In this study, we hypothesized that rhizosphere microbiota affects the resistance of tomato plants against soil-borne bacterial wilt caused by Ralstonia solanacearum .The bacterial wilt-resistant Hawaii 7996 tomato cultivar exhibited marked suppression and induction of disease severity after treatment with upland soil-derived and forest soil-derived microbiotas, respectively, whereas the transplants did not affect the disease severity in the susceptible tomato cultivar Moneymaker.Microbial community analysis revealed the transplant-specific distinct community structure in the tomato rhizosphere and the significant enrichment of specific microbial operational taxonomic units (OTUs) in the rhizosphere of the upland soil microbiota-treated Hawaii 7996.These results suggest that the specific transplanted microbiota alters the bacterial wilt resistance in the resistant cultivar potentially through a priority effect.There are several BW-resistant cultivars of tomato (Wang et al., 1998), pepper (Du et al., 2016), and eggplant (Salgon et al., 2017).One of the well-known BW-resistant tomato cultivars is Hawaii 7996, which exerts the most stable resistance against R. solanacearum infection by several major and minor quantitative trait loci (QTL) (Thoquet et al., 1996; Wang et al., 1998).It is known that the performance of quantitative resistance in Hawaii 7996 is frequently influenced by environmental conditions such as the pathogen strain, temperature, and soil conditions (Wang et al., 2013).Various factors in the rhizosphere affect the composition of the microbial community (Marschner et al., 1986; Dennis et al., 2010).Both biotic and abiotic factors are reported to shape the structural and functional diversities of microbial communities in the rhizosphere (Berg and Smalla, 2009; Bulgarelli et al., 2012; Lundberg et al., 2012).There is growing evidence that suggests the role of the rhizosphere microbiome in protecting the plant against soil-borne diseases (Kyselková et al., 2009; Chialva et al., 2018; Kwak et al., 2018).Although soil properties also contribute to plant growth and health, the physicochemical properties frequently mask the microbial function that regulates plant traits.In this study, we used soil microbiota transplant in tomato plants under defined soil condition to investigate the disease progress of BW in tomato.However, in this study, we focused on the microbiota associated with the resistant cultivar Hawaii 7996 to investigate the role of tomato rhizosphere microbiota in influencing BW resistance.Our hypothesis is that soil microbiota transplant contributes to the formation of distinct rhizosphere microbial communities and to subsequently affect plant traits, especially BW resistance in tomato.The soil MF was isolated from the soil samples using 170 g of soil.The mixture of soil and MES buffer was centrifuged at 500 rpm for 5 min to remove most of the soil particles.This final bacterial suspension derived from 170 g of soil was used as the soil MF for treating 10 tomato seedlings and for the comparison of bacterial community between bulk soil and soil MF (Supplementary Figure S2).The germination and plant growth conditions were 14 h/10 h of a light/dark regime at 28°C for all experiments.When necessary, the soil MF was diluted 10- or 100-fold with 2.5 mM MES buffer or was autoclaved at 121°C for 20 min before treatment to tomato seedlings.The final bacterial suspension was poured onto the soil in the pot containing soil MF-treated plants (grown for 3 weeks after soil MF treatment) at a final concentration of 1 × 107 CFU/g of soil (Supplementary Figure S1B).To investigate the population of R. solanacearum SL341 in the tomato rhizosphere and endosphere, Hawaii 7996 grown in sterilized nursery soil were treated with upland soil MF or forest soil MF, and then after 3 weeks, SL341 strain was inoculated.For disease scoring, three replications were used, each containing 10 plants for the soil MF treatment and control.In order to investigate whether the differential bacterial wilt resistance in Hawaii 7996 treated with soil MFs was due to direct antagonism to R.

