Search Results (227)

Cannabis sativa L. is a multipurpose plant widely cultivated for fiber, food, medicinal products, and the production of bioactive compounds, including psychoactive cannabinoids. Fungal endophytes are a promising source of antimicrobial compounds used for biological control and sustainable crop production. However, the fungal endophytes associated with C. sativa have been poorly investigated, and their biological activities are still largely unexplored. Thus, this study aimed to identify fungal endophytes from C. sativa (marijuana and hemp biotypes) and to screen for their antagonistic activities against some plant pathogens. Based on ITS sequence analysis, a total of 103 fungal endophyte isolates (21 genera) were preliminarily identified from both biotypes, including 62 isolates (13 genera) from hemp and 41 isolates (nine genera) from marijuana. Fusarium was the dominant genus found in hemp (45%), while Nigrospora was the dominant genus isolated from marijuana (32%). Ten selected fungal endophytes were evaluated for in vitro antagonistic activity against four bacterial pathogens, Pectobacterium spp. (PC 01 and PC 02) and Ralstonia solanacearum (RA 01 and RA 02), and four fungal pathogens, Fusarium solani (FU 01), F. oxysporum (FU 02), and Sclerotium sp. (SC 01 and SC 02), all of which are causal agents of potato diseases. Among the tested fungal endophytes, Colletotrichum sp. (SLLC-M24) and Nigrospora sp. (SLLC-H15) exhibited the strongest antifungal activity against Fusarium spp. (FU 01 and FU 02), with inhibition rates ranging from 56 to 64%. In addition, Pestalotiopsis sp. (SLLC-H5) demonstrated effective antibacterial activity against all tested bacterial pathogens, producing inhibition zones ranging from 19 to 23 mm. This finding represents an important step toward discovering novel and promising endophytes associated with Cannabis and their biological control potential for utilization in sustainable agriculture. Full article

Continuous cropping obstacles (CCOs) seriously constrain tomato yield and quality in facility agriculture, primarily due to rhizosphere microbial imbalance. Indigenous synthetic microbial communities (SynCom) offer superior colonization and stability compared to single strains. This study aimed at constructing a simplified SynCom from indigenous rhizobacteria in Northwest China to alleviate tomato CCOs. A total of 155 rhizobacterial strains (29 genera) were isolated. Sixteen strains with significant growth-promoting effects were selected through seedling assays. Based on the carbon source niche overlap index (NOI > 70%) with Ralstonia solanacearum QL-Rs1115, eight candidate strains were retained. Using the broken-stick model, 29 simplified SynComs were constructed. SynCom28, composed of six functionally complementary strains (Azospirillum brasilense, Massilia niabensis, Enterobacter hormaechei, Chryseobacterium sp., Priestia megaterium and Pseudomonas brassicacearum), showed the best performance. Pot experiments revealed that SynCom28 reduced the bacterial wilt disease index to 32.41, with a biocontrol efficacy of 41.72%. Greenhouse trials under continuous cropping demonstrated that SynCom28 significantly increased seedling Dickson quality index (DQI), stem diameter and biomass. Fruit yield increased by 12.98–15.30% across the 2nd to 4th cropping cycles (p < 0.05). Fruit quality parameters were also enhanced, with soluble sugar, lycopene, and vitamin C contents increasing by 47.22–65.07%, 33.07–81.71% and 80.56–166.67%, respectively. In conclusion, the indigenous simplified SynCom28 effectively alleviates tomato CCOs, enhancing growth, yield, and quality while suppressing bacterial wilt, providing a promising strategy for sustainable facility agriculture. Full article

