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Bacterial wilt (BW), caused by Ralstonia solanacearum, is one of the devastating diseases in tomatoes (Solanum lycopersicum L.). The use of resistant cultivars and breeding for genetic resistance is the most effective, economical, and environmentally friendly management strategy for this disease. It is necessary to screen diverse germplasm and cultivated genotypes to identify resistant resources and to develop resistant cultivars in tomatoes to combat the changing pathogen isolates. This study evaluated 40 United States Department of Agriculture (USDA) tomato accessions for their BW resistance to the R. solanacearum isolate P822 under greenhouse conditions. The tomato plants were inoculated and visually assessed to observe their symptoms, and the disease severity was scored on a scale of 0 to 4 (0 = no leaf wilted, 1 = 25% of leaves wilted, 2 = 50% leaves wilted, 3 = 75% of leaves wilted, and 4 = 100% leaves wilted). Five accessions (PI 645370, PI 647306, PI 600993, PI 355110, and PI 270210) were observed as BW resistance, with PI 645370 showing the greatest resistance. The broad-sense heritability for BW resistance was estimated as 59.9% and 42.8% based on a 0–4 scale of disease incidence and the disease severity index, respectively. Two distinct clusters (sub-populations) were detected among 39 of the 40 accessions. The five identified BW-resistant accessions were distributed in both clusters, suggesting a likely difference in the genetic base among the five resistance accessions. The resistant accessions will contribute significantly to the tomato breeding program to develop new cultivars with BW resistance. [ABSTRACT FROM AUTHOR]

Bacterial wilt, caused by the Ralstonia solanacearum species complex, is one of the most damaging bacterial diseases in tobacco and other Solanaceae crops. In this study, we conducted an analysis and comparison of transcriptome landscape changes in seedling roots of three tobacco BC4F5 lines, C244, C010, and C035, with different resistance to bacterial wilt at 3, 9, 24, and 48 h after R. solanacearum infection. A number of biological processes were highlighted for their differential enrichment between C244, C010, and C035, especially those associated with cell wall development, protein quality control, and stress response. Hence, we performed a genome-wide identification of seven cell wall development-related gene families and six heat shock protein (Hsp) families and proposed that genes induced by R. solanacearum and showing distinct expression patterns in C244, C010, and C035 could serve as a potential gene resource for enhancing bacterial wilt resistance. Additionally, a comparative transcriptome analysis of R. solanacearum-inoculated root samples from C244 and C035, as well as C010 and C035, resulted in the identification of a further 33 candidate genes, of which Nitab4.5_0007488g0040, a member of the pathogenesis-related protein 1 (PR-1) family, was found to positively regulate bacterial wilt resistance, supported by real-time quantitative PCR (qRT-PCR) and virus-induced gene silencing (VIGS) assays. Our results contribute to a better understanding of molecular mechanisms underlying bacterial wilt resistance and provide novel alternative genes for resistance improvement. [ABSTRACT FROM AUTHOR]

Aim: We aim to find a simple agricultural waste processing method to improve soil water retention and soil enzymes vitality, control soil-borne pathogens, and enhance plant resistance against biotic stress. Methods: We extracted polysaccharides from different agricultural wastes. We tested the antimicrobial activity of the extracted polysaccharides on different soil-borne pathogens and the effect of the addition of these polysaccharides on the soil water status and soil enzymes. Besides this, we investigated the efficiency of the peanut shells polysaccharides in improving tomato growth and defense under Fusarium solani and Ralstonia solanacearum infection in a greenhouse study. Results: Results showed the efficiency of all extracted polysaccharides as antimicrobial agents against different soil-borne pathogens. In addition, all polysaccharides increased the soil water holding capacity by about 116% more than that in the non-treated soil and increased the water retention to reach about 30% after eight days, besides their positive role in improving the soil enzymes, which improves the soil health. The peanut shells polysaccharides, which are the best ones as antimicrobials and soil amendments, showed interesting improvements in tomato growth under normal and pathogen infection conditions. The polysaccharide treatment decreased the bacterial and fusarium wilt in tomato plants, and induced resistance mechanism through up-regulating secondary metabolism defense compounds defense enzymes such as phenylalanine ammonia-lyase, and antioxidant enzymes detoxify the oxidative stress markers. Conclusion: Polysaccharides from agricultural wastes can be a promising soil amendment to improve the soil properties and so improve plant growth and defense mechanism against pathogen infection. [ABSTRACT FROM AUTHOR]

A major constraint to tomato cultivation is bacterial wilt disease. The use of greenhouses to cultivate tomato is vital to controlling the bacterial wilt disease. Bacterial wilt can be successfully managed when farmers are well-informed with better knowledge of bacterial wilt in tomatoes. This study was conducted to assess farmers’ knowledge and experiences on the cultivation practices, prevalence, detection, spread, and control of bacterial wilt disease in tomato in greenhouses in the Volta, Eastern, Central, and Greater Accra regions of Ghana. Questionnaires were administered for fifty (50) greenhouse farmers, purposefully selected using a database of greenhouse tomato producers in southern Ghana provided by the Ministry of Food and Agriculture (MOFA). Frequency data was analyzed using descriptive statistical analysis. The majority (86%) of respondents had formal education. Most of the greenhouses in operation were in the Greater Accra Region, and none was under cultivation in the Volta region at the time of the study. Most respondents have been involved in greenhouse tomato cultivation for barely three years. The frequency of greenhouse tomatoes production varied from one region to the other. Only 28% of greenhouse farmers knew the test to detect the disease with 64% of greenhouse farmers without any knowledge about how the disease spreads. 62% of respondents used roughing and burying of the infected plants to control the disease. Out of the 54 greenhouses (domes) surveyed, 12 were infected with the bacterial wilt disease. Greenhouse farmers had little knowledge on the spread, detection, and control of the bacterial wilt disease of tomato. The findings of this study would lead to the design of targeted training programs on cultivation practices, detection, spread and management of bacterial wilt of tomato to increase yield and boost income levels of greenhouse tomato farmers in Ghana. [ABSTRACT FROM AUTHOR]

The bacterial wilt disease in tomato caused by Ralstonia solanacearum results in harvest losses of up to 90% and significant economic loss to farmers. In this study, 11 R. solanacearum strains were isolated in the largest tomato-growing province in Vietnam. These strains belonged to 3 different groups, and 9/11 strains showed different disease rates in experimental tomato plants. A BHDTSo81 phage specific to R. solanacearum was isolated from a soil sample. Morphological analysis indicated that BHDTSo81 had podovirus morphology and was classified into the Autographiviridae family. The latent period and burst size of BHDTSo81 were calculated to be approximately 145 min and 8.6 ±1.8 virions per infected cell, respectively. In a test of 26 bacterial strains, BHDTSo81 infected 7/11 R. solanacearum strains, while none of the other bacteria tested were susceptible to the phages. R. solanacearum was also challenged in vitro and was inactivated by BHDTSo81 for 40 h in broth. The genome of BHDTSo81 is 41,296 bp long with a total GC content of 63% and contains 46 predicted protein-encoding CDSs (coding sequences). No virulence factor or antibiotic resistance gene was found in the genome. Thus, the initial characteristics of phage BHDTSo81 indicate its potential utility as a control agent against R. solanacearum. [ABSTRACT FROM AUTHOR]

Copyright of Tobacco Science & Technology is the property of Tobacco Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pentatricopeptide repeat (PPR) proteins, with tandem 30–40 amino acids, were characterized as one kind of nucleus coding protein. They have been demonstrated to play important roles in RNA editing, plant growth and development, and plant immunity. Although the PPR gene family has been characterized in some plant species, less is known about this family in peanut, especially their functions in response to Ralstonia solanacearum. In this study, we performed a genome-wide analysis to identify PPR genes and their functions in resistance to R. solanacearum. Here, 389, 481, and 1079 PPR genes were identified from Arachis duranensis, Arachis ipaensis, and Arachis hypogaea, respectively. Allopolyploidization was the main reason for the increased number of the AhPPR members. Gene duplication brought about 367 pairs of homologous genes of PPRs in A. hypogaea. Whole-genome replication, tandem repeats, scattered repeats, and unconnected repeats constituted the replication types. The substitution rates of nonsynonymous (Ka) versus synonymous (Ks) of all homologous pairs were less than 1.0, suggesting that the homologous AhPPRs underwent intense purifying selection pressure and remained conserved in both structure and function. RNA-seq and RT-qPCR analyses showed that AhPPR598 gene was highly expressed in the aerial part of peanut and involved in response to R. solanacearum. The transient expression of AhPPR598 in Nicotiana benthamiana induced the HR-mediated cell death, up-regulated expression of resistant marker genes, and enhanced the resistance to R. solanacearum, suggesting AhPPR598 was a positive regulator of immunity by regulating the JA and SA pathways. These results provide a new understanding of the origin, distribution, and evolution of the AhPPR gene family and potential gene resources for peanut-resistant breeding. [ABSTRACT FROM AUTHOR]

