Plant Defense Responses Research Articles

Development trend, evolution of themes, gaps and challenges of the research investigating ozone effects on vegetation

Tropospheric ozone (O3) is a potent oxidant that can harm plants, making it a key focus of research in ecology and agriculture. However, comprehensive reviews about the developmental history of O3 research on plants are lacking. This review utilized Citespace software to unveil the evolution of the main research themes over time, which correlated with three distinct developmental periods. During the first period, researchers primarily focused on the impact of O3 on photosynthesis and plant defense responses. As time progressed, more in-depth investigations were undertaken including determining the critical levels at which O3 damage to plants occurred, analyzing the source-sink carbon balance and carbon allocation, assessing food security based on risk evaluation, identifying quantitative trait loci (QTL) associated with O3 tolerance, conducting transgenic research, and exploring the combined effect of multiple stressors on vegetation within the context of climate change. Despite these insights, several gaps and challenges remain, that merit future considerations. Greater research efforts should focus on 1) insufficient studies on the combined effects of O3, CO2, and drought in the context of global warming; 2) intermittent elevated O3 events and plant recovery mechanisms under low O3 concentration; 3) reproductive and renewal capacity of species, and t O3 effects on community stability or composition; 4) updating O3 flux measurements to reflect effective O3 flux when O3 index is applied, and challenges in determining species-specific phytotoxicity threshold; and 5) O3-tolerance gene screening and breeding.

Metabolome profiling dissects the oat (Avena sativa L.) innate immune response to Pseudomonas syringae pathovars.

One of the most important characteristics of successful plant defence is the ability to rapidly identify potential threats in the surrounding environment. Plants rely on the perception of microbe-derived molecular pattern chemicals for this recognition, which initiates a number of induced defence reactions that ultimately increase plant resistance. The metabolome acts as a metabolic fingerprint of the biochemical activities of a biological system under particular conditions, and therefore provides a functional readout of the cellular mechanisms involved. Untargeted metabolomics was applied to decipher the biochemical processes related to defence responses of oat plants inoculated with pathovars of Pseudomonas syringae (pathogenic and non-pathogenic on oat) and thereby identify signatory markers that are involved in host or nonhost defence responses. The strains were P. syringae pv. coronafaciens (Ps-c), P. syringae pv. tabaci, P. syringae pv. tomato DC3000 and the hrcC mutant of DC3000. At the seedling growth stage, metabolic alterations in the Dunnart oat cultivar (tolerant to Ps-c) in response to inoculation with the respective P. syringae pathovars were examined following perception and response assays. Following inoculation, plants were monitored for symptom development and harvested at 2-, 4- and 6 d.p.i. Methanolic leaf extracts were analysed by ultra-high-performance liquid chromatography (UHPLC) connected to high-definition mass spectrometry. Chemometric modelling and multivariate statistical analysis indicated time-related metabolic reconfigurations that point to host and nonhost interactions in response to bacterial inoculation/infection. Metabolic profiles derived from further multivariate data analyses revealed a range of metabolite classes involved in the respective defence responses, including fatty acids, amino acids, phenolic acids and phenolic amides, flavonoids, saponins, and alkaloids. The findings in this study allowed the elucidation of metabolic changes involved in oat defence responses to a range of pathovars of P. syringae and ultimately contribute to a more comprehensive view of the oat plant metabolism under biotic stress during host vs nonhost interactions.

Induced Systemic Resistance-Mediated Defense Against Alternaria Blight Disease in Lentil by Pesticide Degrading Plant Growth-Promoting Rhizobacteria.

