Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 70
Filter
1.
ISME J ; 18(1)2024 Jan 08.
Article in English | MEDLINE | ID: mdl-38365227

ABSTRACT

Tailocins are headless phage tail structures that mediate interbacterial antagonism. Although the prototypical tailocins, R- and F-pyocins, in Pseudomonas aeruginosa, and other predominantly R-type tailocins have been studied, their presence in Alphaproteobacteria remains unexplored. Here, we report the first alphaproteobacterial F-type tailocin, named rhizoviticin, as a determinant of the biocontrol activity of Allorhizobium vitis VAR03-1 against crown gall. Rhizoviticin is encoded by a chimeric prophage genome, one providing transcriptional regulators and the other contributing to tail formation and cell lysis, but lacking head formation genes. The rhizoviticin genome retains a nearly intact early phage region containing an integrase remnant and replication-related genes critical for downstream gene transcription, suggesting an ongoing transition of this locus from a prophage to a tailocin-coding region. Rhizoviticin is responsible for the most antagonistic activity in VAR03-1 culture supernatant against pathogenic A. vitis strain, and rhizoviticin deficiency resulted in a significant reduction in the antitumorigenic activity in planta. We identified the rhizoviticin-coding locus in eight additional A. vitis strains from diverse geographical locations, highlighting a unique survival strategy of certain Rhizobiales bacteria in the rhizosphere. These findings advance our understanding of the evolutionary dynamics of tailocins and provide a scientific foundation for employing rhizoviticin-producing strains in plant disease control.


Subject(s)
Bacteriophages , Vitis , Plant Tumors/microbiology , Plant Diseases/prevention & control , Plant Diseases/microbiology , Pseudomonas aeruginosa , Bacteriophages/genetics , Vitis/microbiology
2.
Mol Clin Oncol ; 20(2): 15, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38274088

ABSTRACT

Eribulin is widely used to treat metastatic breast cancer (BC). Higher neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are associated with higher mortality in several cancer types. However, the association between BC prognosis and peripheral immune status remains controversial. In the present study, the relative effects of NLR and PLR on survival in patients with metastatic BC were quantified and their clinical prognostic value was evaluated. This retrospective study included 156 patients with metastatic BC who received eribulin monotherapy at Saitama Medical University International Medical Center. Clinicopathological features were examined (peripheral blood findings and biochemical liver and kidney function test results) and univariate and multivariate analyses were conducted of the overall survival (OS). The 156 patients treated with eribulin had a median follow-up duration of 18.3 months. Before eribulin treatment, patients with absolute lymphocyte counts (ALC) >1,500/µl, NLR <3.0, and PLR <150 had significantly longer OS than those with lower ALC, and higher NLR and PLR (median OS, 25.5 vs. 15.5 months; P<0.01; 20.3 vs. 13.6 months, P<0.01; and 29.2 vs. 14.8 months; P<0.001, respectively). Patients with anemia [hemoglobin (Hb) <10 g/dl] or liver dysfunction [albumin-bilirubin (ALBI) grade 2/3] had significantly shorter OS than those without (P<0.001, respectively). Multivariate analysis revealed low ALBI grade (P<0.001), high Hb (P<0.01) and low PLR (P<0.05) as independent factors of longer OS after eribulin administration. Low PLR, anemia and liver dysfunction might be factors associated with prolonged OS in patients with metastatic BC on eribulin therapy, which could be clinically useful, as their evaluation requires neither new equipment nor invasive testing.

