Salicylic Acid Treatment Research Articles

Exogenous salicylic acid treatment enhances the disease resistance of Panax vietnamensis by regulating secondary metabolite production.

Salicylic acid (SA) is a phenolic compound widely found in plants. It plays a key role in exerting plant disease resistance. Panax vietnamensis Ha & Grushv., a valuable medicinal plant, contains high levels of phenolic compounds, which contribute significantly to the resilience of the plant against stress. However, the precise role of SA in regulating the synthesis of secondary metabolites in P.vietnamensis remains elusive. Two-year-old P. vietnamensis seedlings were treated with exogenous SA. We systematically assessed the changes in the physiological parameters of SA-treated P. vietnamensis leaves, employing transcriptome and metabolome analyses to elucidate the underlying mechanisms. Our results revealed a significant improvement of the plant's antioxidant capacity at 6 h post-treatment. Furthermore, exogenous SA treatment promoted the biosynthesis of lignin and flavonoids such as rutin, coumarin, and cyanidin. In addition, it increased the levels of endogenous SA and jasmonic acid (JA), promoting the disease resistance of the plants. Thus, SA pretreatment enhanced the defense of P. vietnamensis against pathogens. Our study provided novel insights into the potential molecular mechanisms underlying SA-mediated biosynthesis of secondary metabolites. Furthermore, our results provided a theoretical foundation for optimizing the cultivation practices of P.vietnamensis and the application of SA as a plant immunomodulator.

Salicylic acid treatment inhibits cold-induced sweetening by regulating the transcription factors StAP2/ERF and StNAC2 in potato

Abstract Cold-induced sweetening (CIS) results in browning and acrylamide formation in fried potato products. β-Amylase (BAM) and vacuolar invertase (INV) are crucial for starch–sugar conversion in cold-stored potatoes. This research investigates the effects of salicylic acid (SA) treatment on the CIS of potatoes and gene regulation during this process. The findings revealed that the SA treatment significantly alleviated CIS by suppressing StBAM1 and StINV1 expression in potato. Moreover, the expression of two transcription factors (TFs), StAP2/ERF and StNAC2, was inhibited by SA treatment. Transient overexpression of StAP2/ERF (AP2: APETALA2; ERF: ethylene responsive factor) and StNAC2 in tobacco leaves increased the expression of NtBAM1 and NtINV, thus promoting starch–sugar conversion. Furthermore, the β-glucuronidase (GUS) activity demonstrated that StAP2/ERF and StNAC2 increased the promoter activity of StBAM1 and StINV1. This study identifies new TFs in CIS regulation and provides new ideas for alleviating CIS in potato.

Utilizing Plant-Derived Salicylic Acid to Inhibit Leafminer Moth (Noorda blitealis Walker) Infestation on Moringa Oleifera

The experimental trial was conducted at Sakab Farm Limited Satame, Makoda Local Government. Kano State (12°18’20’’N, 8°36’30’’E / 12°16’0’’N, 8°27’50’’E), from October, 2021 to November, 2022. The experiments were established in various field cages in a split plot design with various levels of Salicylic acid (SA) treatments representing the main plots and the spray regimes: 1 weeks after spray (1-WAS), 2 weeks after spray (2-WAS) and 3 weeks after spray (3-WAS), as subplots. Different Concentrations of SA (5mg/l, 10mg/l and 20mg/l) were extracted from plant sources and formed by serial dilution. Ten freshly emerged larvae of Noorda blitealis collected from infested fields were introduced into each of the treatment group containing the treated stands of drumstick. The set up was undisturbed but observed at regular intervals. The results shows that, mean percentage leaves damage varied significantly (P<0.001) among different concentrations of SA and the spray regimes. Larval development time was significantly (P<0.05) prolonged in the higher concentration (20mg/l. SA) and median spray regime (2-WAS). The mean percentage leaves damage and progeny emergence of the moths were considerably low at the same treatment combinations. Moringa plants treated with higher concentrations of SA were also less infested and apparently more tolerant than the other treatments owing to their lower index of susceptibilities. This facility should be incorporated into the integrated control for effective management of Insect pest.

