Enhance Plant Resistance Research Articles

Enhancing Resistance to Cercospora Leaf Spot in Mung Bean (Vigna radiata L.) through Bradyrhizobium sp. DOA9 Priming: Molecular Insights and Bio-Priming Potential.

Mung bean (Vigna radiata L.), a vital legume in Asia with significant nutritional benefits, is highly susceptible to Cercospora leaf spot (CLS) caused by Cercospora canescens, leading to significant yield losses. As an alternative to chemical fungicides, bio-priming with rhizobacteria can enhance plant resistance. This study explores the potential of Bradyrhizobium sp. strain DOA9 to augment resistance in mung bean against CLS via root priming. The results reveal that short (3 days) and double (17 and 3 days) priming with DOA9 before fungal infection considerably reduces lesion size on infected leaves by activating defense-related genes, including Pti1, Pti6, EDS1, NDR1, PR-1, PR-2, Prx, and CHS, or by suppressing the inhibition of PR-5 and enhancing peroxidase (POD) activity in leaves. Interestingly, the Type 3 secretion system (T3SS) of DOA9 may play a role in establishing resistance in V. radiata CN72. These findings suggest that DOA9 primes V. radiata CN72's defense mechanisms, offering an effective bio-priming strategy to alleviate CLS. Hence, our insights propose the potential use of DOA9 as a bio-priming agent to manage CLS in V. radiata CN72, providing a sustainable alternative to chemical fungicide applications.

Plant Defense Mechanisms against Polycyclic Aromatic Hydrocarbon Contamination: Insights into the Role of Extracellular Vesicles.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that pose significant environmental and health risks. These compounds originate from both natural phenomena, such as volcanic activity and wildfires, and anthropogenic sources, including vehicular emissions, industrial processes, and fossil fuel combustion. Their classification as carcinogenic, mutagenic, and teratogenic substances link them to various cancers and health disorders. PAHs are categorized into low-molecular-weight (LMW) and high-molecular-weight (HMW) groups, with HMW PAHs exhibiting greater resistance to degradation and a tendency to accumulate in sediments and biological tissues. Soil serves as a primary reservoir for PAHs, particularly in areas of high emissions, creating substantial risks through ingestion, dermal contact, and inhalation. Coastal and aquatic ecosystems are especially vulnerable due to concentrated human activities, with PAH persistence disrupting microbial communities, inhibiting plant growth, and altering ecosystem functions, potentially leading to biodiversity loss. In plants, PAH contamination manifests as a form of abiotic stress, inducing oxidative stress, cellular damage, and growth inhibition. Plants respond by activating antioxidant defenses and stress-related pathways. A notable aspect of plant defense mechanisms involves plant-derived extracellular vesicles (PDEVs), which are membrane-bound nanoparticles released by plant cells. These PDEVs play a crucial role in enhancing plant resistance to PAHs by facilitating intercellular communication and coordinating defense responses. The interaction between PAHs and PDEVs, while not fully elucidated, suggests a complex interplay of cellular defense mechanisms. PDEVs may contribute to PAH detoxification through pollutant sequestration or by delivering enzymes capable of PAH degradation. Studying PDEVs provides valuable insights into plant stress resilience mechanisms and offers potential new strategies for mitigating PAH-induced stress in plants and ecosystems.

Multi-Omics Analysis Reveals the Molecular Mechanisms of the Glycolysis and TCA Cycle Pathways in Rhododendron chrysanthum Pall. under UV-B Stress

