scholarly journals Xylem Colonization by an HrcV¯ Mutant of Ralstonia solanacearum Is a Key Factor for the Efficient Biological Control of Tomato Bacterial Wilt

1998 ◽  
Vol 11 (9) ◽  
pp. 869-877 ◽  
Author(s):  
Christophe Etchebar ◽  
Danièle Trigalet-Demery ◽  
Frédérique van Gijsegem ◽  
Jacques Vasse ◽  
André Trigalet
Keyword(s):  
Mutant Strain ◽  
Ralstonia Solanacearum ◽  
Lateral Root ◽  
Pathogenic Strain ◽  
Staining Procedure ◽  
Bacterial Suspension ◽  
Marker Genes ◽  
Wild Type ◽  
Root Tips ◽  
Challenge Inoculation

Microscopic studies of the colonization of the vascular tissues of tomato by an HrcV¯ (formerly HrpO¯) mutant strain of Ralstonia solanacearum were carried out after either root inoculation of the mutant strain alone or delayed challenge inoculation by a pathogenic strain. The use of two different marker genes, lacZ and uidA, introduced into either mutant or wild-type strains, respectively, permitted histological observation for the presence of both strains simultaneously. In roots, both strains could be found together in infected root tips and in lateral root emergence sites (lateral root cracks), but these bacterial strains subsequently invaded separate xylem vessels in the root system. At the hypocotyl level, a novel staining procedure, in conjunction with bacterial isolation and counting, showed three vascular colonization patterns: exclusive colonization by each of the competitors or simultaneous presence of each strain in separate xylem vessels. The relative frequencies of these patterns depended upon the root inoculation techniques used. The presence of one population always influenced the density of the other challenge-inoculated population. In plants inoculated with both wild-type and mutant strains, the population of the wild-type strain is lower than in plants inoculated with the wild type alone. In contrast, growth of the HrcV¯ mutant strain was significantly increased in the presence of the pathogenic strain. Two agriculturally acceptable techniques for plant inoculation were tested. Inoculation of plants by transplanting them into soil amended with clay micro-granules impregnated with the HrcV¯ mutant strain gave higher and more reproducible colonization of the plants than inoculation by watering a bacterial suspension on the roots. Significant percentages of exclusive colonization by the HrcV¯ mutant strain were only obtained after the clay microgranule inoculation technique. Competition for space in xylem vessels is one of the possible explanations for the protective ability of the HrcV¯ mutant strain against subsequent invasion by a pathogenic strain.

scholarly journals NtRNF217, Encoding a Putative RBR E3 Ligase Protein of Nicotiana tabacum, Plays an Important Role in the Regulation of Resistance to Ralstonia solanacearum Infection

2021 ◽  
Vol 22 (11) ◽  
pp. 5507
Author(s):  
Ying Liu ◽  
Yuanman Tang ◽  
Xi Tan ◽  
Wei Ding
Keyword(s):  
Nicotiana Tabacum ◽  
Ralstonia Solanacearum ◽  
Plant Immunity ◽  
E3 Ligase ◽  
Marker Genes ◽  
Susceptible Cultivar ◽  
Wild Type ◽  
Disease Symptoms ◽  
Short Time ◽  
Resistance To Ralstonia Solanacearum

E3 ubiquitin ligases, the most important part of the ubiquitination process, participate in various processes of plant immune response. RBR E3 ligase is one of the E3 family members, but its functions in plant immunity are still little known. NtRNF217 is a RBR E3 ligase in tobacco based on the sequence analysis. To assess roles of NtRNF217 in tobacco responding to Ralstonia solanacearum, overexpression experiments in Nicotiana tabacum (Yunyan 87, a susceptible cultivar) were performed. The results illuminated that NtRNF217-overexpressed tobacco significantly reduced multiplication of R. solanacearum and inhibited the development of disease symptoms compared with wild-type plants. The accumulation of H2O2 and O2− in NtRNF217-OE plants was significantly higher than that in WT-Yunyan87 plants after pathogen inoculation. The activities of CAT and SOD also increased rapidly in a short time after R. solanacearum inoculation in NtRNF217-OE plants. What is more, overexpression of NtRNF217 enhanced the transcript levels of defense-related marker genes, such as NtEFE26, NtACC Oxidase, NtHIN1, NtHSR201, and NtSOD1 in NtRNF217-OE plants after R. solanacearum inoculation. The results suggested that NtRNF217 played an important role in regulating the expression of defense-related genes and the antioxidant enzymes, which resulted in resistance to R. solanacearum infection.