Potato (Solanum tuberosum L.) is an important staple and food security crop to many communities in the world. However, potato production and quality is greatly constrained by bacterial wilt, a disease caused by a soil-borne pathogen, Ralstonia solanacearum. Ralstonia solanacearum can be managed through clean seed systems and therefore laboratory testing is a pre-requisite for seed certification to confirm the absence of the pathogen in potato seeds before planting. Molecular diagnostics is the gold standard for detection of R. solanacearum in potato seeds. However, the extraction of genomic DNA from R. solanacearum for molecular diagnostics is complex, tedious, lengthy and/or costly procedure. A simple, rapid and reliable DNA extraction protocol is required for use in routine molecular diagnosis of R. solanacearum, a high-risk quarantine pathogen. In this study, we developed a simple and rapid protocol for extracting genomic DNA from symptomatic and asymptomatic potato tubers infected with R. solanacearum and verified its efficiency for the detection and molecular characterization of the pathogen. The protocol was developed from the evaluation of distilled water, Tris-EDTA (TE) and Tris buffer as a base solution for tissue maceration. The DNA quantity and integrity was determined using the NanoDrop 2000C spectrophotometer and agarose gel electrophoresis, respectively. Both hot and cold solutions produced intact high molecular weight genomic DNA of sufficient yield and purity for molecular-based applications. The detection and determination of phylotypes of R. solanacearum, based on conventional and multiplex polymerase chain reaction (PCR), amplified the expected 280 and 372 bp amplicons, respectively, confirming that the quantity and quality of the extracted pathogen genomic DNA was sufficient for molecular diagnostic applications. The sequencing of the amplified products of the endoglucanase gene produced good quality sequences, which confirmed the R. solanacearum isolates to be members of phylotype II sequevar 1. This protocol is a simple, fast and reliable tool for the extraction of sufficient genomic DNA with high quality, directly from R. solancearum-infected potato tubers for PCR and sequencing applications. Its simplicity and throughput make it valuable for use in routine diagnostics and can be adopted by certification programs to ensure distribution of clean potato seeds to farmers. Full article

Potato (Solanum tuberosum) is a vital global non-cereal food crop severely threatened by bacterial wilt, caused by Ralstonia solanacearum(R. solanacearum). Conventional diagnostics like PCR and ELISA, though effective, are destructive and time-consuming, limiting large-scale field applications. This study investigates hyperspectral imaging (HSI) as a non-invasive, rapid, and accurate alternative for early detection and severity grading of potato bacterial wilt. Using a portable HSI system (400–1000 nm), spectral data were collected from inoculated potato plants (‘Longshu No. 7’) at 0, 24, 48, and 72 h post-inoculation, alongside disease severity assessment (grades 0–4). After comprehensive spectral preprocessing and feature band extraction via Competitivse Adaptive Reweighted Sampling (CARS), we developed two distinct sets of models: one for early detection (temporal classification) using Partial Least Squares-Discriminant Analysis (PLS-DA) and Principal Component Analysis-Linear Discriminant Analysis (PCA-LDA), and another for severity grading. The SNV + SG + MC + PLS-DA model achieved exceptional accuracy, exceeding 97% for early detection, while the MSC + SG + MC + CARS + PLS-DA model yielded >97% accuracy for severity grading. These results were supported by low misclassification rates in confusion matrices. This work establishes a robust HSI-based framework for high-throughput screening of resistant potato germplasm and advances precision agriculture strategies for bacterial wilt management. Full article

Moko disease (Ralstonia solanacearum race 2) is one of the most destructive bacterial diseases affecting bananas and plantains worldwide. The pathogen infects banana plants, causing yellowing and wilting of younger leaves, and plant death. Disease management remains challenging due to the pathogen’s aggressiveness, rapid dissemination, and limited availability of effective control products. The aim of this study was to determine the chemical composition of the Pimenta dioica essential oil (PDEO) obtained by hydro-distillation and to evaluate its antibacterial activity against R. solanacearum race 2. Gas chromatography-mass spectrometry (GC-MS) analysis identified 19 compounds in the essential oil. Eugenol (72.6%), was the predominant component, followed by caryophyllene (6.13%) and Beta-Myrcene (4.17%). In vitro assays demonstrated complete inhibition of bacterial growth at 500 µL L⁻¹. Probit analysis estimated the minimum inhibitory concentration 95% (MIC₉₅) value 297.6 µL L⁻¹. In plants evaluation using banana vitroplants showed that PDEO at 500 µL L⁻¹ effectively reduced disease severity and prevented internal corm discoloration without causing phytotoxic effects. These findings demonstrate the strong antibacterial activity of P. dioica essential oil against R. solanacearum race 2 and highlight its potential as a natural alternative for the management of Moko disease in banana production systems. Full article

