Exogenous Application Of Salicylic Acid Research Articles

Efficacy of Three Antiviral Agents and Resistant Cultivars on Tomato Yellow Leaf Curl Virus in Tomato

Recently, several in vitro studies have reported antiviral activity of agents of systemic acquired resistance against plant virus infection, but the approach has not been applied in a wide range of agricultural fields. The objective of this study was to evaluate the inhibitory effect of the exogenous application of salicylic acid (SA), chitosan (CH), or eugenol (EG) in tomato yellow leaf curl virus (TYLCV) infection of greenhouse-grown tomato plants. In vitro, the initial time of symptom was observed in TYLCV-infected plants (VP) of the resistant cultivar ‘Superdotaerang’ at 12 days post inoculation (dpi) after application of antiviral agents. At 32 dpi, the disease rate of TYLCV in the CHT+VP (0.1% chitosan and virus infected control) treated plants was 87.5%, lower than that of the other treatment. However, the virus content in the CHT+VP treated plants was higher than those of the other treatments, and SA, EG, and CH did not show significant effect on plant height or shoot and root fresh weight. Our results from summer-cultivated greenhouse-grown tomatoes show that none of the tested agents had an inhibitory activity on viral infection or yield of tomato ‘Dotaerangsola’cultivar. In contrast, all treated ‘TY Giants’ cultivars that possessed TYLCV resistance genes Ty-1 and Ty-3a did not show typical symptoms and the virus content was remarkably lower than those in the TYLCV treated plants in ‘Superdotaerang’. The results of this research indicated that the planting of resistant tomato cultivars was effective method instead of using SA, EG, and CH (known as resistance-inducing factors for control) of TYLCV in the field.

N-Methyltransferase CaASHH3 Acts as a Positive Regulator of Immunity against Bacterial Pathogens in Pepper.

Proteins with conserved SET domain play a critical role in plant immunity. However, the means of organization and functions of these proteins are unclear, particularly in non-model plants such as pepper (Capsicum annum L.). Herein, we functionally characterized CaASHH3, a member of class II (the ASH1 homologs H3K36) proteins in pepper immunity against Ralstonia solanacearum and Pseudomonas syringae pv tomato DC3000 (Pst DC3000). The CaASHH3 was localized in the nucleus, and its transcript levels were significantly enhanced by R. solanacearum inoculation (RSI) and exogenous application of salicylic acid (SA), methyl jasmonate (MeJA), ethephon (ETH), and abscisic acid (ABA). Knockdown of CaASHH3 by virus-induced gene silencing (VIGS) compromised peppers’ resistance to RSI. Furthermore, silencing of CaASHH3 impaired hypersensitive-response (HR)-like cell death response due to RSI and downregulated defense-associated marker genes, including CaPR1, CaNPR1, and CaABR1. The CaASHH3 protein was revealed to affect the promoters of CaNPR1, CaPR1, and CaHSP24. Transiently over-expression of CaASHH3 in pepper leaves elicited HR-like cell death and upregulated immunity-related marker genes. To further study the role of CaASHH3 in plant defense in vivo, CaASHH3 transgenic plants were generated in Arabidopsis. Overexpression of CaASHH3 in transgenic Arabidopsis thaliana enhanced innate immunity against Pst DC3000. Furthermore, CaASHH3 over-expressing transgenic A. thaliana plants exhibited upregulated transcriptional levels of immunity-associated marker genes, such as AtNPR1, AtPR1, and AtPR2. These results collectively confirm the role of CaASHH3 as a positive regulator of plant cell death and pepper immunity against bacterial pathogens, which is regulated by signaling synergistically mediated by SA, JA, ET, and ABA.

Salicylic Acid Enhances Heat Stress Resistance of Pleurotus ostreatus (Jacq.) P. Kumm through Metabolic Rearrangement.

