Deploying cultivars containing resistance genes is an economical and effective method for managing pathogen outbreaks but is subject to a trade-off in which more effective control often accelerates the emergence of virulent, resistance-breaking pathogen strains (durability-effectiveness trade-off). Coordinating the deployment of resistance genes spatially and temporally could mitigate this trade-off. Using a novel spatiotemporal model, we explored whether coordinating the deployment of four resistant crop cultivars, each carrying a different resistance gene, spatially and temporally within a landscape could improve epidemic management and resistance durability. We also examined how the efficacy of different deployment strategies varied based on initial pathogen load, virulence allele frequency, pathogen source location and dispersal characteristics, and the frequency of non-host crops in the landscape. Even with landscape-level coordination, a durability-effectiveness trade-off remained, in which the strategies that most effectively reduced outbreaks resulted in a greater prevalence of virulent pathogen strains, especially when initial virulence frequencies were high. Rotating resistant cultivars every 5 years was the most effective strategy for resistance durability. However, the control effectiveness of this strategy was heavily influenced by the spatial arrangement of the cultivars within each rotation, with coordination across the whole landscape providing the best balance between durability and effectiveness. Combining non-host crops with resistance gene rotation strategies consistently reduced disease incidence and enhanced durability, proving extremely effective even when deployed across as little as 25% of the landscape. Our study highlights the potential benefit of coordinated spatial and temporal planning at the landscape level when using resistant cultivars for crop disease management.
Corynespora leaf spot, caused by Corynespora cassiicola, is an emerging disease in crops that significantly impacts both yield and quality. Currently, the use of fungicides to control Corynespora leaf spot has led to the development of varying degrees of resistance in the pathogen. Therefore, it is crucial to screen for highly effective fungicides with novel modes of action. This study evaluated the antifungal activity of 1-hydroxyphenazine (1OH-PHZ) against multiple phytopathogenic fungi, with a half-maximal effective concentration (EC50) of 19.23 μg/ml against C. cassiicola hyphae. In vivo assay demonstrated antifungal activity of 67.22 and 45.03% on detached tomato leaves and fruits, respectively, at a dose of 500.0 μg/ml. Microscopic and ultrastructural observations revealed hyphal collapse, surface wrinkling, and indistinct organelle boundaries following treatment. Integrated transcriptomic and metabolomic analyses showed differentially expressed genes and differentially abundant metabolites, primarily affecting amino acid metabolism and biosynthesis pathways. Molecular docking, dynamic simulations, and microscale thermophoresis assays demonstrated that 1OH-PHZ binds to PLP-dependent transferase (PLPDT), exhibiting a binding free energy of -7.2 kcal/mol and a dissociation constant (Kd) value of 1.16 μM. Collectively, these findings suggest that 1OH-PHZ potentially binds to PLPDT, thereby disrupting amino acid metabolism and biosynthesis, which subsequently affects the synthesis and morphological development of the fungal cell wall and cell membrane. Through the combination and screening of highly active fungicidal substances, this study offers mechanistic insights that support the potential development of 1OH-PHZ as a novel agricultural fungicide for managing C. cassiicola infections.
Sclerotinia sclerotiorum is a devastating phytopathogenic fungus with a broad host range, which is partly attributed to its ability to detoxify a wide array of host-derived secondary metabolites. Among these, flavonoids are one of the most widespread classes of plant secondary metabolites and are ubiquitously present in both host and non-host plants of S. sclerotiorum. Understanding the mechanisms by which non-host flavonoids inhibit this pathogen is therefore crucial, not only for elucidating the biochemical basis of non-host resistance but also for discovering novel plant-derived fungicides. In this study, we compared the differential inhibitory effects of various flavonoid types—including isoflavones, flavonols, flavanones, and citrus-derived polymethoxyflavones (PMFs) —on S. sclerotiorum. Our results revealed differential sensitivities of the fungus to these compounds, corresponding with its varying metabolic capabilities. Furthermore, transcriptomic analysis demonstrated that the non-host flavonoid nobiletin and the host-derived, degradable flavonol quercetin elicit fundamentally different gene expression responses in the fungus. Further physiological and biochemical analyses showed that nobiletin induced ROS accumulation in S. sclerotiorum at later stages of treatment, but had no significant effects on plasma membrane integrity or carbohydrate metabolism. The partial rescue of growth inhibition by ascorbic acid suggests that ROS accumulation contributes to the antifungal activity of nobiletin. These findings provide new insights into the antifungal mechanisms of PMFs and support their potential application in fungicide development.