Enzymatic and antioxidative responses are key defense mechanisms in plants following pathogen invasion, collectively known as induced systemic resistance (ISR). Alternaria sp., a well-known soil-borne pathogen, causes blight diseases in various crops. This study investigates the defence response in lentil plants through the treatment-induced application of two multipotent pesticide degrading plant growth-promoting rhizobacteria (PGPR), Bacillus cereus and Bacillus safensis, to mitigate the destructive effects of Alternaria. Both bacterial strains were applied in different carrier-based bioformulations via soil drenching. We assessed the modulation of defense-related enzymes by various combinational treatments with the Alternaria pathogen. The in vitro production of antimicrobial compounds was analyzed using GC-MS to confirm their pathogen-suppressive capabilities. Field trials showed a positive correlation between treatments and improvements in yield and growth index (GI). The highest (180%) enzymatic induction of phenylalanine ammonia lyase (PAL) followed by catalase (CAT)(100%) and polyphenol oxidase (PPO) (54%), was observed in treatments with B. cereus alone or in combination with B. safensis, in presence of Alternaria, in respect to the control. In vitro analysis revealed the production of antimicrobial compounds, including benzoic acid derivatives, cyclotetrasiloxanes, hexacosane, chlorpyrifos, and phthalates, which may contribute to pathogen suppression. Our findings demonstrate that these biocontrol agents (BCAs) not only stimulate the plant's enzymatic defense system but also enhance growth, seed yield and produce several antimicrobial compounds in vitro. Thus, pesticide-tolerant PGPR, used in this study, exhibit both disease control and plant growth-promoting properties, offering promising applications in sustainable agriculture.

The Deubiquitinating Enzyme AMSH1 Contributes to Plant Immunity Through Regulating the Stability of BDA1

Plants utilize plasma membrane localized receptors like kinases (RLKs) or receptor-like proteins (RLPs) to recognize pathogens and activate pattern-triggered immunity (PTI) responses. A gain-of-function mutation in the Arabidopsis RLP SNC2 (SUPPRESSOR OF NPR1-1, CONSTITUTIVE 2) leads to constitutive activation of defense responses in snc2-1D mutant plants. Transcription factors, SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1) and CALMODULIN-BINDING PROTEIN 60g (CBP60g), define two parallel pathways downstream of SNC2. The autoimmunity of snc2-1D was partially affected by single mutations in SARD1 or CBP60g but completely suppressed by the sard1 cbp60g double mutant. From a suppressor screen using sard1-1 snc2-1D, we identified a deubiquitinating enzyme ASSOCIATED MOLECULE WITH THE SH3 DOMAIN OF STAM 1 (AMSH1) as a key component in SNC2-mediated plant immunity. A loss-of-function mutation in AMSH1 can suppress the autoimmune responses of sard1-1 snc2-1D. In eukaryotes, selective protein degradation often occurs through the ubiquitination/deubiquitination system. The deubiquitinating enzymes that remove ubiquitin from target proteins play essential roles in controlling the level of target protein ubiquitination and degradation. As loss of AMSH1 results in decreased BDA1 abundance and BDA1 is a transmembrane protein required for SNC2-mediated immunity, AMSH1 likely contributes to immunity regulation through controlling BDA1 stability.

Structure-function relation of cytokinins determines their differential efficiency in mediating tobacco resistance against Pseudomonas syringae.

The classic plant growth-promoting phytohormone cytokinin has been identified and established as a mediator of pathogen resistance in different plant species. However, the resistance effect of structurally different cytokinins appears to vary and may regulate diverse mechanisms to establish resistance. Hence, we comparatively analysed the impact of six different adenine- and phenylurea-type cytokinins on the well-established pathosystem Nicotiana tabacum-Pseudomonas syringae. The efficiency of resistance effects was evaluated based on impacts on the host plant defence response by scoring infection symptoms and the direct impact on the pathogen by assessment of proliferation in planta. To identify common and cytokinin-specific components involved in resistance effects, transcriptome profiling and targeted metabolomics were conducted in leaves treated with the different cytokinins. We observed clearly different potentials of the tested cytokinins in either suppressing infection symptoms or pathogen proliferation. Gene regulation and metabolite analyses revealed cytokinin-type specific impacts on defence components, such as salicylic acid and related signalling, expression of PR proteins, and regulation of specialised metabolism. Cytokinins also strongly affected plant cell physiological parameters, such as a remarkable decrease in amino acid pools. Hence, this study provides comparative information on the efficiency of diverse cytokinins in mediating resistance in one well-studied pathosystem and insights into the specific regulation of resistance effects mediated by different cytokinin molecules. This is particularly relevant for studies on the function of cytokinins or other phytohormones and compounds interacting with cytokinin activities in the context of pathogen infections and other stress scenarios, considering the diverse cytokinins present in plants.