Effect on Yield and Alkaloid Content of Salicylic Acid Treatment in Different Growth Periods of Poppy

Amaç: Araştırma, haşhaşın farklı gelişme dönemlerinde salisilik asit uygulamasının, bitkisel özellikler, tohum verimi ve bazı alkaloitlerin içeriği üzerine etkisini araştırmak amacıyla yürütülmüştür.
 Materyal ve Yöntem: Çalışmada; TMO2 haşhaş çeşidi kullanılarak, geleneksel gübreleme üzerine rozet, sapa kalkma, rozet + sapa kalkma, tomurcuklanma, sapa kalkma + tomurcuklanma ve rozet+sapa kalkma+ tomurcuklanma dönemlerinde 100 ppm’lik salisilik asit uygulanmıştır.
 Araştırma Bulguları: Haşhaşın farklı gelişme dönemlerinde salisilik asit uygulamasının bitki boyu dışında incelenen özelliklere etkisi, istatistiksel olarak önemli (P

Detection and Estimation of Endogenous Jasmonic Acid and Salicylic Acid in Potato Genotypes Imposed with Defense Modulators Using High Performance Liquid Chromatography

Jasmonic Acid (JA) and Salicylic Acid (SA) are pivotal signaling molecules involved in the complex network of plant defense mechanisms. Enhancing the levels of JA and SA through exogenous application or genetic manipulation has shown promising results in bolstering plant resistance to a wide range of diseases. This study investigates the effects of JA, SA and Compost Tea (CT) treatments on the endogenous JA and SA responses of four distinct potato genotypes-KH (Kufri Himalini, Solanum tuberosum), KJ (Kufri Jyothi, Solanum tuberosum), AC4 (Solanum sparsipillium) and AC6 (Solanum spegzinii). High-Performance Liquid Chromatography (HPLC) analysis was conducted to determine endogenous detectable levels of JA and SA defence phytohormones. The absorption spectra showed peak absorptions at 295 nm and 325 nm for JA (25 µg ml-1) and SA (10 µg ml-1) respectively. Retention times of JA and SA were determined to be RT-3.74 and RT-2.86 min respectively. The genotypes were subjected to various concentrations of JA and SA, and their respective impacts on endogenous JA and SA were measured. Genotype-specific responses were evident, with all genotypes displaying distinct sensitivities with respect to endogenous detectable JA in CT (KH-15.42 µg ml-1, KJ-133.67 µg ml-1, AC4-10.36 µg ml-1, AC6-7.92 µg ml-1), JA (KH-83.03 µg ml-1, KJ-184.14 µg ml-1, AC4-286.95 µg ml-1, AC6-9.2 µg ml-1) treatments while no detectable JA and SA was observed in Control, SA and JA+SA combined treatments. JA could enhance higher amount of detectable endogenous JA than CT treatment. The application of JA and SA enhancement could demonstrate success in various other crops rendering resistance against diseases in an eco-friendly approach.

Salicylic acid and chitosan mitigate high temperature stress of rice via growth improvement, physio-biochemical adjustments and enhanced antioxidant activity