UV-B radiation is becoming a bigger threat to plants as a result of the ozone layer’s depletion. As an alpine plant, Rhododendron chrysanthum Pall. (R. chrysanthum) may grow regularly under UV-B radiation throughout its lengthy acclimatization period, although the mechanism of acclimatization is still poorly understood. The current investigation uncovered a number of adaptation strategies that R. chrysanthum has developed in reaction to UV-B rays. UV-B radiation impeded photosynthesis and damaged the photosystem, according to OJIP testing. Through transcriptomics and proteomics analyses, this study found that the differential proteins and differential genes of R. chrysanthum were significantly enriched in glycolysis and tricarboxylic acid (TCA) cycle pathways after UV-B treatment. The metabolomics results showed that a total of eight differential metabolites were detected in the glycolytic and TCA cycle pathways, and the changes in the expression of these metabolites reflected the final outcome of gene regulation in the glycolytic and TCA cycle pathways. The combined experimental results demonstrated that R. chrysanthum’s photosynthetic system was impacted by UV-B stress and, concurrently, the plant activated an adaptation mechanism in response to the stress. To maintain its energy supply for growth, R. chrysanthum adapts to UV-B stress by adjusting the expression of the relevant proteins, genes, and metabolites in the glycolytic and TCA cycling pathways. This study provides a new perspective for understanding the changes in the carbon metabolism of R. chrysanthum under UV-B stress and its mechanisms for UV-B resistance, and provides an important theoretical basis for the study of enhancing plant resistance to stress.

Lipids Mediate Arbuscule Development and Senescence in Tomato Roots Colonized by Arbuscular Mycorrhizae Fungus under Drought Stress.

Arbuscular mycorrhizae (AM) symbiosis can enhance plant resistance to drought stress (DS). This study aimed to investigate the DS effects on lipids at different stages of symbiosis and to link lipid profiles to arbuscule dynamics in tomato roots colonized by AM fungi. DS increased mycorrhizal colonization and arbuscule abundance at an early stage but decreased them at a later stage, delayed arbuscule development, and accelerated arbuscule senescence at a later stage. DS decreased the contents of phospholipids (PLs) and saturated neutral lipids (NLs) at the early stage but increased the contents of saturated PLs and unsaturated NLs at the late stage. Specifically, DS inhibited AM-specific PL contents but increased AM-specific NL contents, which was supported by the expression of RAM2, STR/STR2. These data indicate the negative effect of DS on AM symbiosis and arbuscule dynamics with the effect size depending on the symbiosis stage, which highlights the importance of the symbiosis stage under abiotic stress.

Pseudomonas thivervalensis K321, a promising and effective biocontrol agent for managing apple Valsa canker triggered by Valsa mali

Plant growth-promoting rhizobacteria (PGPR) have been reported to suppress various diseases as potential bioagents. It can inhibit disease occurrence through various means such as directly killing pathogens and inducing systemic plant resistance. In this study, a bacterium isolated from soil showed significant inhibition of Valsa mali. Morphological observations and phylogenetic analysis identified the strain as Pseudomonas thivervalensis, named K321. Plate confrontation assays demonstrated that K321 treatment severely damaged V. mali growth, with scanning electron microscopy (SEM) observations showing severe distortion of hyphae due to K321 treatment. In vitro twigs inoculation experiments indicated that K321 had good preventive and therapeutic effects against apple Valsa canker (AVC). Applying K321 on apples significantly enhanced the apple inducing systemic resistance (ISR), including induced expression of apple ISR-related genes and increased ISR-related enzyme activity. Additionally, applying K321 on apples can activate apple MAPK by enhancing the phosphorylation of MPK3 and MPK6. In addition, K321 can promote plant growth by solubilizing phosphate, producing siderophores, and producing 3-indole-acetic acid (IAA). Application of 0.2% K321 increased tomato plant height by 53.71%, while 0.1% K321 increased tomato fresh weight by 59.55%. Transcriptome analysis revealed that K321 can inhibit the growth of V. mali by disrupting the integrity of its cell membrane through inhibiting the metabolism of essential membrane components (fatty acids) and disrupting carbohydrate metabolism. In addition, transcriptome analysis also showed that K321 can enhance plant resistance to AVC by inducing ISR-related hormones and MAPK signaling, and application of K321 significantly induced the transcription of plant growth-related genes. In summary, an excellent biocontrol strain has been discovered that can prevent AVC by inducing apple ISR and directly killing V. mali. This study indicated the great potential of P. thivervalensis K321 for use as a biological agent for the control of AVC.

