Join the green team: Inducers of plant immunity in the plant disease sustainable control toolbox

Sunlight-sensitive carbon dots for plant immunity priming and pathogen defence

Global food production faces persistent threats from environmental challenges and pathogenic attacks, leading to significant yield losses. Conventional strategies to combat pathogens, such as fungicides and disease-resistant breeding, are limited by environmental contamination and emergence of pathogen resistance. Herein, we engineered sunlight-sensitive and biodegradable carbon dots (CDs) capable of generating reactive oxygen species (ROS), offering a novel and sustainable approach for plant protection. Our study demonstrates that CDs function as dual-purpose materials: priming plant immune responses and serving as broad-spectrum antifungal agents. Foliar application of CDs generated ROS under light, and the ROS could damage the plant cell wall and trigger cell wall-mediated immunity. Immune activation enhanced plant resistance against pathogens without compromising photosynthetic efficiency or yield. Specifically, spray treatment with CDs at 240 mg/L (2 mL per plant) reduced the incidence of grey mould in N. benthamiana and tomato leaves by 44% and 12%, respectively, and late blight in tomato leaves by 31%. Moreover, CDs (480 mg/L, 1 mL) combined with continuous sunlight irradiation (simulated by xenon lamp, 9.4 × 105 lux) showed a broad-spectrum antifungal activity. The inhibition ratios for mycelium growth were 66.5% for P. capsici, 8% for S. sclerotiorum and 100% for B. cinerea, respectively. Mechanistic studies revealed that CDs effectively inhibited mycelium growth by damaging hyphae and spore structures, thereby disrupting the propagation and vitality of pathogens. These findings suggest that CDs offer a promising, eco-friendly strategy for sustainable crop protection, with potential for practical agricultural applications that maintain crop yields and minimize environmental impact.

1H NMR metabolomic profiling of resistant and susceptible oil palm root tissues in response to Ganoderma boninense at the nursery stage

Oil palm plantations face serious challenges from Ganoderma boninense, a pathogen that causes basal stem rot (BSR), leading to significant productivity losses, with an estimated economic impact of 68.73%. Ganoderma spreads through direct root contact and airborne spores, affecting plantations across Indonesia, Malaysia, and other countries. Understanding the mechanisms of oil palm resistance to Ganoderma is crucial for developing effective strategies. Metabolomic profiling, ¹H NMR spectroscopy, offers a promising tool for identifying and quantifying metabolic changes associated with Ganoderma resistance. This study, ¹H NMR was employed to analyze root tissues of resistant, susceptible, and control oil palm seedlings exposed to Ganoderma. The results indicated that PCA effectively differentiated resistant palms from susceptible ones, while PLS-DA identified 14 significant metabolites. Further analysis using OPLS-DA and ROC revealed that ascorbic acid, D-gluconic acid, D-fructose, and 2-oxoisovalerate could serve as potential biomarkers for screening resistant palms. The metabolites identified in this study hold considerable promise for supporting breeding programs to develop oil palm varieties with enhanced resistance to BSR.

A putative elicitor CcHE1 from Cytospora chrysosperma enhances plant resistance to phytopathogenic fungi

BACKGROUND

Plant pathogens secrete a large number of effectors to host cells during the infection processes, which will manipulate plant immunity and promote fungal infection. Contrarily, some of the effectors can be recognized by the host plants, and then activate the immunity reactions. Therefore, unveiling the critical roles of effectors during the pathogen-plant interactions will benefit disease control.

RESULTS

In this study, we screened and identified a candidate effector, CcHE1, from Cytospora chrysosperma, the main agent of wood canker disease and causes serious loss annually in China. Transient expression of CcHE1 in N. benthamiana leaves showed that it triggered plant cell death in a dose-dependent manner. Subsequently, we found that infiltration injection of 5 μM CcHE1 into N. benthamiana and poplar leaves could not cause cell necrosis but triggered strong defense responses, including reactive oxygen species accumulation, callose deposition, and up-regulated expression of defense-related genes, and NbBAK1 and NbSOBIR1 are needed for plant defense response induced by CcHE1. Importantly, the CcHE1 could enhance the plant resistance to several tested pathogenic fungal species such as Botrytis cinerea, Colletotrichum gloeosporioides, C. chrysosperma, Botryosphaeria dothidea and Cryphonectria parasitica, but had no antifungal activity. Remarkably, deletion of CcHE1 did not affect the growth and pathogenicity of C. chrysosperma.

CONCLUSION

Our results found a putative elicitor CcHE1 which can induce plant immunity, and therefore improve plant broad-spectrum disease resistance. These results provide a new insight into disease control. © 2025 Society of Chemical Industry.

