Search Results (229)

Phosphorus (P) deficiency is a major constraint on crop productivity, and rapeseed (Brassica napus L.) is particularly sensitive to low phosphorus (LP) stress, yet the role of salicylic acid (SA) in alleviating LP stress in this crop remains poorly understood. Here, we investigated how exogenous SA alleviates LP stress in rapeseed seedlings. SA was applied at 0.1 mM and 0.2 mM under LP conditions, and its effects on plant growth, physiological traits, and transcriptomic responses were evaluated. SA treatment significantly ameliorated LP-induced growth inhibition, increased chlorophyll content and peroxidase activity, and reduced superoxide anion accumulation. RNA-seq analysis revealed that SA up-regulated the expression of phosphate transporter (PHT) family genes and activated genes involved in nitric oxide biosynthesis, flavonoid biosynthesis, glutathione metabolism, and nitrogen metabolism. These findings indicate that SA enhances LP tolerance in rapeseed through coordinated regulation of phosphorus acquisition, antioxidant defense, and key metabolic pathways, highlighting the potential of exogenous SA as an approach that could be further explored to improve phosphorus use efficiency under phosphorus-limited conditions in controlled environments, with field validation still needed. Full article

Plants are constantly exposed to a wide range of abiotic stresses that have significant negative impacts on growth and yield. Plant acclimation to these stresses is governed by integrated classical phytohormone and plant peptide hormone signalling networks that control the ability of a plant to survive and adapt to extreme environments. Classical phytohormones, including abscisic acid, auxins, gibberellins, cytokinins, jasmonates, salicylic acid, brassinosteroids, and the recently recognised phytomelatonin, act in concert with peptide-based plant hormones, among which C-terminally encoded peptides (CEPs) play prominent roles in coordinating stress perception, signal transduction, and adaptive responses throughout the plant. These integrated networks control stomatal behaviour, photosynthesis, osmolyte and antioxidant levels, root architecture, and energy metabolism, thereby helping plants maintain homeostasis and optimise survival while sustaining minimal growth under unfavourable conditions. Under stressful conditions, these networks do not operate in isolation but form highly dynamic, context-dependent regulatory circuits in which each physiological process is simultaneously regulated by multiple hormones acting through convergent and overlapping signalling pathways. Phytomelatonin has emerged as a particularly important integrative node within these networks, functioning both as a potent direct antioxidant through sequential ROS-scavenging catabolite cascades and as a bidirectional regulator of classical phytohormone signalling under diverse abiotic stresses. New technologies in the fields of transcriptomics, proteomics, phosphoproteomics, metabolomics, and systems biology have provided new information on the dynamic relationships between classical phytohormones and plant peptide hormones, revealing candidate regulatory nodes and transcription factor networks that mediate stress adaptation at molecular, biochemical, and physiological levels. However, it is important to distinguish between correlative associations identified through omics profiling and causal regulatory relationships validated through rigorous genetic and biochemical experimentation, as most omics-derived candidates remain to be functionally established. Empirical studies demonstrate how these networks can be used to improve crops by increasing stress tolerance through modulating classical phytohormone and plant peptide hormone signalling, including through exogenous phytomelatonin application, CRISPR-mediated hormone pathway editing, and CEP pathway manipulation, to produce resilient cultivars without reducing yields. Although these advances represent significant progress, challenges remain, including the inherent complexity and redundancy of the networks, context-dependence and severity-dependence of hormonal responses, the persistence of a significant translational gap between laboratory findings and field application, and incomplete mechanistic understanding of peptide hormone roles under combined stress conditions. Addressing these challenges will require integrative multi-omics approaches, higher-order computational modelling, and rigorous field-based functional validation alongside emerging tools such as synthetic biology and precision breeding. Full article