The Key Targets of NO-Mediated Post-Translation Modification (PTM) Highlighting the Dynamic Metabolism of ROS and RNS in Peroxisomes.

Nitric oxide (NO) has been firmly established as a key signaling molecule in plants, playing a significant role in regulating growth, development and stress responses. Given the imperative of sustainable agriculture and the urgent need to meet the escalating global demand for food, it is imperative to safeguard crop plants from the effects of climate fluctuations. Plants respond to environmental challenges by producing redox molecules, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), which regulate cellular, physiological, and molecular processes. Nitric oxide (NO) plays a crucial role in plant stress tolerance, acting as a signaling molecule or free radical. NO is involved in various developmental processes in plants through diverse mechanisms. Exogenous NO supplementation can alleviate the toxicity of abiotic stresses and enhance plant resistance. In this review we summarize the studies regarding the production of NO in peroxisomes, and how its molecule and its derived products, (ONOO-) and S-nitrosoglutathione (GSNO) affect ROS metabolism in peroxisomes. Peroxisomal antioxidant enzymes including catalase (CAT), are key targets of NO-mediated post-translational modification (PTM) highlighting the dynamic metabolism of ROS and RNS in peroxisomes.

Transcriptome Profiles Reveal Key Regulatory Networks during Single and Multifactorial Stresses Coupled with Melatonin Treatment in Pitaya (Selenicereus undatus L.).

In response to evolving climatic conditions, plants frequently confront multiple abiotic stresses, necessitating robust adaptive mechanisms. This study focuses on the responses of Selenicereus undatus L. to both individual stresses (cadmium; Cd, salt; S, and drought; D) and their combined applications, with an emphasis on evaluating the mitigating effects of (M) melatonin. Through transcriptome analysis, this study identifies significant gene expression changes and regulatory network activations. The results show that stress decreases pitaya growth rates by 30%, reduces stem and cladode development by 40%, and increases Cd uptake under single and combined stresses by 50% and 70%, respectively. Under stress conditions, enhanced activities of H2O2, POD, CAT, APX, and SOD and elevated proline content indicate strong antioxidant defenses. We identified 141 common DEGs related to stress tolerance, most of which were related to AtCBP, ALA, and CBP pathways. Interestingly, the production of genes related to signal transduction and hormones, including abscisic acid and auxin, was also significantly induced. Several calcium-dependent protein kinase genes were regulated during M and stress treatments. Functional enrichment analysis showed that most of the DEGs were enriched during metabolism, MAPK signaling, and photosynthesis. In addition, weighted gene co-expression network analysis (WGCNA) identified critical transcription factors (WRKYs, MYBs, bZIPs, bHLHs, and NACs) associated with antioxidant activities, particularly within the salmon module. This study provides morpho-physiological and transcriptome insights into pitaya's stress responses and suggests molecular breeding techniques with which to enhance plant resistance.

Characterization of the Serine Protease TlSP1 from Trichoderma longibrachiatum T6 and Its Function in the Control of Heterodera avenae in Wheat.