Sustainably increasing rice (Oryza sativa L.) becomes more challenging due to environmental stresses. High temperature stress resulting from global warming impact of climate change is highly damaging as it can cause growth and yield reduction of rice via cellular and physio-biochemical impairments. Application of either salicylic acid or chitosan can possibly increase plant's tolerance to different abiotic stresses; however, their combined mitigation effects remained inadequately explored. Thus, the objective of the current study was to evaluate the mitigation potential of combined salicylic acid and chitosan against high temperature stress of rice. The experiment was conducted in a factorial combination of two temperature regimes (optimum temperature [control] and high temperature); two salicylic acid levels (−SA: 0 mg L−1 and +SA: 140 mg L−1); and two chitosan levels (−Ch: 0 mg L−1, +Ch: 100 mg L−1) following a completely randomized design. High temperature impaired rice growth and productivity by negatively influencing all tested parameters; however, salicylic acid and chitosan could significantly mitigate those impairments. The mitigation on growth and yield contributing parameters was recorded at best 11 %, 21 %, 12 %, 75 %, 61 %, 46 %, 27 %, and 43 % for plant height, leaf area, shoot dry matter, pollen viability, effective tiller percentage, filled grain percentage, 1000-grain weight, and grain yield respectively. Highest alleviation in physio-biochemical parameters was also found at best 35 %, 68 %, and 67 % for leaf greenness, net photosynthetic rate, and stomatal conductance respectively with 28 % and 60 % respective increase in transpiration rate and proline concentration. Superoxide dismutase, catalase, ascorbate peroxidase and peroxidase activity were also boosted as high as 1.6-folds, 1.4-folds, 1.9-folds, and 2.6-folds respectively with subsequent reduction of 32 % lipid peroxidation and 34 % hydrogen peroxide concentration. For all tested parameters, the best positive effects were observed under combined salicylic acid and chitosan treatment. Individually, salicylic acid was found more effective than chitosan; however, their combined application resulted in significantly better alleviation responses over their individual application for most studied parameters. Our findings would contribute in present understanding of high temperature stress and would also help in strategizing better-suited management practices toward sustainable rice productivity.

Transcriptome analysis of tomato plants following salicylic acid-induced immunity against Clavibacter michiganensis ssp. michiganensis.

Salicylic acid (SA) is known to be involved in the immunity against Clavibacter michiganensis ssp. michiganensis (Cmm) that causes bacterial canker in tomato. To identify the candidate genes associated with SA-inducible Cmm resistance, transcriptome analysis was conducted via RNA sequencing in tomato plants treated with SA. SA treatment upregulated various defense-associated genes, such as PR and GST genes, in tomato cotyledons. A comparison of SA- and Cmm-responsive genes revealed that both SA treatment and Cmm infection commonly upregulated a large number of genes. Gene Ontology (GO) analysis indicated that the GO terms associated with plant immunity were over-represented in both SA- and Cmm-induced genes. The genes commonly downregulated by both SA treatment and Cmm infection were associated with the cell cycle and may be involved in growth and immunity trade-off through cell division. After SA treatment, several proteins that were predicted to play a role in immune signaling, such as resistance gene analogs, Ca2+ sensors, and WRKY transcription factors, were transcriptionally upregulated. The W-box element, which was targeted by WRKYs, was over-represented in the promoter regions of genes upregulated by both SA treatment and Cmm infection, supporting the speculation that WRKYs are important for the SA-mediated immunity against Cmm. Prediction of protein-protein interactions suggested that genes encoding receptor-like kinases and EF-hand proteins play an important role in immune signaling. Thus, various candidate genes involved in SA-inducible Cmm resistance were identified.

Physiological and Transcriptional Analysis Provides Insights into Tea Saponin Biosynthesis and Regulation in Response to SA in Camellia vietnamensis Huang

Camellia vietnamensis Huang is an important and famous woody oil crop with high economic value in China because of its high-quality, edible, and medicinal oil. As one of its major active components, tea saponin (triterpenoid saponin) has shown anticancer, antioxidant, bacteriostatic, and other pharmacological activities. In this study, C. vietnamensis was used as an experimental material to determine the tea saponin content and physiological activity indicators after salicylic acid (SA) treatment and to analyze the differential expression genes of key metabolic pathways in response to SA by combining transcriptome data. The results showed that SA treatment increased the content of tea saponin and total phenols in leaves; effectively promoted the activity of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX); and decreased the content of malondialdehyde (MDA). A total of 60,038 genes, including 5871 new genes, were obtained by the RNA-seq. There were 6609 significantly differential expression genes mainly enriched in pathways such as sesquiterpenoid and triterpenoid biosynthesis, terpenoid backbone biosynthesis, diterpenoid biosynthesis, and flavonoid biosynthesis. The SA-induced key structural genes (SQS, SQE, bAS, CYP450, and UGT) and transcription factors related to the tea saponin biosynthetic pathway were screened by weighted gene co-expression network analysis (WGCNA). The results of this study could provide a theoretical basis and a new technical method to improve the content of tea saponin, with its excellent anticancer activity, in C. vietnamensis.