Leveraging light-gated channelrhodopsins for strengthening plant physiological responses.

Strengthening plant physiological traits is crucial for sustainable plant improvement. The underlying molecular mechanisms of rhodopsin-based plant improvement remain largely unknown. However, a recent study by Ding et al. offers some insights by exploring how light-gated channelrhodopsins regulate cytosolic Ca2+ conductance, reactive oxygen species (ROS) signals, and plant defense responses in tobacco.

A pentatomomorpha-specific salivary protein activates plant immunity and is critical for insect feeding

The stinkbug Riptortus pedestris, notorious for inducing soybean staygreen-like syndrome, employs a range of salivary proteins to manipulate the host plant for its benefit. Here, we show that RpSP1, a salivary protein specific to Pentatomomorpha, triggers plant defense responses in multiple plant species. RpSP1 interacts with and stabilizes a HSP40 family protein GmSPIP1 and is dependent on GmSPIP1 to induce cell death. We show that a critical 22-amino acid peptide within RpSP1 acts as an intracellular insect-derived elicitor. Furthermore, RpSP1 enhances insect-feeding efficiency. The dual functionality of RpSP1 is highlighted by the significant reduction of soybean staygreen-like syndrome following its overexpression in soybean plants or knockdown in insects. Our findings elucidate the complex molecular interactions between plants and herbivores, positioning RpSP1 as a crucial target for developing advanced pest management strategies with broad implications for agricultural biology.

Proteomic Variation in the Oral Secretion of Spodoptera exigua and Spodoptera littoralis Larvae in Response to Different food Sources

The Spodoptera genus is defined as the pest-rich genus because it contains some of the most destructive lepidopteran crop pests, characterized by a wide host range. During feeding, the caterpillars release small amounts of oral secretion (OS) onto the wounded leaves. This secretion contains herbivore-induced molecular patterns (HAMPs) that activate the plant defense response, as well as effectors that may inhibit or diminish the plant’s anti-herbivory response. In this study, we explored the protein components of the OS of two Spodoptera species, Spodoptera exigua and Spodoptera littoralis. We identified 336 and 276 proteins, respectively, with a major role in digestion. Using a label-free quantitative proteomics approach, we investigated changes in protein abundance in the OS of both species after switching from a laboratory artificial diet to detached pepper and tomato leaves. Several proteins, such as various lipases, polycalin and a β-1,3-glucan binding protein, were more abundant in the OS of leaf-fed larvae in both species. Conversely, a tryptophan-aspartic acid (WD)-repeat containing protein significantly decreased upon feeding on plant leaves in both species. Phenotypic plasticity dependent on each Spodoptera-plant combination was observed for several peptidases, potentially related to the need to overcome the effects of proteinase inhibitors differentially produced by the two plant species, and for several REPAT proteins, possibly related to the specific modulation of each Spodoptera-plant interaction. Altogether, our results provide useful information for understanding the interaction of these two polyphagous Spodoptera species with the host plants, and help to identify evolutionary traits that may influence the outcome of herbivory in each of these two related species.

Crosstalk Between Abiotic and Biotic Stresses Responses and the Role of Chloroplast Retrograde Signaling in the Cross-Tolerance Phenomena in Plants

In the natural environment, plants are simultaneously exposed to multivariable abiotic and biotic stresses. Typical abiotic stresses are changes in temperature, light intensity and quality, water stress (drought, flood), microelements availability, salinity, air pollutants, and others. Biotic stresses are caused by other organisms, such as pathogenic bacteria and viruses or parasites. This review presents the current state-of-the-art knowledge on programmed cell death in the cross-tolerance phenomena and its conditional molecular and physiological regulators, which simultaneously regulate plant acclimation, defense, and developmental responses. It highlights the role of the absorbed energy in excess and its dissipation as heat in the induction of the chloroplast retrograde phytohormonal, electrical, and reactive oxygen species signaling. It also discusses how systemic- and network-acquired acclimation and acquired systemic resistance are mutually regulated and demonstrates the role of non-photochemical quenching and the dissipation of absorbed energy in excess as heat in the cross-tolerance phenomenon. Finally, new evidence that plants evolved one molecular system to regulate cell death, acclimation, and cross-tolerance are presented and discussed.