Dual stimuli-responsive prodrug co-delivery nanosystem of salicylic acid and bioavailable silicon for long-term immunity in plant

Plant-induced resistance plays a crucial role in the plant defense system by activating intrinsic immune mechanisms. In this study, a novel amidase- and redox-responsive codelivery nanosystem was developed by covalently linking salicylic acid (SA) to functionalized disulfide-doped mesoporous silica nanoparticles (MSNs-ss-NH2) for the efficient delivery of SA and bioavailable silicon concurrently. Physicochemical characterization confirmed the successful preparation of MSNs-ss-SA, demonstrating its structural integrity and glutathione and amidase responsive degradation mechanism. With a particle size of approximately 90 nm, MSNs-ss-SA could penetrate the stomata of rice leaves, facilitating the efficient intracellular transport of SA and bioavailable silicon. Biological activity assays revealed that MSNs-ss-SA exhibited superior efficacy in inducing resistance to rice sheath blight compared to conventional SA, which was primarily due to its ability to enhance physical barrier formation, strengthen antioxidant defense systems, upregulate the expression of key defense-related genes, and increase chitinase synthesis, collectively triggering both systemic acquired resistance and induced systemic resistance. Most importantly, biological safety assessments confirmed its excellent compatibility with rice plants, aquatic organisms, soil ecosystems, and human cell models. Therefore, the prodrug system of SA and bioavailable silicon shows a significant potential for sustainable agricultural plant disease management.

Design, Synthesis, and Anti-Oomycete and Antifungal Activities of Novel Paeonol Derivatives Containing a Pyrazole Ring

Paeonol is the main active ingredient in the Chinese medicinal herb peony root bark. To discover biorational natural product-based fungicides, 25 paeonol derivatives (5a-y) containing a pyrazole ring were designed and synthesized by ingeniously introducing a pyrazole five-membered heterocyclic ring, and their structures were well characterized by 1H NMR, 13C NMR, high-resolution mass spectrometer (HRMS), and m.p. The stereochemical configurations of six target compounds, 5c, 5f, 5g, 5o, 5s, and 5v, were unambiguously subjected to single-crystal X-ray diffraction. Furthermore, we evaluated the bioactivities of these target compounds as anti-oomycete and antifungal agents against two serious agricultural diseases, Phytophthora capsici and Fusarium graminearum. Among all tested compounds, (1) nine compounds 5b-d, 5f, 5g, 5r, 5s, 5u, 5w displayed promising anti-oomycete against P. capsici, with EC50 values ranging from 22.1 to 34.5 mg/L, and the protective effect of the target compounds against P. capsici in vivo further confirmed the above results. (2) Six compounds 5g, 5k, 5m, 5t, 5w, 5x displayed promising antifungal against F. graminearum, with EC50 values ranging from 38.2 to 86.0 mg/L. Moreover, some interesting results of structure-activity relationships were also observed. The results of this study pave the way for further design, synthesis, and development of paeonol derivatives as potential botanical anti-oomycete and antifungal agents in crop protection.

The Candida quercitrusa strain Cq-C08 induces plant resistance to root-knot nematodes

Introduction

Root-knot nematodes (RKNs), belonging to the genus Meloidogyne, are plant parasitic nematodes with a broad host range, causing substantial economic losses annually. The selection and utilization of novel biological control resources are crucial for managing RKNs diseases.

Methods

This study isolated Candida quercitrusa Cq-C08 from rhizosphere soil, which the efficacy of Cq-C08 against Meloidogyne incognita was investigated through laboratory experiments, pot and plot trials, and analysis of the transcriptomic data from cucumber roots treated with Cq-C08.

Results and discussion

This study isolated Candida quercitrusa Cq-C08 from rhizosphere soil, and a series of experiments confirmed that the fermentation broth had a lethal rate of 100% against M. incognita J2s within 12 h and exhibited a significant repellent effect on the nematodes. In pot and plot tests, the strain Cq-C08 achieved a control effect over 50% against M. incognita and significantly promoted cucumber (Cucumis sativus, Zhongnong No. 6, China) growth. Inoculation experiments confirmed that the Cq-C08 strain could activate key immune signaling pathways of salicylic acid (SA) and jasmonic acid (JA). Split-root tests showed significant induced resistance of cucumber to M. incognita by 32.3%. Comparative transcriptome analysis confirmed that strain Cq-C08 could regulate the host's basal immune response and oxidative burst response through SA, JA, and ethylene (ET) signaling pathways, and alter secondary metabolism, activating the synthesis of cucurbitacin and auxins, which promotes plant immune regulation and growth. These results prove that C. quercitrusa Cq-C08 has high control effects against M. incognita and the potential to be developed into a biological control product against root-knot nematodes.