Salicylic acid (SA) is involved in plant defense responses to environmental stressors by modulating gene expression and specialized metabolites production, enhancing plant adaptive resilience through systemic signaling pathways. This study investigates the impact of exogenous application of SA on the metabolism of iridoids and phenolic compounds—characteristic specialized metabolites of the Nepeta species, associated with diverse biological activities. Nepetalactone (NL) is a characteristic monoterpene iridoid, while rosmarinic acid (RA) represents the most abundant phenolic compound within the genus. We explored the effects of varying SA concentrations (2 µM, 5 µM, 10 µM, and 20 µM) on iridoid and phenolic metabolism in in vitro-grown Nepeta nuda, following 7 days and 28 days of elicitation. A significant increase in trans,trans-NL content was observed after 7-day exposure to 2 µM SA, while prolonged exposure led to a decrease in its levels, particularly at higher SA concentrations. Gene expression analysis revealed that 7 days of exposure to lower concentrations of SA upregulated genes coding for NAD-dependent nepetalactol-related short-chain dehydrogenase/reductases (NEPSs), key regulatory enzymes catalyzing the final steps of NL biosynthesis. In contrast, prolonged exposure to 20 µM SA downregulated genes coding for geraniol 8-hydroxylase (NnG8H) and 8-hydroxygeraniol oxidoreductase (Nn8HGO), which resulted in reduced iridoid content. Conversely, SA treatment notably increased RA content after prolonged exposure to 20 µM SA, which is a result of the enhanced expression of all analyzed RA biosynthesis-related genes. These findings demonstrate that both concentration and duration of SA treatment are critical determinants of elicitation outcomes in N. nuda. Strategic manipulation of these parameters can redirect metabolic flux toward either iridoid or phenolic compounds production, and enhance biotechnological production of specialized metabolites in N. nuda. Full article

Environmental stress factors, especially salinity, are among the most important abiotic stresses that negatively affect plant production worldwide. High salt levels in irrigation water are a major abiotic stress factor that significantly reduces spinach physiological functioning and production, particularly in irrigated areas. Improving the salt tolerance of spinach is critical for sustainable production, and in this study, we tested the hypothesis that exogenous proline (5 µM), ascorbic acid (1 mM), and salicylic acid (1 mM) applications, applied separately, would reduce salinity stress. These applications were performed at regular 14-day intervals starting from the third true leaf stage. For this purpose, plants were exposed to irrigation water salinities of 0.38, 2.0, 4.0, 7.0, 10.0, and 15.0 dS m⁻¹, and growth, photosynthetic performance, antioxidant enzyme activities, lipid peroxidation, endogenous proline, and mineral contents were assessed. Increasing salinity to 15 dS m⁻¹ decreased leaf area by 53.23% and stomatal conductance by 83.07%, and all these physiological changes were statistically significant. Under salinity conditions, catalase, guaiacol peroxidase, glutathione reductase, glutathione S-transferase, and superoxide dismutase activities increased by 1.13–2.52-fold, while ascorbate peroxidase activity decreased by 59.69%. Malondialdehyde levels increased 6-fold with salinity, indicating enhanced oxidative damage. Consequently, yield decreased by 31% under 15 dS m⁻¹ salinity. Although all exogenous applications alleviated salinity stress, the most significant improvement was observed in proline application. Proline increased yield and chlorophyll content by 9% and 8.5%, respectively, and also increased antioxidant enzyme activities by 24.4–66.7%. Salicylic acid treatment increased the K⁺/Na⁺ ratio by 26.6%, and ascorbic acid treatment increased the Ca²⁺/Na⁺ ratio by 36.6%. Overall, low-dose proline application was found to improve photosynthetic pigment content and stomatal conductance, antioxidant defenses, and ion homeostasis in spinach against salinity stress, providing a stronger protective effect compared to ascorbic acid and salicylic acid. Furthermore, it can be concluded that proline application could be an effective way to manage salinity-induced limitations to physiological processes and yields, providing practical applications for sustainable production under saline irrigation conditions. Full article

Salicylic acid (SA) is a key regulator of plant immunity and contributes to defence against Plasmodiophora brassicae, the causal agent of clubroot disease in canola (Brassica napus) and other crucifers. Exogenous SA applications have reduced clubroot severity in some Brassica pathosystems, yet the effectiveness of foliar SA treatment against the predominant resistance-breaking pathotype 3A in western Canada remains unclear. This study evaluated the effects of weekly foliar applications of 0, 1, 5, or 10 mM SA on clubroot development in two B. napus var. napobrassica cultivars under greenhouse and growth chamber conditions. Plants inoculated with pathotype 3A were assessed for disease severity, pathogen resting spore load, plant height, and transcript accumulation of SA-responsive genes. Overall, SA treatments resulted in modest reductions in disease severity and resting spore concentrations; however, treatment effects did not reach statistical significance in most cases. Collectively, foliar SA applications provided limited suppression of clubroot caused by pathotype 3A. Further optimization of SA concentration, timing, and delivery, particularly when targeting the root zone, may be required before SA can be considered a complementary tool in integrated clubroot management. Full article