Potato is an important crop, used not only for food production but also for various industrial applications. With the introduction of the potato as a staple food strategy, the potato industry in China has grown rapidly. However, issues related to bacterial wilt, exacerbated by factors such as seed potato transportation and continuous cropping, have become increasingly severe in the primary potato cultivation regions of China, leading to significant economic losses. The extensive genetic diversity of Ralstonia solanacearum (R. solanacearum), which is the pathogen of bacterial wilt, has led to a lack of highly resistant potato genetic resources. There is a need to identify and cultivate potato varieties with enhanced resistance to reduce the adverse impact of this disease on the industry. We screened 55 accessions of nine different wild potato species against the bacterial wilt pathogen R. solanacearum PO2-1, which was isolated from native potato plants and belongs to phylotype II. Three accessions of two species (ACL24-2, PNT880-3, and PNT204-23) were identified with high resistance phenotypes to the tested strains. We found these accessions also showed high resistance to different phylotype strains. Among them, only PNT880-3 was capable of flowering and possessed viable pollen, and it was diploid. Consistent with the high resistance, decreased growth of R. solanacearum was detected in PNT880-3. All these findings in our study reveal that the wild potato PNT880-3 was a valuable resistance source to bacterial wilt with breeding potential. [ABSTRACT FROM AUTHOR]

Plant‐pathogenic Ralstonia strains cause bacterial wilt disease by colonizing xylem vessels of many crops, including tomato. Host resistance is the best control for bacterial wilt, but resistance mechanisms of the widely used Hawaii 7996 tomato breeding line (H7996) are unknown. Using growth in ex vivo xylem sap as a proxy for host xylem, we found that Ralstonia strain GMI1000 grows in sap from both healthy plants and Ralstonia‐infected susceptible plants. However, sap from Ralstonia‐infected H7996 plants inhibited Ralstonia growth, suggesting that in response to Ralstonia infection, resistant plants increase inhibitors in their xylem sap. Consistent with this, reciprocal grafting and defence gene expression experiments indicated that H7996 wilt resistance acts in both above‐ and belowground plant parts. Concerningly, H7996 resistance is broken by Ralstonia strain UW551 of the pandemic lineage that threatens highland tropical agriculture. Unlike other Ralstonia, UW551 grew well in sap from Ralstonia‐infected H7996 plants. Moreover, other Ralstonia strains could grow in sap from H7996 plants previously infected by UW551. Thus, UW551 overcomes H7996 resistance in part by detoxifying inhibitors in xylem sap. Testing a panel of xylem sap compounds identified by metabolomics revealed that no single chemical differentially inhibits Ralstonia strains that cannot infect H7996. However, sap from Ralstonia‐infected H7996 contained more phenolic compounds, which are known to be involved in plant antimicrobial defence. Culturing UW551 in this sap reduced total phenolic levels, indicating that the resistance‐breaking Ralstonia strain degrades these chemical defences. Together, these results suggest that H7996 tomato wilt resistance depends in part on inducible phenolic compounds in xylem sap. [ABSTRACT FROM AUTHOR]

Bacterial wilt, caused by Ralstonia solanacearum, one of the most destructive phytopathogens, leads to significant annual crop yield losses. Type III effectors (T3Es) mainly contribute to the virulence of R. solanacearum, usually by targeting immune-related proteins. Here, we clarified the effect of a novel E3 ubiquitin ligase (NEL) T3E, RipAW, from R. solanacearum on pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and further explored its action mechanism. In the susceptible host Arabidopsis thaliana, we monitored the expression of PTI marker genes, flg22-induced ROS burst, and callose deposition in RipAW- and RipAWC177A-transgenic plants. Our results demonstrated that RipAW suppressed host PTI in an NEL-dependent manner. By Split-Luciferase Complementation, Bimolecular Fluorescent Complimentary, and Co-Immunoprecipitation assays, we further showed that RipAW associated with three crucial components of the immune receptor complex, namely FLS2, XLG2, and BIK1. Furthermore, RipAW elevated the ubiquitination levels of FLS2, XLG2, and BIK1, accelerating their degradation via the 26S proteasome pathway. Additionally, co-expression of FLS2, XLG2, or BIK1 with RipAW partially but significantly restored the RipAW-suppressed ROS burst, confirming the involvement of the immune receptor complex in RipAW-regulated PTI. Overall, our results indicate that RipAW impairs host PTI by disrupting the immune receptor complex. Our findings provide new insights into the virulence mechanism of R. solanacearum. [ABSTRACT FROM AUTHOR]

Potato bacterial wilt (BW) caused by Ralstonia solanacearum, is one of the major constraints to potato production in Cameroon. In order to reduce yield losses due to BW, this study aimed at investigating the effect of limestone on bacterial wilt disease, and on the R. solanacearum's population in the soil. Potato tubers were grown in pots in a screen house of the University of Dschang, from February to May 2021. The experimental design was a split plot design made up of three replicates of two potato genotypes (Dosa and Jacob 2005), 05 limestone rates (14.7 g, 29 g, 44,1 g, 58.8 g and 73.5 g per plant) and 2 controls (no liming without inoculation and no liming with pathogen inoculation). Plants were inoculated with 25 ml of bacterial suspension, containing 108 CFU/ml. The bacterial population in the soil was assessed by counting colonies under microscope. Data were collected on BW incidence, bacterial population in the soil, soil pH, yield components and latent infection. The results showed that low BW incidence was associated with high rate of limestone in both genotypes. Limestone rate increased soil pH while reducing the pathogen population in the soil. The higher tuber weight/plant was obtained with limestone rate ≥58.8 g/plant. Liming enabled to avoid latent infection during storage. Thus, soil amendment with limestone at 58.8 g/plant can reduce R. solanacearum population in the soil and lower the impact of bacterial in the field as well as in the store in Dschang locality. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Botany is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bacterial wilt, caused by the soil-borne pathogen Ralstonia solanacearum, poses a significant threat to tomato crops worldwide. This study aims to assess the microbial potential of rhizobacterial isolates obtained from spent mushroom compost in suppressing bacterial wilt of tomatoes. Spent mushroom compost is a byproduct of mushroom cultivation and is known to harbor diverse microbial communities with potential plantbeneficial properties. Tomato leaves that were contaminated were collected from a number of places in the Rawalpindi Area, Punjab, Pakistan. Rhizobacterial isolates were collected from the rhizosphere of tomato plants grown in the presence of spent mushroom compost. These isolates were then subjected to laboratory evaluations for their antagonistic activity against R. solanacearum. Selected rhizobacterial isolates were further characterized for their plant growth-promoting traits. The potential of these isolates to enhance tomato plant growth and confer resistance against bacterial wilt was evaluated through greenhouse experiments. Results indicated that certain rhizobacterial isolates exhibited substantial antagonistic activity against R. solanacearum. Additionally, these isolates demonstrated multiple plant growth-promoting traits, suggesting a potential dual role in both pathogen suppression and plant enhancement. Greenhouse experiments revealed a significant reduction in the incidence of bacterial wilt in tomato plants and increase in the growth promotion traits were observed while treated with the selected rhizobacterial isolates alone and in combination compared to control groups. The findings from this study highlight the promising role of rhizobacterial isolates associated with spent mushroom compost in managing bacterial wilt in tomatoes. [ABSTRACT FROM AUTHOR]