Phytophthora ramorum, the sudden oak death (SOD) pathogen, has invaded U.S. nurseries and western forests repeatedly. Invasions by three distinct clonal lineages (NA1, NA2, and EU1) have affected U.S. wildland forests since 2001. Most recently, NA2 established an invasive population in coastal forests surrounding Port Orford in southwest Oregon. This is the first instance of NA2 encountered outside of a nursery. We assessed this new invasion's diversity and population structure using single-nucleotide polymorphisms from whole genome sequences of 195 isolates. Genomes were sampled from the nursery trade and from the forest invasion surrounding Port Orford. The NA2 forest invasion lacks genetic diversity and likely originated from a single introduction. A subset of NA2 isolates (10.8%) were genetically distant from all other isolates including each other. This distance was correlated with frequency of genomic runs of homozygosity. No evidence of hybridization was found, though NA2 and EU1 mating types are compatible and their ranges in wild forests overlap. Aggressiveness and sporulation of NA2 isolates were measured on three host tree species and compared with isolates of other lineages. NA2 and EU1 phenotypes were similar. NA2 caused larger lesions on Douglas-fir and tanoak seedlings than NA1, the lineage of the original introduction into Oregon forests. Results indicate that the NA2 population is not distinct from the older EU1 Oregon population in terms of population diversity, disease aggressiveness, or potential for spread. However, the introduction of NA2 has increased the SOD epidemic's range, risk of hybridization, overall genetic diversity, and adaptive potential.
Citrus huanglongbing (HLB), caused by the phloem-colonizing ‘ Candidatus Liberibacter asiaticus’ (CLas), is a devastating disease worldwide. CLas systemically infects all organs containing phloem. How CLas causes pathogenicity in different organs remains poorly understood. Here, we conducted transmission electron microscope and light microscope analyses of different organs in a grove and greenhouse at four time points over a year. Compared with the healthy controls, increased phloem cell death was observed in CLas-positive tissues, including leaf, fruit albedo, pedicel, and columella, as well as bark tissues of the branches and trunk, but not in root and seed coat tissues. CLas infection causes more phloem callose deposition in leaf, fruit albedo, pedicel, and columella, as well as bark tissues of the branches and trunk, but not, or to a lesser extent, in root and seed coat tissues. Our data demonstrate that CLas triggers phloem cell death and callose deposition in photosynthetic tissues but not, or to a lesser extent, in nonphotosynthetic tissues. CLas infection also caused starch accumulation in mature leaves and branch bark and starch depletion in roots. Our data have revealed the sequential order of HLB disease development. CLas triggers phloem cell death and callose deposition, which cause phloem transportation blockage and subsequent starch accumulation in leaves. Starch accumulation leads to chloroplast degeneration and subsequent blotchy mottling and yellowing symptoms. Root decay mainly results from carbon starvation, which further contributes to HLB symptom development, such as nutrient deficiency, tree decline, and death. In sum, CLas causes disease effects on photosynthetic and nonphotosynthetic tissues via distinct mechanisms. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
Pantoea ananatis is an emerging bacterial pathogen in rice with increasing reports across global rice-growing regions. While previous studies have suggested its presence in the seed, direct evidence for seed-to-plant transmission in rice remains limited. In this study, we characterized P. ananatis isolates recovered from naturally contaminated rice seeds and evaluated their potential for vertical transmission through two successive plant generations. Nine isolates from three rice varieties were assessed for their impact on germination, seedling health, and symptom development. Disease progression was tracked across generations, and host genotype effects were also explored. Isolates from the highly susceptible variety JiBoYa exhibited elevated virulence in rice, suggesting genotype-dependent pathogenicity. Disease onset in second-generation plants occurred approximately 30 days earlier than in the first, accompanied by significantly increased disease severity and compromised seed production. These results provide compelling evidence that P. ananatis can be vertically transmitted in rice and may accumulate across generations, leading to enhanced virulence expression. We propose further molecular and epidemiological investigations to elucidate the mechanisms underlying seedborne persistence, virulence diversity, and the broader implications for pathogen management.