solanacearum, the antimicrobial activity of the rhizosphere soil of Hawaii 7996 treated with either upland soil MF or forest soil MF was tested.The rhizosphere soil was collected from the tomato plants.The inoculated soil (1 g) from three replicates was collected to measure the colony forming units (CFUs) of R. solanacearum every 2.5 h until 10 h on semiselective SMSA medium (Engelbrecht, 1994).For Illumina sequencing of the 16S rRNA gene amplicon, amplicon libraries were developed using the PCR primers 341F and 805R (Herlemann et al., 2011).To identify taxa that were significantly different between the Hawaii 7996 rhizosphere microbiota under the ASPMI treated with two different soil MFs, we used DESeq2 package.However, the physicochemical properties were similar between the sterilized nursery soils that were treated with the four soil MFs (Supplementary Table S2 and Supplementary Figure S3).These results suggest that the ASPMI method successfully eliminated the differential effect of physicochemical properties among the field soil samples, which enabled the evaluation of plant–microbiota interactions under controlled soil conditions using various soil MFs.The bacterial community structure of both soil MFs and bulk soils was compared to determine whether the isolated soil MF represented the microbiota of the respective bulk soil.Therefore, this indicated that the isolated soil MFs represented the bacterial community of the respective bulk soils.The ASPMI method was used to test the differential effect of various soil MFs against BW disease in the BW-resistant tomato cultivar (Hawaii 7996) and BW-susceptible cultivar (Moneymaker).In this study, 18 different soil MFs from various natural ecosystems in Korea were used to test BW resistance by inoculation of R. solanacearum strain SL341.Each microbiota transplant exhibited differential BW progress in the resistant cultivar Hawaii 7996 (Figure 1A and Supplementary Figure S4).To further investigate the effect of microbiota on BW resistance on Hawaii 7996, four different soils from various natural ecosystems in Korea were selected based on the distinct and differential quantitative resistance of tomato BW and the reproducibility of the results after several repetitive experiments.The BW disease progression was significantly different among the soil MF-treated Hawaii 7966 plants.Treatment of upland soil MF was more effective to suppress disease progress in the Hawaii 7996 cultivar The forest soil MF-treated Hawaii 7996 plants exhibited the highest susceptibility to BW disease.However, the progression of BW in Moneymaker plants was similar among the plants treated with different soil MFs (Figure 1B).Figure 1 Bacterial wilt (BW) disease progression in tomato cultivars treated with soil microbial fractions (MFs) evaluated by ASPMI method.BW disease progression by R. solanacearum SL341 in the tomato cultivar Hawaii 7996 treated with four different soil MFs (A) and in the susceptible cultivar Moneymaker treated with soils MFs (B).BW disease progression in the Hawaii 7996 cultivar inoculated with six different R.

solanacearum strains (C).Evaluation of BW disease progression by R. solanacearum LMG 17139 strain in Hawaii 7996 treated with upland soil MF or forest soil MF (D).Effect of heat-killed soil MFs (autoclave MF) (E) on BW disease progression in the Hawaii 7996 cultivar.Bacterial population of SL341 in the tomato roots was not significantly different at 5 dpi between upland soil MF transplant and forest soil MF transplant, while that with forest soil MF transplant was significantly higher than that with upland soil MF transplant at 14 dpi (Figure 2B).Similarly, bacterial population of SL341 in the tomato stems was not significantly different at 5 dpi between upland soil MF transplant and forest soil MF transplant.Overall, the bacterial population of SL341 in tomato roots and stems treated with different soil MFs was coincident to the bacterial wilt progress in Hawaii 7996 (Figure 1A).Figure 2 Population dynamics of R. solanacearum SL341 in the tomato rhizosphere (A), roots (B), stems (C) of resistant cultivar treated by upland soil MF and forest soil MF over time.Hawaii 7996 is highly resistant to R.