XopAE Effector from Xanthomonas phaseoli pv. manihotis Targets HSP20-Like p23 Cochaperone to Suppress Plant Basal Immunity.

Pathogenic bacteria use Type 3 effector proteins to manipulate host defenses and alter metabolism to favor their survival and spread. The non-model bacterial pathogen Xanthomonas phaseoli pv. manihotis (Xpm) causes devastating disease in cassava. The molecular role of Type 3 effector proteins from Xpm in causing disease is largely unknown. Here, we report that the XopAE effector from Xpm suppresses plant defense responses. Our results showed that XopAE is a suppressor of basal defenses such as callose deposition and the production of reactive oxygen species (ROS). XopAE targets a small heat shock protein (Mep23-1 cochaperone) in cassava and its homolog Atp23-1 in Arabidopsis. XopAE localizes to the nucleus and in scattered points throughout the cell border, while Mep23-1 shows a nucleocytoplasmic localization. Upon interaction, XopAE hijacks Mep23-1 to the scattered points throughout the cell border and they also interact in nucleus. Our results indicate that the interaction between XopAE and Mep23-1 is essential for suppressing basal plant defense. This study is one of the first to address the molecular mechanisms deployed by Xpm to cause disease in cassava, a non-model crop plant.

Effectiveness of Plant-Induced Resistance Against Root-Knot Nematode Depends on the Policy of Using Inducer on the Host Plant.

This research was conducted to determine the relationship between plant defense responses and the extent of treatment applied to either the aerial parts or roots of the plant. The experimental treatments included different methods of application (spraying versus soil drenching), varying treatment areas (one-sixth, one-third, half, or all of the plant's aerial parts and roots) with SA, and infecting the plants with root-knot nematodes. Evaluation of plant growth and nematode pathogenicity indices in the greenhouse section, H2O2 accumulation rate, and phenylalanine ammonia lyase enzyme activity (in aerial parts and roots) were carried out in biochemical experiments. The results showed that treating less than one-third of the aerial parts with salicylic acid (SA) did not significantly impact plant growth or nematode pathogenicity indices. However, it did lead to a notable increase in hydrogen peroxide (H2O2) accumulation, while phenylalanine ammonia lyase (PAL) enzyme activity remained unchanged. In contrast, treating more than one-third of the aerial parts resulted in decreased nematode pathogenicity and enhanced production of defense compounds. Notably, treatments targeting the roots consistently demonstrated a more pronounced effect on nematode suppression and increased defense compound levels, emphasizing the importance of root treatment, as this is where nematodes are primarily present. Overall, the study highlights the differential impact of treatment location and extent on plant defense mechanisms and suggests that strategic targeting of either aerial or root tissues can optimize plant responses against nematode attacks.

Resolving spatially distinct phytohormone response zones in Arabidopsis thaliana roots colonized by Fusarium oxysporum.

Jasmonic acid (JA), ethylene (ET) and salicylic acid (SA) are the three major phytohormones coordinating plant defense responses, and all three are implicated in the defense against the fungal pathogen Fusarium oxysporum. However, their distinct modes of action and possible interactions remain unknown, in part because all spatial information on their activity is lacking. Here, we set out to probe this spatial aspect of plant immunity by using live-microscopy with newly developed fluorescence-based transcriptional reporter lines. We have created a GreenGate vector collection of Plant Immune system Promoters (GG-PIPs) that allow us to image local activation of immune pathways with single-cell resolution. Using this system, we demonstrate that SA and JA act spatially separate from each other in distinct sets of root cells neighboring the fungal colonization site, while ET contributes to both sets. SA & ET induce the hypersensitive response as a first line of defense, while JA & ET govern active defense against the pathogen in a separate, second line of defense. Such an approach to resolve the plant's immune responses on an individual cell level has been lacking, and this work demonstrates that this microscopy-based approach can contribute to understanding plant immune responses in detail.

