Exogenous Application Of Proline Research Articles

Exogenous proline suppresses endogenous proline and proline-production genes but improves the salinity tolerance capacity of salt-sensitive rice by stimulating antioxidant mechanisms and photosynthesis

Salinity is a critical environmental stress factor that significantly reduces crop productivity and yield. A mutant B-type response regulator gene (hst1) has been shown to promote salinity tolerance in the YNU genotype. Previous studies on the hst1 gene showed a higher proline production capacity under salt stress. Using almost identical genetic backgrounded salt-tolerant (YNU) and salt-sensitive (Sister line) rice genotypes, we tested the function of proline in the hst1 gene salinity-tolerance mechanism by applying exogenous proline under control and salt-stress conditions. Morpho-physiological, biochemical, and molecular analysis of ST and SS plants was performed to clarify the salinity tolerance mechanism mediated by the exogenous proline. The ST and SS genotypes accumulated exogenous proline, and the ST genotype has higher proline levels than the SS genotype. However, exogenous proline improved salt tolerance only in the SS genotype. Exogenous proline promotes plant and root growth by stimulating photosynthetic pigments and photosynthesis. The exogenous proline has a reductive effect on MDA, and H2O2 protects plants against ROS. Interestingly, exogenous proline lowers Na+ and raises K+ accumulations under salt stress. In the SS genotype, exogenous proline increases the activity of antioxidant enzymes (SOD, CAT, and APX) to protect against salinity-induced damage. The exogenous proline application down-regulates proline-synthesis genes (OsP5CS1 and OsP5CR) and up-regulates proline-degradation genes. Also, exogenous proline increases the expression of the OsSalT and OsGRAS29 genes, improving salinity tolerance in the SS genotype. Our study has demonstrated that proline plays a significant role in conferring salt tolerance with the salinity-tolerance-related hst1 mechanisms.

A REVIEW ON IMPROVEMENT OF SALT TOLERANCE IN RICE (ORYZA SATIVA L) BY INCREASING ANTIOXIDANT DEFENCE SYSTEMS USING EXOGENOUS APPLICATION OF PROLINE

Rice (Oryza sativa L) stands as a staple food crop globally particularly in the regions with warm climates. However, its cultivation faces significant challenges from abiotic stresses like salinity, which hinder crop growth and productivity. Salinity stress disrupts essential physiological processes, leading to reduced yields and compromised food security. In response to this pressing concern, this review investigates the potential of exogenous proline application to enhance salt tolerance in rice. The study delves into the intricate mechanisms underlying salinity stress in rice plants, highlighting its detrimental effects on growth, ion balance, and cellular metabolism. Salinity-induced oxidative stress, characterized by the accumulation of reactive oxygen species (ROS), exacerbates cellular damage, impairing plant growth and development. Proline, an amino acid known for its multifaceted roles in stress mitigation, emerges as a promising candidate for enhancing salt tolerance in rice. Exogenous application of proline demonstrates significant improvements in rice growth, yield and physiological attributes under saline conditions. The study elucidates the impact of exogenous proline on various aspects of rice physiology, including seed germination, water relations, and oxidative stress mitigation. By enhancing nutrient uptake, maintaining ion homeostasis, and fortifying antioxidant defences, proline offers a promising avenue for sustainable rice production in the face of escalating salinity stress. In conclusion, this study underscores the pivotal role of exogenous proline in augmenting salt tolerance in rice, offering insights into novel strategies for mitigating the adverse effects of salinity stress on crop yields.

Exogenous application of nano-silicon, potassium sulfate, or proline enhances physiological parameters, antioxidant enzyme activities, and agronomic traits of diverse rice genotypes under water deficit conditions