Interaction between pathogenesis-related (PR) proteins and phytohormone signaling pathways in conferring disease tolerance in plants

Pathogenesis-related (PR) proteins are critical defense signaling molecules induced by phytopathogens. They play a vital role in plant's defense signaling pathways and innate immunity, particularly in systemic acquired resistance (SAR) and serve as key molecular markers of plant defense. Overexpressing PR genes, such as chitinase, thaumatin, glucanase, thionin and defensin, either individually or in combination, have significantly boosted plants' defense responses against various pathogens. However, signaling pathways regulating the expression of these versatile proteins remain only partially understood. Plant hormones like salicylic acid (SA) and jasmonic acid (JA) are known for their well-established roles in regulating PR gene responses to pathogens and other stress conditions. PR genes interact with various components of hormonal signaling pathways, including receptors (e.g., NPR1 in SA signaling), transcription factors (e.g., MYC2 in JA signaling), and cis-regulating elements (e.g., W-box), to modulate plant defense responses. Recent studies have highlighted the contributions of different plant hormones to plant immunity and their interactions with PR proteins in a process known as hormonal crosstalk, which helps coordinate immunity activation. This review provides a comprehensive overview of the PR proteins, their complexity, and hormonal crosstalk in immunity, aiming to understand these interactions for improved pathogen resistance.

Integrative transcriptome and WGCNA analysis reveal key genes mainly in response to Alternaria alternata in Populus simonii × P. nigra

In order to explore the molecular mechanisms of Populus simonii × P. nigra response to stress and screen for genes conferring resistance to Alternaria alternata, we carried out measurements of physiological and biochemical indices and transcriptomic sequence analysis of leaves of Populus simonii × P. nigra inoculated with A. alternata. The results showed that the variation trends of multiple hormone contents and enzyme activities were broadly similar at different time points, with H2O2, SA, JA, PPO, SOD, PAL and POD showing a trend of increasing and then decrease after inoculation with the pathogen. The contents of H2O2 peaked on the second day and subsequently declined. The contents of SA and JA, as well as the enzymatic activities of SOD, PAL, and POD, reached their maxima on the third day before exhibiting a downward tendency. In contrast, the activity of PPO peaked on the fourth day. Whereas ABA content continued to increase until the fifth day and CAT content decreased and then increased. We subsequently identified 14,997 differentially expressed genes (DEGs) among the transcriptomic sequences(|log2FoldChange| > 1 and FDR value < 0.05), with genes encoding members of the ERF, MYB, bZIP, and WRKY transcription factor families being differentially expressed. Gene modules that were significantly associated with the ABA, PAL, JA, and SOD activity were identified using weighted gene co-expression network analysis (WGCNA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these genes were mainly related to biological stress, signal transduction, cell wall, and photosynthesis. Within these modules, we also identified hub genes in the regulatory network, including GLK1/2 transcriptional activators, 14-3-3 proteins, cytosine 5 methyltransferases, and a variety of proteins associated with photosynthesis and respiration. This study showed that these hub genes, which play a pivotal role in the co-expression network, which may indicate a potential role in defense process of Populus simonii × P. nigra against A. alternata. Additionally, we analyzed the gene expression regulation and defense mechanisms of Populus simonii × P. nigra adversity stress, providing new insights into how plants respond to biological stress.

NbNAC1 enhances plant immunity against TMV by regulating isochorismate synthase 1 expression and the SA pathway

Salicylic acid (SA) plays important roles in plant local and systemic resistance. Isochorismate synthase 1 (ICS1) is a key enzyme in SA synthesis. Pathogens infection triggered the ICS1 expression and induced SA production. However, the molecular regulation mechanism of ICS1 against virus infection remains unclear. Here, we employed molecular genetics and physiobiochemical approaches to confirm a transcription factor NbNAC1 from Nicotiana benthamiana is a positive regulator of resistance against tobacco mosaic virus (TMV). The pathways NbNAC1 and NbICS1 can be triggered by TMV infection. Silencing NbNAC1 accelerated TMV-induced oxidative damage and increased reactive oxygen species (ROS) production. It also weakened both local and systemic resistance against TMV and decreased the expression of NbICS1, SA signaling gene NbNPR1, and SA defense-related genes. The effects of NbNAC1-silencing were restored by overexpression of NbICS1 or foliar SA applications. Overexpressing NbNAC1 prevented oxidative damage and reduced the production of ROS, enhanced plant resistance against viral pathogen, and activated NbICS1 expression, and SA downstream signaling and defense-related genes. NbNAC1 localized in nuclear and emerged the ability of transcriptional regulation. ChIP and EMSA results indicated that NbNAC1 directly binds to a fragment containing GAAATT motif of NbICS1 promoter. Luciferase reporter assays confirmed that NbNAC1 activates NbICS1 expression. Taken together, our results demonstrate that NbNAC1 plays a critical role in plant immunity through activation of SA production.