Pleurotus ostreatus (Jacq.) P. Kumm is cultivated worldwide, and its growth is seriously threatened by heat stress. Here, we performed a comprehensive analysis to investigate the influence of the phytohormone salicylic acid (SA) in P. ostreatus under HS. The results showed that the hyphal growth recovery rate and the antioxidant capacity of P. ostreatus increased with exogenous SA application (0.01 mmol/L and 0.05 mmol/L) after HS treatment. Metabolomic and transcriptomic analyses showed that SA application (0.05 mmol/L) weakened central carbon metabolism to allow cells to survive HS efficiently. In addition, SA shifted glycolysis to one-carbon metabolism to produce ROS scavengers (GSH and NADPH) and reduced ROS production by altering mitochondrial metabolism. SA also maintained nucleotide homeostasis, led to membrane lipid remodeling, activated the MAPK pathway, and promoted the synthesis of cell-wall components. This study provides a reference for further study of SA in microorganisms.

Lack of antagonism between salicylic acid and jasmonate signalling pathways in poplar.

Salicylic acid (SA) and jasmonic acid (JA) often play distinct roles in plant defence against pathogens. Research from Arabidopsis thaliana has established that SA- and JA-mediated defences are more effective against biotrophs and necrotrophs, respectively. These two hormones often interact antagonistically in response to particular attackers, with the induction of one leading to suppression of the other. Here, we report a contrasting pattern in the woody perennial Populus: positive SA-JA interplay. Using genetically engineered high SA lines of black poplar and wild-type lines after exogenous hormone application, we quantified SA and JA metabolites, signalling gene transcripts, antifungal flavonoids and resistance to rust (Melampsora larici-populina). Salicylic acid and JA metabolites were induced concurrently upon rust infection in poplar genotypes with varying resistance levels. Analysis of SA-hyperaccumulating transgenic poplar lines showed increased jasmonate levels, elevated flavonoid content and enhanced rust resistance, but no discernible reduction in growth. Exogenous application of either SA or JA triggered the accumulation of the other hormone. Expression of pathogenesis-related (PR) genes, frequently used as markers for SA signalling, was not correlated with SA content, but rather activated in proportion to pathogen infection. We conclude that SA and JA pathways interact positively in poplar resulting in the accumulation of flavonoid phytoalexins.

FOLIAR APPLICATION OF SALICYLIC ACID AND CALCIUM CHLORIDE ENHANCE HEAT STRESS TOLERANCE IN TOMATO

The aim of this research was to enhance heat stress tolerance potential in local tomato germplasm through exogenous application of salicylic acid (SA) and calcium chloride (CaCl2). Various concentrations of salicylic acid (e.g., control, 2.5 mM, 3.5 mM and 4.5 mM) and calcium chloride (e.g., control, 0.3 mM, 0.4 mM and 0.5 mM) were applied for the duration of forty days. Physiological parameters include (stomatal conductance, photosynthetic rate, transpiration rate and water use efficiency) as well as biochemical attributes (chlorophyll content, enzyme activities of catalase, peroxidase and superoxidase dismutase) of selected tomato genotypes estimated under heat stress conditions. The results revealed that SA and CaCl2 application enhanced vegetative growth of tomato genotypes as compared with control plants. An increased concentration of SA and CaCl2 showed the improved photosynthetic rate, chlorophyll content and induced transpiration rate and stomatal conductance and antioxidant enzyme activity. The study proved that foliar spray of SA and CaCl2 involved in stabilizing the cell as well as cellular integrity under heat stress environment.

Alleviation of Salt-Inhibited Germination and Seedling Growth of Kidney Bean by Seed Priming and Exogenous Application of Salicylic Acid (SA) and Hydrogen Peroxide (H2O2)