solanacearum strains; however, this cultivar was susceptible to strain SL341 in sterile soil without microbiota transplantation.Therefore, we tested whether other strains of R. solanacearum could affect BW resistance under the same conditions.Furthermore, the upland soil MF-treated Hawaii 7996 cultivar inoculated with the LMG17139 strain exhibited significantly (repeated measures ANOVA, p < 0.001) delayed BW disease progression compared to the control and forest soil MF (Figure 1D).No significant difference of disease progress was observed between control and forest soil MF.Next, the effect of soil MF on BW disease progression was evaluated by treating the Hawaii 7996 cultivar with autoclaved (heat-killed) soil MFs.Although each soil MF affected BW disease progression in the BW-resistant Hawaii 7996 cultivar but not in the BW-susceptible cultivar, we needed to test whether the rhizosphere microbiota of Hawaii 7996 treated by upland soil MF would inhibit the growth of bacterial pathogens by direct antagonistic effects.To test this, we incubated R.

solanacearum SL341 in the rhizosphere soils from Hawaii 7996 cultivars treated with an upland soil MF or a forest soil MF.Effect of Transplanted Soil MFs on the Microbiota Structure in the Tomato Rhizosphere.The effect of soil MF or MES buffer treatment (control) on the bacterial community structure was investigated in the tomato rhizosphere.Comparative analysis of alpha-diversity indices [Shannon diversity index (H′)] revealed that there was a significant difference in the alpha diversity of the tomato rhizosphere microbiota (ANOVA with HSD post hoc test, p < 0.05), except between the rhizosphere microbiota of control and alluvial soil MF-treated plants and between the rhizosphere microbiota of paddy soil MF-treated and forest soil MF-treated plants.Bray–Curtis dissimilarity multivariate analysis was performed for tomato rhizosphere microbiota post soil MF treatment.ADONIS revealed that the rhizosphere microbiota of Hawaii 7996 exhibited significant differences in the microbial community structure between the groups (R2 = 0.37946, p < 0.001).Figure 3 Microbial community analysis of rhizosphere in the Hawaii 7996 cultivar treated with different soil microbial fractions (MFs).(A) Comparative alpha-diversity analysis of bacterial community among the bacterial wilt (BW)-resistant Hawaii 7996 cultivars treated with four different MFs.Additionally, the rhizosphere microbiota of tomato plants was distinct from the microbiota of bulk soils in the same pot, which contained the initially treated MFs.There was no significant difference in species richness and evenness between the rhizosphere and bulk soils treated with upland soil MF and forest soil MF (Supplementary Figure S6A).Bray–Curtis dissimilarity measures revealed that there was a significant difference (R2 = 0.37838, p < 0.001) in the microbial communities among bulk soils and rhizosphere soils of tomato plants treated with the upland soil MF or forest soil MF (Supplementary Figure S6B).The microbial community composition of the tomato rhizosphere was comparatively evaluated between the upland soil MF-treated and forest soil MF-treated plants.The rhizosphere microbiota of the upland soil MF-treated tomato plants was different from that of forest soil MF-treated tomato plants (Figures 3A, B).The potential candidate OTUs for the network hub, module hub, and connector were identified based on the rhizosphere microbial community data of upland soil MF-treated (Figure 4A) and forest soil MF-treated tomato plants (Figure 4B).The network analysis revealed that the peripherals were the most abundant nodes in the network hub.Additionally, no network hub was detected in the rhizosphere of upland and forest soil MF-treated tomato plants (Figures 4C, D).Figure 4 Co-occurrence network of rhizosphere of tomato treated with upland soil microbial fraction (MF) (A) and forest soil MF (B).Each symbol represents an OTU from rhizosphere network of upland soil MF-treated plants (C) and forest soil MF-treated plants (D) adopted for detailed module analysis.The RA of microbes in the module hubs ranged from 0.496 to 1.042% for upland soil MF-treated plants and from 0.451 to 1.158% for forest soil MF-treated plants (Supplementary Figure S7).The number of network topological properties was compared among the rhizospheres of tomato treated with four different soil MFs.The microbiota network of the rhizosphere of upland soil MF-treated plants exhibited a higher number of network topological properties than the rhizosphere of forest soil MF-treated plants (Supplementary Table S6).Figure 5 Relative abundance (%) of