All Roads Lead to Rome: Pathways to Engineering Disease Resistance in Plants

Unlike animals, plants are unable to move and lack specialized immune cells and circulating antibodies. As a result, they are always threatened by a large number of microbial pathogens and harmful pests that can significantly reduce crop yield worldwide. Therefore, the development of new strategies to control them is essential to mitigate the increasing risk of crops lost to plant diseases. Recent developments in genetic engineering, including efficient gene manipulation and transformation methods, gene editing and synthetic biology, coupled with the understanding of microbial pathogenicity and plant immunity, both at molecular and genomic levels, have enhanced the capabilities to develop disease resistance in plants. This review comprehensively explains the fundamental mechanisms underlying the tug-of-war between pathogens and hosts, and provides a detailed overview of different strategies for developing disease resistance in plants. Additionally, it provides a summary of the potential genes that can be employed in resistance breeding for key crops to combat a wide range of potential pathogens and pests, including fungi, oomycetes, bacteria, viruses, nematodes, and insects. Furthermore, this review addresses the limitations associated with these strategies and their possible solutions. Finally, it discusses the future perspectives for producing plants with durable and broad-spectrum disease resistance.

The BASIDIN effector of the fungus Moniliophthora perniciosa promotes positive effects on the seed germination and seedlings development of Lactuca sativa

Plant resistance inducers that activate plant defense mechanisms may be useful in reducing agrotoxic use. Lettuce is among the most economically important leafy vegetable crops in the world. Since lettuce propagates through seeds, the use of high-quality seeds is extremely important for establishing the crop. Several studies have demonstrated the potential of alternative methods of seed treatment with the aim of increasing productivity. Based on this premise, we tested the effect of the rBASIDIN effector regarding its ability to induce germination and physiological changes in lettuce seedlings through seed treatment. The seeds were treated for 30 min by soaking with 50 µg mL-1, 75 µg mL-1 and 100 µg mL-1 of the recombinant effector protein rBASIDIN. Seeds treated with distilled water and 10 mmol of Tris-HCl served as controls. The physiological parameters evaluated were germination percentage at 4 and 7 days, seedling length (aerial part and root), dry and fresh mass, electrical conductivity, and enzymatic activity. Seeds treated with 50 and 75 µg mL-1 of rBASIDIN germinated earlier than the controls. Treatment with rBASIDIN at a concentration of 50 µg mL-1 resulted in seedlings with an average root length of 1.51 cm, while the average lengths of the controls (H2O and buffer) were 0.86 and 0.70 cm respectively. Seed treatment with rBASIDIN caused an increase in the fresh and dry weight of the plants. The lowest electrolyte leakage was detected in seeds treated with the three concentrations of rBASIDIN compared to the controls. Regarding the activity of defense enzymes, seedlings treated with rBASIDIN at lower concentrations showed higher chitinase and β-glucanase activity compared to the controls. The results indicated that the rBASIDIN effector plays an important signaling role in lettuce seeds, since small doses are already sufficient to induce changes in physiological parameters to obtain more vigorous plants.

Melatonin induces resistance against Colletotrichum gloeosporioides in mango fruit via regulation of defense-related genes by MiWRKY45 transcription factor

Anthracnose caused by Colletotrichum gloeosporioides is a major disease leading to postharvest loss of mango fruit. Melatonin (MT) is a natural bioactive molecule that has multiple physiological functions in plants. This study investigated the effect of exogenous MT on mango disease resistance against C. gloeosporioides and related molecular mechanism. MT treatment at 1 mmol L-1 limited the expansion of anthracnose in mango inoculated with C. gloeosporioides, which was associated with increased level of defense-related indexes, including activities of phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL) and peroxidase (POD), expression of MiPAL, Mi4CL and MiPOD and contents of total phenolics, flavonoids and lignin. RT-qPCR analysis of 15 MiWRKY members revealed that MiWRKY45 had the highest expression in response to MT + C. gloeosporioides. MiWRKY45 transcription factor was identified as a nucleus-localized transcriptional activator based on subcellular localization and transcriptional activation assays. MiWRKY45 bound to W-box motif and activated the expression of MiPAL, Mi4CL and MiPOD, as verified by DNA affinity purification-seq (DAP-seq), yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays. Transient transformation analysis revealed that MiWRKY45 positively regulated phenylpropanoid pathway, thereby enhancing mango resistance. These results suggest that MiWRKY45, as a positive regulator, is involved in MT-induced resistance against anthracnose in mangoes.