Water deficit is a critical obstacle that devastatingly impacts rice production, particularly in arid regions under current climatic fluctuations. Accordingly, it is decisive to reinforce the drought tolerance of rice by employing sustainable approaches to enhance global food security. The present study aimed at exploring the effect of exogenous application using different biostimulants on physiological, morphological, and yield attributes of diverse rice genotypes under water deficit and well-watered conditions in 2-year field trial. Three diverse rice genotypes (IRAT-112, Giza-178, and IR-64) were evaluated under well-watered (14400 m3/ha in total for the entire season) and water deficit (9170 m3/ha) conditions and were exogenously sprayed by nano-silicon, potassium sulfate, or proline. The results showed that drought stress substantially decreased all studied photosynthetic pigments, growth traits, and yield attributes compared to well-watered conditions. In contrast, antioxidant enzyme activities and osmoprotectants were considerably increased compared with those under well-watered conditions. However, the foliar application of nano-silicon, potassium sulfate, and proline substantially mitigated the deleterious effects of drought stress and markedly enhanced photosynthetic pigments, antioxidant enzyme activities, growth parameters, and yield contributing traits compared to untreated stressed control. Among the assessed treatments, foliar spray with nano-silicon or proline was more effective in promoting drought tolerance. The exogenous application of proline improved chlorophyll a, chlorophyll b, and carotenoids by 21.4, 19.6 and 21.0% followed by nano-silicon treatment, which enhanced chlorophyll a, chlorophyll b, and carotenoids by 21.1, 17.6 and 9.5% compared to untreated control. Besides, the application of proline demonstrated a superior improvement in the content of proline by 52.5% compared with the untreated control. Moreover, nano-silicon exhibited the maximum enhancement of catalase and peroxidase activity compared to the other treatments. The positive impacts of applied exogenously nano-silicon or proline significantly increased panicle length, number of panicles/plant, number of grains/panicle, fertility percentage, 1000-grain weight, panicle weight, and grain yield, compared to untreated plants under water deficit conditions. In addition, the physiological and agronomic performance of evaluated rice genotypes significantly contrasted under drought conditions. The genotype Giza-178 displayed the best performance under water deficit conditions compared with the other genotypes. Consequently, the integration of applied exogenously nano-silicon or proline with tolerant rice genotype as Giza-178 is an efficient approach to ameliorating drought tolerance and achieving agricultural sustainability under water-scarce conditions in arid environments.

<em>In Vitro</em> Effect of PEG and Proline on Callus Growth and Minerals Values in Basmati Rice (<em>Oryza sativa</em>)

Purpose: Drought is a universal issue that disturbs photosynthetic system, adversely affecting quality and crop yield. The study was conducted to determine response of polyethylene glycol (PEG) as stressing agent alone or combination with proline on four fine rice genotypes for callus components as well as biochemical parameters like Chromium (Cr), Magnesium (Mg), Manganese (Mn), Iron (Fe), Phosphorus (P).Research Method: Callus was induced on media having 4.43g/L MS + 4mg/L 2, 4-D (2, 4-dichlorophenoxy acetic acid) + 30g/L sucrose + 1.76g/L phytagel with different levels of PEG “1.25g/L and 2.5g/L” with and without 1ml/L proline.Findings: Callus was used for different analyses after 30 days and results showed that PEG treatments have a negative effect on callus fresh weight, callus dry weight, days to callus induction, callus percentage, and mineral nutrients like K, Cr, Mg, Mn, Fe, P. PEG 2.5g/L showed a greater decrease as compared to PEG 1.25g/L. Proline significantly raises callus growth alone or in combination with PEG but less than control whereas callus dry weight, K, and Ca contents increased more than control when proline applied alone or with PEG combination.Originality/value: Exogenous proline application improves callus growth rate as well as macro- micro elements by mitigating the effect of PEG.

Exogenous application of proline and glucose on saline-stressed cucumber seedlings

Exogenous application of proline and glucose on saline-stressed cucumber seedlings

Identification of the Key Genes Involved in Proline-Mediated Modification of Cell Wall Components in Rice Seedlings under Trivalent Chromium Exposure.

Chromium (Cr) toxicity exerts a detrimental effect on various physiological, biochemical, and molecular attributes of plants including the structure and functions of cell walls. On the other hand, the exogenous application of proline (Pro) is a beneficial strategy to overcome Cr toxicity. Therefore, it is a novel strategy to find the key genes associated with cell wall composition in rice under trivalent Cr with/without Pro application. A total of 203 genes were activated in the four cell wall biosynthesis pathways under chromium stress, namely cellulose (60), hemicellulose (57), lignin (35), and pectin (51). Based on the expression abundance of microarrays, the number of differentially expressed genes, and the expression level of genes, the lignin pathway was a crucial pathway in response to Cr treatments, followed by the cellulose pathway. Through the estimation of gene expression variation factors between 'Cr' and 'Cr+Pro' treatments, OsUGP1, OsBGLU24, OsBGLU29, OsBGLU33, OsBMY1, and OsBMY2 in the cellulose pathway; OsXTH9, OsXTH10, OsXTH16, OsGAUT3, OsGAUT19, OsGAUT28, OsXTH1, OsGAUT12, and OsGAUT21 in the hemicellulose pathway; OsPAL3, OsPAL3, OsPOX1, and OsPRX77 in the lignin pathway; and OsPME25, OsPGL27, OsPME26, OsPGL9, and OsPLL12 in the pectin pathway are the key genes involved in cell wall modification during Cr exposure with exogenous Pro application. The Pro-mediated activation of these genes could be crucial players in modifying the cell wall structure and composition of rice plants under Cr stress, which needs to be further clarified.