the keystone taxa in co-occurrence network of rhizosphere in the upland soil MF-treated plants (A) and forest soil MF-treated plants (B).The critical factors determining the structure of rhizosphere microbiota are the soil type and soil physicochemical properties (Schutter et al., 2001; Bulluck et al., 2002; Marschner et al., 2004; İnceoğlu et al., 2012).Because the physiochemical properties of soil strongly influence the rhizosphere microbiome structure (Staley and Konopka, 1985; Amann et al., 1995; Hugenholtz et al., 1998; Lauber et al., 2008), we established the ASPMI method to evaluate the BW resistance of tomatoes treated with various soil MFs under sterile soil conditions.It is likely that application of soil MFs to aseptically germinated tomato seedlings aided in microbial colonization of the rhizosphere of tomato to sculpt a unique rhizosphere microbial community in the sterilized soil.In this study, the upland soil MF-treated Hawaii 7996 cultivars exhibited higher BW disease resistance than the plants treated with other soil MFs.Interestingly, the soil MF treatment did not protect the BW-susceptible cultivar Moneymaker (Figures 1A, B).However, the MFs of upland soil and forest soil did not exhibit any antimicrobial effect against R. solanacearum (Supplementary Figure S5).This suggested that pathogen invasion was not affected by microbiota transplant in tomato roots, and there might be no antagonistic effect by upland soil MF to bacterial pathogen.Interestingly, in the same BW-resistant tomato cultivar, bacterial population of SL341 in planta was dramatically increased over time by forest soil MF treatment but not by upland soil MF treatment (Figure 2).It is likely that microbiota transplant somehow influenced the BW resistance of tomato Hawaii 7996 to have altered disease progress, i.e. tomato plants with upland soil-derived microbiota hindered the multiplication of bacterial pathogen in planta.Several reports have illustrated that R. solanacearum in the resistant tomato cultivar is limited to colonize inside of tomato plants and not able to multiply in the stem, although the resistant cultivar contains significant number of bacteria in the roots and shoots (Grimault et al., 1994; Saile et al., 1997).The upland soil MF treatment conferred higher resistance to BW only in the BW-resistant cultivar, which further indicated that the alteration of BW disease resistance is mediated by the rhizosphere microbiome.It would be interesting to evaluate whether certain groups of microbial taxa or the microbial community enhance BW disease susceptibility in BW-resistant cultivars.In this study, the ASPMI method was used to harvest microbes to obtain the soil MF from a variety of natural bulk soils and to analyze the biological effect of the isolated soil MF.However, the soil MF enabled the reproducible investigation of plant host response, i.e., tomato BW resistance, to its microbiota compared to the field soil microbiota.In this study, two soil MFs, upland soil MF and forest soil MF, displayed differential effects on the BW resistance of Hawaii 7996 under ASPMI.Similarly, the rhizosphere bacterial community structure was significantly different between the upland soil MF-treated and forest soil MF-treated tomato plants (Figure 3A).These results indicate that the differential composition of bacterial taxa observed in the rhizosphere of the plants treated with various soil MFs may potentially influence the BW resistance.In this study, most of the network nodes and connectors in the rhizosphere of upland soil MF-treated and forest soil MF-treated plants exhibited a relatively low abundance of putative keystone taxa (Supplementary Figure S7).The rhizosphere microbiome of upland soil MF-treated plants exhibited a higher complexity in the network in this study.The rhizosphere network of upland soil MF-treated plants contained more nodes and edges when compared to the rhizosphere network of forest soil MF-treated plants.It would be interesting to investigate how the rhizosphere microbiota influences BW resistance in Hawaii 7996 once the genes are cloned.In conclusion, our ASPMI method can successfully be used to evaluate the effects of microbiota transplantation on the BW resistance of tomatoes, and this study is the first to show that quantitative traits of plant, such as disease resistance, can be altered by soil microbiota transplantation.Plant species and soil type cooperatively shape the structure and function of microbial communities in the rhizosphere.Plant P. 44, 105–123.Plant Soil 261, 199–208.nov., R. solanacearum phylotype IV strains as Ralstonia syzygii subsp.Soils 34, 397–410.