Salinity is a dominant obstacle to the proper germination of seeds, growth of seedlings, and, consequently, the production of crops. The priming of seeds with different treating agents can efficiently impart salinity tolerance. Kidney bean is a nutritious and popular vegetable crop in the world. Literature shows that salt stress negatively disturbs the germination and growth of kidney beans. In the present research, we investigated the potentiality of salicylic acid (SA) and hydrogen peroxide (H2O2) as priming and exogenous agents to alleviate the salinity-inhibited germination and growth of kidney beans. The seeds were pretreated with SA (1 mM and 2 mM) and H2O2 (0.1 mM and 0.15 mM) and soaked in normal tap water (hydro-priming) for 60 min. In addition, for the control experiment, untreated seeds were used. Finally, primed seeds were subjected to salt stress (150 mM NaCl). Our results exhibited that salt stress considerably lowered the percentage of germination (GP), germination index (GI), seed vigor index (SVI), shoot length (SL), root length (RL), shoot–root fresh and dry biomass, and plant growth. The results also exhibited that salt stress significantly decreased the relative water content (RWC) and photosynthetic pigments such as chlorophyll, carotenoids, lycopene, and beta-carotene contents. The SA- and H2O2- and hydro-priming stimulated the GP, GI, SL, RL, SVI, and seedling growth. Data also revealed that the supplementation of SA and H2O2 enhanced RWC and photosynthetic pigments. When compared to other treatments, pretreatment with 1 mM SA was determined to be comparatively more effective at imparting the salt tolerance of kidney beans. Overall, these results, via a heatmap and principal component analysis, uncovered that priming and exogenous applications of SA and H2O2 can improve salt tolerance and enhance germination and seedling characteristics of kidney beans.

Transcriptome and Metabolome Profiling Reveal the Resistance Mechanisms of Rice against Brown Planthopper.

Brown planthopper (Nilaparvata lugens Stål, BPH) is one of the most destructive insects affecting rice production. To better understand the physiological mechanisms of how rice responds to BPH feeding, we analyzed BPH-induced transcriptomic and metabolic changes in leaf sheaths of both BPH-susceptible and -resistant rice varieties. Our results demonstrated that the resistant rice reduced the settling, feeding and growth of BPH. Metabolic analyses indicated that BPH infestation caused more drastic overall metabolic changes in the susceptible variety than the resistant rice. Differently accumulated metabolites (DAMs) belonging to flavonoids were downregulated in the susceptible rice but upregulated in resistant variety. Transcriptomic analyses revealed more differentially expressed genes (DEGs) in susceptible rice than resistant rice, and DEGs related to stimulus were significantly upregulated in resistant rice but downregulated in susceptible rice. Combined analyses of transcriptome and metabolome showed that many DEGs and DAMs were enriched in phenylpropane biosynthesis, flavonoid biosynthesis, and plant hormone signal transduction. We conducted correlation analyses of DEGs and DAMs in these pathways and found a high correlation between DEGs and DAMs. Then, we found that the contents of endogenous indole 3-acetic acid (IAA) in resistant rice was lower than that of susceptible rice after BPH feeding, while the salicylic acid (SA) content was the opposite. For functional analysis, an exogenous application of IAA decreased rice resistance to BPH, but the exogenous application of SA increased resistance. In addition, biochemical assessment and quantitative PCR analysis showed that the lignin content of resistant accession was constitutively higher than in susceptible accession. By adding epigallocatechin, the substrate of anthocyanidin reductase (ANR), to the artificial diet decreased the performance of BPH. We first combined a transcriptome-metabolome-wide association study (TMWAS) on rice resistance to BPH in this study. We demonstrated that rice promoted resistance to BPH by inducing epigallocatechin and decreasing IAA. These findings provided useful transcriptomic and metabolic information for understanding the rice-BPH interactions.

AUXIN RESPONSE FACTOR 16 (StARF16) regulates defense gene StNPR1 upon infection with necrotrophic pathogen in potato.