Bacterial wilt (BW), caused by soil-borne bacteria of the Ralstonia solanacearum species complex (RSSC), is a serious disease affecting eggplant (Solanum melongena) in tropical and subtropical regions. Resistance to BW in eggplant has been identified in several accessions and wild relatives, but no source has shown broad and stable resistance across diverse strains and environmental conditions. In the first screening trial, six eggplant genotypes, including five previously identified as resistant to RSSC, were evaluated along with two tomato checks against eight BW strains representing two phylotypes (I and II) and three biovars (2, 3, and 4). In the second screening trial, 26 hybrids developed from seven parental eggplant genotypes (including the six evaluated genotypes in the first screening plus an additional one) were evaluated, together with the parents, against three BW strains (Pss97, Pss2016, and Pss4). The results showed that the parental line EG048 was highly susceptible, whereas EG44 was resistant to the three strains, with a disease index (DI) of ≤20%. Furthermore, fourteen hybrids were classified as resistant or moderately resistant to the three strains. Among them, hybrid EG27 was categorized as highly resistant to all three strains with a disease index of 5.6–7.3%. In addition, three hybrids (EG8, EG20, and EG29) were highly resistant or resistant to all three strains, with a disease index of 3.8–15.8%. A strong positive correlation was observed between wilting percentage and disease index in the eggplant hybrids across the tested strains. Our results provide valuable support for eggplant breeding programs aimed at developing hybrid rootstocks with broader and potentially broad-spectrum resistance to RSSC in tomato and eggplant. Full article

RipP1 is a well-characterized avirulence effector that induces a hypersensitive response (HR) in three tobacco species. However, the molecular mechanisms by which host proteins recognize RipP1 to activate a defense response and modulate host–pathogen interactions remain largely unknown. In this study, we screened a Nicotiana benthamiana cDNA library via yeast two-hybrid assay and identified FRIGIDA-like protein 4a (FRL4a) as a host protein interacting with RipP1. Secondary structure analysis of FRL4a and construction of serial mutants revealed that the ClyA-like domain of FRL4a is the key region mediating its interaction with RipP1. Using virus-induced gene silencing (VIGS) and quantitative real-time PCR (qPCR) analysis, we found that the ability of RipP1 to induce HR was significantly attenuated in FRL4a-silenced plants, and RipP1 no longer suppressed the ethylene signaling pathway. Pathogenicity tests by inoculating R. solanacearum on N. benthamiana with different FRL4a expression levels showed enhanced bacterial wilt resistance in FRL4a-silenced plants but increased susceptibility in FRL4a-overexpressing plants. Collectively, these findings demonstrate that RipP1 suppresses the ethylene pathway through its interaction with FRL4a, and FRL4a acts as a negative regulator of tobacco resistance to bacterial wilt. Full article

Bacterial wilt caused by Ralstonia solanacearum is a major constraint on tomato (Solanum lycopersicum L.) production, yet the molecular basis of quantitative resistance remains poorly understood. In this study, comparative transcriptome profiling was performed on resistant (‘ZM3’) and susceptible (‘ZM86’) tomato inbred lines following pathogen inoculation in roots, stems, and leaves. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were conducted to identify resistance-associated regulatory modules and hub genes. The results revealed distinct gene expression patterns between the two genotypes after infection. Several co-expression modules were significantly associated with resistance or susceptibility traits. Functional enrichment analysis showed that differentially expressed genes were mainly involved in plant hormone signal transduction, plant–pathogen interaction, phenylpropanoid biosynthesis, and cell wall modification. Genes related to ethylene and salicylic acid signaling were strongly induced following infection, whereas brassinosteroid-associated genes showed genotype-dependent expression patterns. Network analysis further identified several hub genes within defense-related modules, including ACO (Solyc04g007980), ERF1 (Solyc09g091950), MAPK9, receptor-like kinase RLK (Solyc07g006770), and a dirigent family gene (Solyc10g008900). Taken together, our results suggest that tomato resistance to Ralstonia solanacearum involves a coordinated defense network integrating hormone-mediated transcriptional regulation and structural reinforcement, and provides candidate genes for breeding bacterial wilt-resistant cultivars. Full article