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Tomato Diseases: Bacterial Wilt

Water and nutrients can’t reach branches and leaves, starving the plant.This 20-page guide is filled with tips you need to know to have a successful tomato crop, whether you’re a beginning or experienced gardener.Interior of main stem (when split) is dark and water-soaked, the result of plugged water-conducting tissue.Bacteria are most active in temperatures above 75ºF, in wet conditions, and when soil has a high pH.Cut a portion of an infected stem (for best results, choose one at or near ground level).Look for the telltale white, milky ooze running out of cut stem end.Avoid physical damage to roots and stems, especially when planting and cultivating.Control root-knot nematodes, which are known to weaken tomato roots and allow bacteria access to plants.Avoid planting other Solanaceous crops (potato, pepper, and eggplant) in the same area, too – they are susceptible to the bacterium.Avoid planting other crops (potato, pepper, and eggplant) in the same area, too – they are susceptible to the bacterium.Neptune, Tropic Bay, and Kewalo are varieties that are considered to be partially resistant to bacterial wilt, although they are not commonly grown.Neptune, Tropic Bay, and Kewalo are varieties that are considered to be partially resistant to bacterial wilt, although they are not commonly grown.Bacterial wilt also attacks eggplant, pepper, potato, cosmos, and sunflower.As an Amazon Associate and Rakuten Advertising affiliate I earn from qualifying purchases. .

Partial Resistance to Bacterial Wilt in Transgenic Tomato Plants

Tomato line F7926-96, susceptible to bacterial wilt, was transformed with Agrobacterium strain C58C1 containing a plasmid construction carrying a modified LF cDNA. .

Tomato: Big Beef Southern Bacterial Wilt

Southern Bacterial Wilt is a disease of tomatoes, eggplant, pepper, potato and sunflowers.Some tomato varieties are resistant (Saturn, Venus, Neptune, Tropic Bay, and Kewalo).To test for Southern Bacterial Wilt in tomatoes, cut a piece of stem from near ground level and put it in a jar of water. .

Yield and Disease Resistance for Three Bacterial Wilt-resistant

The determinate hybrid tomato ‘Red Mountain’, which is susceptible to bacterial wilt, was used as the scion and nongrafted control.Valued at $1.24 billion, fresh market tomato is the second most valuable vegetable crop grown in the United States [U.S. Department of Agriculture (USDA), 2016].Ralstonia solanacearum race 1 is an economically devastating soilborne pathogen that affects tomato throughout the southeastern United States (Ji et al., 2007; McAvoy et al., 2012).Grafting of susceptible tomato cultivars onto resistant rootstocks is an effective cultural technique for managing BW (McAvoy et al., 2012; Rivard and Louws, 2008).McAvoy et al. (2012) noted that certain rootstocks may improve yield compared with nongrafted plants when grown in conditions with low amounts of BW.Research using grafted tomato grown in greenhouses and open-field conditions lacking any history of soilborne pathogens has shown that certain rootstocks can increase fruit size, weight, and count compared with nongrafted controls (Kyriacou et al., 2017).To address the lack in information on commercially available BW-resistant rootstocks, we conducted the following study with the objectives of 1) assessing BW resistance of three resistant rootstocks in a commercial tomato field with known history of BW infestation, 2) determine whether there are yield benefits or penalties when using these rootstocks in conditions with no recent history of BW in open field production, and 3) compare the effects of grafting on yield in different climatic regions of North Carolina.HCRS and PRS were chosen as they represent the two largest vegetable producing regions in North Carolina.Scions were initially pruned to two leaders and the nongrafted control to one, which is the commercial standard practice for the production area (Fig.Nongrafted tomato plants showing severe bacterial wilt symptoms at the on-farm location in Salisbury, NC in naturally infested soils.Nongrafted tomato plants showing severe bacterial wilt symptoms at the on-farm location in Salisbury, NC in naturally infested soils.Nongrafted tomato plants showing severe bacterial wilt symptoms at the on-farm location in Salisbury, NC in naturally infested soils.Soil type at HCRS was an Orangeburg sandy loam with pH 6.2 and cation exchange capacity (CEC) of 4.0 meq/100 cm3.Preplant soil fumigation of 147 lb/acre chloropicrin + 86 lb/acre 1,3-dichloropropene (PicChlor-60; Cardinal Professional Products, Hollister, CA) occurred both years at PRS and HCRS.Prebedding lime and fertilizer application followed the North Carolina Department of Agriculture and Consumer Services Agronomic Division recommendations based on soil test results (Hardy et al., 2014).Weekly fertigation and pesticide applications followed standard management practices for the southeastern United States (Kemble et al., 2016).Individual blocks consisted of a raised bed 6 inches high by 5 ft wide and were prepared under North Carolina standard plasticulture protocols (Ivors, 2010).One initial pruning occurred to remove suckers early in the season and plants were trained using the stake and weave method (Kemble et al., 2016).Stand counts based on the number of plants unaffected by BW were collected during harvest at OF (Fig.Two to three harvests per location occurred at the end of the season once fruit reached the mature green/early breaker stage (USDA, 1991).Additionally, the combined weights and counts for all three grades were calculated and represent total marketable fruit.Stand count at OF was analyzed by year to account for potentially different levels of BW infestation.When appropriate, Tukey’s honestly significant difference was used as a post hoc mean separation test, and, for reporting, data were back-transformed.