Walnut (Juglans regia) is an economically significant woody oil tree species widely cultivated in China. However, its production is increasingly threatened by extreme low-temperature events, such as unseasonal frosts and late-spring cold. Salicylic acid (SA) is a key phytohormone known to enhance cold tolerance in plants, yet its underlying mechanism in walnut remains unclear. In this study, we present the first integrated analysis combining physiological measurements, transcriptomics, and metabolomics to investigate how exogenous SA improves cold tolerance in walnut leaves. Our results showed that SA treatment significantly increased the accumulation of soluble sugars, chlorophyll, and proline, enhanced peroxidase (POD) activity, and reduced malondialdehyde (MDA) levels under cold stress. Multi-omics analysis revealed that SA modulated the expression of genes involved in multiple hormone signaling pathways, including those of SA, auxin, jasmonic acid, and abscisic acid, and altered corresponding hormone levels. Notably, carbohydrate metabolism emerged as a central pathway mediating SA-induced cold adaptation. Weighted gene co-expression network analysis (WGCNA) further identified several core candidate genes, such as JrTGA, JrPP2C, JrTPS, and JrBAM, which may play key roles in this process. Collectively, this study provides the first multi-omics perspective on the regulatory network underlying SA-enhanced cold tolerance in walnut. These findings offer both a theoretical and technical foundation for applying SA in cold-resistant walnut cultivation and contribute to the development of stress-resilient production strategies. Full article

BASIC PENTACYSTEINE (BPC) transcription factors are plant-specific and play crucial roles in regulating plant development and responses to abiotic stresses. However, the genomic characteristics of the BPC gene family in Brassica juncea and its regulatory mechanisms in response to light and salicylic acid remain poorly understood. In this study, we identified 25 BjuBPC genes in the B. juncea genome using bioinformatic approaches. All BjuBPC proteins were predicted to localize exclusively to the nucleus, with their distribution scattered across 14 chromosomes of B. juncea. Phylogenetic analysis classified these BjuBPC genes into three subfamilies (A, B, and C). The 25 BjuBPC genes showed strong collinearity with BPC orthologs from Arabidopsis thaliana, Brassica rapa, and Brassica nigra, and members of the same subfamily shared highly conserved exon–intron architectures and motif compositions, and a highly conserved canonical GAGA DNA-binding domain. Expression profiling across tissues revealed both tissue-specific and constitutive expression patterns among BjuBPC members. Subsequent expression analyses under four light qualities and exogenous salicylic acid treatment demonstrated that BjuBPC1, BjuBPC9, and BjuBPC24 were specifically responsive to both light and salicylic acid signals, with markedly strong induction by blue light. These findings provide valuable insights for future functional characterization of BjuBPC genes and enhance our understanding of their biological roles in B. juncea. Full article

Alfalfa mosaic virus (AMV) is a devastating plant pathogen with an extensive host range, yet effective control strategies remain limited. This study investigated the prophylactic efficacy and molecular mechanisms of two plant immune inducers, the Paecilomyces variotii extract DYDS and the antiviral agent Dufulin, against AMV infection in cowpea (Vigna unguiculata). Our results demonstrate that both agents possess potent antiviral activity, with inactivation, protective, and therapeutic efficacies all exceeding 21.00%. Notably, DYDS exhibited superior overall performance. RT-qPCR and immunofluorescence assays confirmed a significant downregulation of AMV coat protein (CP) expression in treated plants. Furthermore, exogenous application of these inducers mitigated chlorophyll loss and markedly augmented the activities of key defense enzymes’ activity, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO), and L-phenylalanine ammonia-lyase (PAL), peaking at 5 days post-inoculation. In silico molecular docking simulations further revealed that DYDS and Dufulin interact spontaneously with the AMV-CP, yielding binding free energies of −6.5 and −5.8 kcal/mol, respectively. Gene expression analysis indicated that these inducers trigger a robust immune response through the integrated activation of the salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) signaling pathways. Collectively, these findings suggest that DYDS and Dufulin provide a dual mode of action—direct viral inhibition and host immune priming—offering a promising and sustainable approach for the management of AMV in leguminous crops. Full article