3.
Oncol Lett ; 26(5): 495, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37854859

ABSTRACT

Collagen disorders are chronic autoimmune diseases with a complex clinical course; however, the risk of breast cancer in patients with collagen disorders remains unclear. The present study aimed to investigate long-term outcomes in women with breast cancer and collagen disorders. A total of 25 patients with breast cancer and collagen disorders who were treated between January 2004 and December 2011 were included. The clinicopathological factors, treatment, recurrence-free survival (RFS) and overall survival (OS) were reviewed. The mean age was 56.4±12.6 years, and 14, eight and three patients had cancer of clinical stages I, II and III, respectively. Regarding comorbid collagen disorders, 11 patients had rheumatoid arthritis, four had systemic lupus erythematosus, four had polymyositis/dermatomyositis, two had mixed connective tissue disease, two had Sjogren's syndrome, one had scleroderma and one had adult-onset Still's disease. The expression statuses of hormone receptors (HR) and human epidermal growth factor receptor 2 (HER2) were HR(+), HER2(+) and HR(-)HER2(-) in 20 (80.0%), four (16.0%) and four (16.0%) patients, respectively. A total of 22 (84.0%) patients received steroids or immunosuppressive drugs for collagen disorders. The collagen disorder group had a higher mean Ki-67 labeling index than the control group (41.1 vs. 20.8%; P=0.007). After median observation periods of 103 and 114 months, the RFS and OS rates were lower in the collagen group than in the control group (64.5 and 80.7% vs. 85.3 and 94.3%, respectively; P<0.01). Patients with breast cancer and collagen disorders had relatively high Ki-67 expression, and relatively low RFS and OS rates. Thorough follow-up is necessary for patients with breast cancer who also have collagen disorders and high Ki-67 values.

4.
Pathol Int ; 73(9): 413-433, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37378453

ABSTRACT

Vimentin is a stable mesenchymal immunohistochemical marker and is widely recognized as a major marker of mesenchymal tumors. The purpose of the present study was to investigate if the vimentin expression status might serve as a significant predictor of outcomes in patients with invasive breast carcinoma of no special type (IBC-NST) and to investigate, by comprehensive RNA sequencing analyses, the mechanisms involved in the heightened malignant potential of vimentin-positive IBC-NSTs. This study, conducted using the data of 855 patients with IBC-NST, clearly identified vimentin expression status as a very important independent biological parameter for accurately predicting the outcomes in patients with IBC-NST. RNA sequence analyses clearly demonstrated significant upregulation of coding RNAs known to be closely associated with cell proliferation or cellular senescence, and significant downregulation of coding RNAs known to be closely associated with transmembrane transport in vimentin-positive IBC-NSTs. We conclude that vimentin-positive IBC-NSTs show heightened malignant biological characteristics, possibly attributable to the upregulation of RNAs closely associated with proliferative activity and cellular senescence, and downregulation of RNAs closely associated with transmembrane transport in IBC-NSTs.


Subject(s)
Breast Neoplasms , Humans , Female , Vimentin , Breast Neoplasms/pathology
5.
Microorganisms ; 11(4)2023 Apr 14.
Article in English | MEDLINE | ID: mdl-37110448

ABSTRACT

Pseudomonas cannabina pv. alisalensis (Pcal) causes bacterial blight on cabbage. We previously conducted a screening for reduced virulence using Tn5 transposon mutants and identified one of the transcriptional factors, HexR, as a potential Pcal virulence factor. However, the role of HexR in plant pathogenic Pseudomonas virulence has not been investigated well. Here, we demonstrated that the Pcal hexR mutant showed reduced disease symptoms and bacterial populations on cabbage, indicating that HexR contributes to Pcal virulence. We used RNA-seq analysis to characterize the genes regulated by HexR. We found that several type three secretion system (T3SS)-related genes had lower expression of the Pcal hexR mutant. Five genes were related to T3SS machinery, two genes were related to type three helper proteins, and three genes encoded type three effectors (T3Es). We also confirmed that T3SS-related genes, including hrpL, avrPto, hopM1, and avrE1, were also down-regulated in the Pcal hexR mutant both in culture and in vivo by using RT-qPCR. T3SS functions to suppress plant defense in host plants and induce hypersensitive response (HR) cell death in non-host plants. Therefore, we investigated the expression profiles of cabbage defense-related genes, including PR1 and PR5, and found that the expressions of these genes were greater in the Pcal hexR mutant. We also demonstrated that the hexR mutant did not induce HR cell death in non-host plants, indicating that HexR contributes in causing HR in nonhost plants. Together, these results indicate that the mutation in hexR leads to a reduction in the T3SS-related gene expression and thus an impairment in plant defense suppression, reducing Pcal virulence.