The Ralstonia solanacearum species complex (RSSC) is a globally significant plant pathogenic bacterium. Given the lack of effective chemical controls, phage therapy has emerged as a promising biocontrol alternative. While combining phages with antibiotics can counteract phage resistance, RSSC may still evolve concurrent resistance to both agents. However, the fitness consequences and underlying mechanisms of such resistance remain unclear. In this study, a novel RSSC phage was isolated to experimentally investigate the trade-offs between resistance and virulence in evolved strains. Compared to the wild-type, phage-resistant, antibiotic-resistant, and dual-resistant mutants showed no significant differences in growth rate, exopolysaccharide and lipopolysaccharide production. However, their motility, soil survival, and biofilm formation were significantly impaired, with the most severe decline observed in the dual-resistant mutants. Furthermore, phage-resistant strains exhibited enhanced antibiotic resistance, while antibiotic-resistant strains displayed cross-resistance. The antibiotic resistance gene bla_OXA-249 was upregulated only in antibiotic-resistant strains. In phage-resistant bacteria, the abortive infection system was activated. A reduction in bacterial cell numbers post-infection indicated that phage resistance limits phage propagation via a “suicidal” mechanism. These findings reveal that resistance evolution in RSSC carries substantial fitness costs and highlight phage steering as a novel strategy for designing phage agents. Full article

Soil-borne pathogens significantly threaten crop production and global food security, while high-performance antipathogenic materials are scarce. In this study, green and efficient Ag/AgCl nanoparticles (Ag/AgCl-NPs) were developed using an aqueous extract of ginger-straw waste as the raw material. The synthesized Ag/AgCl-NPs exhibited a spherical morphology with an average size of approximately 40 nm, good crystal structure, and abundant surface groups. Additionally, they exhibited excellent antimicrobial activity against representative soil-borne pathogens, including Ralstonia solanacearum (MIC = 20 μg/mL; MBC = 40 μg/mL) and Fusarium oxysporum (spore MIC = 20 μg/mL; mycelial EC₅₀ = 64.596 μg/mL). The antimicrobial mechanism was attributed to cell membrane disruption and oxidative stress induction. This study provides an excellent antimicrobial agent for controlling crop soil-borne pathogens. Full article

It has previously been found that CaWRKY40 is employed by pepper to activate immunity against Ralstonia solanacearum and to activate thermotolerance context-specifically, but the underlying mechanisms are not fully understood. Here, CaGβ, a subunit in the heterotrimeric G protein complex that was originally found to probably interact with CaWRKY40, was expressional and functionally characterized; the results showed that CaGβ was upregulated by R. solanacearum infection; its silencing by virus-induced silencing impaired pepper immunity against R. solanacearum infection, accompanied by downregulation of immunity-related marker genes, including CaPR1, CaDEF1, CaNPR1, and CaPR-STH2. In addition, CaGβ–CaWRKY40 interaction was confirmed by BiFC and pull-down assay using prokaryotically expressed proteins, and activations of immunity-related CaPR1, CaPR-STH2, and CaNPR1 by CaWRKY40 were all promoted, but the activation of thermotolerance-related CaHSP24 by CaWRKY40 blocked CaGβ through its interaction with CaWRKY40. All these data indicate that immunity against R. solanacearum and its antagonism to thermotolerance in pathogen-infected pepper plants are mediated by CaWRKY40 through physical interaction with CaGβ. Full article

Microparticles (MPs) are delivery systems for bioactive compounds with particle sizes in the micrometer range (1–1000 μm). This study reports a green protocol for the biosynthesis of ZnO-, MgO-, and CaO-MPs using the probiotic strains Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and Leuconostoc mesenteroides. Ultraviolet–visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and dynamic light scattering (DLS) were used for the preliminary characterization of the metal oxide MPs. Antimicrobial activity was evaluated against pathogenic and phytopathogenic microorganisms, including Salmonella typhimurium, Staphylococcus aureus, Escherichia coli, and Ralstonia solanacearum. UV-Vis analysis revealed previously reported blue shifts in the ZnO- and CaO-MPs. DLS measurements showed particle sizes larger than 1000 nm in 95% of the cases, while smaller sizes were observed by SEM. The stability of the MPs, based on their zeta potential values, ranged from relatively to moderately stable. This study demonstrates that the six probiotic lactic acid bacteria strains are capable of synthesizing ZnO-MPs, CaO-MPs, and MgO-MPs. All MPs exhibited antimicrobial activity against pathogens and phytopathogens at different concentrations. Although similar antimicrobial effects have been reported for metal oxide nanoparticles produced by probiotic bacteria, considering the potential environmental and human health impacts of nanoparticles, the use of safer materials obtained through green synthesis—such as metal oxide MPs—may represent a more suitable alternative. Full article