Serine protease is an extracellular protease secreted by biocontrol fungi that can effectively control nematode diseases by degrading nematode eggshells and enhancing plant resistance. Trichoderma longibrachiatum T6, an important biocontrol fungus, has been demonstrated to effectively parasitize and degrade Heterodera avenae cysts, eggs, and second-stage juveniles (J2s). However, the genes that encoding serine protease and their functions in T. longibrachiatum T6 have not been thoroughly investigated. In this study, we successfully cloned and sequenced the serine protease gene TlSP1 in T. longibrachiatum T6. Our results revealed that the expression level of the TlSP1 gene was induced and significantly increased in T. longibrachiatum T6 after inoculation with H. avenae cysts. The full-length sequence of the coding region (CDS) of TlSP1 gene was 1230 bp and encoded a protein consisting of 409 amino acids. Upon the transformation of the TlSP1 gene into Pichia pastoris X33, the purified recombinant TlSP1 protein exhibited optimal activity at a temperature of 50 °C and pH 8.0. Following 4-10-day of treatment with the purified recombinant TlSP1 protein, the eggshells and content were dissolved and exuded. The number of nematodes invading wheat roots was reduced by 38.43% in the group treated with both TlSP1 and eggs on one side (P1+N) compared to the control group, while the number of nematodes invading wheat roots was reduced by 30.4% in the TlSP1 and eggs two-sided treatment group (P1/N). Furthermore, both the P1+N and P1/N treatments significantly upregulated genes associated with defense enzymes (TaPAL, TaCAT, TaSOD, and TaPOD), genes involved in the lignin synthesis pathway (TaC4H, Ta4CL2, TaCAD1, and TaCAD12), and salicylic acid (SA)-responsive genes (TaNPR1, TaPR1, and TaPR2) and led to the high expression of jasmonic acid (JA)-responsive genes (TaPR4, TaOPR3, and TaAOS2). This study has highlighted the significant role of the TlSP1 gene in facilitating H. avenae eggshells' dissolution, preventing nematode invasion in the host plant, and boosting plant resistance in wheat.

Ss4368: Pathogen-Associated Molecular Pattern for Inducing Plant Cell Death and Resistance to Phytophthora capsici.

Plant recognition of pathogen-associated molecular patterns (PAMPs) is pivotal in triggering immune responses, highlighting their potential as inducers of plant immunity. However, the number of PAMPs identified and applied in such contexts remains limited. In this study, we characterize a novel PAMP, designated Ss4368, which is derived from Scleromitrula shiraiana. Ss4368 is specifically distributed among a few fungal genera, including Botrytis, Monilinia, and Botryotinia. The transient expression of Ss4368 elicits cell death in a range of plant species. The signaling peptides, three conserved motifs, and cysteine residues (C46, C88, C112, C130, and C148) within Ss4368 are crucial for inducing robust cell death. Additionally, these signaling peptides are essential for the protein's localization to the apoplast. The cell death induced by Ss4368 and its homologous protein, Bc4368, is independent of the SUPPRESSOR OF BIR1-1 (SOBIR1), BRI1-ASSOCIATED KINASE-1 (BAK1), and salicylic acid (SA) pathways. Furthermore, the immune responses triggered by Ss4368 and Bc4368 significantly enhance the resistance of Nicotiana benthamiana to Phytophthora capsici. Therefore, we propose that Ss4368, as a novel PAMP, holds the potential for developing strategies to enhance plant resistance against P. capsici.

Effect of drought acclimation on sugar metabolism in millet.

Drought stress triggers sugar accumulation in plants, providing energy and aiding in protection against oxidative damage. Plant hardening under mild stress conditions has been shown to enhance plant resistance to severe stress conditions. While sugar accumulation and metabolism under drought stress have been well-documented in crop plants, the effect of drought acclimation treatment on sugar accumulation and metabolism has not yet been explored. In this study, we investigated the impact of drought stress acclimation on sugar accumulation and metabolism in the leaves and root tissues of two commonly cultivated foxtail millet (Setaria italica L.) genotypes, 'PI 689680' and 'PI 662292'. Quantification of total sugars (soluble sugar, fructose, glucose, and sucrose), their related enzymes (SPS, SuSy, NI, and AI), and the regulation of their related transcripts (SiSPS1, SiSuSy1, SiSWEET6, SiA-INV, and SiC-INV) revealed that drought-acclimated (DA) plants exhibited levels of these indicators comparable to those of control plants. However, under subsequent drought stress conditions, both the leaves and roots of non-acclimated plants accumulated higher levels of total sugars, displayed increased activity of sugar metabolism enzymes, and showed elevated expression of sugar metabolism-related transcripts compared to drought-acclimated plants. Thus, acclimation-induced restriction of sugar accumulation, transport, and metabolism could be one of the metabolic processes contributing to enhanced drought tolerance in millet. This study advocates for the use of acclimation as an effective strategy to mitigate the negative impacts of drought-induced metabolic disturbances in millet, thereby enhancing global food security and promoting sustainable agricultural systems.