We demonstrate a new regulatory mechanism in the jasmonic acid (JA) and salicylic acid (SA)mediated crosstalk in potato defense response, wherein, miR160 target StARF16 (a geneinvolved in growth and development) binds to the promoter of StNPR1 (a defense gene) andnegatively regulates its expression to suppress the SA pathway. Overall, our study establishes theimportance of StARF16 in regulation of StNPR1 during JA mediated defense response uponnecrotrophic pathogen interaction. Plants employ antagonistic crosstalk between salicylic acid (SA) and jasmonic acid (JA) to effectively defend them from pathogens. During biotrophic pathogen attack, SA pathway activates and suppresses the JA pathway via NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1). However, upon necrotrophic pathogen attack, how JA-mediated defense response suppresses the SA pathway, is still not well-understood. Recently StARF10 (AUXIN RESPONSE FACTOR), a miR160 target, has been shown to regulate SA and binds to the promoter of StGH3.6 (GRETCHEN HAGEN3), a gene proposed to maintain the balance between the free SA and auxin in plants. In the current study, we investigated the role of StARF16 (a miR160 target) in the regulation of the defense gene StNPR1 in potato upon activation of the JA pathway. We observed that a negative correlation exists between StNPR1 and StARF16 upon infection with the pathogen. The results were further confirmed through the exogenous application of SA and JA. Using yeast one-hybrid assay, we demonstrated that StARF16 binds to the StNPR1 promoter through putative ARF binding sites. Additionally, through protoplast transfection and chromatin immunoprecipitation experiments, we showed that StARF16 could bind to the StNPR1 promoter and regulate its expression. Co-transfection assays using promoter deletion constructs established that ARF binding sites are present in the 2.6 kb sequence upstream to the StNPR1 gene and play a key role in its regulation during infection. In summary, we demonstrate the importance of StARF16 in the regulation of StNPR1, and thus SA pathway, during JA-mediated defense response upon necrotrophic pathogen interaction.

Exogenous Application of Salicylic Acid and Hydrogen Peroxide Ameliorate Cadmium Stress in Milk Thistle by Enhancing Morpho-Physiological Attributes Grown at Two Different Altitudes.

Cadmium (Cd+2) is a potential and widespread toxic environmental pollutant, mainly derived from a rapid industrial process that has inhibitory effects on growth, physiological, and biochemical attributes of various plant species, including medicinal plants such as Silybum marianum L. Gaertn commonly known as milk thistle. Plant signaling molecules, when applied exogenously, help to enhance/activate endogenous biosynthesis of potentially important signaling molecules and antioxidants that boost tolerance against various abiotic stresses, e.g., heavy metal stress. The present study documented the protective role of salicylic acid (SA;0.25 μM) and hydrogen peroxide (H2O2; 10 μM) priming, foliar spray, and combinational treatments in reducing Cd+2 toxicity (500 μM) in milk thistle grown at two diverse ecological zones of Balochistan Province of Pakistan i.e., Quetta (Qta) and Turbat (Tbt). The morpho-physiological and biochemical attributes of milk thistle were significantly affected by Cd+2 toxicity; however, priming and foliar spray of SA and H2O2 significantly improved the growth attributes (root/shoot length, leaf area, and root/shoot fresh and dry weight), photosynthetic pigments (Chl a, b, and carotenoids) and secondary metabolites (Anthocyanin, Soluble phenolics, and Tannins) at both altitudes by suppressing the negative impact of Cd+2. However, the oxidative damage parameters, i.e., MDA and H2O2, decreased astonishingly under the treatment of signaling molecules, thereby protecting membrane integrity under Cd+2 stress. The morphological variations were profound at the low altitude (Tbt) as compared to the high altitude (Qta). Interestingly, the physiological and biochemical attributes at both altitudes improved under SA and H2O2 treatments, thus hampered the toxic effect of Cd+2. These signaling compounds enhanced tolerance of plants under heavy metal stress conditions with the consideration of altitudinal, and ambient temperature variations remain to be the key concerns.

Exogenous application of salicylic acid for regulation of sunflower growth under abiotic stress: a systematic review

Exogenous application of salicylic acid for regulation of sunflower growth under abiotic stress: a systematic review

Salicylic acid enhances tolerance of Valeriana officinalis L. to bentazon herbicide