Eutrema salsugineum is a model species for studying stress resistance, particularly extreme salinity, and is often compared with Arabidopsis thaliana. Previous research has shown that basal salicylic acid (SA) levels are significantly lower in E. salsugineum than in A. thaliana. In this study, subtractive hybridization revealed that SA-related genes were extensively induced in Arabidopsis but not in Eutrema. Using exogenous SA and the biosynthesis inhibitor paclobutrazol (PBZ), we further demonstrated that the low endogenous SA level in Eutrema significantly upregulates dehydroascorbate reductase (DHAR) and glutathione reductase (GR) gene expression, doubling the pools of total ascorbic acid and total glutathione. While SA treatment decreased the ratios of reduced ascorbic acid (ASA) to dehydroascorbate (DHA) and reduced glutathione (GSH) to oxidized glutathione (GSSG), PBZ treatment increased them, correspondingly modulating DHAR and GR activities and gene expression. The resulting enhancement of these key non-enzymatic antioxidants is a critical mechanism underpinning the superior salt tolerance of Eutrema. Full article

Pear black spot disease is a serious fungal disease during pear production; salicylic acid is a core signaling molecule that regulates the expression of plant disease resistance genes. To elucidate the intrinsic association between salicylic acid-induced resistance to pear black spot disease and lignin biosynthesis, in vitro plantlets of two pear cultivars, ‘Xinli No.7’ and ‘Xueqing’, were employed as experimental materials. After 60 h SA pretreatment, the leaves were inoculated with the pathogen Alternaria alternata. Leaf samples were harvested at 0, 8, 16, 24, and 48 h post-inoculation to determine phenylalanine ammonia-lyase activity, quantify lignin content, and analyze the transcript levels of genes involved in lignin synthesis. The results demonstrated that, relative to the untreated control group, SA treatment significantly enhanced phenylalanine ammonia-lyase activity and promoted lignin accumulation in both ‘Xinli No.7’ and ‘Xueqing’. Moreover, multiple key genes associated with lignin biosynthesis—including PbrPAL1, Pbr4CL1, PbrCOMT, PbrCCoAOMT, PbrCAD, and PbrPOD—were markedly upregulated, with their expression levels increasing by 3.5–15 fold. Transcript profiles of PbrHCT1, PbrHCT4, and PbrC3H1 exhibited cultivar-specific divergence between the two varieties. Notably, the susceptible cultivar ‘Xueqing’ displayed a distinct lag phase and attenuated response in the expression of all lignin-related genes compared with the other cultivar. This study provides reference for green prevention and sustainable development of pear. Full article

Salinity stress is a major constraint on the growth and productivity of sugar beet (Beta vulgaris L.). This study evaluated the potential of exogenously applied putrescine (Put) and salicylic acid (SA) to enhance salt stress tolerance. Thirty-day-old seedlings were grown for seven days under control conditions before being subjected to eight treatments for 10 days: (i) Control, (ii) Control + 0.6 mM Put, (iii) Control + 0.6 mM SA, (iv) Control + 0.6 mM Put + 0.6 mM SA, (v) Salinity (150 mM NaCl), (vi) Salinity + 0.6 mM Put, (vii) Salinity + 0.6 mM SA, and (viii) Salinity + 0.6 mM Put + 0.6 mM SA. Put and SA were applied once as a foliar spray at the onset of the treatments. Salt stress significantly reduced plant growth, biomass, chlorophyll content, and photosynthetic efficiency, while increasing reactive oxygen species (particularly H₂O₂) and lipid peroxidation. Foliar applications of Put and SA alleviated these adverse effects, either individually or in combination. Put primarily enhanced plant growth rate, shoot length, plant height, shoot and root biomass, leaf relative water content, respiration activity, and sucrose accumulation. SA improved root length, photosynthetic activity, water-use efficiency, and proline accumulation. When applied together, Put and SA combinedly increased growth rate, shoot length, plant height, shoot biomass, leaf relative water content, stomatal conductance, and the maximum quantum yield of PSII, while more prominently reducing malondialdehyde and H₂O₂ accumulation and enhancing antioxidant enzyme activities. These findings suggest that foliar application of Put and SA enhances salinity tolerance in sugar beet seedlings by improving antioxidant enzyme activities, osmolyte accumulation, and ion homeostasis, thereby mitigating oxidative stress under saline conditions. This outcome could contribute to potential applications in breeding programs and stress management in saline-prone regions. Full article