Ferritin From Striped Stem Borer (Chilo suppressalis) Oral Secretion Acts as an Effector Helping to Maintain Iron Homoeostasis and Impair Defenses in Rice.

The striped stem borer (Chilo suppressalis, SSB) is a highly destructive insect pest in rice (Oryza sativa). SSB oral secretions (OSs) can induce plant defense responses in rice. However, the specific effectors in SSB OSs that mediate these interactions with rice remain poorly understood. In this study, hallmarks of ferroptosis-like plant defense response, such as the reprogramming of ferroptosis-related genes, reduced glutathione levels, accumulation of ferric ion, and enhanced lipid peroxidation by reactive oxygen species (ROS), were detected in rice subjected to SSB infestation and SSB OSs treatment. Furthermore, we identified and characterized a protein from SSB OSs, the ferritin CsFer1, which plays a critical role in the regulation of plant iron homoeostasis. CsFer1 was shown to possess Fe2+ binding capacity and ferroxidase activity. Through recombinant CsFer1 protein treatment, overexpression of CsFer1 in rice and SSB larvae with silencing CsFer1 feeding in rice, we found that CsFer1 helped maintain iron homoeostasis under SSB infestation, suppressing H2O2 and JA accumulation, ultimately compromising rice resistance to herbivorous pests. Moreover, such a phenomenon about the regulation of iron homoeostasis and suppression of insect resistance was observed in the CsFer1 overexpressed tobacco. Collectively, these findings suggest that CsFer1 functions as an effector involved in the regulation of iron homoeostasis- and lipid peroxidation-related plant defense during plant-insect interaction.

Feeding Preferences and Salivary Protein Profiles of Spodoptera frugiperda on Saccharum Species.

The invasion of the fall armyworm poses substantial threats to local agricultural safety, including the sugarcane industry. Exploring the insect-resistance mechanism is crucial for breeding resistant varieties. This study selected three representative materials from the Saccharum genus─Saccharum officinarum L. (Badila), S. spp. hybrid (GT58), and Saccharum spontaneum (SES208), to investigate feeding preferences and developmental fitness of Spodoptera frugiperda. Larvae exhibited a strong preference and highest fitness parameters in Badila leaves compared to SES208. Additionally, proteomic analyses of larval saliva from insects feeding on Badila and SES208 were carried out to test the types and abundance of proteins on different hosts. Furthermore, we identified fatty acid-binding protein 1-like activates plant defense responses, while aldehyde dehydrogenase negatively suppressed plant defense response. Our findings suggest that the plasticity of salivary proteins induced by different host plants, and also offer new insights into the molecular interactions between S. frugiperda and plants.

Tomato Defenses Under Stress: The Impact of Salinity on Direct Defenses Against Insect Herbivores.

Abiotic stressors, such as salt stress, can reduce crop productivity, and when combined with biotic pressures, such as insect herbivory, can exacerbate yield losses. However, salinity-induced changes to plant quality and defenses can in turn affect insect herbivores feeding on plants. This study investigates how salinity stress in tomato plants (Solanum Lycopersicum cv. Better Boy) impacts the behavior and performance of a devastating insect pest, the tomato fruitworm caterpillar (Helicoverpa zea). Through choice assays and performance experiments, we demonstrate that salt-stressed tomato plants are poor hosts for H. zea, negatively affecting caterpillar feeding preferences and growth rates. While changes in plant nutritional quality were observed, the primary factor influencing insect performance appears to be direct ionic toxicity, which significantly impairs multiple life history parameters of H. zea including survival, pupation, adult emergence, and fecundity. Plant defense responses show complex interactions between salt stress and herbivory, with two proteinase inhibitor genes - PIN2 and AspPI, showing a higher induced response to insect herbivory under salt conditions. However, plant defenses do not seem to be the main driver of reduced caterpillar performance on salt-treated plants. Furthermore, we report reduced oviposition by H. zea moths on salt-treated plants, which was correlated with altered volatile emissions. Our findings reveal that H. zea exhibits optimal host selection behaviours for both larval feeding and adult oviposition decisions, which likely contribute to its success as an agricultural pest. This research provides insights into the complex interactions between abiotic stress, plant physiology, and insect behaviour, with potential implications for pest management strategies in saline agricultural environments.