Proline Enhances Resistance and Recovery of Oilseed Rape after a Simulated Prolonged Drought.

This study was carried out to evaluate the effect of exogenous proline on the growth, biochemical responses, and plant recovery of drought-stressed oilseed rape plants after renewed irrigation. The experiment was conducted under controlled laboratory conditions. After 21 days of cultivation, 3-4 leaf stage seedlings were sprayed with proline (1 mM), then subjected to prolonged drought stress for 8 days to achieve a severe water deficit, next, irrigation was resumed and recovery was assessed after 4 days. The results show that exogenous application of proline reduced the drought-induced growth inhibition of seedlings while maintaining relative water content (RWC) and growth parameters closer to those of irrigated plants. Proline had a positive effect on chlorophyll accumulation and membrane permeability while decreasing ethylene, H2O2, and MDA levels. Moreover, after 4 days of recovery, the H2O2 content of the proline-treated plants was significantly lower (2-fold) and the MDA content was close to that of continuously irrigated plants. Thus, all these biochemical reactions influenced plant survival: after drought + proline treatment, the number of surviving plants was two times higher than that of drought-treated plants. The findings show that exogenous proline has antioxidant, osmotic, and growth-promoting properties that improve the drought tolerance of winter oilseed rape plants and is, therefore, beneficial for drought adaptation in oilseed rape.

Development of light-emitting Episcia lilacina leaf by applying Vibrio campbellii RMT1 and extending the glowing by CaCl2 and yeast extract.

Glowing Episcia lilacina was generated through foliar application of the bioluminescent bacterium Vibrio campbellii RMT1. Firstly, different nutrient formulas were tested, incorporating yeast extract and various inorganic salts, such as CaCl2, MgCl2, MgSO4, KH2PO4, K2HPO4, and NaCl, in order to enhance bacterial growth and light emission. The combination of 0.15% of yeast extract and 0.3% of CaCl2 in a nutrient broth (NB) + 1% NaCl medium extended light emission to 24h and resulted in higher light intensity compared to other combinations of yeast extract and inorganic salts. The peak intensity reached approximately 1.26 × 108 relative light units (RLU) at 7h. The optimal presence of inorganic salt ions likely contributed to enhanced light emission, while the yeast extract acted as a nutrient source. Secondly, the effect of proline on salt-induced stress symptoms was investigated by applying 20mM proline to the glowing plant. Additionally, a 0.5% agar nutrient was spread on the leaves prior to bacteria application to support bacterial growth and penetration. Exogenous proline application led to a significant accumulation of proline in plant cells, resulting in decreased malondialdehyde (MDA) levels. However, the proline accumulation also reduced the light intensity of the bioluminescent bacteria. This study demonstrates the potential for generating light on a living plant using bioluminescent bacteria. Further understanding of the interaction between plants and light-emitting bacteria could contribute to the development of sustainably light-emitting plants.

Accumulation of Proline in Plants under Contaminated Soils-Are We on the Same Page?