ABSTRACT Metal oxide nanoparticles (NPs) possess antibacterial activities and can be used for the control of phytopathogenic bacteria. The objective of this work was to evaluate the antibacterial activity of pure and doped NPs against Dickeya zeae, Pantoea ananatis, and Xanthomonas vasicola pv. vasculorum in vitro, and to assess the efficacy of preventive and curative application of zinc oxide (ZnO), nickel oxide (NiO), and silver-doped zinc oxide (ZnO:Ag) NPs for the control of white spot (WS) and bacterial leaf streak (BLS) in vivo. Bacterial growth inhibition was first evaluated by measuring the diameter of the inhibition zone formed in Petri dishes. Subsequently, the severity of WS and BLS diseases was evaluated in a greenhouse calculating the area under the disease progress curve. The in vitro antibacterial activity was not influenced by the increase in the concentration of doping elements for most NPs. ZnO NPs doped with Ag, K, and Mo; ZnOCl doped with Ag, and pure NPs (Ag2O, CuO, and NiO) showed antibacterial activity against D. zeae, P. ananatis, and X. vasicola pv. vasculorum with relatively similar inhibition zones at different concentrations. Commercial copper showed antibacterial activity only against D. zeae. NiO NPs in preventive and curative applications reduced WS and BLS severities, whereas commercial copper application increased WS severity and reduced BLS severity. The use of NPs has promising applications and further evaluation of their formulation, application form, and timing is necessary for new strategies to control the activity of phytopathogenic bacteria.

Soil degradation has been accelerated by the use of chemical pesticides and poor agricultural practices, which has had an impact on crop productivity. Recently, there has been a lot of interest in the use of eco-friendly biochar applications to enhance soil quality and sequester carbon in sustainable agriculture. This study aimed to determine the individual and combined effects of Leaf Waste Biochar (LWB) and the bio-control agent Trichoderma harzianum (BCA) on the development of bacterial wilt in eggplants (Solanum melongena) caused by Ralstonia solanacearum (RS). The effects of LWB and BCA on eggplant physiology and defense-related biochemistry were comprehensively examined. Inoculated (+RS) and un-inoculated (–RS) eggplants were grown in potting mixtures containing 3% and 6% (v/v) LWB, both with and without BCA. The percentage disease index was considerably reduced (90%) in plants grown in the 6% LWB+ BCA amended treatments. Moreover, the plants grown in LWB and inoculated with BCA had higher phenolics, flavonoids and peroxidase contents compared to the non-amended control. The level of NPK was significantly increased (92.74% N, 76.47% P, 53.73% K) in the eggplants cultivated in the 6% LWB + BCA composition. This study has shown that the association of T. harzianum with biochar improved plant growth and reduced R. solanacearum induced wilt. Furthermore, the combined impact of biochar and T. harzianum was greater in terms of wilt suppression and increase in plant physiological measurements when the biochar concentration was 6%. Biochar and bio-control agents triggered biochemical alterations, thus enhancing the management of disease-infested soils.

Bacterial wilt of cucurbits, caused by Erwinia tracheiphila, is spread by spotted (Diabrotica undeimpunctata howardi) and striped (Acalymma vittatum) cucumber beetles and results in major losses for US cucurbit (Cucurbitaceae spp.) growers. Organic growers of muskmelon (Cucumis melo) lack reliable control measures against bacterial wilt. During previous field trials in Iowa, USA, a system called mesotunnels, which are 3.5-ft-tall barriers covered with a nylon mesh insect netting, resulted in a higher marketable yield of organic ‘Athena’ muskmelon than low tunnels or noncovered plots. However, satisfactory pollination and weed control are challenging in mesotunnels because the netting covers the crop for most or all of the growing season, and economic feasibility of these systems has not been determined. Consequently, two field trials conducted in Iowa from 2020 to 2022 evaluated strategies to ensure pollination under mesotunnels in commercial-scale plots, assess effectiveness of teff (Eragrostis tef) as a living mulch for weed control in mesotunnel systems, and compare the profitability of the treatment options for organic ‘Athena’ muskmelon. The treatments used during the pollination trial were as follows: full season, in which mesotunnels remained sealed all season and bumble bees (Bombus impatiens) were added at the start of bloom for pollination; open ends, wherein both ends of the tunnels were opened at the start of bloom then reclosed 2 weeks later; and on-off-on, in which nets were removed at the start of bloom and then reinstalled 2 weeks later. The full-season treatment had significantly higher marketable yield than the other treatments in two of three trial years. Plants with the full season and open ends treatments had a bacterial wilt incidence

Ralstonia solanacearum causes a lethal bacterial wilt disease in many crops, leading to huge losses in crop production every year. Understanding of plant–R. solanacearum interactions will aid to develop efficient strategies to control the disease. As a soilborne pathogen, R. solanacearum naturally infects plants via roots. A huge limitation in studying plant–R. solanacearum interactions is the large variation of R. solanacearum infection assay due to the variable soil conditions and uneven inoculum exposure. Here, we developed a robust and reliable Petri-dish inoculation method which allows consistent and stable infection in young plant seedlings. This method is easy to use, takes about only 10 days from seed germination to the completion of inoculation assay, and requires less inoculum of bacteria as well as growth chamber space. We proved the efficacy of the seedling Petri-dish inoculation method by analyzing plant defense primed by molecular patterns, resistance of defense-related plant mutants, and virulence of R. solanacearum mutants. Furthermore, we demonstrated that the seedling Petri-dish inoculation method can be applied to other host plants such as tobacco and has great potential for high-throughput screening of resistant plant germplasms to bacterial wilt in the future.

Abstract Background Tobacco bacterial wilt (TBW) caused by Ralstonia solanacearum is the most serious soil-borne disease of tobacco that significantly reduces crop yield. However, the limited availability of resistance in tobacco hinders breeding efforts for this disease. Results In this study, we conducted hydroponic experiments for the root expression profiles of D101 (resistant) and Honghuadajinyuan (susceptible) cultivars in response to BW infection at 0 h, 6 h, 1 d, 3 d, and 7d to explore the defense mechanisms of BW resistance in tobacco. As a result, 20,711 and 16,663 (total: 23,568) differentially expressed genes (DEGs) were identified in the resistant and susceptible cultivars, respectively. In brief, at 6 h, 1 d, 3 d, and 7 d, the resistant cultivar showed upregulation of 1553, 1124, 2583, and 7512 genes, while the susceptible cultivar showed downregulation of 1213, 1295, 813, and 7735 genes. Similarly, across these time points, the resistant cultivar had downregulation of 1034, 749, 1686, and 11,086 genes, whereas the susceptible cultivar had upregulation of 1953, 1790, 2334, and 6380 genes. The resistant cultivar had more up-regulated genes at 3 d and 7 d than the susceptible cultivar, indicating that the resistant cultivar has a more robust defense response against the pathogen. The GO and KEGG enrichment analysis showed that these genes are involved in responses to oxidative stress, plant–pathogen interactions, cell walls, glutathione and phenylalanine metabolism, and plant hormone signal transduction. Among the DEGs, 239 potential candidate genes were detected, including 49 phenylpropane/flavonoids pathway-associated, 45 glutathione metabolic pathway-associated, 47 WRKY, 48 ERFs, eight ARFs, 26 pathogenesis-related genes (PRs), and 14 short-chain dehydrogenase/reductase genes. In addition, two highly expressed novel genes (MSTRG.61386-R1B-17 and MSTRG.61568) encoding nucleotide-binding site leucine-rich repeat (NBS-LRR) proteins were identified in both cultivars at 7 d. Conclusions This study revealed significant enrichment of DEGs in GO and KEGG terms linked to glutathione, flavonoids, and phenylpropane pathways, indicating the potential role of glutathione and flavonoids in early BW resistance in tobacco roots. These findings offer fundamental insight for further exploration of the genetic architecture and molecular mechanisms of BW resistance in tobacco and solanaceous plants at the molecular level.