Design, synthesis, antifungal, and antibacterial evaluation of ferulic acid derivatives bearing amide moiety

Natural compounds' derivatives as lead structures could effectively solve plant disease problems. In this article, amide compounds and amide ester compounds were synthetized through ferulic acid as the parent nucleus structure, and their biological activities in vitro and in vivo were evaluated. Compound 1q was screened out as the one with the best activity performance toward Xanthomonas axonopodis pv. citri (Xac), which displayed the inhibition rate of 100% and the EC50 as low as 4.56 μg/mL. The results of in vivo experiments on citrus leaves infected with Xac showed that compound 1q had a protective efficacy of 60.98% and a curative efficacy of 26.56%. The mechanism of action as well as molecular docking was previously studied using extracellular polysaccharide (EPS) content, bacterial membrane permeability, and scanning electron microscopy (SEM) observations. Experimental results show that compound 1q can become an antibacterial agent for preventing and managing plant diseases.

Transcriptomic Study of Nicotiana tabacum Treated with the Bacterial Protein CspD Reveals Some Specific Abiotic Stress Responses

The ability of a cold-shock protein CspD from Bacillus thuringiensis to protect both dicots and monocots against various pathogens is well confirmed under both greenhouse and field conditions; however, the molecular basis of this phenomenon at the transcriptomic level still remains unexplored. Expression profiles of some marker genes associated with SAR/ISR nonspecific resistance pathways and ROS scavengers were examined in CspD-treated Nicotiana tabacum plants, and the RNA-seq analysis of CspD-treated plants was first carried out. The ISR markers PDF1.2 and PR4 were overexpressed locally in treated tobacco leaves with the maximum 2.4- and 5.7-fold change, respectively, reached 12 h after the leaf treatment with CspD; PDF1.2 was also up-regulated 4.8-fold four days after the inoculation of treated plants with TMV. The ROS scavenger analysis demonstrated overexpression of Cu-Zn superoxide dismutase in both treated (with the maximum 5.4-fold change observed 6 h after the treatment) leaves and leaves from the upper tier ("system" leaves, 6.5-fold change observed 4 days after the treatment). The ROS assay confirmed endogenous accumulation of superoxide in CspD-treated leaves 6 and 24 h after the treatment. An in silico comparative study of Arabidopsis orthologs of highly up-regulated tobacco genes induced by CspD with Arabidopsis genes activated by some other molecular patterns revealed the specific CspD-induced expression of Cu-Zn superoxide dismutase and some other genes associated with light and cold responses. This study may contribute to a better understanding of cross-talking between abiotic stress and nonspecific immunity in plants.

Plant growth-promoting microorganisms drive K strategists through deterministic processes to alleviate biological stress caused by Fusarium oxysporum

Soybean root rot, caused by soil-borne pathogens such as Fusarium oxysporum, frequently occurs in Northeast China and leads to a decline in soil health and becoming a bottleneck for soybean yield in the region. To address this issue, applying beneficial microorganisms and altering soil microbial community structure have become effective strategies. In this study, the 90-day soybean pot experiment was conducted to explore the assembly process and life strategy selection of bacterial communities in the rhizosphere of healthy (inoculated with Funneliformis mosseae, F group and treated with Pseudomonas putida, P group) and diseased (inoculated with F. oxysporum, O group) soybean plants, as well as the recovery effect of beneficial microorganisms on soil-borne diseases (combined treatments OP and OF). Results indicated that in healthy soils (P and F), microbial community assembly process in the soybean rhizosphere was entirely governed by heterogeneous selection (HeS, 100 %). However, inoculated with P. putida (OP) was primarily driven by stochastic processes (HeS 40 %, dispersal limitation (DL) 60 %), and the F. mosseae treatment (OF) predominantly followed a deterministic process (HeS 89 %, DL 11 %) in diseased soils. Inoculation of plant growth-promoting microorganisms (PGPMs) in diseased soil drove the life strategy of the rhizosphere bacterial community from r- to K-strategy, evident from the lower rRNA operon (rrn) copy numbers (O 3.7, OP 2.1, OF 2.3), higher G+ to G- ratios (O 0.47, OP 0.58, OF 0.57), and a higher abundance of oligotrophs (O 50 %, OP 53 %, OF 54 %). In healthy (P and F) and diseased (O, OP, OF) rhizosphere soils, OTU820, OTU6142, and OTU8841 under the K-strategy, and OTU6032 and OTU6917 under the r-strategy, which served as keystone species, had a significant promoting relationship with plant biomass and defense capabilities ( p ＜0.05). Additionally, inoculation of PGPMs improved autotoxin degradation and positively correlated with bacterial life strategies in both healthy and diseased soils (P, F, OP and OF) ( p ＜0.05). These findings enhance our understanding of soil-microbe interactions and offer new insights and precise control measures for soybean disease management and soil environment remediation.