Heterologous expression in E. coli and functional characterization of the tomato CPR enzymes

NADPH-cytochrome P450 reductase (CPR) is a key enzyme transferring electrons to cytochrome P450. In tomatoes (Solanum lycopersicum), two CPR genes, SlCPR1 and SlCPR2, were identified. In all the tested tomato tissues, SlCPR2 showed higher expression levels than SlCPR1. SlCPR2 expression increased significantly with jasmonic acid treatment. No significant changes were observed with salicylic acid or drought stress treatment. The cDNA of SlCPRs were expressed in Escherichia coli without any amino acid modification. And the heterologously expressed SlCPR enzymes were reacted with several protein and chemical substrates. SlCPR2 was more active than SlCPR1. Both SlCPR1 and SlCPR2 exhibited strong activity across a pH range of 6.0 to 9.0, with peak activity at pH 8.0. The study opens possibilities for CPR control, biocatalyst development, and exploring oxidase enzyme functions.

Prolonged vase life by salicylic acid treatment and prediction of vase life using petal color senescence of cut lisianthus

This study investigated the effects of exogenous salicylic acid (SA) concentrations (0, 0.1, 0.3, or 0.5 mM), treatment timing (vegetative or reproductive period), and cultivation methods (soil or hydroponic cultivation) on the vase life of four lisianthus cultivars after flower cutting. A 0.5 mM concentration of the SA application during the reproductive period resulted in the longest average vase life of 15.3 d for the Blue Picote cultivar after flower cutting. A colorimeter and a chlorophyll meter were used to observe and quantify petal color changes after cutting, and the color changes during the senescence stages are visualized using a three-dimensional color space. The three-dimensional visualization demonstrated the color senescence for each measurement period. Based on these data, we used automated machine learning algorithms to predict the vase longevity, and the predictive model showed a good accuracy. This model is expected to be widely used in the floricultural industry.

A 4D Proteome Investigation of the Potential Mechanisms of SA in Triggering Resistance in Kiwifruit to Pseudomonas syringae pv. actinidiae.

Kiwifruit bacterial cankers caused by Pseudomonas syringae pv. actinidiae (Psa) are a serious threat to the kiwifruit industry. Salicylic acid (SA) regulates plant defense responses and was previously found to enhance kiwifruit's resistance to Psa. However, the underlying mechanisms of this process remain unclear. In this study, we used 4D proteomics to investigate how SA enhances kiwifruit's resistance to Psa and found that both SA treatment and Psa infection induced dramatic changes in the proteomic pattern of kiwifruit. Psa infection triggered the activation of numerous resistance events, including the MAPK cascade, phenylpropanoid biosynthesis, and hormone signaling transduction. In most cases, the differential expression of a number of genes involved in the SA signaling pathway played a significant role in kiwifruit's responses to Psa. Moreover, SA treatment upregulated numerous resistance-related proteins, which functioned in defense responses to Psa, including phenylpropanoid biosynthesis, the MAPK cascade, and the upregulation of pathogenesis-related proteins. We also found that SA treatment could facilitate timely defense responses to Psa infection and enhance the activation of defense responses that were downregulated in kiwifruit during infection with Psa. Thus, our research deciphered the potential mechanisms of SA in promoting Psa resistance in kiwifruit and can provide a basis for the use of SA to enhance kiwifruit resistance and effectively control the occurrence of kiwifruit bacterial cankers.