7.
Front Plant Sci ; 13: 1004184, 2022.
Article in English | MEDLINE | ID: mdl-36186055

ABSTRACT

Plants protect themselves from microorganisms by inducing pattern-triggered immunity (PTI) via recognizing microbe-associated molecular patterns (MAMPs), conserved across many microbes. Although the MAMP perception mechanism and initial events during PTI have been well-characterized, knowledge of the transcriptomic changes in plants, especially monocots, is limited during the intermediate and terminal stages of PTI. Here, we report a time-series high-resolution RNA-sequencing (RNA-seq) analysis during PTI in the leaf disks of Brachypodium distachyon. We identified 6,039 differentially expressed genes (DEGs) in leaves sampled at 0, 0.5, 1, 3, 6, and 12 hours after treatment (hat) with the bacterial flagellin peptide flg22. The k-means clustering method classified these DEGs into 10 clusters (6 upregulated and 4 downregulated). Based on the results, we selected 10 PTI marker genes in B. distachyon. Gene ontology (GO) analysis suggested a tradeoff between defense responses and photosynthesis during PTI. The data indicated the recovery of photosynthesis started at least at 12 hat. Over-representation analysis of transcription factor genes and cis-regulatory elements in DEG promoters implied the contribution of 12 WRKY transcription factors in plant defense at the early stage of PTI induction.

8.
Virchows Arch ; 481(2): 161-190, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35695928

ABSTRACT

Tumor budding grade is a very useful histological prognostic indicator for colorectal cancer patients. Recently, it has been also reported as a significant prognostic indicator in invasive breast carcinoma patients. Our group and others have previously reported that the presence of a fibrotic focus in the tumor is a very useful histological finding for accurately predicting the prognosis in patients with invasive carcinoma of no special type (ICNST) of the breast. The purpose of the present study was to investigate whether a grading system incorporating tumor budding in a fibrotic focus is superior to the conventional grading system for tumor budding to accurately predict outcomes in patients with ICNST. According to our new grading system, we classified the tumors into grade I (164 cases), grade II (581 cases), and grade III (110 cases), and the results clearly demonstrated the significant superiority of the new grading system over that of conventional tumor budding alone for accurately predicting outcomes in patients with ICNST. Our findings strongly suggest that tumor cells and tumor-stromal cells interaction play very important roles in tumor progression rather than tumor cells alone.


Subject(s)
Breast Neoplasms , Carcinoma , Breast/pathology , Breast Neoplasms/pathology , Carcinoma/pathology , Female , Fibrosis , Humans , Neoplasm Grading
9.
Mol Plant Pathol ; 23(6): 885-894, 2022 06.
Article in English | MEDLINE | ID: mdl-35233886

ABSTRACT

Pseudomonas amygdali pv. tabaci (formerly Pseudomonas syringae pv. tabaci; Pta) is a gram-negative bacterium that causes bacterial wildfire disease in Nicotiana tabacum. The pathogen establishes infections by using a type III secretion system to inject type III effector proteins (T3Es) into cells, thereby interfering with the host__s immune system. To counteract the effectors, plants have evolved disease-resistance genes and mechanisms to induce strong resistance on effector recognition. By screening a series of Pta T3E-deficient mutants, we have identified HopAZ1 as the T3E that induces disease resistance in N. tabacum 'N509'. Inoculation with the Pta ∆hopAZ1 mutant did not induce resistance to Pta in N509. We also found that the Pta ∆hopAZ1 mutant did not induce a hypersensitive response and promoted severe disease symptoms in N509. Furthermore, a C-terminal truncated HopAZ1 abolished HopAZ1-dependent cell death in N509. These results indicate that HopAZ1 is the avirulence factor that induces resistance to Pta by N509.