Acyl hydrazone derivatives with trifluoromethylpyridine as potential agrochemical for controlling plant diseases

BACKGROUND

Crops are consistently under siege by a multitude of pathogens. These pathogenic microorganisms, including viruses and bacteria, result in substantial reductions in quality and yield globally by inducing detrimental crop diseases, thus posing a significant challenge to global food security. However, the biological activity sepectrum of commercially available pesticides is limited and the pesticide efficacy is poor, necessitating the urgent development of broad-spectrum and efficient strategies for crop disease prevention and control.

RESULTS

The bioassay results revealed that certain target compounds demonstrated outstanding in vivo antiviral efficacy against cucumber mosaic virus and tobacco mosaic virus. In particular, compound D6 showed remarkable antiviral activity against CMV, significantly higher than that of the control agent ningnanmycin. Mechanism of action studies have shown that compound D6 could enhance the activity of defense enzymes and upregulate the expression of genes related to disease resistance, thereby enhancing the antiviral effects in plants. In addition, these compounds displayed superior inhibitory activity against plant bacterial diseases. For Xoo, compound D10 showed an excellent inhibitory effect that was better than that of the control agent bismerthiazol. Scanning electron microscopy and fluorescence double-staining experiments revealed that compound D10 effectively inhibited bacterial growth by disrupting the cell membrane.

CONCLUSION

A series of trifluoromethyl hydrazone derivatives were designed and synthesized, and it was found that they have control effects on plant viruses and bacterial diseases. In addition, this study revealed the mechanism of action of the active compounds and demonstrated their potential as multifunctional crop protectants. © 2024 Society of Chemical Industry.

Carbohydrate elicitor-induced plant immunity: Advances and prospects

The perceived negative impacts of synthetic agrochemicals gave way to alternative, biological plant protection strategies. The deployment of induced resistance, comprising boosting the natural defense responses of plants, is one of those. Plants developed multi-component defense mechanisms to defend themselves against biotic and abiotic stresses. These are activated upon recognition of stress signatures via membrane-localized receptors. The induced immune responses enable plants to tolerate and limit the impact of stresses. A systemic cascade of signals enables plants to prime un-damaged tissues, which is crucial during secondary encounters with stress. Comparable stress tolerance mechanisms can be induced in plants by the application of carbohydrate elicitors such as chitin/chitosan, β-1,3-glucans, oligogalacturonides, cellodextrins, xyloglucans, alginates, ulvans, and carrageenans. Treating plants with carbohydrate-derived elicitors enable the plants to develop resistance appliances against diverse stresses. Some carbohydrates are also known to have been involved in promoting symbiotic signaling. Here, we review recent progresses on plant resistance elicitation effect of various carbohydrate elicitors and the molecular mechanisms of plant cell perception, cascade signals, and responses to cascaded cues. Besides, the molecular mechanisms used by plants to distinguish carbohydrate-induced immunity signals from symbiotic signals are discussed. The structure-activity relationships of the carbohydrate elicitors are also described. Furthermore, we forwarded future research outlooks that might increase the utilization of carbohydrate elicitors in agriculture in order to improve the efficacy of plant protection strategies.

Symphony of survival: Insights into cross-talk mechanisms in plants, bacteria, and fungi for strengthening plant immune responses

Plants coexist with a diverse array of microorganisms, predominantly bacteria and fungi, in both natural and agricultural environments. While some microorganisms positively influence plant development and yield, others can cause harm to the host, leading to significant adverse impacts on the environment and the economy. Plant growth-promoting microorganisms (PGPM), including plant growth-promoting bacteria, arbuscular mycorrhizal fungus (AMF), and rhizobia, have been found to increase plant biomass production by synthesizing hormones, fixing nitrogen, and solubilizing phosphate and potassium. Numerous studies have contributed to unraveling the complex process of plant-microbe interactions in recent decades. In light of the increasing global challenges such as population growth, climate change, and resource scarcity, it has become imperative to explore the potential of plant-bacteria-fungi crosstalk in promoting sustainability. This review aims to bridge existing knowledge gaps, providing a roadmap for future research in this dynamic field by synthesizing current knowledge and identifying emerging trends.