Cell wall-associated receptor kinase GhWAKL26 positively regulates salt tolerance by maintaining Na+ and K+ homeostasis in cotton

Cell wall-associated receptor kinases (WAKs/WAKLs), are a specialized class of plant receptor kinases essential for signaling during stress conditions. However, there has been no report on the involvement of WAKs/WAKLs in salt tolerance in cotton. In this study, we report the functional characterization of GhWAKL26, whose expression is induced by salt, with its levels increasing over time and with higher salt concentrations. In addition, the fusion protein of GhWAKL26 and GFP was localized to the plasma membrane. In transgenic Arabidopsis, the dry weight, fresh weight, and root length were significantly higher than those of wild-type plants, indicating enhanced salt tolerance. While in GhWAKL26-silenced cotton seedlings, H2O2, O2−, and MDA content were increased, and chlorophyll content was reduced under salt stress, displaying compromised salt tolerance. RNA-seq analysis revealed that the silencing of GhWAKL26 resulted in the down-regulation of expression levels of certain ion transport-related genes under salt stress, concurrently leading to an increased Na+/K+ ratio in cotton seedlings. Overall, our findings indicate that GhWAKL26 enhanced plant resistance to salt stress in cotton by regulating the balance of Na+ and K+ ions.

Advances in functional studies of plant MYC transcription factors.

Myelocytomatosis (MYC) transcription factors (TFs) belong to the basic helix-loop-helix (bHLH) family in plants and play a central role in governing a wide range of physiological processes. These processes encompass plant growth, development, adaptation to biotic and abiotic stresses, as well as secondary metabolism. In recent decades, significant strides have been made in comprehending the multifaceted regulatory functions of MYCs. This advancement has been achieved through the cloning of MYCs and the characterization of plants with MYC deficiencies or overexpression, employing comprehensive genome-wide 'omics' and protein-protein interaction technologies. MYCs act as pivotal components in integrating signals from various phytohormones' transcriptional regulators to orchestrate genome-wide transcriptional reprogramming. In this review, we have compiled current research on the role of MYCs as molecular switches that modulate signal transduction pathways mediated by phytohormones and phytochromes. This comprehensive overview allows us to address lingering questions regarding the interplay of signals in response to environmental cues and developmental shift. It also sheds light on the potential implications for enhancing plant resistance to diverse biotic and abiotic stresses through genetic improvements achieved by plant breeding and synthetic biology efforts.

Nano-enhanced defense: Titanium-enriched Alginate–Bentonite coating augments Bacillus amyloliquefaciens D203 efficacy against Magnaporthe oryzae in Kenyan rice cultivation