Subject(s)
Nicotiana , Wildfires , Bacterial Proteins/metabolism , Plant Diseases/microbiology , Pseudomonas , Pseudomonas syringae , Nicotiana/microbiology
10.
Microbes Environ ; 37(1)2022.
Article in English | MEDLINE | ID: mdl-35264479

ABSTRACT

Pseudomonas syringae pv. tabaci 6605 (Pta6605) is a foliar plant pathogen that causes wildfire disease on tobacco plants. It requires chemotaxis to enter plants and establish infection. While chemotactic signals appear to be the main mechanism by which Pta6605 performs directional movement, the involvement of aerotaxis or energy taxis by this foliar pathogen is currently unknown. Based on domain structures and similarity with more than 50 previously identified putative methyl-accepting chemotaxis proteins (MCPs), the genome of Pta6605 encodes three potential aerotaxis transducers. We identified AerA as the main aerotaxis transducer and found that it possesses a taxis-to-serine-and-repellent (Tsr)-like domain structure that supports a periplasmic 4HB-type ligand-binding domain (LBD). The secondary aerotaxis transducer, AerB, possesses a cytosolic PAS-type LBD, similar to the Aer of Escherichia coli and Pseudomonas aeruginosa. Aerotaxis ability by single and double mutant strains of aerA and aerB was weaker than that by wild-type Pta6605. On the other hand, another cytosolic PAS-type LBD containing MCP did not make a major contribution to Pta6605 aerotaxis in our assay system. Furthermore, mutations in aerotaxis transducer genes did not affect surface motility or chemotactic attraction to yeast extract. Single and double mutant strains of aerA and aerB showed less colonization in the early stage of host plant infection and lower biofilm production than wild-type Pta6605. These results demonstrate the presence of aerotaxis transducers and their contribution to host plant infection by Pta6605.


Subject(s)
Chemotaxis , Pseudomonas syringae , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Chemotaxis/genetics , Escherichia coli/metabolism , Methyl-Accepting Chemotaxis Proteins , Plant Diseases , Pseudomonas syringae/genetics , Pseudomonas syringae/metabolism , Nicotiana
11.
Life (Basel) ; 12(1)2022 Jan 06.
Article in English | MEDLINE | ID: mdl-35054469

ABSTRACT

Rhizoctonia solani is a necrotrophic plant pathogen with a wide host range. R. solani is a species complex consisting of thirteen anastomosis groups (AGs) defined by compatibility of hyphal fusion reaction and subgroups based on cultural morphology. The relationship between such classifications and host specificity remains elusive. Here, we investigated the pathogenicity of seventeen R. solani isolates (AG-1 to 7) in Japan towards Arabidopsis thaliana using leaf and soil inoculations. The tested AGs, except AG-3 and AG-6, induced symptoms in both methods with variations in pathogenicity. The virulence levels differed even within the same AG and subgroup. Some isolates showed tissue-specific infection behavior. Thus, the AGs and their subgroups are suggested to be not enough to define the virulence (host and tissue specificity) of R. solani. We also evaluated the virulence of the isolates on Arabidopsis plants pretreated with salicylic acid, jasmonic acid, and ethylene. No obvious effects were detected on the symptom formation by the virulence isolates, but ethylene and salicylic acid slightly enhanced the susceptibility to the weak and nonvirulent isolates. R. solani seems to be able to overcome the induced defense by these phytohormones in the infection to Arabidopsis.