Agricultural soil degradation is occurring at unprecedented rates, not only as an indirect effect of climate change (CC) but also due to intensified agricultural practices which affect soil properties and biodiversity. Therefore, understanding the impacts of CC and soil degradation on plant physiology is crucial for the sustainable development of mitigation strategies to prevent crop productivity losses. The amino acid proline has long been recognized for playing distinct roles in plant cells undergoing osmotic stress. Due to its osmoprotectant and redox-buffering ability, a positive correlation between proline accumulation and plants' tolerance to abiotic stress has been pointed out in numerous reviews. Indeed, proline quantification is used systematically by plant physiologists as an indicator of the degree of tolerance and a measurement of the antioxidant potential in plants under stressful conditions. Moreover, the exogenous application of proline has been shown to increase resilience to several stress factors, including those related to soil degradation such as salinity and exposure to metals and xenobiotics. However, recent data from several studies often refer to proline accumulation as a signal of stress sensitivity with no clear correlation with improved antioxidant activity or higher stress tolerance, including when proline is used exogenously as a stress reliever. Nevertheless, endogenous proline levels are strongly modified by these stresses, proving its involvement in plant responses. Hence, one main question arises-is proline augmentation always a sign of improved stress resilience? From this perspective, the present review aims to provide a more comprehensive understanding of the implications of proline accumulation in plants under abiotic stress induced by soil degradation factors, reinforcing the idea that proline quantification should not be employed as a sole indicator of stress sensitivity or resilience but rather complemented with further biochemical and physiological endpoints.

Proline metabolism as a mechanism for the energy dissipation in VaP5CSF129A transgenic tobacco plants under water deficit

In plants, proline accumulation in cells is a common response to alleviate the stress caused by water deficits. It has been shown that foliar proline spraying, as well as its overaccumulation in transgenic plants can increase drought tolerance, as proline metabolism plays important roles in cell redox balance and on energy dissipation pathways. The aim of this work was to evaluate the role of exogenous proline application or its endogenous overproduction as a potential mechanism for energy dissipation. For this, wild-type and VaP5CSF129A transgenic tobacco plants were sprayed with proline (10 mM) and submitted to water deficit. Changes in plant physiology and biochemistry were evaluated. Transcriptional changes in the relative expression of genes involved in proline synthesis and catabolism, NAD (P)-dependent malate dehydrogenase (NAD(P)-MDH), alternative oxidase (AOX), and VaP5CSF129A transgene were measured. Exogenous proline reduced the negative effects of water deficit on photosynthetic activity in both genotypes; with the transgenic plants even less affected. Water deficit caused an increase in the relative expression of proline biosynthesis genes. On the other hand, the expression of catabolism genes decreased, primarily in transgenic plants. Exogenous proline reduced activity of the NADP-MDH enzyme and decreased expression of the AOX and NADP-MDH genes, mainly in transgenic plants under water stress. Finally, our results suggest that proline metabolism could act as a complementary/compensatory mechanism for the energy dissipation pathways in plants under water deficit.

Assessment of proline function in higher plants under extreme temperatures.

Climate change and abiotic stress factors are key players in crop losses worldwide. Among which, extreme temperatures (heat and cold) disturb plant growth and development, reduce productivity and, in severe cases, lead to plant death. Plants have developed numerous strategies to mitigate the detrimental impact of temperature stress. Exposure to stress leads to the accumulation of various metabolites, e.g. sugars, sugar alcohols, organic acids and amino acids. Plants accumulate the amino acid 'proline' in response to several abiotic stresses, including temperature stress. Proline abundance may result from de novo synthesis, hydrolysis of proteins, reduced utilization or degradation. Proline also leads to stress tolerance by maintaining the osmotic balance (still controversial), cell turgidity and indirectly modulating metabolism of reactive oxygen species. Furthermore, the crosstalk of proline with other osmoprotectants and signalling molecules, e.g. glycine betaine, abscisic acid, nitric oxide, hydrogen sulfide, soluble sugars, helps to strengthen protective mechanisms in stressful environments. Development of less temperature-responsive cultivars can be achieved by manipulating the biosynthesis of proline through genetic engineering. This review presents an overview of plant responses to extreme temperatures and an outline of proline metabolism under such temperatures. The exogenous application of proline as a protective molecule under extreme temperatures is also presented. Proline crosstalk and interaction with other molecules is also discussed. Finally, the potential of genetic engineering of proline-related genes is explained to develop 'temperature-smart' plants. In short, exogenous application of proline and genetic engineering of proline genes promise ways forward for developing 'temperature-smart' future crop plants.