Ralstonia solanacearum species complex (RSSC) is a soil borne plant pathogen causing bacterial wilt on various important crops, including Solanaceae plants. The bacterial pathogens within the RSSC produce exopolysaccharide (EPS), a highly complicated nitrogen-containing heteropolymeric polysaccharide, as a major virulence factor. However, the biosynthetic pathway of the EPS in the RSSC has not been fully characterized. To identify genes in EPS production beyond the EPS biosynthetic gene operon, we selected the EPS-defective mutants of R. pseudosolanacearum strain SL341 from Tn5-inserted mutant pool. Among several EPS-defective mutants, we identified a mutant, SL341P4, with a Tn5-insertion in a gene encoding a putative NDP-sugar epimerase, a putative membrane protein with sugar-modifying moiety, in a reverse orientation to EPS biosynthesis gene cluster. This protein showed similar to other NDP-sugar epimerases involved in EPS biosynthesis in many phytopathogens. Mutation of the NDP-sugar epimerase gene reduced EPS production and biofilm formation in R. pseudosolanacearum. Additionally, the SL341P4 mutant exhibited reduced disease severity and incidence of bacterial wilt in tomato plants compared to the wild-type SL341 without alteration of bacterial multiplication. These results indicate that the NDP-sugar epimerase gene is required for EPS production and bacterial virulence in R. pseudosolanacearum.

Ralstonia solanacearum species complex (RSSC) strains are bacteria that colonize plant xylem tissue and cause vascular wilt diseases. However, individual strains vary in host range, optimal disease temperatures and physiological traits. To increase our understanding of the evolution, diversity and biology of the RSSC, we performed a meta-analysis of 100 representative RSSC genomes. These 100 RSSC genomes contain 4940 genes on average, and a pangenome analysis found that there are 3262 genes in the core genome (~60 % of the mean RSSC genome) with 13 128 genes in the extensive flexible genome. A core genome phylogenetic tree and a whole-genome similarity matrix aligned with the previously named species ( R. solanacearum , R. pseudosolanacearum , R. syzygii ) and phylotypes (I–IV). These analyses also highlighted a third unrecognized sub-clade of phylotype II. Additionally, we identified differences between phylotypes with respect to gene content and recombination rate, and we delineated population clusters based on the extent of horizontal gene transfer. Multiple analyses indicate that phylotype II is the most diverse phylotype, and it may thus represent the ancestral group of the RSSC. We also used our genome-based framework to test whether the RSSC sequence variant (sequevar) taxonomy is a robust method to define within-species relationships of strains. The sequevar taxonomy is based on alignments of a single conserved gene (egl). Although sequevars in phylotype II describe monophyletic groups, the sequevar system breaks down in the highly recombinogenic phylotype I, which highlights the need for an improved, cost-effective method for genotyping strains in phylotype I. Finally, we enabled quick and precise genome-based identification of newly sequenced RSSC strains by assigning Life Identification Numbers (LINs) to the 100 strains and by circumscribing the RSSC and its sub-groups in the LINbase Web service.

Common bean (Phaseolus vulgaris) is one of the major legume crops cultivated worldwide. Bacterial wilt (BW) of common bean (Curtobacterium flaccumfaciens pv. flaccumfaciens), being a seed-borne disease, has been a challenge in common bean producing regions. A genome-wide association study (GWAS) was conducted to identify SNP markers associated with BW resistance in the USDA common bean core collection. A total of 168 accessions were evaluated for resistance against three different isolates of BW. Our study identified a total of 14 single nucleotide polymorphism (SNP) markers associated with the resistance to BW isolates 528, 557, and 597 using mixed linear models (MLMs) in BLINK, FarmCPU, GAPIT, and TASSEL 5. These SNPs were located on chromosomes Phaseolus vulgaris [Pv]02, Pv04, Pv08, and Pv09 for isolate 528; Pv07, Pv10, and Pv11 for isolate 557; and Pv04, Pv08, and Pv10 for isolate 597. The genomic prediction accuracy was assessed by utilizing seven GP models with 1) all the 4,568 SNPs and 2) the 14 SNP markers. The overall prediction accuracy (PA) ranged from 0.30 to 0.56 for resistance against the three BW isolates. A total of 14 candidate genes were discovered for BW resistance located on chromosomes Pv02, Pv04, Pv07, Pv08, and Pv09. This study revealed vital information for developing genetic resistance against the BW pathogen in common bean. Accordingly, the identified SNP markers and candidate genes can be utilized in common bean molecular breeding programs to develop novel resistant cultivars.

PAMP-triggered immunity (PTI) is the first layer of plant defense response that occurs on the plant plasma membrane. Recently, the application of a rhizobacterium, Bacillus amyloliquefaciens strain PMB05, has been demonstrated to enhance flg22Pst- or harpin-triggered PTI response such as callose deposition. This PTI intensification by PMB05 further contributes to plant disease resistance to different bacterial diseases. Under the demand for rapid and large-scale screening, it has become critical to establish a non-staining technology to identify microbial strains that can enhance PTI responses. Firstly, we confirmed that the expression of the GSL5 gene, which is required for callose synthesis, can be enhanced by PMB05 during PTI activation triggered by flg22 or PopW (a harpin from Ralstonia solanacearum). The promoter region of the GSL5 gene was further cloned and fused to the coding sequence of gfp. The constructed fragments were used to generate transgenic Arabidopsis plants through a plant transformation vector. The transgenic lines of AtGSL5-GFP were obtained. The analysis was performed by infiltrating flg22Pst or PopW in one homozygous line, and the results exhibited that the green fluorescent signals were observed until after 8 h. In addition, the PopW-induced fluorescent signal was significantly enhanced in the co-treatment with PMB05 at 4 h after inoculation. Furthermore, by using AtGSL5-GFP to analyze 13 Bacillus spp. strains, the regulation of PopW-induced fluorescent signal was observed. And, the regulation of these fluorescent signals was similar to that performed by callose staining. More importantly, the Bacillus strains that enhance PopW-induced fluorescent signals would be more effective in reducing the occurrence of bacterial wilt. Taken together, the technique by using AtGSL5-GFP would be a promising platform to screen plant immunity-intensifying microbes to control bacterial wilt.

【Objective】The impact of anaerobic disinfection (ASD) on the properties of tobacco field soil, major soil-borne diseases of tobacco, and their yield and quality is investigated by employing effective and pollution-free soil improvement techniques through the application of different organic materials.【Method】The field experiment wasconducted in two tobacco production areas in Dapu and Nanxiong, Guangdong Province. Three treatment groups of rice bran (MK), wood chips (MX) and rice bran mixed with wood chips (KX) were set up for soil anaerobic disinfection (ASD), and that without the addition of organic materials was used as CK, then soil properties, occurrence of major diseases and economic traits of tobacco were analyzed between different treatments.【Result】The results showed that ASD treatments with organic materials significantly increased soil pH value, soil enzyme activity and soil nutrient content in two production areas when compared with CK, while reduced soil EC value. In the Dapu production area, the mass fractions of soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium increased by 29.0%-40.6%, 7.0%-24.2%, 18.0%-24.4%, 25.9%-43.0%, and 37.5%-81.7%, respectively, compared to the control group (CK). The incidence rates of tobacco blue mold and black shank disease decreased by 5.8-17.3 and 7.5-15.8 percentage points, respectively, compared to CK. The disease severity index decreased by 34.7%-69.0% and 30.4%~68.9%, respectively, compared to CK. In the Nanxiong production area, the mass fractions of soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium increased by 0.1%-35.2%, 55.8%-89.4%, 19.7%-30.0%, 22.2%-27.5%, and 34.0%-76.3%, respectively, compared to CK. The incidence rates of tobacco blue mold and black shank disease decreased by 5.6-12.6 and 11.7-18.0 percentage points, respectively, compared to CK. The disease severity index decreased by 16.1%-63.7% and 43.4%-64.3%, respectively, compared to CK. In both production areas, the average tobacco yield per hectare increased by at least 1 949.25 yuan compared to CK. The proportion of high-grade tobacco in Dapu and Nanxiong production areas increased by 1.2~4.2 and 0.7-2.9 percentage points, respectively, compared to CK. The results of redundancy analysis showed that the incidence of bacterial wilt and black shank of flue-cured tobacco in Dapu was greatly affected by sucrase activity, and the incidence of flue-cured tobacco in Nanxiong was greatly affected by urease activity.【Conclusion】Adding MK (10 t/hm2) for ASD treatment in tobacco fields with frequent continuous cropping and severe soil-borne diseases. This treatment can effectively improve soil characteristics and enhance the quality of tobacco production.