Rice blast disease, caused by Magnaporthe oryzae, poses a significant threat to global rice production, necessitating the development of effective and sustainable management strategies. Biological control using beneficial microbes like Bacillus amyloliquefaciens has emerged as a promising approach due to its ability to enhance plant resistance and reduce disease incidence. Nano-encapsulation of bacteria, which involves embedding beneficial microbes within nanomaterials, offers a novel method to improve the stability, survival, and efficacy of these biocontrol agents. This study evaluated the capacity of encapsulated Bacillus amyloliquefaciens D203, embedded within an alginate-bentonite coating infused with titanium nanoparticles (TNs), to stimulate defense responses in rice seedlings challenged by the Magnaporthe oryzae the causal agent of rice blast disease. Encapsulation was achieved using the extrusion technique, with some modifications. Using a completely randomized design, the experiment was conducted in a greenhouse, with four treatments replicated four times. The experiment used the popular Kenyan rice variety "BASMATI 370”. The study investigated the impact of strain D203 on the incidence, severity, and area under disease progress curves related to M. oryzae, as well as the expression of defense-related enzymes. The results demonstrated that rice plants derived from seeds coated with the D203 encapsulated B. amyloliquefaciens strain exhibited higher levels of defense-related enzyme expression, including peroxidase (POD), phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD) and catalase (CAT), compared to controls. In addition, the incidence and severity of the disease were markedly lower in plants treated with encapsulated B. amyloliquefaciens compared to controls, sometimes paralleling the efficacy of hexaconazole treatment. These findings suggest that the encapsulation of strain D203 has the potential to enhance resistance against rice blast disease by inducing systemic resistance through the production of antioxidant enzymes.

OsABA3 is Crucial for Plant Survival and Resistance to Multiple Stresses in Rice

Preharvest sprouting (PHS) is a serious problem in rice production as it leads to reductions in grain yield and quality. However, the underlying mechanism of PHS in rice remains unclear. In this study, we identified and characterized a preharvest sprouting and seedling lethal (phssl) mutant. The heterozygous phssl/+ mutant exhibited normal plant development, but severe PHS in paddy fields. However, the homozygous phssl mutant was seedling lethal. Gene cloning and genetic analysis revealed that a point mutation in OsABA3 was responsible for the mutant phenotypes. OsABA3 encodes a molybdenum cofactor (Moco) sulfurase. The activities of the sulfureted Moco-dependent enzymes such as aldehyde oxidase (AO) and xanthine dehydrogenase (XDH) were barely detectable in the phssl mutant. As the final step of abscisic acid (ABA) de novo biosynthesis is catalyzed by AO, it indicated that ABA biosynthesis was interrupted in the phssl mutant. Exogenous application of ABA almost recovered seed dormancy of the phssl mutant. The knock-out (ko) mutants of OsABA3 generated by CRISPR-Cas9 assay, were also seedling lethal, and the heterozygous mutants were similar to the phssl/+ mutant showing reduced seed dormancy and severe PHS in paddy fields. In contrast, the OsABA3 overexpressing (OE) plants displayed a significant increase in seed dormancy and enhanced plant resistance to PHS. The AO and XDH activities were abolished in the ko mutants, whereas they were increased in the OE plants. Notably, the Moco-dependent enzymes including nitrate reductase (NR) and sulfite oxidase (SO) showed reduced activities in the OE plants. Moreover, the OE plants exhibited enhanced resistances to osmotic stress and bacterial blight, and flowered earlier without any reduction in grain yield. Taken together, this study uncovered the crucial functions of OsABA3 in Moco sulfuration, plant development, and stress resistance, and suggested that OsABA3 is a promising target gene for rice breeding.

Wheat lesion mimic homology gene TaCAT2 enhances plant resistance to biotic and abiotic stresses

Lesion mimic mutants (LMMs) refer to the spontaneous formation of disease-like spots on leaves without any obvious pathogen infection. The LMM genes can regulate plant immunity, thus promoting the defense of crops against pathogens. However, there is a lack of systematic understanding of the regulatory mechanism of LMMs in wheat. This study identified a wheat LMM TaCAT2, a homolog of the Arabidopsis CAT2. The prediction of the cis-regulatory element revealed that TaCAT2 was involved in the response of plants to various hormones and stresses. RT-qPCR analysis indicated that TaCAT2 was significantly up-regulated by NaCl, drought, and Fusarium graminearum infection. Fluorescence microscopy showed that the TaCAT2 was localized to the peroxisome. Overexpression of TaCAT2 enhanced plant resistance to Phytophthora infestation and F. graminearum by constitutionally activating SA and JA pathways. VIGS of TaCAT2 enhanced the sensitivity of wheat to F. graminearum. Further, TaCAT2 enhanced stress resistance by scavenging the excessive ROS and increasing the activities of antioxidative enzymes. This study lays the basis for the functional identification of TaCAT2 and its applicability in the disease resistance of wheat.