Salicylic acid improving physiological and phytochemical changes in Stevia rebaudiana under salt stress and estimating steviol glycoside by LC-MS/MS

Almost every area of plant development is negatively impacted by stress. Salicylic acid (SA), when supplied exogenously, has been demonstrated to be a regulatory hormone that may mitigate the harmful effects of salt stress. Diabetics, hypertensive and health-conscious people substitute Stevia rebaudiana for sugar. Salinity is the global problem directly affecting the quality and quantity of stevia. Each group received 100 mM NaCl treatment for seven days followed by 0.1 mM, 0.2 mM and 0.05 mM SA treatment. Salt stress reduces the amount of chlorophyll (P<0.001) and the antioxidant capacity (P<0.001) which is restored by SA treatment. Salt stress increased proline (P<0.001), MDA (P<0.001) and other antioxidant enzymes (P<0.001), with the exception of catalase (P<0.05). Furthermore, salt stress has a negative impact on stevioside production which SA assisted in improving. Salt stress hampered the biology and phytochemistry of Stevia. SA restored antioxidants, chlorophyll, proline and phytochemicals. SA also helped to improve the steviol production in salt stress which is significantly lower in normal plants. Method developed to estimate steviol level can also be helpful to different industries involved in stevia products.

Mitigation of Salinity-Induced Growth Inhibition of Maize by Seed Priming and Exogenous Application of Salicylic Acid

Soil salinity has come to be recognized as a global challenge to the sustainability of farming systems due to its adverse effects on crop quality and production, particularly in coastal regions of the world. Although maize (Zea mays L.), a C4 plant, has the capacity to withstand a medium degree of salinity, maize is vulnerable to salinity stress during its early growth phases. Therefore, in order to develop strategies to improve maize adaptability in saline settings, it is essential to increase our understanding of maize response to salt stress and tolerance mechanisms. According to reports, plants are known to be able to withstand salt stress when phytohormones are applied. Salicylic acid (SA), a widely-used plant hormone, has been shown to increase a plant's ability to withstand salt stress. In order to reduce the growth inhibition of maize caused by salt, the aim of this study was to clarify and assess the potential impact of priming and exogenous administration of salicylic acid (SA). The results revealed that salt stress decreased seed germination, seedling fresh and dry weight, leaf relative water content (RWC), and photosynthetic pigments of maize. Salicylic Acid (SA) treatment increased germination percentage (43-69%), shoot (24-56%) and root length (13-37%), dry weight of shoot and root (35-171%), RWC (34-39%), and chlorophyll contents (12-36%) of maize under salt stress. The findings highlight the need for additional research to fully understand the underlying mechanisms and explore SA's potential mitigating effects in lowering salt stress as well as its potential practical applications in agricultural practices.

Salicylic acid and putrescine treatments reduce yellowing, decay and retain postharvest quality of bitter gourd (Momordica charantia L.) during cold storage

Bitter gourd is a valuable cucurbitaceous vegetable rich in various beneficial phytochemicals such phenols, antioxidants, saponins, charantin etc. In spite of high medicinal value bitter gourd faces significant postharvest losses due to factors such as mass reduction, tissue softening, yellowing, and fungal contamination, especially when stored under ambient conditions. To combat these issues, immature green bitter gourd fruits (16 DAP) were subjected to different concentrations of salicylic acid (SA) at 5, 7.5, and 10 mM) and putrescine (PUT) at 1, 2, and 3 mM, through a 15-minute dipping process. In contrast, untreated fruits were dipped in distilled water and served as the control group. These treated and control fruits were subsequently stored at 10 ºC with a relative humidity range of 85–95 % for 20 days. Results showed that among all treatments, bitter gourd fruits treated with 10 mM SA exhibited the most noteworthy outcomes. They retained higher levels of total phenols (26.28 μg GAE 100 g-1), radical scavenging activity (27.95 %), ascorbic acid content (50.0 mg 100 g-1 FW), and total chlorophyll (0.32 mg g-1 FW) on the 20th day of storage. Additionally, the 10 mM SA treatment demonstrated the highest inhibition of α-amylase and α-glucosidase activity, as well as the lowest decay percentage when compared to the control. On the other hand, 3 mM PUT treatment resulted in greater fruit firmness (27.45 N), lower per cent postharvest loss weight (6.60 %), and reduced pectin methyl esterase (PME) activity (0.0075 µmol min-1 g-1 FW). These findings were further validated through principal component analysis (PCA), which highlighted that bitter gourd fruits could be effectively stored for up to 20 days at 10 ºC with pre-storage treatment involving 10.0 mM SA and 3.0 mM PUT. Overall higher quality and shelf-life of bitter gourd were obtained in bitter gourd treated with 10.0 mM SA. Consequently, it is recommended that the application of SA and PUT represents an environmentally friendly approach to preserve the quality of bitter gourd during storage, benefiting both retailers and consumers alike.