Pepper (Capsicum annuum), a widely cultivated vegetable of significant economic importance globally, is frequently subjected to attacks from pathogens such as Ralstonia solanacearum, as well as high-temperature stress. However, the mechanisms by which pepper combats these stresses remain poorly understood. Herein, we reported that the expression of the leucine-rich repeat protein CaLRR13, which lacks a nucleotide-binding site (NBS), kinase domains, and a transmembrane region, was transcriptionally activated by both R. solanacearum inoculation and high-temperature stress. Through transient overexpression in the epidermal cells of Nicotiana benthamiana leaves, we found that CaLRR13 localized in both the cytoplasm and the nuclei. Reducing the expression of CaLRR13 via virus-induced gene silencing (VIGS) increased the sensitivity of pepper to R. solanacearum infection and high-temperature exposure, accompanied by reduced expression of immunity- and thermotolerance-related genes, including CaWRKY40, CaPR1, CaNPR1, CaDEF1, and CaHSP24. In contrast, transient overexpression of CaLRR13 in pepper leaves induced a like-hypersensitive response (HR) and enhanced the expression of the aforementioned immunity- and thermotolerance-related genes. Thus, we conclude that CaLRR13 plays a positive role in pepper immunity against R. solanacearum and thermotolerance, providing a new perspective on the crosstalk and management of plant responses to these two stresses. Full article

Sesame bacterial wilt, caused by the pathogen Ralstonia solanacearum, is a major constraint for continuous cropping. Deciphering the defense mechanisms of sesame is therefore essential to the development of novel and effective control strategies. The Non-expressor of Pathogenesis-Related 1 (NPR1) plays a key role in regulating salicylic acid (SA)-mediated systemic acquired resistance (SAR). In this study, we reported that leaf treatments with 50 μg/mL benzothiadiazole (BTH) resulted in increased protection of sesame against Ralstonia solanacearum. We clarified the structure, expression patterns, and function of a NPR1 homologous gene, SiNPR1, in sesame. The SiNPR1 gene open reading frame comprises 1758 bp, and it encodes 585 amino acids. Phylogenetic analysis revealed that SiNPR1 is closely related to NPR1-like in Olea europaea and clustered with other members of the families Monocotyledon and Dicotyledon. Quantitative real-time PCR (qRT-PCR) results demonstrated that the expression of the SiNPR1 gene was organ-specific and could be induced by BTH. The yeast two-hybrid assay confirmed that SiNPR1 directly interacts with SiTGA2. In conclusion, these results suggest that SiNPR1 plays a pivotal role in the BTH-dependent systemic acquired resistance in sesame. Full article

Lysobacter enzymogenes is well known for producing extracellular enzymes and bioactive molecules that suppress a wide range of plant pathogens, including fungi such as Rhizoctonia and Fusarium spp. and oomycetes such as Phytophthora infestans. It also exhibits antagonistic effects against Gram-negative bacteria through the type IV secretion system. Interestingly, L. enzymogenes JCK1421, isolated from the rhizosphere of pine forests, showed neither antifungal nor antibacterial activity, in contrast to other L. enzymogenes strains. However, foliar application of JCK1421 significantly reduced disease symptoms in tomato seedlings challenged with Ralstonia solanacearum. To elucidate the underlying defense mechanisms, comparative transcriptome analysis integrated with network and pathway enrichment approaches was performed. Comparative transcriptome and network analyses identified signaling modules activated by JCK1421 in pathogen-free plants and further enhanced upon R. solanacearum challenge. In challenged plants, JCK1421 treatment strongly induced resistance-related genes, including those encoding Ca²⁺-dependent proteins and ion channels, hormone biosynthesis components, and mitogen-activated protein kinase cascades—hallmarks of plant immune responses. These findings demonstrate that JCK1421 provides an effective model for investigating microbe-associated defense activation in plants, highlighting its potential as an eco-friendly agent for sustainable crop protection. Full article