Whole Genome Sequencing of Bacillus velezensis AMR25, an Effective Antagonist Strain against Plant Pathogens.

The most serious problems for cultivated grapes are pathogenic microorganisms, which reduce the yield and quality of fruit. One of the most widespread disease of grapes is "gray mold", caused by the fungus Botrytis cinerea. Some strains of Bacillus, such as Bacillus halotolerans, Bacillus amyloliquefaciens, and Bacillus velezensis, are known to be active against major post-harvest plant rots. In this study, we showed that the endophytic bacteria B. velezensis strain AMR25 isolated from the leaves of wild grapes Vitis amurensis Rupr. exhibited antimicrobial activity against grape pathogens, including B. cinerea. The genome of B. velezensis AMR25 has one circular chromosome with a length of 3,909,646 bp. with 3689 open reading frames. Genomic analysis identified ten gene clusters involved in the nonribosomal synthesis of polyketides (macrolactin, bacillene, and difficidin), lipopeptides (surfactin, fengycin, and bacillizin), and bacteriocins (difficidin). Also, the genome under study contains a number of genes involved in root colonization, biofilm formation, and biosynthesis of phytohormones. Thus, the endophytic bacteria B. velezensis strain AMR25 shows great promise in developing innovative biological products for enhancing plant resistance against various pathogens.

AlphaFold-guided redesign of a plant pectin methylesterase inhibitor for broad-spectrum disease resistance

Plant cell walls are a critical site where plants and pathogens continuously struggle for physiological dominance. Here we show that dynamic remodeling of pectin methylesterification of plant cell walls is a component of the physiological and co-evolutionary struggles between hosts and pathogens. A pectin methylesterase (PsPME1) secreted by Phytophthora sojae decreases the degree of pectin methylesterification, thus synergizing with an endo-polygalacturonase (PsPG1) to weaken plant cell walls. To counter PsPME1-mediated susceptibility, a plant-derived pectin methylesterase inhibitor protein, GmPMI1, protects pectin to maintain a high methylesterification status. GmPMI1 protects plant cell walls from enzymatic degradation by inhibiting both soybean and P. sojae pectin methylesterases during infection. However, constitutive expression of GmPMI1 disrupted the trade-off between host growth and defense responses. We therefore used AlphaFold structure tools to design a modified form of GmPMI1 (GmPMI1R) that specifically targets and inhibits pectin methylesterases secreted from pathogens but not from plants. Transient expression of GmPMI1R enhanced plant resistance to oomycete and fungal pathogens. In summary, our work highlights the biochemical modification of the cell wall as an important focal point in the physiological and co-evolutionary conflict between hosts and microbes, providing an important proof of concept that AI-driven structure-based tools can accelerate the development of new strategies for plant protection.