To elucidate the comprehensive mechanism by which nitric oxide (NO) enhances low-temperature tolerance in cucumber, we utilized two cucumber cultivars (Jinyan No. 4 and Jinyou No. 1) as experimental materials. By integrating transcriptomic analysis with physiological indicators, we investigated the physiological and molecular mechanisms underlying the NO-mediated improvement of cold tolerance. Both molecular and physiological data revealed that phytohormone signal transduction and alpha-linolenic acid metabolism were significantly affected by low-temperature stress alone and in combination with exogenous SNP treatment in both cultivars. Under low-temperature stress, most transcripts associated with abscisic acid (ABA) biosynthesis, ABA signal transduction, and flavonoid biosynthesis were coordinately downregulated in cucumber. In contrast, transcripts related to secondary metabolism, lipid metabolism, glutathione biosynthesis, and hormone signal transduction—including salicylic acid (SA), ethylene (ETH), gibberellin (GA), and jasmonic acid (JA) pathways—were coordinately upregulated. Additionally, exogenous SNP was found to regulate both phytohormone signal transduction and endogenous hormone levels. These results suggest that exogenous NO improves low-temperature tolerance in cucumber seedlings primarily by modulating phytohormone signaling and secondary metabolism. Full article

Maize ear rot is an important fungal disease in maize production, mainly caused by pathogens such as Fusarium graminearum, which seriously affects the yield and quality of maize. This study investigated the changes in the activity of defense-related enzymes in maize grains and their transcriptome response characteristics after exogenous SA treatment under Fusarium graminearum stress. The results showed that treatment with 0.01 mmol/L salicylic acid (SA) significantly inhibited the growth of Fusarium graminearum hyphae, while enhancing the activities of phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD), β-1,3-glucanase (β-1,3-GA), and polyphenol oxidase (PPO) in maize grains, and reducing the content of malondialdehyde (MDA), effectively alleviating the damage of Fusarium graminearum to the maize grain membrane system. Transcriptome analysis identified multiple key genes involved in SA-mediated disease resistance pathways, including disease-related proteins (PR10), acidic terpenoids, aspartic proteases, proteins containing BTB/POZ and MATH domains (BPM4), and PPT3 transporters. This study reveals the physiological and molecular mechanisms by which exogenous SA enhances maize resistance to ear rot, providing an important theoretical basis for further understanding the regulatory network of SA in plant disease resistance. Full article

One of the important traits of many plant growth-promoting rhizobacteria (PGPR) is the biocontrol of phytopathogens. Some PGPR metabolize phytohormone abscisic acid (ABA); however, the role of this trait in plant–microbe interactions is scarcely understood. Phytopathogenic fungi produce ABA and use this property as a negative regulator of plant resistance. Therefore, interactions between ABA-producing necrotrophic phytopathogen Botrytis sp. BA3 with ABA-metabolizing rhizobacterium Rhodococcus sp. P1Y were studied in a batch culture and in gnotobiotic hydroponics with sunflower seedlings. Rhizobacterium P1Y possessed no antifungal activity against BA3 and metabolized ABA, which was synthesized by BA3 in vitro and in associations with sunflower plants infected with this fungus. Inoculation with BA3 and the application of exogenous ABA increased the root ABA concentration and inhibited root and shoot growth, suggesting the involvement of this phytohormone in the pathogenesis process. Strain P1Y eliminated negative effects of BA3 and exogenous ABA on root ABA concentration and plant growth. Both microorganisms significantly modulated the hormonal status of plants, affecting indole-3-acetic, salicylic, jasmonic and gibberellic acids, as well as cytokinins concentrations in sunflower roots and/or shoots. The hormonal effects were complex and could be due to the production of phytohormones by microorganisms, changes in ABA concentrations and multiple levels of crosstalk in hormone networks regulating plant defense. The results suggest the counteraction of rhizobacteria to ABA-producing phytopathogenic fungi through the metabolism of fungal ABA. This expands our understanding of the mechanisms related to the biocontrol of phytopathogens by PGPR. Full article