Effects of Using Salicylic acid, Potassium chloride, and a Mixture of Salicylic acid and Potassium chloride Treatments on Salt-stressed Cucumis sativus CV. Malaysia timun2 Germination

Effects of Using Salicylic acid, Potassium chloride, and a Mixture of Salicylic acid and Potassium chloride Treatments on Salt-stressed Cucumis sativus CV. Malaysia timun2 Germination

Growth of Mustard under Open Field Conditions with Salicylic Acid and Antimicrobial Thiourea

Mustard plants were subjected to varying doses of thiourea (TU) and salicylic acid (SA) to assess their response as growth regulators. The primary objective of this study was to investigate the hypothesis that the growth regulator SA can enhance the protection of the photosynthetic apparatus by up-regulating morphological traits in these plants. The experimental design involved sowing mustard seeds under natural environmental conditions in a field setting. Upon reaching the 15-day growth stage, the plants were subjected to different TU and SA treatment levels for 3 days. Subsequently, they were allowed to continue growing for 90 days. Various morphological traits were meticulously evaluated in the standing mustard plants. Following the application of SA and TU, noticeable improvements were observed in the number of nodes, primary branches, leaf area, and intermodal length of the plants. The data suggested that the morphological traits in the mustard plants were up-regulated by applying SA and TU. Furthermore, after using these substances, a detailed analysis of the alterations in functional groups within the leaves was conducted.. KEYWORDS :Brassica juncea, Growth regulators, Morphology, Salicylic acid, Thiourea

Exogenous citric acid, salicylic acid, and putrescine treatments preserve the postharvest quality and physicochemical properties of broccoli (Brassica oleracea L. var. italica) during cold storage.

To extend the postharvest storage life of broccoli samples (Brassica oleracea L. var. italica), an exogenous application of citric acid (CA), salicylic acid (SA), and putrescine (PUT) was tested in multiple combinations (0.5 and 1 mM) at 4 ± 0.5°C and 90 ± 5% relative humidity (RH) for 21 days (d). The weight loss (WL), respiration rate (RR), total soluble solids (TSS), pH, color (L*, a*, b*, chroma, and hue angle), proximate and mineral contents, phenolic and flavonoid contents, and other biochemical properties of the treated and untreated broccoli samples were evaluated throughout the storage duration. The lowest WL was observed when exposed to 0.5 mM of PUT. 1 mM CA and PUT treatments were affected by RR, depending on storage conditions. The lowest TSS content was observed in broccoli samples treated with 0.5 mM CA among all treatments. The chroma value of the samples was preserved by the 0.5 mM SA treatment. The most abundant element in broccoli samples was potassium in the control application, followed by a 1 mM SA treatment. In addition, the protein content was the highest in the 1 mM PUT treatment. The highest vitamin C was determined in the 1 mM CA treatment, and the most abundant vanillic acid was found in broccoli exposed to the 0.5 mM and treatment. Glucose content was determined at the lowest level in the 0.5 mM SA treatment, while higher increases occurred in other treatments. In terms of these findings, 1 mM CA, 1 mM SA, and 1 mM PUT delay WL, RR, and color degradation and prolong the storage life of broccoli samples stored at 4 ± 0.5°C. It was concluded that the biochemical content, fresh weight, and green color of broccoli samples throughout postharvest and storage can be maintained longer by exogenous application of these natural compounds. Therefore, we recommend 1 mM PUT and 1 mM CA treatments to maintain the quality of broccoli by minimizing losses in morphological properties, mineral, and biochemical compositions during postharvest storage.

A putative E3 ubiquitin ligase substrate receptor degrades transcription factor SmNAC to enhance bacterial wilt resistance in eggplant.