The involvement of phytohormones in plant–pathogen interaction

Plant–pathogen interactions involve intricate signaling networks that coordinate the plant immune response. Recognition of pathogens through pattern recognition receptors (PRRs) triggers activation of mitogen-activated protein kinase (MAPK) pathways, initiating a cascade of defense mechanisms. Central to these responses is the synthesis of phytohormones such as salicylic acid (SA), auxins–indole-3-acetic acid (IAA), and gibberellins–gibberellic acid (GA), pivotal for immune activation. This review explores the multifaceted roles of these phytohormones in plant immunity, drawing on recent findings from Arabidopsis thaliana and Gossypium hirsutum studies. The review discusses MAPK-mediated activation of TGA1/4 (TGACG sequence-specific binding protein 1/4) transcription factors enhancing SA biosynthesis via isochorismate synthase (ICS). Increased SA levels activate NPR1, promoting gene expression in immune-related pathways including systemic acquired resistance (SAR). Concurrently, pathogen-induced IAA synthesis activates auxin-responsive genes crucial for immune responses. Elevated biosynthesis of IAA from L-tryptophan activates these genes by degrading repressor molecules. IAA acts antagonistically to SA, conserving energy during pathogen infection. Additionally, GA is vital for plant growth and development, operating DELLA (Asp–Glu–Leu–Leu–Ala) protein degradation with the formation of a complex with gibberellin insensitive dwarf 1 (GID1). Once DELLA prevents releasing GA-related response reactions, it is extremelly crucial for GA actions. In general, the review explores the intricate interplay between SA, IAA, and GA, highlighting SA's antagonistic regulation of GA signaling and the synergistic effects of auxin and GA. Understanding these hormone–mediated pathways is crucial for elucidating precise mechanisms underlying plant immunity. Insights gained could inform strategies to enhance plant resistance against pathogens, contributing to sustainable agriculture and global food security efforts.

The role of reactive oxygen species in plant-virus interactions.

Reactive oxygen species (ROS) play a complex role in interactions between plant viruses and their host plants. They can both help the plant defend against viral infection and support viral infection and spread. This review explores the various roles of ROS in plant-virus interactions, focusing on their involvement in symptom development and the activation of plant defense mechanisms. The article discusses how ROS can directly inhibit viral infection, as well as how they can regulate antiviral mechanisms through various pathways involving miRNAs, virus-derived small interfering RNAs, viral proteins, and host proteins. Additionally, it examines how ROS can enhance plant resistance by interacting with hormonal pathways and external substances. The review also considers how ROS might promote viral infection and transmission, emphasizing their intricate role in plant-virus dynamics. These insights offer valuable guidance for future research, such as exploring the manipulation of ROS-related gene expression through genetic engineering, developing biopesticides, and adjusting environmental conditions to improve plant resistance to viruses. This framework can advance research in plant disease resistance, agricultural practices, and disease control.

SpSIZ1 from hyperaccumulator Sedum plumbizincicola orchestrates SpABI5 to fine-tune cadmium tolerance.

Sedum plumbizincicola is a renowned hyperaccumulator of cadmium (Cd), possesses significant potential for eco-friendly phytoremediation of soil contaminated with Cd. Nevertheless, comprehension of the mechanisms underpinning its Cd stress response remains constrained, primarily due to the absence of a comprehensive genome sequence and an established genetic transformation system. In this study, we successfully identified a novel protein that specifically responds to Cd stress through early comparative iTRAQ proteome and transcriptome analyses under Cd stress conditions. To further investigate its structure, we employed AlphaFold, a powerful tool for protein structure prediction, and found that this newly identified protein shares a similar structure with Arabidopsis AtSIZ1. Therefore, we named it Sedum plumbizincicola SIZ1 (SpSIZ1). Our study revealed that SpSIZ1 plays a crucial role in positively regulating Cd tolerance through its coordination with SpABI5. Overexpression of SpSIZ1 significantly enhanced plant resistance to Cd stress and reduced Cd accumulation. Expression pattern analysis revealed higher levels of SpSIZ1 expression in roots compared to stems and leaves, with up-regulation under Cd stress induction. Importantly, overexpressing SpSIZ1 resulted in lower Cd translocation factors (Tfs) but maintained relatively constant Cd levels in roots under Cd stress, leading to enhanced Cd stress resistance in plants. Protein interaction analysis revealed that SpSIZ1 interacts with SpABI5, and the expression of genes responsive to abscisic acid (ABA) through SpABI5-dependent signaling was significantly up-regulated in SpSIZ1-overexpressing plants with Cd stress treatment. Collectively, our results illustrate that SpSIZ1 interacts with SpABI5, enhancing the expression of ABA downstream stress-related genes through SpABI5, thereby increasing Cd tolerance in plants.