12.
Plant Pathol J ; 37(6): 566-579, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34897249

ABSTRACT

Ralstonia syzygii subsp. indonesiensis (Rsi, former name: Ralstonia solanacearum phylotype IV) PW1001, a causal agent of potato wilt disease, induces hypersensitive response (HR) on its non-host eggplant (Solanum melongena cv. Senryo-nigou). The disaccharide trehalose is involved in abiotic and biotic stress tolerance in many organisms. We found that trehalose is required for eliciting HR on eggplant by plant pathogen Rsi PW1001. In R. solanacearum, it is known that the OtsA/OtsB pathway is the dominant trehalose synthesis pathway, and otsA and otsB encode trehalose-6-phosphate (T6P) synthase and T6P phosphatase, respectively. We generated otsA and otsB mutant strains and found that these mutant strains reduced the bacterial trehalose concentration and HR induction on eggplant leaves compared to wild-type. Trehalose functions intracellularly in Rsi PW1001 because addition of exogenous trehalose did not affect the HR level and ion leakage. Requirement of trehalose in HR induction is not common in R. solanacearum species complex because mutation of otsA in Ralstonia pseudosolanacearum (former name: Ralstonia solanacearum phylotype I) RS1002 did not affect HR on the leaves of its non-host tobacco and wild eggplant Solanum torvum. Further, we also found that each otsA and otsB mutant had reduced ability to grow in a medium containing NaCl and sucrose, indicating that trehalose also has an important role in osmotic stress tolerance.

13.
Microbiol Res ; 253: 126869, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34597823

ABSTRACT

Chemotaxis is crucial for Pseudomonas syringae pv. tabaci (Pta) 6605 to evoke disease in tobacco plants. Pta6605 harbors more than fifty genes for methyl-accepting chemotaxis proteins (mcp), but almost all are functionally uncharacterized. Previously we identified a dCache_1 type MCP in Pta6605 that mediates chemotaxis to γ-aminobutyric acid, called McpG. In this study, we characterized four more dCache_1 type MCPs, three of which, PscA, PscB, and PscC2, are responsible for sensing amino acids. Using a capillary chemotaxis assay, we observed that PscA, PscB, and PscC2 mutant strains had reduced chemotaxis to most amino acids, indicating that PscA and PscB mediate chemotaxis to 14 amino acids, while PscC2 has a slightly narrower ligand recognition, mediating chemotaxis to 12 amino acids. Other cellular functions were also affected in ΔpscB and ΔpscC2: swarming motility was reduced, and biofilm formation was increased. Furthermore, ΔpscB and ΔpscC2 but not ΔpscA had reduced virulence in the host tobacco plant. On the other hand, ΔpscC1 was defective in motility and did not even respond to yeast extract and was unable to cause disease. These findings supported the idea that the chemosensory pathway correlated with virulence-related phenotypes. Amino acids are abundant in tobacco apoplast; having multiple MCPs appears to support the invasion of Pta6605 into the plant.


Subject(s)
Amino Acids , Bacterial Proteins , Host Microbial Interactions , Pseudomonas syringae , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Host Microbial Interactions/physiology , Pseudomonas syringae/genetics , Pseudomonas syringae/pathogenicity , Nicotiana/microbiology
14.
Oxf Med Case Reports ; 2021(9): omab083, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34527256

ABSTRACT

Breast cancer arising from fibroadenoma (FA) is rare, in which almost all reported cases are human epidermal growth factor receptor 2 (HER2)-negative. This is the first report to describe a case of HER2-positive breast cancer arising from FA that was treated with chemotherapy plus anti-HER2 therapy. In this early case, upfront surgery outcomes guided the selection of appropriate systemic therapy. A 31-year-old woman previously diagnosed with FA experienced tumor growth. Core needle biopsy and imaging studies confirmed a diagnosis of stage IIA HER2-positive invasive ductal carcinoma (IDC) with no evidence of lymph node metastasis (cT2N0M0). Breast-conserving surgery was performed. Pathological diagnosis revealed stage IA IDC with a predominant intraductal component (pT1aN0M0), arising from FA. In conclusion, we encountered an extremely rare case of HER2-positive breast cancer arising from FA in which pathological infiltration was difficult to predict based on preoperative imaging.