The exopolysaccharide (EPS), xanthan or xanthan gum secreted by the Xanthomonas genus of bacterial pathogens gives them the characteristic mucoid colony phenotype. Lack of xanthan production leads to reduced or attenuated virulence of the pathogen. We have previously described spontaneous non-mucoid variants of Xanthomonas oryzae pv. oryzae (Xoo) which accumulate in long-term stationary phase cultures, and this phenomenon was termed stationary phase variation and variant colonies as stationary phase variants (SPVs). In this study, we demonstrate that many of the SPVs harbour variations in the lipopolysaccharide (LPS) outer antigen (O-antigen) biosynthetic gene cluster. Genotyping of SPVs revealed insertion of endogenous IS elements or slipped strand mispairing (SSM) the LPS O-antigen locus as the major types of variation. Several of these SPVs exhibited reversion to wild type mucoid phenotype via restoration of the wild type genotype. Additionally, the reverting type SPVs generated virulence lesions upon in-planta inoculations. The results indicate that phase variation occurs in the LPS O-antigen biosynthetic gene cluster of Xoo during long term stationary phase cultures and we discuss its possible adaptive significance.
Clonostachys rosea has long been the primary model for studying mycoparasitism within its genus; however, the potential of other species remains largely unexplored. In this study, we established a PEG-CaCl2-mediated protoplast transformation system for Clonostachys reniana. Our results demonstrate for the first time that this species is amenable to genetic manipulation and produces transformants with genetic stability, providing a reliable platform for functional genomic research in this fungus. Using Green Fluorescent Protein (GFP) tagging, we achieved stable transformants that retained wild-type physiological traits. Crucially, our data indicated that C. reniana utilizes a distinct mycoparasitic mechanism, which differs from the well-established sequential process of adhesion, coiling, and lysis seen in C. rosea. Confocal and scanning electron microscopy (SEM) revealed that C. reniana, following initial coiling and invasive structure formation, penetrates the host hyphae of Botryosphaeria dothidea. It then grows longitudinally within the hyphal lumen, absorbing nutrients and eliminating the pathogen from the inside. Furthermore, C. reniana hyphae can colonize the intercellular spaces of the stem periderm in 84K poplar (Populus alba × P. glandulosa), while displaying a distinct tissue-specific behavior in the roots by forming a mantle on the root surface resembling that of ectomycorrhizae. These findings establish C. reniana as a highly promising secondary model species within the Clonostachys genus. By uncovering a novel "internal-consumption" mycoparasitic mode, this study expands our understanding of the ecological diversity of biocontrol fungi and provides a powerful genetic toolset for future functional genomic research.