Exogenous application of proline and glycine betaine mitigates nickel toxicity in mung bean plants by up-regulating growth, physiological and yield attributes

Exogenous application of proline and glycine betaine mitigates nickel toxicity in mung bean plants by up-regulating growth, physiological and yield attributes

Fisiologia e produção de pinheira sob estresse hídrico e aplicação de prolina

The objective of this study was to evaluate the physiology and production of sugar-apple as a function of irrigation intervals and foliar application of proline under the conditions of Paraíba's semi-arid region. A randomized block design was laid out in a 4 × 2 factorial scheme, with treatments resulting from the combination of four irrigation intervals (1, 4, 8 and 12 days) and two concentrations of proline (0 and 10 mM), with four replicates, and the plot consisted of four usable plants. Increase in irrigation intervals reduced the gas exchange of sugar-apple plants at 298 days after transplanting. Exogenous application of proline at concentration of 10 mM increased contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids and fruit fresh mass in plants grown under 12-day irrigation intervals.

Mitigation of PEG-Induces Drought Stress in Wheat (Triticum durum) by Exogenous Application of Proline

Drought is considered one of the most important environmental stresses that has serious limitations on production of most crop plants, including wheat. Proline is an amino acid closely associated with plant responses to environmental constraints. This research aims to study the response of four varieties of durum wheat (Triticum durum) subjected to water stress stimulated by polyethylene glycol (20% PEG-6000) which is equivalent to osmotic potential of -1.2 Mpa. A total of 4 wheat genotypes were grown hydroponically and four treatments were imposed. Wheat plants exposed to drought stress showed reduced growth, which was correlated with reduced relative water content, chlorophyll content and stomatal conductance as evidenced by principle component analysis (PCA). It also revealed that electrolyte leakage and malondialdehyde (MDA) accumulations were closely related with the declined growth and wheat plants development under drought stress. Importantly, application of 6 mM of exogenous proline improved the growth responses of wheat plants to drought stress. Proline strengthened numerous physio-biochemical processes coupled with decreasing in MDA levels which indicates successful adaptation of wheat plants to drought stress. The results of PCA strongly supported that application of proline in stressful conditions ameliorated the responses of wheat mostly by enhancing physiological and biochemical activities. Eventually, it can be concluded that proline supplementation is one of the useful approaches to alleviate the adverse effects of water stress on wheat crop.

Effect of Exogenous Application of Proline in Drought Stress Condition in Maize at Seedling Stage

Effect of Exogenous Application of Proline in Drought Stress Condition in Maize at Seedling Stage

Exogenous application of proline and phosphorus help improving maize performance under salt stress

Salinity is one of the important abiotic stresses that challenge crop productivity worldwide. Crop nutrition management and exogenous application of proline may help improve plant salt tolerance. This study investigated the effects of exogenous proline (100 mM) and phosphorus (P; 10 and 100 mg kg−1 sand) application on the growth, P content and ionic balance in maize under salt stress. Seedlings of a maize hybrid 30Y87 were grown in sand-filled pots maintained under normal (1 dS m−1) and salt stress conditions (6 dS m−1). Salt stress caused a significant reduction in plant photosynthetic efficiency, plant growth, and shoot and root P contents and tissue potassium (K+) contents whereas a significant increase in tissue sodium (Na+) and chloride (Cl−) was also noted. However, the application of proline and P ameliorated the impact of salt stress by restricting the Na+ and Cl− uptake and accumulation, and significantly improved plant light absorption capacity, plant growth, P contents and tissue K+ contents under both control and salt stress conditions. In this regard, the application of proline with a high rate of P nutrition was more effective. In conclusion, co-application of proline with a high rate of P nutrition synergistically restricted the Na+ and Cl− accumulation and improved the plant growth under salt stress.

Using Exogenous Melatonin, Glutathione, Proline, and Glycine Betaine Treatments to Combat Abiotic Stresses in Crops.