Fungal effector genes involved in the suppression of chitin signaling as novel targets for the control of powdery mildew disease via a nontransgenic RNA interference approach.

Chitin is a crucial component of fungal cell walls and an effective elicitor of plant immunity; however, phytopathogenic fungi have developed virulence mechanisms to counteract the activation of this plant defensive response. In this study, the molecular mechanism of chitin-induced suppression through effectors involved in chitin deacetylases (CDAs) and their degradation (EWCAs) was investigated with the idea of developing novel dsRNA-biofungicides to control the cucurbit powdery mildew caused by Podosphaera xanthii. The molecular mechanisms associated with the silencing effect of the PxCDA and PxEWCAs genes were first studied through dsRNA cotyledon infiltration assays, which revealed a ≈80% reduction in fungal biomass and a 50% decrease in gene expression. To assess the impact on powdery mildew disease control, in vitro and in planta assays were carried out in growth chamber and glasshouse experiments, with ≈50% reduction in disease symptoms after 8 days postinoculation (dpi) in leaf discs and 12 dpi in plants' leaves, respectively. This control was extended for 21 days when the dsRNAs were protected on the carbon dot nanocarriers. Additionally, the uptake of the dsRNAs by fungal spores was observed 12 h postapplication via confocal microscopy, and efficient processing of dsRNAs into siRNAs by the melon RNAi machinery was observed 24 h postspraying through sRNA-seq. This study highlights notable advancements in environmentally friendly disease management, and features the technological potential of RNA-based fungicides together with nanotechnology for cucurbit powdery mildew control. © 2025 Society of Chemical Industry.

Elevated CO2 alters soybean physiology and defense responses, and has disparate effects on susceptibility to diverse microbial pathogens.

Increasing atmospheric CO2 levels have a variety of effects that can influence plant responses to microbial pathogens. However, these responses are varied, and it is challenging to predict how elevated CO2 (eCO2) will affect a particular plant-pathogen interaction. We investigated how eCO2 may influence disease development and responses to diverse pathogens in the major oilseed crop, soybean. Soybean plants grown in ambient CO2 (aCO2, 419 parts per million (ppm)) or in eCO2 (550 ppm) were challenged with bacterial, viral, fungal, and oomycete pathogens. Disease severity, pathogen growth, gene expression, and molecular plant defense responses were quantified. In eCO2, plants were less susceptible to Pseudomonas syringae pv. glycinea (Psg) but more susceptible to bean pod mottle virus, soybean mosaic virus, and Fusarium virguliforme. Susceptibility to Pythium sylvaticum was unchanged, although a greater loss in biomass occurred in eCO2. Reduced susceptibility to Psg was associated with enhanced defense responses. Increased susceptibility to the viruses was associated with reduced expression of antiviral defenses. This work provides a foundation for understanding how future eCO2 levels may impact molecular responses to pathogen challenges in soybean and demonstrates that microbes infecting both shoots and roots are of potential concern in future climatic conditions.

A B-Box (BBX) Transcription Factor from Cucumber, CsCOL9 Positively Regulates Resistance of Host Plant to Bemisia tabaci.