There is a long history to cultivate the Pogostemon cablin in Guangdong Province, and it is a famous medicinal material. The bacterial wilt is the important disease that impacts the production and quality of P. cablin. Aiming to the control effects of metabolites of Alternaria sp. GHX-P17 strain that is belonging to an endophytic fungus isolated from the stems and leaves of P. cablin and the mechanism of disease resistance on bacterial wilt, a laboratory experiment had been conducted to investigate the incidence and severity of bacterial wilt in P. cablin at different time after artificial to inoculate the strain of Alternaria sp. GHX-P17 and to spray the crude extracts of the metabolites, and disease index (DI) was calculated. The activity changes of protective enzymes of phenylalanine ammonia lyase (PAL), peroxidase (POD）and superoxide dismutase (SOD) were determined in different time in P. cablin. The results were as follows: (1) The DI was significantly lower in the treatment groups with the crude extracts of Alternaria sp. GHX-P17 at different concentrations than that of control groups, and the DI decreased by 27.16% in the treatment groups at 204 h after inoculation. The variance analysis showed significant differences (P

Ginger has been a leading spice crop in Ethiopia until ginger bacterial wilt disease interrupted its production. The disease transmission is mainly through infected planting materials and products. Regeneration of healthy planting materials is among the best option to minimize the disease impact. This research aimed to induce and produce disease-free in vitro micro-rhizome in a combination of sucrose, BAP, ammonium nitrate, and silver nitrate. The results from observations indicated that sucrose and BAP were best combinations for induction of disease free micro-rhizomes. Ammonium nitrate and silver nitrate showed lower induction than sucrose and BAP combinations alone. The maximum viable number of micro-rhizome (5.67) and shoot number (10.33) were from 80.0 g/l sucrose and 6.0 mg/l BAP contained medium. Viability test indicated 80 % of the micro-rhizomes were sprouted after one month in soil. The micro-rhizome production potential observed in this experiment can enhance disease-free ginger production.

CRISPR/Cas is a breakthrough genome editing system because of its precision, target specificity, and efficiency. As a speed breeding system, it is more robust than the conventional breeding and biotechnological approaches for qualitative and quantitative trait improvement. Tomato (Solanum lycopersicum L.) is an economically important crop, but its yield and productivity have been severely impacted due to different abiotic and biotic stresses. The recently identified SlHyPRP1 and SlDEA1 are two potential negative regulatory genes in response to different abiotic (drought and salinity) and biotic stress (bacterial leaf spot and bacterial wilt) conditions in S. lycopersicum L. The present study aimed to evaluate the drought, salinity, bacterial leaf spot, and bacterial wilt tolerance response in S. lycopersicum L. crop through CRISPR/Cas9 genome editing of SlHyPRP1 and SlDEA1 and their functional analysis. The transient single- and dual-gene SlHyPRP1 and SlDEA1 CRISPR-edited plants were phenotypically better responsive to multiple stress factors taken under the study. The CRISPR-edited SlHyPRP1 and SlDEA1 plants showed a higher level of chlorophyll and proline content compared to wild-type (WT) plants under abiotic stress conditions. Reactive oxygen species accumulation and the cell death count per total area of leaves and roots under biotic stress were less in CRISPR-edited SlHyPRP1 and SlDEA1 plants compared to WT plants. The study reveals that the combined loss-of-function of SlHyPRP1 along with SlDEA1 is essential for imparting significant multi-stress tolerance (drought, salinity, bacterial leaf spot, and bacterial wilt) in S. lycopersicum L. The main feature of the study is the detailed genetic characterization of SlDEA1, a poorly studied 8CM family gene in multi-stress tolerance, through the CRISPR/Cas9 gene editing system. The study revealed the key negative regulatory role of SlDEA1 that function together as an anchor gene with SlHyPRP1 in imparting multi-stress tolerance in S. lycopersicum L. It was interesting that the present study also showed that transient CRISPR/Cas9 editing events of SlHyPRP1 and SlDEA1 genes were successfully replicated in stably generated parent-genome-edited line (GEd0) and genome-edited first-generation lines (GEd1) of S. lycopersicum L. With these upshots, the study’s key findings demonstrate outstanding value in developing sustainable multi-stress tolerance in S. lycopersicum L. and other crops to cope with climate change.

Background: Tobacco bacterial wilt (TBW) caused by Ralstonia solanacearum is the most serious soil-borne disease of tobacco that significantly reduces crop yield. However, the limited availability of resistance in tobacco hinders breeding efforts for this disease. Results: In this study, we conducted hydroponic experiments for the root expression profiles of D101 (resistant) and Honghuadajinyuan (susceptible) cultivars in response to BW infection at 0 h, 6 h, 1 d, 3 d, and 7d to explore the defense mechanisms of BW resistance in tobacco. As a result, 20,711 and 16,663 (total: 23,568) differentially expressed genes (DEGs) were identified in the resistant and susceptible cultivars, respectively. In brief, at 6 h, 1 d, 3 d, and 7 d, the resistant cultivar showed upregulation of 1553, 1124, 2583, and 7512 genes, while the susceptible cultivar showed downregulation of 1213, 1295, 813, and 7735 genes. Similarly, across these time points, the resistant cultivar had downregulation of 1034, 749, 1686, and 11,086 genes, whereas the susceptible cultivar had upregulation of 1953, 1790, 2334, and 6380 genes. The resistant cultivar had more up-regulated genes at 3 d and 7 d than the susceptible cultivar, indicating that the resistant cultivar has a more robust defense response against the pathogen. The GO and KEGG enrichment analysis showed that these genes are involved in responses to oxidative stress, plant–pathogen interactions, cell walls, glutathione and phenylalanine metabolism, and plant hormone signal transduction. Among the DEGs, 239 potential candidate genes were detected, including 49 phenylpropane/flavonoids pathway-associated, 45 glutathione metabolic pathway-associated, 47 WRKY, 48 ERFs, eight ARFs, 26 pathogenesis-related genes (PRs), and 14 short-chain dehydrogenase/reductase genes. In addition, two highly expressed novel genes (MSTRG.61386-R1B-17 and MSTRG.61568) encoding nucleotide-binding site leucine-rich repeat (NBS-LRR) proteins were identified in both cultivars at 7 d. Conclusions: This study revealed significant enrichment of DEGs in GO and KEGG terms linked to glutathione, flavonoids, and phenylpropane pathways, indicating the potential role of glutathione and flavonoids in early BW resistance in tobacco roots. These findings offer fundamental insight for further exploration of the genetic architecture and molecular mechanisms of BW resistance in tobacco and solanaceous plants at the molecular level. [ABSTRACT FROM AUTHOR]

Continuous cropping is the primary cultivation method in Chinese facility agriculture, and the challenge of it stands as a global issue in soil remediation. Growing tomatoes continuously on the same plot for an extended period can result in outbreaks of tomato bacterial wilt. It is caused by the soil-borne bacterium Ralstonia solanacearum, a widespread plant pathogen that inflicts considerable damage on economically significant crops worldwide. Simultaneously, this plant pathogen proves extremely resilient, as it can adhere to plant residues and persist through the winter, continuing to infect plants in subsequent years. Scientists have dedicated considerable efforts towards finding effective methods to manage this disease. This article delineates the characteristics of tomato bacterial wilt and the various types of pathogenic bacteria involved. It systematically reviews the progress in research aimed at controlling tomato bacterial wilt, encompassing both physical and biological aspects concerning soil and plants. Emphasis is placed on the principles and current applications of these control measures, alongside proposed improvements to address their limitations. It is anticipated that the future of tomato bacterial wilt control will revolve around the development of a novel environmental protection system and efficient control strategies, focusing on microecological management and enhancing tomato resistance against bacterial wilt through breeding. [ABSTRACT FROM AUTHOR]