scholarly journals Defects in Rhizobial Cyclic Glucan and Lipopolysaccharide Synthesis Alter Legume Gene Expression During Nodule Development

2008 ◽  
Vol 21 (1) ◽  
pp. 50-60 ◽  
Author(s):  
Alejandra L. D'Antuono ◽  
Thomas Ott ◽  
Lene Krusell ◽  
Vera Voroshilova ◽  
Rodolfo A. Ugalde ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mutant Strain ◽  
Early Recognition ◽  
Lotus Japonicus ◽  
Cdna Array ◽  
Nodule Development ◽  
Marker Genes ◽  
Wild Type ◽  
Mesorhizobium Loti ◽  
Expression Of Genes

cDNA array technology was used to compare transcriptome profiles of Lotus japonicus roots inoculated with a Mesorhizobium loti wild-type and two mutant strains affected in cyclic β(1-2) glucan synthesis (cgs) and in lipopolysaccharide synthesis (lpsβ2). Expression of genes associated with the development of a fully functional nodule was significantly affected in plants inoculated with the cgs mutant. Array results also revealed that induction of marker genes for nodule development was delayed when plants were inoculated with the lpsβ2 mutant. Quantitative real-time reverse-transcriptase polymerase chain reaction was used to quantify gene expression of a subset of genes involved in plant defense response, redox metabolism, or genes that encode for nodulins. The majority of the genes analyzed in this study were more highly expressed in roots inoculated with the wild type compared with those inoculated with the cgs mutant strain. Some of the genes exhibited a transient increase in transcript levels during intermediate steps of normal nodule development while others displayed induced expression during the final steps of nodule development. Ineffective nodules induced by the glucan mutant showed higher expression of phenylalanine ammonia lyase than wild-type nodules. Differences in expression pattern of genes involved in early recognition and signaling were observed in plants inoculated with the M. loti mutant strain affected in the synthesis of cyclic glucan.

scholarly journals Transcriptional Regulator YqeI, Locating at ETT2 Locus, Affects the Pathogenicity of Avian Pathogenic Escherichia coli

Animals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1658
Author(s):  
Mei Xue ◽  
Yating Xiao ◽  
Dandan Fu ◽  
Muhammad Akmal Raheem ◽  
Ying Shao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mutant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Bacterial Suspension ◽  
Adhesion Assay ◽  
Wild Type ◽  
Avian Pathogenic Escherichia Coli ◽  
Semisolid Medium ◽  
Pathogenic Escherichia Coli

Avian pathogenic Escherichia coli (APEC) is the leading cause of systemic infections in poultry worldwide and has a hidden threat to public health. Escherichia coli type three secretion system 2 (ETT2), similar to the Salmonella pathogenicity island SPI1, is widely distributed in APEC and associated with virulence. The function of YqeI, which is one of the hypothetical transcriptional regulators locating at the ETT2 locus of APEC, is unknown. In this study, we successfully obtained the mutant strain AE81ΔyqeI of the wild type strain AE81 and performed the transcriptional profiling assays. Additionally, the transcriptional sequencing results revealed that YqeI influenced localization, locomotion and biological adhesion and so on. The transmission electron microscope observation showed that the wild type strain AE81 possessed long curved flagella, whereas the mutant strain AE81ΔyqeI hardly had any. The strain AE81ΔyqeI exhibited lower motility than AE81 after culturing the dilute bacterial suspension on a semisolid medium. It was also found that the survival ability of AE81ΔyqeI weakened significantly when AE81ΔyqeI was cultured with 0%, 10%, 20%, 30%, 40% and 50% SPF serum in PBS, and AE81ΔyqeI had decreased adherence to DF-1 cells compared with AE81 in the bacterial adhesion assay. The bacterial colonization assay indicated that the virulence of AE81ΔyqeI was reduced in the heart, liver, spleen, and lung. These results confirmed that the transcription regulator YqeI is involved in APEC’s pathogenicity, and this study provides clues for future research.

scholarly journals Induction of Lateral Root Structure Formation on Petunia Roots: A Novel Effect of GMI1000 Ralstonia solanacearum Infection Impaired in Hrp Mutants

2006 ◽  
Vol 19 (6) ◽  
pp. 597-606 ◽  
Author(s):  
Lena Zolobowska ◽  
Frédérique Van Gijsegem
Keyword(s):  
Ralstonia Solanacearum ◽  
Lateral Root ◽  
Plant Pathogens ◽  
Lateral Roots ◽  
Root Tips ◽  
Whole Plant ◽  
Systemic Spread ◽  
Mutant Strains ◽  
Architecture Development ◽  
Lateral Structures