Salicylic acid is an important phytohormone, with regulation role in responses of plants to biotic and abiotic stress, especially detoxification of herbicides. For this purpose, the effect of three rates of salicylic acid (SA) (zero, 0.5, and 1 mM) and six doses of bentazon (zero, 50%, 75%, 100%, 125%, and 150% of recommended dose) on physiological response of valerian (Valeriana officinalis L.) were evaluated in the completely randomized factorial design with three replicates. The results showed that application of bentazon, especially at high levels (125% and 150% of recommended dose, in the absence of SA, exacerbated the rate of phytotoxicity damage, malondialdehyde (MDA) content, catalase (CAT), gaiacol peroxidase (GPX), and ascorbate peroxidase (APX) activity. Exogenous application of SA positively impacted bentazon- and unbentazon-exposed (control) plants, even under elevated concentration of herbicide (50% higher than recommended dose). Highest protection of the bentazon-exposed plants was observed at 0.5 and 1 mM level of SA, respectively. Combination of exogenous application (pre-treatment) of SA and bentazon herbicide reduced MDA content compared with ones were exclusively bentazon-exposed. In addition, exogenous application of SA enhanced antioxidant enzyme system, and increased APX and GPX enzyme activity. Results of present research indicated that external application of SA could be able to increase tolerance to oxidative stress generated in bentazon-exposued plants of valerian by reducing phytotoxicity and mutating antioxidant enzymatic system and antioxidant metabolites content.

Effect of Salicylic Acid and Calcium Chloride on Lipid peroxidation and Scavenging Capacity of Radical of red bean (Phaseolus calcaratus L.) under Salt Stress

Soil salinity is one of the critical challenges for development of culture area of agricultural crops. In the present study a pot experiment was conducted in factorial based on completely randomized design aimed to investigate the impact of exogenous application of salicylic acid (SA 0, 0.75 and 1.5 mM) and calcium chloride (CaCl2 0, 50 and 100 mM), solely or in combination, on plant growth, photosynthetic pigments (total chlorophyll (Chl), carotenoids, anthocyanin), and some metabolic parameters (reducing sugars, proline, lipid peroxidation and scavenging ability on DPPH (2,2-diphenyl-1-picrylhydrazyl) radical) of red bean exposed to salt stress (0, 25 and 75 mM NaCl). Results showed that exogenous application of SA or calcium (Ca) alone improved plant performance under NaCl stress. Growth slowed down under salinity. Malondialdehyde (MDA), DPPH radical, anthocyanin, and proline content were increased under salinity stress. However, application of SA and Ca enhanced the growth parameters, improved the Chl, carotenoids, and reducing sugars content, and significantly reduced MDA and DPPH radical in plants. Therefore, induced tolerance to salinity as the result of SA and Ca application may be related to the regulation of antioxidative responses. Furthermore, the beneficial effect of SA and Ca were achieved by applications of 0.75 mM SA and 50 mM CaCl2, which are recommended to improve red bean performance under saline conditions. In conclusion, exogenous application of SA and Ca improved salinity stress tolerance through the regulation of antioxidant system.

Salicylic acid mitigating damage to the photosynthetic apparatus and quality of Eugenia myrcianthes seedlings under water deficit

Abstract This study aimed to evaluate the effect of exogenous application of salicylic acid on the photosynthetic metabolism and quality of Eugenia myrcianthes seedlings under water deficit and their recovery potential after rehydration. Two water regimes were evaluated, as follows: control - plants irrigated daily (I) and water deficit (S), with and without the application of 400 mg L–1 of salicylic acid (SA), totaling four treatments. Seedlings were evaluated at three times: at the beginning of the experiment (T0), that is, when the irrigation was interrupted; when the photosynthetic rate reached values close to zero (P0 - 15 days after irrigation interruption), that is, when irrigation restarted; and when the photosynthetic rate was recovered (REC). Eugenia myrcianthes seedlings were negatively affected when subjected to water restriction; salicylic acid attenuated the damage to the photosynthetic apparatus by acting positively on the relative water content in the leaves, SPAD index, photosynthetic metabolism, superoxide dismutase and peroxidase enzyme activity, and seedling growth in P0. Eugenia myrchiantes presented potential for recovery after resumption irrigation. The application of SA contributed to the maintenance of gas exchanges, photochemical processes and quality of E. myrcianthes seedlings during and after water deficit, suggesting the promotion of plant resistance induction.