BACKGROUND: Bacterial wilt induced by Ralstonia solanacearum is regarded as one of the most devastating diseases. However, excessive and repeated use of the same bactericides has resulted in development of bacterial resistance. Targeting bacterial virulence factors, such as type III secretion system (T3SS), without inhibiting bacterial growth is a possible assay to discover new antimicrobial agents. RESULTS: In this work, identifying new T3SS inhibitors, a series of mandelic acid derivatives with 2‐mercapto‐1,3,4‐thiazole moiety was synthesized. One of them, F‐24, inhibited the transcription of hrpY gene significantly. The presence of this compound obviously attenuated hypersensitive response (HR) without inhibiting bacterial growth of R. solanacearum. The transcription levels of those typical T3SS genes were reduced to various degrees. The test of the ability of F‐24 in protecting plants demonstrated that F‐24 protected tomato plants against bacterial wilt without restricting the multiplication of R. solanacearum. The mechanism of this T3SS inhibition is through the PhcR‐PhcA‐PrhG‐HrpB pathway. CONCULSION: The screened F‐24 could inhibit R. solanacearum T3SS and showed better inhibitory activity than previously reported inhibitors without affecting the growth of the strain, and F‐24 is a compound with good potential in the control of R. solanacearum. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In order to determine the contribution of GmFLS2a/b to soybean resistance against I Ralstonia i , we first generated soybean I fls2a/b i mutant plants using CRISPR-Cas9-mediated genome editing. Keywords: bacterial wilt; CRISPR; disease; pathogen; Ralstonia; resistance; soybean EN bacterial wilt CRISPR disease pathogen Ralstonia resistance soybean 17 22 6 09/11/23 20231001 NES 231001 Data availability All the data and materials integral to this study are available within the article and the Supporting Information. However, upon stem injection, both mutant lines showed enhanced susceptibility, suggesting that, once I Ralstonia i is inside plant tissues, GmFLS2 contributes significantly to soybean defense against I Ralstonia i , likely by perceiving the polymorphic flg22 SP Rso sp and initiating defense signaling. [Extracted from the article]

Plant disease limits crop production, and host genetic resistance is a major means of control. Plant pathogenic Ralstonia causes bacterial wilt disease and is best controlled with resistant varieties. Tomato wilt resistance is multigenic, yet the mechanisms of resistance remain largely unknown. We combined metaRNAseq analysis and functional experiments to identify core Ralstonia‐responsive genes and the corresponding biological mechanisms in wilt‐resistant and wilt‐susceptible tomatoes. While trade‐offs between growth and defence are common in plants, wilt‐resistant plants activated both defence responses and growth processes. Measurements of innate immunity and growth, including reactive oxygen species production and root system growth, respectively, validated that resistant plants executed defence‐related processes at the same time they increased root growth. In contrast, in wilt‐susceptible plants roots senesced and root surface area declined following Ralstonia inoculation. Wilt‐resistant plants repressed genes predicted to negatively regulate water stress tolerance, while susceptible plants repressed genes predicted to promote water stress tolerance. Our results suggest that wilt‐resistant plants can simultaneously promote growth and defence by investing in resources that act in both processes. Infected susceptible plants activate defences, but fail to grow and so succumb to Ralstonia, likely because they cannot tolerate the water stress induced by vascular wilt. [ABSTRACT FROM AUTHOR]

This article explores the use of tomato grafts to improve yield and resistance to bacterial wilt disease. Bacterial wilt is a significant issue in tomato production, leading to reduced fruit quality and quantity. The study utilized different tomato hybrids grafted onto a wilt-resistant brinjal rootstock and found that grafting was successful, with a high success rate and field establishment. The grafted plants also demonstrated resistance to bacterial wilt. This research provides valuable insights into the potential of grafting as a solution to mitigate biotic challenges in tomato cultivation. [Extracted from the article]

The highly destructive soil-borne pathogen Ralstonia solanacerum (Smith) Yabuuchi et al. (RS) affects a variety of solanaceous plants and causes catastrophic diseases leading to massive economic losses across the globe. Biochemical assays separate this bacterium's strains into 5 races and 5 biovars by host range. This bacterium's race 1 biovar 1, which is endemic to the south-eastern United States, infects many different vegetable and ornamental species. Some solanaceous vegetables and ornamental crops are infected by RS race 3 biovar 2, which causes brown rot, bacterial wilt, and Moko disease. The race 3 biovar 3 is not hosted by tobacco. The most devastating RS diseases affect solanaceous crops like potatoes, tobacco, pepper, tomatoes, and eggplant. This review offers a thorough examination of this bacterium's impacts on solanaceous crops, emphasizing their economic impact. It also emphasizes the importance of integrated disease management, including current developments in control methods (biological, physical, chemical, cultural, and integrated) and bio-control effectiveness and suppression mechanisms, to combat deadly bacterial wilt diseases. Avirulent RS, Pseudomonas, Bacillus, and Streptomyces spp. strains are examples of well-known Biological Control Agents (BCAs). Research shows that plant waste, animal manure, and organic materials reduce bacterial wilt. It's crucial to incorporate pest management for bacterial wilt infections. This review also identifies intriguing possibilities for future study and collaboration on this bacterium. Understanding this bacterium's complexity and using effective management measures can lessen its detrimental effects on agriculture. [ABSTRACT FROM AUTHOR]

The blueberry industry, a fast-growing industry in Florida, is threatened by bacterial wilt, caused by the Ralstonia solanacearum species complex (RSSC). In 2016, distinct RSSC populations were found in Florida causing disease in blueberry. Currently, there are no tools that discriminate between RSSC populations pathogenic to blueberry and other RSSC strains. Early detection of specific RSSC strains is critical, and the Microbe Finder (MiFi) web application is a sensitive and specific tool used to detect known target pathogens in sequenced samples. MiFi is used to develop e-probes and subsequently query sample metagenomes with them. We report the development and validation of e-probes for three different RSSC populations pathogenic to blueberry using the MiFi platform. We also present preliminary data to assess the feasibility of a cost-effective integrated diagnostics system, MiFi, in combination with MinION, a pocket-sized, portable sequencer. The e-probes were validated in silico, generating simulated metagenomes; in vitro by using blueberry DNA spiked with pathogen DNA; and in vivo with soil and stem samples. We tested several methods of DNA extraction for soil and blueberry stems and several MinION libraries with or without barcodes. MiFi blueberry e-probes effectively identified target pathogens at a very specific level with high sensitivity. The MiFi system combined with MinION sequencing using Flongle cells was optimized to produce results in one day. Further optimization and tests can improve greatly the cost effectiveness and flexibility of this system by adding e-probes to test for new blueberry strains and many other pathogens affecting blueberry in one test. [Figure: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Ralstonia solancearum causes bacterial wilt disease on diverse plant hosts. R. solanacearum cells enter a host from soil or infested water through the roots, then multiply and spread in the water-transporting xylem vessels. Despite the low nutrient content of xylem sap, R. solanacearum grows very well inside the host, using denitrification to respire in this hypoxic environment. R. solanacearum growth in planta also depends on the successful deployment of protein effectors into host cells via a type III secretion system (T3SS). The T3SS is absolutely required for R. solanacearum virulence, but it is metabolically costly and can trigger host defenses. Thus, the pathogen's success depends on optimized regulation of the T3SS. We found that a byproduct of denitrification, the toxic free-radical nitric oxide (NO), positively regulates the R. solanacearum T3SS both in vitro and in planta. Using chemical treatments and R. solanacearum mutants with altered NO levels, we show that the expression of a key T3SS regulator, hrpB, is induced by NO in culture. Analyzing the transcriptome of R. solanacearum responding to varying levels of NO both in culture and in planta revealed that the T3SS and effectors were broadly upregulated with increasing levels of NO. This regulation was specific to the T3SS and was not shared by other stressors. Our results suggest that R. solanacearum may experience an NO-rich environment in the plant host and that this NO contributes to the activation of the T3SS during infection. [Graphic: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

The bacterial wilt disease caused by Ralstonia solanacearum is a significant threat to eggplant production. Breeding and promoting resistant varieties is one of the most effective methods to manage bacterial wilt. Conducting QTL (quantitative trait locus) mapping of resistant genes can substantially enhance the breeding of plant resistance to bacterial wilt. In this study, a population of 2200 F2 individuals derived from resistant and susceptible materials was utilized to establish extreme resistance and susceptibility pools. Following resequencing analysis of the parents and extreme pools, the QTL were examined using the DEEP-BSA software and QTLseqr R package (version 0.7.5.2). The results revealed that the detection of 10 QTL sites on chromosomes 5, 8, 9, and 11 by the five algorithms of the DEEP-BSA software. Additionally, the candidate region of 62 Mb–72 Mb on chromosome 5 was identified in all five algorithms of the DEEP-BSA software, as well as by the QTLseqr R package. Subsequent gene annotation uncovered 276 genes in the candidate region of 62 Mb–72 Mb on chromosome 5. Additionally, RNA-seq results indicated that only 13 genes had altered expression levels following inoculation with R. solanacearum in the resistant materials. Based on the expression levels, SMEL4_05g015980.1 and SMEL4_05g016110.1 were identified as candidate genes. Notably, SNP annotation identified a non-synonymous mutation in the exonic region of SMEL4_05g015980.1 and a variant in the promoter region of SMEL4_05g016110.1. The research findings have practical significance for the isolation of bacterial wilt resistance genes in eggplant and the development of resistance to bacterial wilt varieties in eggplant.