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Bacterial Wilt in Tomato Plants

Warning signs: The plant may start to look wilted in the mornings but then perk up over the course of the day.Bacterial wilt can live for years in soil without a host plant present.Weeds that can act as hosts to the bacteria without showing symptoms of bacterial wilt.If you suspect bacterial wilt in your garden (and even if you don’t), follow these tips to prevent its spread:.To be safe, dig out the soil around the plants too, rather than pulling them and leaving infected root fragments behind.Immediately remove and burn any affected plants before the bacteria are released back into the soil.To be safe, dig out the soil around the plants too, rather than pulling them and leaving infected root fragments behind.Minimize Injury: Don’t over cultivate plants, and be very careful not to damage roots.Garden Smart: Work in infested areas last, then disinfect implements immediately afterward with bleach.You can also try solarizing your garden soil, although this has shown limited results with bacterial wilt.You can also try solarizing your garden soil, although this has shown limited results with bacterial wilt.Check with your local agricultural extension service to find out if any varieties are working in your area. .

Bacillus amyloliquefaciens Strain PMB05 Intensifies Plant Immune

strains are able to confer disease resistance to bacterial wilt, their effects on PTI signals triggered by PAMP from R. solanacearum and on the occurrence of bacterial wilt were assayed.Before assay, a gene that encodes harpin from R.

solanacearum , PopW, was applied as a PAMP.Results revealed that the B. amyloliquefaciens strain PMB05 was the one strain among 9 Bacillus rhizobacterial strains which could significantly intensify the PopW-induced hypersensitive response (HR) on Arabidopsis leaves.strains on tomato plants showed that only the use of PMB05 resulted in significantly increased resistance to bacterial wilt.Moreover, the PTI signals were also intensified in the tomato leaves.In this study, we sought to determine the effects of strains of Bacillus species on the PTI signals activated by a PAMP from R.

solanacearum and their contribution to disease resistance against bacterial wilt disease.strains isolated from rhizosphere on PopW-mediated HR, rapid ROS generation, and callose deposition in Arabidopsis plants were then assayed.The 3-week-old plants were then used in further experiments, including a HR assay, plant defense signals assay, and biocontrol efficacy assay.Bacterial wilt pathogen from tomato, R. solanacearum strain Ps152, was incubated on an 2,3,5-triphenyltetrazolium chloride (TZC) agar plate at 28°C for 48 h (Kelman 1954; Lin et al.