B-box (BBX) transcription factors play crucial roles in plant growth, development, and defense responses to biotic and abiotic stresses. In this study, we cloned a BBX transcription factor gene, CsCOL9I, from cucumber and analyzed its role in the plant's defense against the feeding of Bemisia tabaci. CsCOL9 is expressed throughout all developmental stages in cucumber, with the highest expression in the leaves. CsCOL9 is induced by B. tabaci feeding, salicylic acid (SA), methyl jasmonate (MeJA), and hydrogen peroxide (H2O2). Cucumber plants with CsCOL9 silence (TRV2-CsCOL9) and overexpression (1301-CsCOL9) were obtained and analyzed. After CsCOL9 silencing, survival rates and host selectivity for B. tabaci increased; however, the expression levels of genes encoding enzymes (CsSOD, CsRBOH, CsPOD), activities of superoxide dismutase (SOD) and peroxidase (POD), and content of H2O2 in plants were all reduced. CsCOL9 overexpression led to decreased survival rates and host selectivity for B. tabaci. Conversely, the expression levels of genes (CsSOD, CsRBOH and CsPOD), activities of SOD and POD, and content of H2O2 increased after CsCOL9 overexpression in plants. Collectively, our results demonstrate CsCOL9 positively regulates cucumber resistance to B. tabaci by activating reactive oxygen species bursts. This study lays a theoretical foundation for the application of CsCOL9 in cucumber resistance breeding and green pest control of B. tabaci.

Chromosome 1 QTLs associated with response to bacterial leaf spot in Beta vulgaris

AbstractBacterial leaf spot (BLS), caused by Pseudomonas syringae pathovar aptata (Psa), is a seedborne, foliar disease affecting members of the Amaranthaceae and Cucurbitaceae families, including table beet and Swiss chard crops. There is no known resistance to BLS in beet or chard. A diversity panel, modified from the Wisconsin Beta Diversity Panel (WBDP) and comprised of 219 accessions from the Beta vulgaris crop complex, was assembled and genotyped for single nucleotide polymorphism data. These accessions were screened by foliar inoculation of Psa and visually evaluated for percentage of diseased leaf tissue. Overall, sugar beet and Beta vulgaris subsp. maritima accessions had the lowest BLS response, whereas table beet accessions had the largest range of responses. Phenotypic means were adjusted using best linear unbiased estimates, and two different software programs, GWASpoly and GAPIT3, were utilized to conduct a genome‐wide association study (GWAS). Leaf color was found to be significantly associated with and correlated with BLS response scores, and was used as a covariate in GWAS analysis. An association with BLS response was detected on chromosome 1 in the full WBDP, explaining upward of 21% of the variation in the phenotype. The marker associated with this quantitative trait locus (QTL), Chr1_61344476, showed an additive relationship between dosage and BLS response. Eleven candidate genes, described and annotated in sugar beet, were associated with this QTL. Some of these include F Box domains, RNA‐binding proteins, and calcium‐dependent kinases, all of which have roles in plant defense responses. Marker Chr1_61344476 may be useful in breeding for BLS resistance in members of the Beta vulgaris crop complex.

Symbiosis vs pathogenesis in plants: Reflections and perspectives.

Plant-microbe partnerships constitute a complex and intricately woven network of connections that have evolved over countless centuries, involving both cooperation and antagonism. In various contexts, plants and microorganisms engage in mutually beneficial partnerships that enhance crop health and maintain balance in ecosystems. However, these associations also render plants susceptible to a range of pathogens. Understanding the fundamental molecular mechanisms governing these associations is crucial, given the notable susceptibility of plants to external environmental influences. Based on quorum sensing signals, phytohormone, and volatile organic carbon (VOC) production and others molecules, microorganisms influence plant growth, health, and defense responses. This review explores the multifaceted relationships between plants and their associated microorganisms, encompassing mutualism, commensalism, and antagonism. The molecular mechanisms of symbiotic and pathogenic interactions share similarities but lead to different outcomes. While symbiosis benefits both parties, pathogenesis harms the host. Genetic adaptations optimize these interactions, involving coevolution driving process. Environmental factors influence outcomes, emphasizing the need for understanding and manipulation of microbial communities for beneficial results. Research directions include employing multi-omics techniques, functional studies, investigating environmental factors, understanding evolutionary trajectories, and harnessing knowledge to engineer synthetic microbial consortia for sustainable agriculture and disease management.