Ralstonia solanacearum is a soilborne plant pathogen that invades its host via roots. As in many gram-negative bacterial plant pathogens, the R. solanacearum Hrp type III secretion system is essential for interactions of the bacterium with plants; however, the related mechanisms involved in disease expression are largely unknown. In this work, we examined the effects of infection by R. solanacearum GMI1000 and Hrp mutants on the root system of petunia plants. Both the wild-type and mutant strains disturbed the petunia root architecture development by inhibiting lateral root elongation and provoking swelling of the root tips. In addition, GMI100 but not the Hrp mutants induced the formation of new root lateral structures (RLS). This ability is shared by other, but not all, R. solanacearum strains tested. Like lateral roots, these new structures arise from divisions of pericycle founder cells which, nevertheless, exhibit an abnormal morphology. These RLS are efficient colonization sites allowing extensive bacterial multiplication. However, they are not required for the bacterial vascular invasion that leads to the systemic spread of the bacterium through the whole plant, indicating that, instead, they might play a role in the rhizosphere-related stages of the R. solanacearum life cycle.

scholarly journals Epsc Involved in the Encoding of Exopolysaccharides Produced by Bacillus amyloliquefaciens FZB42 Act to Boost the Drought Tolerance of Arabidopsis thaliana

2018 ◽  
Vol 19 (12) ◽  
pp. 3795 ◽  
Author(s):  
Xiang Lu ◽  
Shao-Fang Liu ◽  
Liang Yue ◽  
Xia Zhao ◽  
Yu-Bao Zhang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Drought Tolerance ◽  
Plant Growth ◽  
Mutant Strain ◽  
Root Length ◽  
Bacillus Amyloliquefaciens ◽  
Lateral Root ◽  
Primary Root ◽  
Defense Responses ◽  
Marker Genes

Bacillus amyloliquefaciens FZB42 is a plant growth-promoting rhizobacteria that stimulates plant growth, and enhances resistance to pathogens and tolerance of salt stress. Instead, the mechanistic basis of drought tolerance in Arabidopsis thaliana induced by FZB42 remains unexplored. Here, we constructed an exopolysaccharide-deficient mutant epsC and determined the role of epsC in FZB42-induced drought tolerance in A. thaliana. Results showed that FZB42 significantly enhanced growth and drought tolerance of Arabidopsis by increasing the survival rate, fresh and dry shoot weights, primary root length, root dry weight, lateral root number, and total lateral root length. Coordinated changes were also observed in cellular defense responses, including elevated concentrations of proline and activities of superoxide dismutase and peroxidase, decreased concentrations of malondialdehyde, and accumulation of hydrogen peroxide in plants treated with FZB42. The relative expression levels of drought defense-related marker genes, such as RD29A, RD17, ERD1, and LEA14, were also increased in the leaves of FZB42-treated plants. In addition, FZB42 induced the drought tolerance in Arabidopsis by the action of both ethylene and jasmonate, but not abscisic acid. However, plants inoculated with mutant strain epsC were less able to resist drought stress with respect to each of these parameters, indicating that epsC are required for the full benefit of FZB42 inoculation to be gained. Moreover, the mutant strain was less capable of supporting the formation of a biofilm and of colonizing the A. thaliana root. Therefore, epsC is an important factor that allows FZB42 to colonize the roots and induce systemic drought tolerance in Arabidopsis.

scholarly journals Overexpression of the manganese/cadmium transporter OsNRAMP5 reduces cadmium accumulation in rice grain

2020 ◽  
Vol 71 (18) ◽  
pp. 5705-5715 ◽  
Author(s):  
Jia-Dong Chang ◽  
Sheng Huang ◽  
Noriyuki Konishi ◽  
Peng Wang ◽  
Jie Chen ◽  
...  
Keyword(s):  
Lateral Root ◽  
Ion Homeostasis ◽  
Toxic Metal ◽  
Rice Grain ◽  
Wild Type ◽  
Root Tips ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Cd Accumulation ◽  
Cd Translocation

Abstract Rice is a major dietary source of the toxic metal cadmium (Cd), and reducing its accumulation in the grain is therefore important for food safety. We selected two cultivars with contrasting Cd accumulation and generated transgenic lines overexpressing OsNRAMP5, which encodes a major influx transporter for manganese (Mn) and Cd. We used two different promoters to control the expression, namely OsActin1 and maize Ubiquitin. Overexpression of OsNRAMP5 increased Cd and Mn uptake into the roots, but markedly decreased Cd accumulation in the shoots, whilst having a relatively small effect on Mn accumulation in the shoots. The overexpressed OsNRAMP5 protein was localized to the plasma membrane of all cell types in the root tips and lateral root primordia without polarity. Synchrotron X-ray fluorescence mapping showed that the overexpression lines accumulated more Cd in the root tips and lateral root primordia compared with the wild-type. When grown in three Cd-contaminated paddy soils, overexpression of OsNRAMP5 decreased concentration of Cd in the grain by 49–94% compared with the wild type. OsNRAMP5-overexpression plants had decreased Cd translocation from roots to shoots as a result of disruption of its radial transport into the stele for xylem loading, demonstrating the effect of transporter localization and polarity on ion homeostasis.