2010).To assay the effect of Bacillus spp.strains on PopW-triggered callose deposition, the leaves of A. thaliana Col-0 were infiltrated with the mixture containing the protein extract of PopW and the bacterial suspension of each Bacillus sp.strain.To assay the effect of Bacillus strains on PopW-induced rapid H 2 O 2 generation, an observation was performed at 1 h postinfiltration with the mixture containing the protein extract of PopW and the bacterial suspension of each Bacillus sp.strain.In order to determine whether the Bacillus-intensified HR was associated with the PTI, the reduction of the HR ratio on Arabidopsis thaliana Col-0 was assayed upon the inhibition of calcium influx and NADPH oxidase.Intensification of PAMP-mediated ROS generation and callose deposition by B. amyloliquefaciens strain PMB05 on tomato.To observe the effect of B. amyloliquefaciens strain PMB05 on PAPM-triggered callose deposition and ROS generation, tomato leaves were infiltrated as described above.The HR ratios for Arabidopsis leaves produced with 0.5, 1.0, 1.5, and 2.0 mg/ml of PopW protein were 22.8, 41.9, 56.3, and 69.6%, respectively (Fig.Intensification of PopW-induced HR by Bacillus spp.strains did not induce HR in the leaves of A. thaliana Col-0 plants.The results indicated that none of the bacterial strains increased the PopW-induced HR ratio significantly, except strain PMB05 (Fig.The PMB05 strain increased the HR ratio to 45.2%, a significant increase from 21.4% in the treatment with PopW alone.PopW-induced hypersensitive response (HR) ratio intensified by Bacillus spp.The assay was performed with the mixtures of PopW and bacterial suspensions of distinct Bacillus spp.Intensification of PopW-mediated callose deposition by Bacillus spp.strains.To assess the association between increasing HR and PTI activation, the intensification of PopW-mediated callose deposition and H 2 O 2 generation by PMB05 was assayed on Arabidopsis plants.However, no signal was observed in the treatment with PMB05, DR237, DR238, DR242, DR243, DR244, DR258, DR301, or DR303 alone.However, the assay showed no visible increase in the signals in the treatments with other Bacillus spp.Compared with the treatment with PopW alone, the intensity in the PopW treatment with PMB05 was significantly increased to 467.4%, whereas the intensities with DR237, DR238, DR242, DR243, DR244, DR258, DR301, and DR303 were 90.9, 76.5, 91.0, 85.4, 102.1, 110.4, 81.8, and 93.5%, respectively (Fig.strains on callose deposition upon PopW treatment in Arabidopsis thaliana.A, Results of the callose deposition induced by the infiltration with PopW alone or the mixtures of PopW and distinct Bacillus spp.strains in Arabidopsis plants.Intensification of PopW-mediated ROS generation by Bacillus spp.strains.strain alone.Compared with the treatment with PopW alone, the intensity in the PopW treatment with PMB05 was significantly increased to 323.8%.Meanwhile, the intensities in the treatments with DR237, DR238, DR242, DR243, DR244, DR258, DR301, and DR303 were 80.1, 70.4, 82.4, 95.2, 78.3, 87.9, 121.0, and 88.4%, respectively (Fig.A, Rapid H 2 O 2 generation induced by PopW alone or the mixtures of PopW and distinct Bacillus spp.strains in Arabidopsis plants.To observe the rapid ROS generation, the infiltrated leaves were collected and stained with 20 μM of H 2 DCFDA at 1 h postinfiltration.The results revealed that the PopW-mediated HR was intensified by PMB05 to 50.2% compared with 23.9% with the blank treatment (Fig.Disease resistance intensified by Bacillus sp.To assess whether the resistance against bacterial wilt was improved by strain PMB05, the disease severity on tomato caused by R. solanacearum Ps152 was assayed.The results revealed that the disease severity following PMB05 treatment (36.7%) was lower than that following DR237 (73.5%), DR238 (56.8%), DR242 (54.2%), DR243 (59.1%), DR244 (62.5%), DR258 (83.7%), DR301 (72.4%), DR303 (68.9%), and control treatment (86.6%) at 1 week postinoculation (Fig.strains on control of tomato bacterial wilt.The treatments with the Bacillus sp.Intensification of PAMP-mediated ROS generation and callose deposition by B.