Abstract Ralstonia solanacearum is a soil-borne bacterium that causes bacterial wilt disease in over 250 plant species. It has been identified as one of the top ten most serious plant pathogenic bacteria globally, causing significant crop yield loss every year. Despite its large impact on agricultural economics, the molecular mechanisms underlying plant defense against Ralstonia infection and by which Ralstonia grows within the plant xylem remain largely unexplored. In a recent article, Ke et al. discovered a distinct pathogen effector, which acted as an immune elicitor in plants but also played dual roles in compromising plant immune activation and increasing nutrient acquisition from the host plants for pathogen propagation.

Ralstonia solanacearum, the causal agent of bacterial wilt, is a devastating plant pathogenic bacterium that infects more than 450 plant species. Until now, there has been no efficient control strategy against bacterial wilt. In this study, we screened a library of 100 plant-derived compounds for their antibacterial activity against R. solanacearum. Twelve compounds, including harmine, harmine hydrochloride, citral, vanillin, and vincamine, suppressed bacterial growth of R. solanacearum in liquid medium with an inhibition rate higher than 50%. Further focus on harmine revealed that the minimum inhibitory concentration of this compound is 120 mg/L. Treatment with 120 mg/L of harmine for 1 and 2 h killed more than 90% of bacteria. Harmine treatment suppressed the expression of the virulence-associated gene xpsR. Harmine also significantly inhibited biofilm formation by R. solanacearum at concentrations ranging from 20 mg/L to 60 mg/L. Furthermore, application of harmine effectively reduced bacterial wilt disease development in both tobacco and tomato plants. Collectively, our results demonstrate the great potential of plant-derived compounds as antibacterial agents against R. solanacearum, providing alternative ways for the efficient control of bacterial wilt. [ABSTRACT FROM AUTHOR]

The RIPENING-INHIBITOR (RIN) transcriptional factor is a key regulator governing fruit ripening. While RIN also affects other physiological processes, its potential roles in triggering interactions with the rhizosphere microbiome and plant health are unknown. Here we show that RIN affects microbiome-mediated disease resistance via root exudation, leading to recruitment of microbiota that suppress the soil-borne, phytopathogenic Ralstonia solanacearum bacterium. Compared with the wild-type (WT) plant, RIN mutants had different root exudate profiles, which were associated with distinct changes in microbiome composition and diversity. Specifically, the relative abundances of antibiosis-associated genes and pathogen-suppressing Actinobacteria (Streptomyces) were clearly lower in the rhizosphere of rin mutants. The composition, diversity, and suppressiveness of rin plant microbiomes could be restored by the application of 3-hydroxyflavone and riboflavin, which were exuded in much lower concentrations by the rin mutant. Interestingly, RIN-mediated effects on root exudates, Actinobacteria, and disease suppression were evident from the seedling stage, indicating that RIN plays a dual role in the early assembly of disease-suppressive microbiota and late fruit development. Collectively, our work suggests that, while plant disease resistance is a complex trait driven by interactions between the plant, rhizosphere microbiome, and the pathogen, it can be indirectly manipulated using "prebiotic" compounds that promote the recruitment of disease-suppressive microbiota. The RIPENING-INHIBITOR (RIN) gene in tomato is well known for its role in regulating hormone metabolism and fruit ripening. This study shows that RIN is also important for plant immunity through root exudation-mediated recruitment of disease-suppressive microbiota. [ABSTRACT FROM AUTHOR]

Introduction: Mulberry bacterial wilt is a serious destructive soil-borne disease caused by a complex and diverse group of pathogenic bacteria. Given that the bacterial wilt has been reported to cause a serious damage to the yield and quality of mulberry, therefore, elucidation of its main pathogenic groups is essential in improving our understanding of this disease and for the development of its potential control measures. Methods: In this study, combined metagenomic sequencing and culturedependent approaches were used to investigate the microbiome of healthy and bacterial wilt mulberry samples. Results: The results showed that the healthy samples had higher bacterial diversity compared to the diseased samples. Meanwhile, the proportion of opportunistic pathogenic and drug-resistant bacterial flora represented by Acinetobacter in the diseased samples was increased, while the proportion of beneficial bacterial flora represented by Proteobacteria was decreased. Ralstonia solanacearum species complex (RSSC), Enterobacter cloacae complex (ECC), Klebsiella pneumoniae, K. quasipneumoniae, K. michiganensis, K. oxytoca, and P. ananatis emerged as the main pathogens of the mulberry bacterial wilt. Discussion: In conclusion, this study provides a valuable reference for further focused research on the bacterial wilt of mulberry and other plants. [ABSTRACT FROM AUTHOR]

Tomato (Solanum lycopersicum L.) is an important grown vegetable in Vietnam. Bacterial wilt caused by Pseudomonas solanacearum has been considered to be an important disease resulting in a harvest loss up to 90% and significant economic loss to farmers. In this study, two bacteriophages DLDT_So2 and BHDT_So9 specific to P. solanacearum were isolated. Morphological analysis indicated that DLDT_So2 and BHDT_So9 had podovirus morphology and were classified into Autographiviridae family. The latent period and burst size of DLDT_So2 was found to be approximately 120 min and 20.0 ± 2.4 virions per infected cell. Meanwhile, the latent period of BHDT_So9 was 140 min with a burst size of 11.5 ± 2.8 virions per infected cell. Of the 23 bacterial strains tested, the phages infected 7/11 strains of P. solanacearum and none of the other bacteria tested were susceptible to the phages. Stability of the phages at different temperatures, pHs, solvents was also investigated. The genomes of DLDT_So2 and BHDT_So9 are 41,341 bp and 41,296 bp and long with a total GC content of 63%, contains 48 and 46 predicted protein-encoding CDSs. No virulence or antibiotic resistance genes were found in the genomes, suggesting they would be useful biocontrol agents against P. solanacearum. Classification of the phage using average nucleotide identity, phylogenetic analysis was also carried out. The two phages represented new species when they had overall average nucleotide identity of < 95%. This is first report of the isolation and characterization of P. solanacearum-specific phages from tomato farms in Vietnam. [ABSTRACT FROM AUTHOR]

Potato (Solanum tuberosum) is an important crop globally and is grown across many regions in China, where it ranks fourth in the list of staple foods. However, its production and quality are severely affected by bacterial wilt caused by Ralstonia solanacearum. In this study, we identified StTOPP6, which belongs to the type one protein phosphatase (TOPP) family, and found that transient knock down of StTOPP6 in potato increased resistance against R. solanacearum. RNA-seq analysis showed that knock down of StTOPP6 activated immune responses, and this defense activation partly depended on the mitogen-activated protein kinase (MAPK) signal pathway. StTOPP6 inhibited the expression of StMAPK3 , while overexpression of StMAPK3 enhanced resistance to R. solanacearum , supporting the negative role of StTOPP6 in plant immunity. Consistent with the results of knock down of StTOPP6 , overexpressing the phosphatase-dead mutation StTOPP6m also attenuated infection and up-regulated MAPK3, showing that StTOPP6 activity is required for disease. Furthermore, we found that StTOPP6 affected the StMAPK3-mediated downstream defense pathway, eventually suppressing the accumulation of reactive oxygen species (ROS). Consistent with these findings, plants with knock down of StTOPP6 , overexpression of StTOPP6m , and overexpression of StMAPK3 all displayed ROS accumulation and enhanced resistance to R. solanacearum. Taken together, the findings of our study demonstrate that StTOPP6 negatively regulates resistance to bacterial wilt by affecting the MAPK3-mediated pathway. [ABSTRACT FROM AUTHOR]

