome with meager transfer to leaves (the translocation factors were less than one). Spearman's rank correlation coefficient showed a strong positive correlation between the metal concentration in sediments and its content in T. latifolia leaves (rs = 0.786 at p < 0.001 on average) and roots/rhizome (rs = 0.847 at p < 0.001 on average). In highly contaminated sites, the folia content of chlorophyll a and carotenoids decreased (by 30 and 38%, respectively), while lipid peroxidation enhanced (by 42%) on average compared to S1-S3 sites. These responses were accompanied by increasing non-enzymatic antioxidant content (soluble phenolic compounds, free proline, and soluble thiols) that allow plants to resist under significant anthropogenic loads. QMAFAnM in the five studied rhizosphere substrates varied insignificantly (2.5 × 106 - 3.8 × 107cfug-1 DW) and was decreased only in the most contaminated site (4.5 × 105). The proportion of rhizobacteria capable of fixing atmospheric nitrogen decreased by 1.7 times, solubilizing phosphates by 1.5 times, and synthesizing indol-3-acetic acid by 1.4 times in highly contaminated sites, while the amount of siderophore, 1-aminocyclopropane-1-carboxylate deaminase, and HCN producing bacteria did not considerably change. The results indicate high resistance of T. latifolia to prolonged technogenic impact, probably due to compensatory adaptive changes in the nonenzymatic antioxidant level and presence of beneficial microorganisms. Thus, T. latifolia was found to be a promising metal-tolerant helophyte that could help in mitigation of metal toxicity due to their phytostabilization even in heavily contaminated environment.