Bacterial wilt caused by Ralstonia solanacearum is a severe soil-borne disease globally, limiting the production in Solanaceae plants. SmNAC negatively regulated eggplant resistance to Bacterial wilt (BW) though restraining salicylic acid (SA) biosynthesis. However, other mechanisms through which SmNAC regulates BW resistance remain unknown. Here, we identified an interaction factor, SmDDA1b, encoding a substrate receptor for E3 ubiquitin ligase, from the eggplant cDNA library using SmNAC as bait. SmDDA1b expression was promoted by R. solanacearum inoculation and exogenous SA treatment. The virus-induced gene silencing of the SmDDA1b suppressed the BW resistance of eggplants; SmDDA1b overexpression enhanced the BW resistance of tomato plants. SmDDA1b positively regulates BW resistance by inhibiting the spread of R. solanacearum within plants. The SA content and the SA biosynthesis gene ICS1 and signaling pathway genes decreased in the SmDDA1b-silenced plants but increased in SmDDA1b-overexpression plants. Moreover, SmDDB1 protein showed interaction with SmCUL4 and SmDDA1b and protein degradation experiments indicated that SmDDA1b reduced SmNAC protein levels through proteasome degradation. Furthermore, SmNAC could directly bind the SmDDA1b promoter and repress its transcription. Thus, SmDDA1b is a novel regulator functioning in BW resistance of solanaceous crops via the SmNAC-mediated SA pathway. Those results also revealed a negative feedback loop between SmDDA1b and SmNAC controlling BW resistance.

Exogenous salicylic acid induces defense responses in tea plants against Toxoptera aurantii (Hemiptera: Aphididae).

Toxoptera aurantii is one of the most destructive pests, threatening the yield and quality of tea plantations. The salicylic acid (SA)-mediated signaling pathway is vital for the induction of plant defense responses; however, its role in tea plant resistance to T. aurantii remains unclear. Thus, this study used and electrical penetration graph and monitoring of population dynamics to evaluate the effects of exogenous SA application on T. aurantii feeding behavior and population growth in tea seedlings. Moreover, the effects of SA treatment on the activities of defense-related enzymes were analyzed. Probe counts and the duration of xylem sap ingestion were significantly higher in SA-treated plants than those in the control group. The total duration of passive phloem ingestion was significantly decreased in 0.5 mmol/l SA-treated plants, and the application of 0.5, 1, and 4 mmol/l SA significantly inhibited T. aurantii population growth. In addition, the activities of polyphenol oxidase, peroxidase, and superoxide dismutase were significantly increased in the 0.5 mmol/l SA-treated plants. Overall, this study demonstrates the capacity of exogenous SA to activate defense responses against T. aurantii. These results have crucial implications for understanding the mechanisms of enhanced resistance, thereby providing a sustainable approach for managing T. aurantii.

Preharvest Foliar Spraying Combined with Postharvest Salicylic Acid Treatment Regulates Panzao (Ziziphus jujuba Mill. cv. ‘Jingcang1’) Fruit Quality and Softening during Storage

Panzao (Ziziphus jujuba Mill. cv. ‘Jingcang1’) have a short shelf-life, which hampers their marketability. To investigate effects of combined pre- and postharvest treatments on quality and softening during storage, preharvest Guomantian foliar fertilizer (FF) spray and postharvest salicylic acid (SA) dip were applied to panzao. By day 63 of storage, fruit firmness responded to treatment in the order of FF+SA treatment > FF or SA treatments > Control. All treatments inhibited fruit reddening during storage and, compared with those of the control, alleviated the decline in total soluble solids, ascorbic acid, and phenol contents and decreased the oxidative aging process, which was consistent with the change in firmness. The FF+SA treatment reduced the activities of amylase, cellulase, polygalacturonase, and β-glucosidase, which decreased the degradation of macromolecules including starch, cellulose, and pectin. Principal component analysis showed that FF+SA exhibited a synergistic effect and was the most effective treatment for maintaining fruit quality during storage. FF increased accumulation of nutrients during growth and improved quality, while SA delayed the decline in fruit quality and reduced softening. These results provide the theoretical basis and technical knowledge for improving the shelf-life of panzao during storage and long-distance transportation.