Bacterial wilt negatively impacts the yield and quality of tomatoes. cis-Abienol, a labdane diterpenoid abundantly produced in the trichome secretion of Nicotiana spp., can induce bacterial wilt resistance in plants; however, study on its practical application and acting mechanism is very limited. This study established the application conditions of cis-abienol for inducing tomato bacterial wilt resistance by pot-inoculation experiments and investigated the underlying mechanism by determining the physio-biochemical indexes and transcriptomic changes. The results showed that applying cis-abienol to the roots was the most effective approach for inducing tomato bacterial wilt resistance. The optimal concentration was 60 μg/mL, and 2–3 consecutive applications with 3–6 days intervals were sufficient to induce the bacterial wilt resistance of tomato plants. cis-Abienol could enhance the antioxidant enzyme activity and stimulate the defensive signal transduction in tomato roots, leading to the upregulation of genes involved in the mitogen-activated protein kinase cascade. It also upregulated the expression of JAZ genes and increased the content of jasmonic acid (JA) and salicylic acid (SA), which control the expression of flavonoid biosynthetic genes and the content of phytoalexins in tomato roots. cis-Abienol-induced resistance mainly depends on the JA signalling pathway, and the SA signalling pathway is also involved in this process. This study established the feasibility of applying the plant-derived terpenoid cis-abienol to induce plant bacterial wilt resistance, which is of great value for developing eco-friendly bactericides. [ABSTRACT FROM AUTHOR]

【Objective】 The impact of anaerobic disinfection (ASD) on the properties of tobacco field soil, major soil-borne diseases of tobacco, and their yield and quality is investigated by employing effective and pollution-free soil improvement techniques through the application of different organic materials. 【Method】 The field experiment was conducted in two tobacco production areas in Dapu and Nanxiong, Guangdong Province. Three treatment groups of rice bran (MK), wood chips (MX) and rice bran mixed with wood chips (KX) were set up for soil anaerobic disinfection (ASD), and that without the addition of organic materials was used as CK, then soil properties, occurrence of major diseases and economic traits of tobacco were analyzed between different treatments. 【Result】 The results showed that ASD treatments with organic materials significantly increased soil pH value, soil enzyme activity and soil nutrient content in two production areas when compared with CK, while reduced soil EC value. In the Dapu production area, the mass fractions of soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium increased by 29.0%-40.6%, 7.0%-24.2%, 18.0%-24.4%, 25.9%- 43.0%, and 37.5%-81.7%, respectively, compared to the control group (CK). The incidence rates of tobacco blue mold and black shank disease decreased by 5.8-17.3 and 7.5-15.8 percentage points, respectively, compared to CK. The disease severity index decreased by 34.7%-69.0% and 30.4%~68.9%, respectively, compared to CK. In the Nanxiong production area, the mass fractions of soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium increased by 0.1%-35.2%, 55.8%-89.4%, 19.7%-30.0%, 22.2%-27.5%, and 34.0%-76.3%, respectively, compared to CK. The incidence rates of tobacco blue mold and black shank disease decreased by 5.6-12.6 and 11.7-18.0 percentage points, respectively, compared to CK. The disease severity index decreased by 16.1%-63.7% and 43.4%-64.3%, respectively, compared to CK. In both production areas, the average tobacco yield per hectare increased by at least 1 949.25 yuan compared to CK. The proportion of high-grade tobacco in Dapu and Nanxiong production areas increased by 1.2~4.2 and 0.7-2.9 percentage points, respectively, compared to CK. The results of redundancy analysis showed that the incidence of bacterial wilt and black shank of flue-cured tobacco in Dapu was greatly affected by sucrase activity, and the incidence of flue-cured tobacco in Nanxiong was greatly affected by urease activity. 【Conclusion】 Adding MK (10 t/hm²) for ASD treatment in tobacco fields with frequent continuous cropping and severe soil-borne diseases. This treatment can effectively improve soil characteristics and enhance the quality of tobacco production. [ABSTRACT FROM AUTHOR]

The bacterial wilt caused by Ralstonia solanacearum (Rsc) affects many economically important crop plants, including tomatoes. This bacterium enters the plant through the root system, which plays a vital role in defence against this phytopathogen. However, till now researches have mostly focused on managing the bacterial wilt disease by inducing defence in the aerial plant parts. To understand the efficacy of root-priming with the extract of an endophytic fungus Penicillium sp. PM031 on its host tomato plant for controlling wilt disease, we checked its toxicity effects and disease severity in primed plants. Additionally, we explored the underlying physiological and biochemical mechanisms responsible for disease resistance in primed plants. This study demonstrates natural extract from Penicillium sp. PM031 at the concentration up to 0.06% (w/v) was found to be non-toxic against human liver cell line, and it was not phytotoxic at a concentration of 0.05% (w/v) towards tomato seeds and seedlings. The endophytic fungal extract at a non-toxic concentration elicits the root immunity in the host tomato plant to control Rsc. Root-priming evoked the levels of total phenolics (39%), flavonoid (3.74-fold), lignin (43%), peroxidase (1.8-fold), hydrogen peroxide, and significantly reduced the wilt symptoms by ~ 57% compared to the unprimed plants. We conclude that host can be protected by enhancing precise, tissue-specific immunity using endophytic fungal metabolites acting as plant elicitors. [ABSTRACT FROM AUTHOR]

Bacterial wilt, caused by Ralstonia solanacearum species complex, is one of the most serious and widespread diseases across the globe. No single control method has yet been effective against this pathogen despite the use of several control strategies. The best approach to manage this disease is breeding for resistant varieties, which requires the identification of resistant sources and continuous pathogen screening. There is a lack of knowledge about resistance to bacterial wilt in the available pepper germplasm in India, despite the availability of identified molecular markers for marker-assisted selection of resistance against bacterial wilt. The objective of this study was to assess the degrees of resistance of 21 bell pepper genotypes grown in R. solanacearum contaminated field soils by evaluating the disease incidence per genotype and validate the results by PCR using specific SSR primers associated with bacterial wilt resistance, marker CAMS 451. Those genotypes were previously developed through hybridization with bacterial wilt resistant lines. Two parental resistant lines were included as resistant controls and "California Wonder" variety as susceptible control. Sixteen of the genotypes evaluated showed variable high-level resistance evidenced by disease incidences below 13.33%, while four lines were completely resistant with zero disease incidence. The genotypes were confirmed by PCR. Further, the fruit yield data for the mentioned genotypes was assessed under field conditions which showed a heterotic effect in the recombinants over the parental genotypes. In summary, these genotypes could be used as donors in developing new disease-resistant bell pepper varieties which contribute to the availability of resistant bell pepper germplasm to bacterial wilt. [ABSTRACT FROM AUTHOR]

Bacterial wilt caused by Ralstonia solanacearum ranks the second top important bacterial plant disease worldwide. It is also the most important bacterial disease threatening the healthy development of Casuarina equisetifolia protection forest. 3-hydroxypalmitic acid methyl ester (3-OH PAME) functions as an important quorum sensing (QS) signal regulating the expression of virulence genes in R. solanacearum, and has been regarded as an ideal target for disease prevention and control. To screen native microorganisms capable of degrading 3-OH PAME, samples of C. equisetifolia branches and forest soil were collected and cultured in the medium containing 3-OH PAME as the sole carbon source. Bacteria with over 85% degradation rates of 3-OH PAME after 7-day incubation were further separated and purified. As a result, strain Q1-7 isolated from forest soil and strain Q4-3 isolated from C. equisetifolia branches were obtained and identified as Pseudomonas novel species Pseudomonas forestsoilum sp. nov. and P. tohonis, respectively, according to whole genome sequencing results. The degradation efficiencies of 3-OH PAME of strains Q1-7 and Q4-3 were 95.80% and 100.00% at 48 h, respectively. Both strains showed high esterase activities and inhibited R. solanacearum exopolysaccharide (EPS) and cellulase production. Application of strains Q1-7 and Q4-3 effectively protects C. equisetifolia, peanut and tomato plants from infection by R. solanacearum. Findings in this study provide potential resources for the prevention and control of bacterial wilt caused by R. solanacearum, as well as valuable materials for the identification of downstream quenching genes and the research and development of quenching enzymes for disease control. [ABSTRACT FROM AUTHOR]