15.
Gan To Kagaku Ryoho ; 48(9): 1127-1131, 2021 Sep.
Article in Japanese | MEDLINE | ID: mdl-34521790

ABSTRACT

Occult breast cancer is rare in practice. We studied the clinical outcomes of 5 occult breast cancers, including 2 with Luminal and 3 with non-Luminal subtypes, for which the primary site was not detected in the breast-by-breast MRI. The percentage of occult breast cancers that we encountered at our hospital was 0.11%. The mean age was 54 years. The Ki-67 labeling index value was 30% or higher for all the patients except one. Four patients were administered neoadjuvant chemotherapy and all but one patient received non-mastectomy and axillary dissection plus radiotherapy. We observed recurrent cases in one example each of the Luminal and HER2 subtypes, and both patients were less than 40 years old. The estimates of the probability of 5 year recurrence-free survival and 5 year overall survival were 40.0% and 66.7%, respectively. One recurrence case was a patient negative for ER and positive for HER2 wherein a breast cancer lesion appeared in the breast during post-treatment follow-up. Intrabreast relapse, which is itself rare in occult breast cancer, was observed 4 years postoperatively after standard treatment. Although there was no deviation according to subtype rate, the Ki-67 labeling index value was high and the prognosis was poor in our 5 cases.


Subject(s)
Breast Neoplasms , Adult , Breast Neoplasms/diagnostic imaging , Breast Neoplasms/therapy , Disease-Free Survival , Female , Humans , Magnetic Resonance Imaging , Middle Aged , Neoplasm Recurrence, Local , Prognosis , Receptor, ErbB-2 , Receptors, Estrogen , Receptors, Progesterone
16.
Microbiol Resour Announc ; 10(28): e0040521, 2021 Jul 15.
Article in English | MEDLINE | ID: mdl-34264094

ABSTRACT

Pseudomonas amygdali pv. tabaci strain 6605 is the bacterial pathogen causing tobacco wildfire disease that has been used as a model for elucidating virulence mechanisms. Here, we present the complete genome sequence of P. amygdali pv. tabaci 6605 as a circular chromosome from reads using a PacBio sequencer.

17.
J Surg Case Rep ; 2021(6): rjab199, 2021 Jun.
Article in English | MEDLINE | ID: mdl-34104403

ABSTRACT

Granulomatous mastitis is a rare breast disease that is categorized as a benign tumor with chronic inflammation. Since the cause of the chronic inflammation is usually unknown, it is sometimes called idiopathic granulomatous mastitis (IGM). Although imaging modalities, such as ultrasound, magnetic resonance imaging and mammography can detect tumors, they are sometimes unable to differentiate between benign and malignant tumors. In such cases, biopsy is needed to make a correct diagnosis. We experienced three cases of IGM after breast conserving surgery in breast cancer patients in whom we needed to rule out recurrence of breast cancer. In our cases, tumorectomy was performed in two cases for pathological diagnosis, since neither biopsy nor cytology was able to reveal a conclusive pathological diagnosis. Our management of these three cases might suggest the appropriate management of granulomatous tumors after breast conserving surgery in breast cancer survivors.

18.
Biochem Biophys Rep ; 26: 100944, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33659714

ABSTRACT

Virulence factor regulator (Vfr) is an indispensable transcription factor in the expression of virulence in the phytopathogenic bacteria Pseudomonas syringae. However, the function of Vfr is not known so far. The deletion of vfr resulted in the loss of surface swarming motility and reduced the virulence in P. syringae pv. tabaci (Pta) 6605. In order to identify the target genes of Vfr, we screened the sequences that bind to Vfr by chromatin immune precipitation (ChIP) and sequencing methods using the closely related bacterium P. syringae pv. syringae (Pss) B728a. For this purpose we first generated a strain that possesses the recombinant gene vfr::FLAG in Pss B728a, and performed ChIP using an anti-FLAG antibody. Immunoprecipitated DNA was purified and sequenced with Illumina HiSeq. The Vfr::FLAG-specific peaks were further subjected to an electrophoresis mobility-shift assay, and the promoter regions of locus tag for Psyr_0578 , Psyr_1776, and Psyr_2237 were identified as putative target genes of Vfr. These genes encode plant pathogen-specific methyl-accepting chemotaxis proteins (Mcp). These mcp genes seem to be involved in the Vfr-regulated expression of virulence.