Chitosan nanocomposites as a nano-bio tool in phytopathogen control

Chitosan, an economically viable and versatile biopolymer, exhibits a wide array of advantageous physicochemical and biological properties. Chitosan nanocomposites, formed by the amalgamation of chitosan or chitosan nanoparticles with other nanoparticles or materials, have garnered extensive attention across agricultural, pharmaceutical, and biomedical domains. These nanocomposites have been rigorously investigated due to their diverse applications, notably in combatting plant pathogens. Their remarkable efficacy against phytopathogens has positioned them as a promising alternative to conventional chemical-based methods in phytopathogen control, thus exploring interest in sustainable agricultural practices with reduced reliance on chemical interventions. This review aims to highlight the anti-phytopathogenic activity of chitosan nanocomposites, emphasizing their potential in mitigating plant diseases. Additionally, it explores various synthesis methods for chitosan nanoparticles to enhance readers' understanding. Furthermore, the analysis delves into elucidating the intricate mechanisms governing the antimicrobial effectiveness of these composites against bacterial and fungal phytopathogens.

Begomovirus Transmission to Tomato Plants Is Not Hampered by Plant Defenses Induced by Dicyphus hesperus Knight

Plants can respond to insect infestation and virus infection by inducing plant defenses, generally mediated by phytohormones. Moreover, plant defenses alter host quality for insect vectors with consequences for the spread of viruses. In agricultural settings, other organisms commonly interact with plants, thereby inducing plant defenses that could affect plant-virus-vector interactions. For example, plant defenses induced by omnivorous insects can modulate insect behavior. This study focused on tomato yellow leaf curl virus (TYLCV), a plant virus of the family Geminiviridae and genus Begomovirus. It is transmitted in a persistent circulative manner by the whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), posing a global threat to tomato production. Mirids (Hemiptera: Miridae) are effective biological control agents of B. tabaci, but there is a possibility that their omnivorous nature could also interfere with the process of virus transmission. To test this hypothesis, this study first addressed to what extent the mirid bug Dicyphus hesperus Knight induces plant defenses in tomato. Subsequently, the impact of this plant-omnivore interaction on the transmission of TYLCV was evaluated. Controlled cage experiments were performed in a greenhouse setting to evaluate the impact of mirids on virus transmission and vector acquisition by B. tabaci. While we observed a reduced number of whiteflies settling on plants exposed to D. hesperus, the plant defenses induced by the mirid bug did not affect TYLCV transmission and accumulation. Additionally, whiteflies were able to acquire comparable amounts of TYLCV on mirid-exposed plants and control plants. Overall, the induction of plant defenses by D. hesperus did not influence TYLCV transmission by whiteflies on tomato.

Chiral nanopesticides: the invincible opponent of plant viruses

Viral diseases of plants are exceptionally difficult to control in agriculture production. Recently, Gao et al. discovered that engineered site-selective nanoparticles (NPs), incorporating metal ion-based proteolytic activity and nanoscale chirality, can be used as potent, nontoxic, and environmentally friendly antiviral agents to kill plant viruses.

The chromosome-level genome assembly of an endangered herb Bergenia scopulosa provides insights into local adaptation and genomic vulnerability under climate change

BACKGROUND

Global climate change poses severe threats to biodiversity and ecosystem stability. Rapid climate oscillations potentially lead to species geographic range shifts, population declines, and even extinctions. The rare and endangered species, being critical components of regional biodiversity, hold the key to understanding local adaptation and evolutionary processes shaping species distributions. Therefore, assessing the evolutionary mechanisms of local adaptation and population vulnerability under climate change is crucial for developing conservation strategies of endangered species.

RESULTS

In this study, we assembled a high-quality, chromosome-level genome of the rare and endangered herb Bergenia scopulosa in the Qinling Mountains in East Asia and resequenced 37 individual genomes spanning its entire geographic distributional ranges. By integrating population genetics, landscape genomics, and climate datasets, a substantial number of adaptive single-nucleotide polymorphism loci associated with climate variables were identified. The genotype-environment association analysis showed that some cold-tolerant genes have played pivotal roles in cold environmental adaptation of B. scopulosa. These findings are further corroborated through evolutionary analysis of gene family and quantitative PCR validation. Population genomic analysis revealed 2 distinct genetic lineages in B. scopulosa. The western lineage showed higher genomic vulnerability and more rare cold-tolerance alleles, suggesting its heightened sensitivity to impending climate shifts, and should be given priority conservation in the management practices.

CONCLUSIONS

These findings provide novel insights into local adaptation and genomic vulnerability of B. scopulosa under climate change in the Qinling Mountains in East Asia. Additionally, the study also offers valuable guidance for formulating conservation strategies for the rare and endangered plants.