Soft rot Pectobacteriaceae (SRP) are destructive pathogens of potato crops, posing a global threat to food security. SRP populations exhibit significant genetic heterogeneity, with the prevalence of potato-infecting species shifting over time. In this study, we identified Pectobacterium aroidearum as a novel agent causing severe tuber soft rot in winter-planted potatoes in Guangdong Province, where it co-occurred with P. brasiliense and P. carotovorum. However, the pathogenic potential of P. aroidearum has been largely uncharacterized. Here, comparative virulence assays demonstrated that P. aroidearum is more aggressive than its counterparts. This heightened virulence was linked to enhanced pathogenic traits, including plant cell wall-degrading enzymes (PCWDEs) production, swimming motility, exopolysaccharide (EPS) production, and air-liquid (AL) biofilm formation. Genomic analysis revealed that while core virulence genes are conserved, a type 1 fimbriae-encoding fim cluster is unique to P. aroidearum. Deletion of fimA, fimC, fimD, and fimH impaired bacterial adhesion, EPS production, AL biofilm formation, and full virulence, functionally characterizing this distinctive factor. Genes within the bacterial cellulose synthesis operon were significantly down-regulated across fim mutants. Accordingly, the mutant colonies showed a marked decrease in calcofluor binding compared with the wild-type strain. Genes with significant up-regulation in the mutants were primarily involved in responses to extracellular stimuli. These findings indicate that the fim cluster underpins the threat posed by this emerging pathogen, which warrants increased attention in disease management. The considerable genetic diversity and frequent gene flow among P. aroidearum isolates from various hosts further highlight its epidemiological risk.
Flavescence dorée (FD) is a devastating quarantine disease associated with FD phytoplasma (FDp), leading to substantial economic losses in European viticulture. Despite extensive research, the high variability in experimental results has hindered a comprehensive understanding of the grapevine's (Vitis vinifera) physiological and molecular responses to infection. This study provides a large-scale synthesis of 20 peer-reviewed research papers, comprising a total of 779 observations, using a three-level random-effects meta-analysis model. This advanced statistical approach accounts for dependencies between effect sizes, quantifying the overall impact of FDp on plant productivity, metabolism, and gene expression. FDp infection significantly impairs grapevine reproductive capacity, evidenced by a 22% reduction in the fertility index. Photosynthetic machinery was severely compromised, showing an 81% decrease in chlorophyll a content and a dramatic downregulation of the Rubisco activase gene (-90%). Whereas core energy metabolism genes remained stable, leaf primary metabolism-related compounds showed significant accumulation of sucrose (+35%) and ascorbate (+42%). A key finding was the strong activation of systemic acquired resistance-related pathways, with salicylic acid levels increased by 451%. This defense response was corroborated at the molecular level by the strong upregulation of stress-related genes, such as osmotin (+829%) and thaumatin (+561%). Our meta-analysis reveals a sophisticated pathogen strategy that selectively suppresses the host's photosynthetic and reproductive vigor while maintaining basic metabolic stability to ensure a chronic interaction. These quantitative insights provide crucial targets for resistance breeding and the development of resilience-improving management strategies in the face of ongoing FDp outbreaks. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
Soybean cyst nematode (SCN, Heterodera glycines) causes major yield losses, and Rhg1 locus-mediated genetic resistance is becoming less effective. Hormonal signaling pathways, particularly salicylic acid (SA) and gibberellic acid (GA), are increasingly implicated in nematode resistance, but their use in plant protection remains underexplored. Here, we tested exogenous application of chemical modulators of these pathways for effects on SCN resistance and dependence on the presence or absence of Rhg1-b. We found that foliar application of the SA mimic acibenzolar-S-methyl (ASM) or the systemic acquired resistance mediator pipecolic acid (Pip) conferred strong, genotype-independent resistance, comparable to genetic resistance at Rhg1. Combining ASM with the GA biosynthesis inhibitor paclobutrazol (PBZ) synergistically enhanced protection, reducing cyst formation by 39.2% and effectively making plants moderately resistant to SCN. These effects were observed in the susceptible cultivar Williams 82, as well as across near-isogenic lines with varying Rhg1 copy numbers. ASM alone boosted resistance in resistant Rhg1-b and susceptible Rhg1-c backgrounds, while PBZ provided additional benefits only in Rhg1-c, revealing genotype-specific interactions between hormonal signaling and host resistance. Targeted modulation of SA and GA pathways thus provides an effective and sustainable strategy to suppress SCN, complementing and extending the durability of genetic resistance.