19.
Mol Genet Genomics ; 296(2): 299-312, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33386986

ABSTRACT

Pseudomonas syringae pv. tabaci 6605 (Pta6605) is a causal agent of wildfire disease in host tobacco plants and is highly motile. Pta6605 has multiple clusters of chemotaxis genes including cheA, a gene encoding a histidine kinase, cheY, a gene encoding a response regulator, mcp, a gene for a methyl-accepting chemotaxis protein, as well as flagellar and pili biogenesis genes. However, only two major chemotaxis gene clusters, cluster I and cluster II, possess cheA and cheY. Deletion mutants of cheA or cheY were constructed to evaluate their possible role in Pta6605 chemotaxis and virulence. Motility tests and a chemotaxis assay to known attractant demonstrated that cheA2 and cheY2 mutants were unable to swarm and to perform chemotaxis, whereas cheA1 and cheY1 mutants retained chemotaxis ability almost equal to that of the wild-type (WT) strain. Although WT and cheY1 mutants of Pta6605 caused severe disease symptoms on host tobacco leaves, the cheA2 and cheY2 mutants did not, and symptom development with cheA1 depended on the inoculation method. These results indicate that chemotaxis genes located in cluster II are required for optimal chemotaxis and host plant infection by Pta6605 and that cluster I may partially contribute to these phenotypes.


Subject(s)
Histidine Kinase/genetics , Methyl-Accepting Chemotaxis Proteins/genetics , Nicotiana/microbiology , Pseudomonas aeruginosa/physiology , Pseudomonas syringae/physiology , Chemotaxis , Disease Resistance , Gene Deletion , Histidine Kinase/metabolism , Methyl-Accepting Chemotaxis Proteins/metabolism , Multigene Family , Phylogeny , Plant Diseases/microbiology , Pseudomonas aeruginosa/pathogenicity , Pseudomonas syringae/pathogenicity , Virulence
20.
Plant Cell Physiol ; 61(12): 2067-2076, 2021 Feb 04.
Article in English | MEDLINE | ID: mdl-32991707

ABSTRACT

Ralstonia solanacearum injects type III effectors into host cells to cause bacterial wilt in Solanaceae plants. To identify R. solanacearum effectors that suppress effector-triggered immunity (ETI) in plants, we evaluated R. solanacearum RS1000 effectors for their ability to suppress a hypersensitive response (HR) induced by the avirulence (Avr) effector RipAA in Nicotiana benthamiana. Out of the 11 effectors tested, 4 suppressed RipAA-triggered HR cell death. Among them, RipAC contains tandem repeats of the leucine-rich repeat (LRR) motif, which serves as the structural scaffold for a protein-protein interaction. We found that the LRR domain of RipAC was indispensable for the suppression of HR cell death during the recognition of RipAA and another Avr effector RipP1. By yeast two-hybrid screening, we identified N. benthamiana SGT1, an adaptor protein that forms a molecular chaperone complex with RAR1, as a host factor of the RipAC target. RipAC interacted with NbSGT1 in yeast and plant cells. Upon the formation of the molecular chaperone complex, the presence of RipAC markedly inhibits the interaction between NbSGT1 and NbRAR1. The RipAA- and RipP1-triggered HR cell deaths were not observed in NbSGT1-silenced plants. The introduction of RipAC was complementary to the reduced growth of the R. solanacearum mutant strain in N. benthamiana. These findings indicate that R. solanacearum uses RipAC to subvert the NbSGT1-mediated formation of the molecular chaperone complex and suppress ETI responses during the recognition of Avr effectors.


Subject(s)
Bacterial Proteins/physiology , Glucosyltransferases/metabolism , Plant Immunity , Plant Proteins/metabolism , Ralstonia solanacearum/metabolism , Bacterial Proteins/metabolism , Host-Pathogen Interactions , Nicotiana/metabolism , Nicotiana/microbiology
SELECTION OF CITATIONS
SEARCH DETAIL
...