Integrative analyses of transcriptomes and metabolomes provide insight into salinity adaption in Bangia (Rhodaphyta)

The salinity of the external environment poses a serious threat to most land plants. Although seaweeds can adapt to this, intertidal species are subject to wide fluctuations in salinity, including hypo- and hyper-saline conditions. The red algal genus Bangiales is a typical example; it is one of the oldest eukaryotes with sexual reproduction and has successfully adapted to both marine and freshwater environments. However, there is a dearth of research focused on elucidating the mechanism by which marine Bangia (Bangia fuscopurpurea) adapts to hypo-salinity, as well as the mechanism by which freshwater Bangia (Bangia atropurpurea) adapts to hyper-salinity. The objective of this study is to employ third-generation full-length transcriptome data and untargeted metabolome data, to provide insights into the salinity adaptation mechanism of as well as the evolutionary relationship between both Bangia species. B. fuscopurpurea and B. atropurpurea exhibited 9112 and 8772 differentially expressed genes (DEGs), respectively, during various periods of hyper-saline condition. These genes were primarily enriched in secondary metabolites and energy-related metabolic pathways. Additionally, B. fuscopurpurea displayed 16,285 DEGs during different periods of hypo-saline condition, which were mainly enriched in metabolic pathways related to ion transport and membrane proteins. In the hyper- and hypo-saline adapt response processes of B. fuscopurpurea, a total of 303 transcription factors were identified, which belonged to 26 families. Among these, 85 and 142 differential transcription factors were identified, respectively, mainly belonging to the C2H2 and MYB family. Similarly, in the response process of B. atropurpurea to hyper-saline condition, a total of 317 transcription factors were identified, mainly belonging to 17 families. Among these, 121 differential transcription factors were identified, mainly belonging to the C2H2 and bZIP family. Furthermore, a correlation analysis was conducted to examine the relationship between the transcriptional and metabolic levels of both species under saline adaptation. The findings demonstrated that Bangia exhibits intricate adaptations to salinity, which involve swift regulation of its photosynthetic processes, alternations in membrane contents, and a robust anti-oxidation system to mitigate the effects of excess redox energy during exposure to varying salinity. Notably, the unsaturated fat and glutathione metabolic pathways were found to be significantly enriched in this context.

Some Structural Elements of Bacterial Protein MF3 That Influence Its Ability to Induce Plant Resistance to Fungi, Viruses, and Other Plant Pathogens

The ability of the MF3 protein from Pseudomonas fluorescens to protect plants by inducing their resistance to pathogenic fungi, bacteria, and viruses is well confirmed both in greenhouses and in the field; however, the molecular basis of this phenomenon remains unexplored. To find a relationship between the primary (and spatial) structure of the protein and its target activity, we analyzed the inducing activity of a set of mutants generated by alanine scanning and an alpha-helix deletion (ahD) in the part of the MF3 molecule previously identified by our group as a 29-amino-acid peptide working as the inducer on its own. Testing the mutants' inducing activity using the "tobacco-tobacco mosaic virus" pathosystem revealed that some of them showed an almost threefold (V60A and V62A) or twofold (G51A, L58A, ahD) reduction in inducing activity compared to the wild-type MF3 type. Interestingly, these mutations demonstrated close proximity in the homology model, probably contributing to MF3 reception in a host plant.

Advances in Roles of Salicylic Acid in Plant Tolerance Responses to Biotic and Abiotic Stresses

A multitude of biotic and abiotic stress factors do harm to plants by bringing about diseases and inhibiting normal growth and development. As a pivotal signaling molecule, salicylic acid (SA) plays crucial roles in plant tolerance responses to both biotic and abiotic stresses, thereby maintaining plant normal growth and improving yields under stress. In view of this, this paper mainly discusses the role of SA in both biotic and abiotic stresses of plants. SA regulates the expression of genes involved in defense signaling pathways, thus enhancing plant immunity. In addition, SA mitigates the negative effects of abiotic stresses, and acts as a signaling molecule to induce the expression of stress-responsive genes and the synthesis of stress-related proteins. In addition, SA also improves certain yield-related photosynthetic indexes, thereby enhancing crop yield under stress. On the other hand, SA acts with other signaling molecules, such as jasmonic acid (JA), auxin, ethylene (ETH), and so on, in regulating plant growth and improving tolerance under stress. This paper reviews recent advances in SA's roles in plant stress tolerance, so as to provide theoretical references for further studies concerning the decryption of molecular mechanisms for SA's roles and the improvement of crop management under stress.