Cucurbit yellow vine disease (CYVD), caused by the bacterium Serratia ureilytica, is a phloem-associated disease of cucurbits. This study characterized the spatial and temporal distribution of S. ureilytica in Cucurbita pepo cultivar ‘Delicata’ plants under greenhouse conditions using a GFP-tagged isolate (P01). Seedlings were sampled weekly for four weeks. Transverse sections from the stem, petiole, leaf, shoot apex, and root were imaged by laser scanning confocal and fluorescent dissecting microscopy. In parallel, bacterial abundance in each plant tissue was assessed by quantifying colony-forming units (CFU) via droplet plating over a 4-week time course. Across plant tissues and time points, S. ureilytica fluorescent signal was primarily concentrated in the inner and outer periphery of the bicollateral vascular bundles, with higher magnification images revealing mainly symplastic localization within phloem-associated parenchyma cells. Consistent with the imaging results, bacterial quantification data showed a high abundance of CFUs in the main stem, with an irregular pattern of presence in the distal tissues at later time points. These results suggest that S. ureilytica is predominantly localized within phloem-associated parenchyma and spreads both acropetally and basipetally during infection.
The spread of Phytophthora ramorum, the causal agent of Sudden Oak Death and Sudden Larch Death, has resulted in a destructive loss of trees, woody shrubs, and ornamentals in nurseries and forests in the US, Canada, and Europe since the late 1990s. Twelve lineages of P. ramorum are described that vary in global distribution and virulence. Herein, we present a maximum likelihood phylogeny for P. ramorum inferred using IQ-TREE and Tree-Based Alignment Selector Toolkit (T-BAS). The phylogeny was generated based on six loci (avh120, avh121, btub, gweuk.30.30.1, hsp90, and trp1). This phylogeny of P. ramorum improves on previous phylogenies since it is dynamic and interactive and incorporates a diverse set of all known global lineages from the US, Europe (NA1, NA2, EU1, and EU2), and ancestral lineages from the putative native range in East Asia. The phylogenetic relationships inferred in the T-BAS tree support lineages NP1 and NP2 of P. ramorum as ancestral to NA1 and NA2 lineages found in North America. In addition, East Asian IC1, IC2, IC3, and IC4 lineages are ancestral to EU1 and EU2 lineages found in Europe. We used sequence data generated from isolates of P. ramorum collected from Ireland and Northern Ireland and placed them accurately in the tree. The P. ramorum phylogeny is available through T-BAS within the DeCIFR platform. This “interactive phylogeny” can be used by the research community to rapidly update and better reflect the evolutionary relationships of new lineages of P. ramorum.
Southwestern white pine (Pinus strobiformis) is native to the U.S. and Mexico and is susceptible to the pathogen Cronartium ribicola, which causes the disease white pine blister rust. A major gene, Cr3, confers resistance to the disease. While Cr3 has been observed at low frequency in the periphery of the species range, its presence in the core of the range, in Mexico, is unknown, as are the frequency and geographic pattern of this resistance. We conducted one of the first range-wide assessments of resistance to white pine blister rust in a five-needle pine, evaluating 20,533 seedlings from 475 families over ten years of monitoring. Patterns of Mendelian segregation within open pollinated families were used to infer major gene resistance (MGR) genotypes of maternal parent trees and to estimate its geographic frequency. We identified up to 34 of the 475 parent trees as heterozygous for MGR. Four of the heterozygous parents were located within the core of the species range in Mexico. Range-wide, the estimated Cr3 frequency was 3% in zygotes and 2 to 4% in gametes, depending on trial type. The probability of being stem symptom free was frequent in the northern and eastern portions of the range. These findings inform genetic conservation efforts and identify seed sources for further field testing and reforestation and restoration. Because much of the range lies in Mexico and has yet to be impacted by C. ribicola these results provide a unique opportunity for proactive management in the face of a spreading disease.