amyloliquefaciens strain PMB05 on tomato.To connect the intensification of PTI by B. amyloliquefaciens strain PMB05 with the disease resistance to bacterial wilt of tomato, the effects of PMB05 on PAMP-mediated ROS generation and callose deposition were assayed on tomato leaves.Compared with the treatments with flg22 Rs and PopW alone, the intensities were significantly increased to 545.5 and 1,026.1%, respectively (Fig.Compared with the treatments with flg22 Rs and PopW alone, the intensities were significantly increased to 320.1 and 251.1%, respectively (Fig.In the analyses of both callose deposition and rapid ROS generation, the PMB05 did not induce the production of fluorescent signals as these result in a blank treatment.In the callose deposition assay, the F values for the flg22 Rs and PopW treatments were 309.28 and 607.51, respectively.In the ROS generation assay, the F values for the flg22 Rs and PopW treatments were 303.61 and 83.12, respectively.The results revealed that the growth of R.

solanacearum was inhibited by all the tested Bacillus spp.strains.In this study, we sought to screen bacterial strains from rhizosphere that could intensify PTI to further confer disease resistance against bacterial wilt of tomato caused by R. solanacearum.In this study, then, we expressed and purified the PopW protein from E. coli, and HR necrosis was induced in the infiltrated areas of Arabidopsis leaves postinfiltration.The intensification of PopW-induced HR carried out with Bacillus spp.Increased HR ratios were not observed, however, following the treatments performed with most Bacillus spp.strains.Among all the tested strains, in fact, the B.

amyloliquefaciens strain PMB05 was the only strain that increased the HR ratio upon the infiltration of PopW.Similar results of PTI signal intensification by strain PMB05 were observed in the treatment of PopW in this study.The results indicated that the PTI-intensifying strain, PMB05, was the most effective strain in terms of increasing disease resistance.To link such increased disease resistance in tomato plants with the PTI intensification caused by PMB05, analyses of the defense signals of tomato plants are required.Interestingly, PMB05 is the only strain that has weak antagonistic effects but still effectively enhances resistance to tomato bacterial wilt.Taken together, our results led us to conclude that the disease resistance against tomato bacterial wilt enhanced by B. amyloliquefaciens PMB05 is associated with its intensification of PTI-triggered defense responses.

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MPMI Journal 1994

In plants inoculated through roots, genomic regions on chromosomes 6 and 10 were correlated with resistance.To confirm the existence of a partial resistance gene on chromosome 6, an F 2 individual homozygous for the resistant parent's alleles on chromosomes 7 and 10, but heterozygous for markers on chromosome 6, was selfed.The presence of a partial resistance locus on chromosome 10 was similarly confirmed by analysis of progeny of another F 2 plant chosen on the basis of its marker phenotype. .

Assessment of resistance to bacterial wilt incited by Ralstonia

Bacterial wilt incited by Ralstonia solanacearum has been found the most damaging and widespread diseases of tomato throughout the world and causes heavy yield losses.The symptoms were first observed on leaves and then progressed toward other parts of plants resulting in complete wilting in susceptible cultivars within 14 days. .

MPMI Journal 1996

Several loci governing resistance to bacterial wilt, a disease caused by Ralstonia solanacearum, have been mapped in tomato {Lycopersicon esculentum).An F 2 population derived from a cross between a highly resistant cultivar, Ha-waii7996, and a very susceptible line of L. pimpinellifolium, WVa700, was used to develop a map of molecular markers.Nine independent resistance tests were done on cuttings from plants of this population in a controlled environment culture chamber. .

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