SEED PRIMING AND EXOGENOUS APPLICATION OF SALICYLIC ACID ENHANCE GROWTH AND PRODUCTIVITY OF OKRA (Abelmoschus esculentus L.) BY REGULATING PHOTOSYNTHETIC ATTRIBUTES

Low and uneven germination is a serious problem for the successful production of okra seedlings. Priming of seeds as well as supplementation of different plant growth regulators exhibited better response in successful seedling production which eventually results in higher yield. Therefore, the present study was conducted to evaluate the effects of seed priming and exogenous application of salicylic acid (SA) on okra seed germination and plant development. The okra seeds were primed by 1 mM and 2 mM of SA for 60 minutes whereas the seeds were washed several times with distilled water for the control treatment. Similar doses of SA have been exogenously sprayed to the 12 days okra seedlings for 4 days. The results of the study revealed that seed priming with SA enhanced germination percentage (GP), increased coleoptile length and weight, shoot and root length, and seed vigor index (SVI). Similarly, exogenous application of 1 mM SA increased relative water content (RWC), contents of chlorophyll a, chlorophyll b, total chlorophyll while a higher dose of SA (2 mM) degraded the leaf pigments. Supplementation of SA altered photosynthetic attributes, net photosynthetic (Pn) and transpiration rate (Tr), stomatal conductance (Gs), and water use efficiency (WUE). Moreover, SA treatment reduced the time duration of flower bud initiation and days to first flowering and enhanced the yield per plant. The results of this study indicated that seed priming and exogenous application of SA enhanced germination and okra productivity by regulating RWC and photosynthetic attributes where 1 mM SA is more effective compared to 2 mM SA.

Exogenous salicylic acid-induced drought stress tolerance in wheat (Triticum aestivum L.) grown under hydroponic culture.

Wheat is an important cereal crop, which is adversely affected by water deficit stress. The effect of induced stress can be reduced by the application of salicylic acid (SA). With the objective to combat drought stress in wheat, an experiment was conducted in greenhouse under hydroponic conditions. The treatments consisted of (a) no drought (DD0 = 0 MPa), mild drought (DD1 = -0.40 MPa) and severe drought (DD2 = -0.60 MPa) by applying PEG-8000, (b) two contrasting wheat varieties Barani-17 (drought tolerant) and Anaj-17 (drought-sensitive), and (c) foliar treatments of salicylic acid (0, 50 mM, 75 mM, and 100 mM). Evaluation of wheat plants regarding biochemical, physiological, and morphological attributes were rendered after harvesting of plants. Statistically, maximum shoot and root fresh and dry weights (18.77, 11.15 and 1.99, 1.81 g, respectively) were recorded in cultivar Barani-17 under no drought condition with the application of SA (100 mM). While, minimum shoot and root fresh and dry weights (6.65, 3.14 and 0.73, 0.61 g, respectively) were recorded in cultivar Anaj-2017 under mild drought stress without SA application. The maximum shoot length (68.0 cm) was observed in cultivar Barani-2017 under no drought condition with the application of SA (100 mM). While, maximum root length (59.67 cm) was recorded in cultivar Anaj-17 under moderate drought stress without application of SA. Further, minimum shoot length (28.67 cm) was recorded in Anaj-17 under moderate drought stress without SA application. Minimum root length (38.67 cm) was recorded in cultivar Barani-17 under no drought condition without SA application. Furthermore, maximum physio-biochemical traits, including membrane stability index (MSI), chlorophyl content, photosynthetic rates, stomatal conductance, antioxidant enzymatic activities and relative water content (RWC) were found highest in cultivar Barani-17 under no drought stress and SA application at 100 mM. However, minimum values of these traits were recorded in cultivar Anaj-17 under severe drought stress without SA application. Our results also demonstrated that under severe drought, application of SA at 100 mM significantly increased leaf nitrogen (N), phosphrus (P) and potassium (K) contents and cultivar Barani-17 demonstrated significantly higher values than Anaj-17. The obtained results also indicated that the cultivation of wheat under drought stress conditions noticeably declines the morphological, physiological, and biochemical attributes of the plants. However, the exogenous application of SA had a positive impact on wheat crop for enhancing its productivity.