Plant viruses that cause minimal to no disease symptoms may not support readily detectable virus levels. Such viruses are of concern when they persist in plant germplasm collections or in breeding populations because they can provide inoculum that can be spread and potentially cause outbreaks in susceptible plant species. The mealybug-transmitted cacao mild mosaic virus (CaMMV) causes symptomatic and asymptomatic infection of cacao trees that vary seasonally. The virus accumulates to low levels in leaves and petioles in leaves of at least some cacao genetic groups, which has confounded reliable CaMMV detection. Here, a multiplex recombinase polymerase amplification (RPA) assay was developed to increase the reliability of CaMMV detection. Three RPA primers were designed to amplify two regions of the movement protein gene (mp) of CaMMV, yielding fragments of 362 and 284 base pairs (bp). To increase detection sensitivity and specificity of CaMMV, two guide RNAs (20 bp) targeting both the CaMMV RPA amplicons were designed to activate Cas12a-mediated collateral cleavage of a fluorescent reporter. An RPA detection efficiency of 100% was achieved with respect to six known CaMMV mp variants, while the analytical sensitivity ranged from ~3 to 40 detectable CaMMV genomes. No signal was observed when cloned cacao-infecting badnavirus sequences or virus-free cacao were used as template, indicating that this assay is highly-specific for CaMMV.
Wheat yellow mosaic virus (WYMV) is the main cause of wheat yellow mosaic disease. Although its regulation of protein translation and interactions with host proteins are well studied, independent regulation of the virus genome is poorly understood. This study performed in vitro experiments investigating replication regulation by the 5′ and 3′ untranslated regions of WYMV RNA2. The results confirm that the RNA-dependent RNA polymerase (nuclear inclusion protein b [NIb]) can only recognize and catalyze the synthesis of 3′ 190-nt complementary chains in vitro. RNA structure probing and mutation analysis identified 3597 AUU and 3607 GGCU as novel interaction sites of NIb; both are essential for maintaining normal replication. Our findings provide an empirical basis for in vivo experiments on regulation of WYMV genome replication and provide a theoretical basis for the prevention and control of WYMV-related crop diseases.
Phloem-feeding insects, including the Asian citrus psyllid ( Diaphorina citri), navigate one of the most osmotically challenging diets in nature, the sugar-rich phloem sap. Maintaining osmotic homeostasis is critical for survival, development, and vector competence, particularly in transmitting ‘ Candidatus Liberibacter asiaticus’, the causal agent of citrus greening disease or huanglongbing (HLB). This review synthesizes current knowledge on the physiological, biochemical, and behavioral adaptations that enable D. citri to cope with extreme osmotic pressures. Key strategies include sucrose hydrolysis and conversion into glucose, fructose, and trehalose, as well as redistribution via the hemolymph, and efficient excretion of honeydew, which varies structurally and chemically across different developmental stages and sexes. These adaptations support prolonged phloem feeding, facilitate dual-lifestyle pathogen survival in both phloem and hemolymph, and directly enhance ‘ Ca. L. asiaticus’ acquisition and transmission efficiency. Honeydew as an indicator for feeding behavior, host suitability, and susceptibility to insecticides is also highlighted. Finally, emerging approaches to disrupt osmoregulation, including RNAi-mediated interference with sugar metabolism and water transport, which may provide innovative avenues for integrated management of D. citri and mitigation of HLB spread, are discussed.