Abiotic stresses, such as drought, salinity, heat, cold, and heavy metals, are associated with global climate change and hamper plant growth and development, affecting crop yields and quality. However, the negative effects of abiotic stresses can be mitigated through exogenous treatments using small biomolecules. For example, the foliar application of melatonin provides the following: it protects the photosynthetic apparatus; it increases the antioxidant defenses, osmoprotectant, and soluble sugar levels; it prevents tissue damage and reduces electrolyte leakage; it improves reactive oxygen species (ROS) scavenging; and it increases biomass, maintains the redox and ion homeostasis, and improves gaseous exchange. Glutathione spray upregulates the glyoxalase system, reduces methylglyoxal (MG) toxicity and oxidative stress, decreases hydrogen peroxide and malondialdehyde accumulation, improves the defense mechanisms, tissue repairs, and nitrogen fixation, and upregulates the phytochelatins. The exogenous application of proline enhances growth and other physiological characteristics, upregulates osmoprotection, protects the integrity of the plasma lemma, reduces lipid peroxidation, increases photosynthetic pigments, phenolic acids, flavonoids, and amino acids, and enhances stress tolerance, carbon fixation, and leaf nitrogen content. The foliar application of glycine betaine improves growth, upregulates osmoprotection and osmoregulation, increases relative water content, net photosynthetic rate, and catalase activity, decreases photorespiration, ion leakage, and lipid peroxidation, protects the oxygen-evolving complex, and prevents chlorosis. Chemical priming has various important advantages over transgenic technology as it is typically more affordable for farmers and safe for plants, people, and animals, while being considered environmentally acceptable. Chemical priming helps to improve the quality and quantity of the yield. This review summarizes and discusses how exogenous melatonin, glutathione, proline, and glycine betaine can help crops combat abiotic stresses.

Antigenotoxic and Antimutagenic Potentials of Proline in Allium cepa Exposed to the Toxicity of Cadmium

This study was conducted to evaluate whether the application of proline as a potential osmoprotectant at different doses could improve the genotoxic and mutagenic effects caused by plant exposure to cadmium salts. For this purpose, the Comet assay was used, which allows the rapid detection of DNA damage shortly after its occurrence, before the DNA is repaired, as well as the discrimination of the DNA damage limited to specific cells in a heterogeneous population. After treatment of Allium cepa roots with 75µM CdSO4·H2O (Cd sample), a DNA percentage of 35.24% was recorded in the tail. In the samples treated first with proline and then with cadmium (pre-treatment group), the percentage DNA in the tail was reduced by 24.8% compared with the Cd sample. Instead, in the post-treatment group (samples treated first with cadmium and then with proline), the percentage DNA in the tail was reduced by 69.04% compared with the Cd sample. All cadmium treatments induced chromosomal aberrations (CAs). Compared with the CAs values obtained after Cd treatment, the reduction was 75.6% in the pre-treatment group and 55.39% in the post-treatment group. The results of this study highlighted that exogenous application of proline alleviated the genotoxic effect of cadmium.

Role of Exogenous Application of Proline and Glycine Betaine in the Salinity Tolerance of Solanaceae Family: A Review

Role of Exogenous Application of Proline and Glycine Betaine in the Salinity Tolerance of Solanaceae Family: A Review

Anatomical and Physiological Performance of Jojoba Treated with Proline under Salinity Stress Condition

A field trial study was conducted for two consecutive seasons 2020 and 2021 in approximately 8-month-old jojoba plants to evaluate the physiological responses following salt treatment and the role of proline as a foliar application to enhance jojoba tolerance to salinity stress. Jojoba plants were irrigated once a week for four months with diluted seawater in concentrations of 5000, 10,000, and 15,000 ppm and tap water (control). Anti-stress proline was applied four times throughout the experiment, the first at the beginning of the experiment and another three times at 30-day intervals, at concentrations of 0, 300, and 450 ppm. The effect of proline treatments on jojoba plant behavior includes growth vegetative characteristics, namely plant height increase percentage (PHIP), shoot number increase percentage (NSIP), stem diameter increase percentage (SDIP), number of leaves, leaf thickness, leaf area, and fresh and dry weights of leaves, and chemical characteristics, namely chlorophyll a and b, total chlorophyll, carotenoids, leaf mineral contents (N, P, K, Na, and Cl), total phenolic content (TPC), and proline concentration. Moreover, the impacts of proline on hydrogen peroxide (H2O2), superoxide anion (O2•−), malondialdehyde (MDA), and ion leakage (IL) under salinity stress were investigated. Briefly, proline at 450 ppm enhanced all studied growth and physiological characteristics and promoted the antioxidant system of jojoba plants compared with the control and other treatments. The anatomical structure of leaves was also examined, and favorable variations in the anatomical structure were detected in the stressed and proline-treated plants. Exogenous application of proline enhanced most of this anatomical characteristic of jojoba leaf under saline stress. In conclusion, proline as a foliar application at 450 ppm under salinity stress of 10,000 ppm enhances jojoba tolerance to salinity stress by modifying the physicochemical and morphological characteristics of jojoba plants.