Role of exogenous-applied salicylic acid, zinc and glycine betaine to improve drought-tolerance in wheat during reproductive growth stages

BackgroundDrought has become a dangerous threat to reduce crop productivity throughout the world. Exogenous applications of regulators, micronutrients, and/or osmoprotectants for inducing drought-tolerance in field crops have been effectively adopted. A controlled pot study was performed to investigate the relative efficacy of salicylic acid (SA), zinc (Zn), and glycine betaine (GB) as foliar applications on the growth, tissues pigments content, relative water content (RWC), leaf gas-exchange, antioxidant enzymes activity, reactive oxygen species (ROS) accumulation, osmolytes contents, and the yield parameters of wheat plants subjected to two soil water conditions (85% field capacity: well-watered, 50% field capacity: water-deficient) during reproductive growth stages.ResultsWater deficient conditions significantly decreased the growth, yield parameters, RWC, photosynthesis pigment, and gas-exchange attributes except for intercellular CO2 concentration. However, foliar applications remarkably improved the growth and yield parameters under water deficit conditions. Under drought condition, exogenous applications of SA, Zn, and GB increased the grain yield pot− 1 by 27.99, 15.23 and 37.36%, respectively, as compared to the control treatment. Drought stress statistically increased the contents of hydrogen peroxide (H2O2), superoxide anion radical (O2•−), and malonaldehyde (MDA), and elevated the harmful oxidation to cell lipids in plants, however, they were considerably reduced by foliar applications. Foliar applications of SA, Zn, and GB decreased MDA content by 29.09, 16.64 and 26.51% under drought stress, respectively, as compared to the control treatment. Activities of all antioxidant enzymes, proline content, and soluble sugar were increased in response to foliar applications under water deficit conditions.ConclusionsOverall, foliar application of GB, SA, and Zn compounds improved the drought-tolerance in wheat by decreasing the ROS accumulation, promoting enzymatic antioxidants, and increasing osmolytes accumulation. Finally, GB treatment was most effective in thoroughly assessed parameters of wheat followed by SA and Zn applications to alleviate the adverse effects of drought stress.

Salicylic acid fights against Fusarium wilt by inhibiting target of rapamycin signaling pathway in Fusarium oxysporum

IntroductionBiofungicides with low toxicity and high efficiency are a global priority for sustainable agricultural development. Phytohormone salicylic acid (SA) is an ancient medicine against various diseases in humans and activates the immune system in plants, but little is known of its function as a biofungicide. ObjectivesHere, Fusarium oxysporum, the causal agent of devastating Fusarium wilt and immunodepressed patients, was used as a model system to explore whether SA can enter the pathogen cells and suppress key targets of the pathogen. MethodsOxford Nanopore MinION sequencing and high-throughput chromosome conformation capture (Hi-C) sequencing were used to analyzed the genome of F. oxysporum. In addition, RNA-seq, qRT-PCR, and western blotting were conducted to detect gene and protein expression levels. ResultsWe isolated and sequenced the genome of F. oxysporum from potato dry rot, and the F. oxysporum included 12 chromosomes and 52.3 Mb genomic length. Pharmacological assays showed that exogenous application of SA can efficiently arrest hyphal growth, spore production, and pathogenicity of F. oxysporum, whereas endogenous salicylate hydroxylases significantly detoxify SA. The synergistic growth inhibition of F. oxysporum was observed when SA was combined with rapamycin. Kinase assays showed that SA inhibits FoTOR complex 1 (FoTORC1) by activating FoSNF1 in vivo. Transgenic potato plants with the interference of FoTOR1 and FoSAH1 genes inhibited the invasive growth of hyphae and significantly prevented the occurrence of Fusarium wilt. ConclusionThis study revealed the underlying mechanisms of SA against F. oxysporum and provided insights into SA in controlling various fungal diseases by targeting the SNF1-TORC1 pathway of pathogens.