A Neopestalotiopsis spp. has recently emerged as an invasive fungal pathogen threatening strawberry (Fragaria × ananassa) production in North Carolina by causing leaf spots, fruit rot, and crown rot, resulting in significant production challenges. Understanding pathogen diversity and virulence variability is vital for developing effective disease management strategies and improving host resistance. Sixty-five Neopestalotiopsis isolates were collected from multiple strawberry cultivars across diverse production regions in North Carolina and characterized using a high-resolution melting quantitative real-time PCR (HRM-qPCR) assay targeting a partial β-tubulin (β-tub) gene sequence. HRM-qPCR analysis differentiated the isolates into two distinct genetic groups, comprising 28 and 37 isolates, respectively, indicating substantial genetic diversity within the pathogen population. To establish reliable disease screening methods, four inoculation techniques were evaluated: foliar spray inoculation with spore suspensions and inoculation with Neopestalotiopsis-infested oatmeal grain, both of which consistently produced disease symptoms and were selected for virulence assessments. To further investigate pathogenic variability, 10 arbitrarily selected isolates were evaluated by spray inoculatingon across 15 strawberry cultivars. Significant effects of isolate, cultivar, and isolate × cultivar interactions were observed, suggesting potential pathogenic specialization among isolates. Although all isolates were pathogenic across the cultivars tested, notable variability in virulence was observed among isolate-cultivar combinations. Among the cultivars evaluated, AC Valley Sunset, Jewel, and Malwina consistently exhibited lower disease susceptibility, suggesting greater tolerance to Neopestalotiopsis. These findings improve understanding of the pathogen diversity and host-pathogen interactions and provide valuable information for cultivar selection, breeding programs, and integrated disease management strategies against this emerging pathogen.
Plants restrict microbial entry into their leaves by closing their stomata upon recognition of conserved microbe-associated molecular patterns (MAMPs). The hydathode pore is a stomata-like opening on leaf margins that is thought to lack MAMP recognition and to be an entry point for microbial pathogens. Here, we observed marginal hydathode pore closure in response to abscisic acid and the MAMPs chitin and flg22 in Arabidopsis thaliana leaves. Hydathode pore closure occurs within 3 to 9 h of chitin exposure, and pores reopen after 12 h. Under conditions in which hydathode pores are open, external fluids enter approximately 80% of the marginal hydathodes within a leaf. After hydathode pores close in response to abscisic acid, chitin, or flg22, external fluids accumulate in under 20% of hydathodes within a leaf. MAMP-induced hydathode restriction was similar for dye or fluorescent Pseudomonas syringae pv. tomato bacteria and was dependent on pattern recognition receptors including CERK1 for chitin and FLS2 for flg22. Chitin-induced hydathode limitation was also dependent on the NADPH oxidase RBOHF and was partially hampered in rbohD, lyk4 lyk5, bak1-5 bkk1, and slac1-3 slah3-1 knockout mutants. Together, this work indicates that MAMP recognition regulates entry into the hydathode and induces transient closure of the hydathode pores.
Bacterial wilt caused by Ralstonia pseudosolanacearum poses a significant threat to turmeric (Curcuma longa L.) production in many growing regions. Although plant-associated microbial communities may contribute to disease suppression, the ecological roles of rhizosphere and endosphere microbiomes in turmeric are still underexplored. Here, we characterized rhizosphere and endosphere bacterial communities using 16S rRNA gene amplicon sequencing and evaluated their antagonistic activity against bacterial wilt pathogen of turmeric R. pseudosolanacearum strain RalsTur1. Microbiome profiling revealed compartment-specific patterns in turmeric-associated bacterial communities, with rhizosphere communities strongly structured by geographic location and endosphere communities comparatively stable across field sites. The endosphere core microbiome was dominated by bacterial members in the family Enterobacteriaceae, particularly Enterobacter, along with Pseudomonas, whereas rhizosphere communities included diverse taxa such as Bacillus and members of the Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium group. Interbacterial competition assays showed that several turmeric-associated isolates reduced RalsTur1 populations in vitro. However, in planta assays using tissue-cultured turmeric plants revealed that only the endosphere-derived bacterial community, including Chryseobacterium gleum (ED4), Pseudomonas laurentiana (ED4-21), and Pantoea sp. (WEH1), significantly reduced pathogen populations, resulting in a two-log reduction in pathogen abundance. These findings suggest that colonization within plant tissues may contribute to suppression of vascular pathogens and highlight endophytic bacteria as candidates for further investigation in microbiome-based management of bacterial wilt.