INTERACTION BETWEEN THE AUTOSOMES OF DROSOPHILA MELANOGASTER AS MEASURED BY VIABILITY AND RATE OF DEVELOPMENT

1941 ◽  
Vol 19d (2) ◽  
pp. 75-84
Author(s):  
S. C. Reed
Keyword(s):  
Mutant Strain ◽  
Wild Strain ◽  
Marker Genes ◽  
Positive Contribution ◽  
Wild Type ◽  
Negative Effects ◽  
Rate Of Development ◽  
Positive Effects ◽  
Quantitative Characters ◽  
Negative Effect

Females of an inbred al c: se ss: eyR mutant strain were crossed with males from a "wild" strain that had been inbred (brother × sister) for more than 60 generations. The F1 males were mated with mutant strain females. The backcross offspring would be expected to appear in eight genotypes with equal frequencies were there no differences in viability. The marker genes permitted the scoring of each fly as to whether it was heterozygous or homozygous for each of the mutant autosomes.The genes used as markers probably had a distinctly negative effect upon both viability and rate of development, but the second pair of autosomes in combination with the other mutant autosomes increased viability, when homozygous, to a greater extent than did a heterozygous mutant-wild type pair. Apparently the possible negative effects of the markers al and c were more than offset by other genes on this autosome which had positive effects. The negative effects of the homozygous mutant third and fourth chromosomes were severe when in combination.The interactions of the positive second chromosome and the negative third and fourth chromosomes in the eight genotypes were of some geometric order. It was found that the addition of a "positive" or "negative" autosome to any genotype caused a change in viability in the direction of the added autosome, but the amount of change is at present unpredictable and depends upon the particular combination to which the autosome was added.The relation between the different autosomes and the rate of development was quite different from the relation between autosomes and viability. The second chromosome (marked by al c), which gave the only positive contribution to viability, retarded development more than either the third (se ss) or the fourth (eyR). The effects of the three autosomes on rate of development were not strictly additive.It is concluded that there is interaction of the genes for quantitative characters and this interaction is geometric in nature. The significance of the results in their relation to some theories of the inheritance of quantitative characters is discussed.

scholarly journals Drosophilagenescutandminiatureare associated with the susceptibility to infection bySerratia marcescens

1988 ◽  
Vol 52 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Casper Flyg ◽  
Hans G. Boman
Keyword(s):  
Drosophila Melanogaster ◽  
Serratia Marcescens ◽  
Mutant Strain ◽  
Double Mutant ◽  
Pathogenic Strain ◽  
Peritrophic Membrane ◽  
Wild Type ◽  
Susceptibility To Infection ◽  
Chitinase A ◽  
Bacterial Mutant

SummaryA mutant strain ofDrosophila melanogasterwith five markers on theX-chromosome was found to be more sensitive than the wild type when infected with an insect-pathogenic strain ofSerratia marcescens. Two of the five mutations in this fly strain,cutandminiature, were found to be responsible for this sensitivity. A double-mutant, with bothcutandminiature, was as sensitive toSerratiainfection as was the original sensitiveDrosophilastrain with all five mutations. Recombinant flies with other alleles ofcutandminiaturewere also sensitive. A revertant ofcutwas found to be less sensitive than the parental flies. Our insect pathogenic strain ofSerratiaproduces several proteases and a chitinase. A bacterial mutant, lacking proteases and chitinase, was found to be less virulent than wild-type bacteria. When pupal shells from resistant andcut-miniatureflies were incubated with a mixture of protease and chitinase there was a release ofN-acetyl glucosamine, and 50% more material was liberated from pupal shells of sensitive flies. Sensitive flies reared on sucrose infected withSerratiashowed bacteria in their hemolymph earlier than wild-type flies. We conclude thatDrosophilagenes forcutandminiatureare associated with the sensitivity toSerratiainfection, presumably because the gut peritrophic membrane is more susceptible to bacterial proteases and chitinase.

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

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