Salicylic acid mediated protection of Brassica campestris sp. chinensis from saline stress via SA receptor NPR1 dependent transcriptional regulation and biosynthesis of related biochemicals

Salt stress has a significant impact on plant physiological processes and morphology, resulting in reduced plant performance. This study aimed to evaluate the hormonal regulation of Pakchoi ( Brassica campestris spp. chinensis) in response to saline stress imposition and exogenous salicylic acid application, focusing on morphological and physiological parameters. Saline stress imposition altered the concentration of endogenous hormonal levels, as demonstrated by Jasmonic acid (JA) and abscisic acid (ABA). Alterations in the level of plant hormones coincided with the enhanced reactive oxygen species (ROS) generation and proline accumulation followed by redox imbalances. Proline biosynthesis and antioxidative enzymes were significantly elevated with SA pretreatment. SA augmented stress responses are corroborated by the upregulation of SA signaling genes ( NPR1 and PR-1 ) and with a repressive effect on the expression of JA and ABA synthesis-related genes ( NCED3 , MYC2, PDF1.2 ). Moreover, the concerted action of SA-mediated genes might be associated with upregulation of flavonoid biosynthesis pathway genes ( FLS, CHS, CHI, F3H and ANS ), resulting in an enhanced level of phenolic compounds in SA pre-treated plants. A substantial scavenging property is attributed to phenolic compounds for the maintenance of cellular redox status. The results suggest that SA receptor NPR1 dependent transcriptional regulation and biosynthesis of related biochemicals are collaborative processes to counteract the adverse effects of salinity and maintain plant cellular redox homeostasis. • S.A pretreatment remediates saline stress induced symptoms. • Salicylic acid mediated modulation of endogenous hormones, as well as their signaling genes. • SA Receptor NPR1 dependent transcriptional regulation of biochemicals involves in redox control under saline stress.

Salinity Stress Mitigation by Foliar Feeding of Salicylic Acid on Maize (Zea Mays L.) grown under Hydroponic Culture

Salicylic acid (SA) is mainly associated with the regulation of plant growth particularly in salinity stress conditions and this signaling molecule exists in pivotal parts of plant. The objective of this research analysis was to overcome stress condition by distinct foliar treatments of Salicylic acid, for instance, 0 and 100 mM. Foliar applications of SA on maize were rendered on 10 days later than transplanting under a hydroponics experiment. Plants were grown under non-saline (S0= 0 mM NaCl) and saline (S1= 100 mM NaCl) conditions. Evaluation of biochemical, physiological and morphological attributes of maize was rendered after harvesting of plants. The experimental layout of Completely Randomized Design (CRD) under a factorial arrangement with three replications of each treatment was assigned for this study. According to our results it was confirmed that cultivation of maize under saline condition reduced the morphological, physiological and biochemical attributes of plant. However, exogenous application of SA on maize had a positive impact on the above mentioned traits under presence and absence of saline environment. Finally, it was justified that exogenous application of variable concentration of SA significantly improves whole parameters of maize cultivar.

Use of zeolite and salicylic acid as an adaptation strategy against drought in wheat plants

With the prevalence of water scarcity and a growing demand for food, it is imperative to utilize inexpensive and environmentally friendly materials such as zeolite (Ze) and salicylic acid (SA) in agricultural farms. In this regard, in the present study we measured the effects of exogenous application of Ze (4 g/kg soil and 8 g/kg soil) and SA (1 mM) on wheat plants Cv. Sirvan in both normal (100% FC) and drought stress (40% FC) conditions. The study measured several physiological, biochemical and morphological characteristics, including antioxidant enzyme activities (POD, CAT, APX), soluble sugar, soluble protein, inorganic ions (K+, Ca2+, and Mg2+), grain number and grain yield. SA and Ze (8 g/ kg) significantly improved drought tolerance of wheat plants. SA and Ze (8 g/ kg) also had positive effects on control plants. We therefore concluded that external application of SA (1 mM) and Ze (8 g/ kg) is recommended for improving drought tolerance.