The Virulence of a Dickeya dadantii 3937 Mutant Devoid of Osmoregulated Periplasmic Glucans Is Restored by Inactivation of the RcsCD-RcsB Phosphorelay

ABSTRACT Dickeya dadantii is a pectinolytic phytopathogen enterobacterium that causes soft rot disease on a wide range of plant species. The virulence of D. dadantii involves several factors, including the osmoregulated periplasmic glucans (OPGs) that are general constituents of the envelope of proteobacteria. In addition to the loss of virulence, opg-negative mutants display a pleiotropic phenotype, including decreased motility and increased exopolysaccharide synthesis. A nitrosoguanidine-induced mutagenesis was performed on the opgG strain, and restoration of motility was used as a screen. The phenotype of the opg mutant echoes that of the Rcs system: high level activation of the RcsCD-RcsB phosphorelay is needed to activate exopolysaccharide synthesis and to repress motility, while low level activation is required for virulence in enterobacteria. Here, we show that mutations in the RcsCDB phosphorelay system restored virulence and motility in a D. dadantii opg-negative strain, indicating a relationship between the Rcs phosphorelay and OPGs.

Download Full-text

Increased phosphorylation of the RcsB regulator of the RcsCDB phosphorelay in strains of Dickeya dadantii devoid of osmoregulated periplasmic glucans revealed by Phos-tag gel analysis

Microbiology ◽

10.1099/mic.0.081273-0 ◽

2014 ◽

Vol 160 (12) ◽

pp. 2763-2770 ◽

Cited By ~ 12

Author(s):

Edwige Madec ◽

Sébastien Bontemps-Gallo ◽

Jean-Marie Lacroix

Keyword(s):

Direct Analysis ◽

Soft Rot ◽

Dickeya Dadantii ◽

Constitutive Activation ◽

Pleiotropic Phenotype ◽

Regulator Protein ◽

Wide Range ◽

In The Wild ◽

Rot Disease

Osmoregulated periplasmic glucans (OPGs) are general constituents of many proteobacteria. OPGs are important factors required for full virulence in many pathogens including Dickeya dadantii. D. dadantii causes the soft-rot disease in a wide range of plant species. The pleiotropic phenotype of opg-negative strains includes total loss of virulence and motility, and is linked to the constitutive activation of the RcsCDB phosphorelay, deduced from expression analysis of genes of the RcsCDB regulon. The constitutive activation of the RcsCDB phosphorelay in an opg-negative strain was demonstrated by direct analysis of the phosphorylation level of the RcsB regulator protein in vivo by using a Phos-tag retardation gel approach, and was correlated with the phenotype and the expression of motility genes. Data revealed a low level of RcsB phosphorylated form in the wild-type strain and a slight increase of phosphorylation in opgG mutant strains sufficient to induce the pleiotropic phenotype observed.

Download Full-text

Screening, Identification and Efficacy Evaluation of Antagonistic Bacteria for Biocontrol of Soft Rot Disease Caused by Dickeya zeae

Microorganisms ◽

10.3390/microorganisms8050697 ◽

2020 ◽

Vol 8 (5) ◽

pp. 697 ◽

Cited By ~ 1

Author(s):

Jieling Li ◽

Ming Hu ◽

Yang Xue ◽

Xia Chen ◽

Guangtao Lu ◽

...

Keyword(s):

Antimicrobial Activity ◽

Prevention And Control ◽

Pathogenic Bacteria ◽

Soft Rot ◽

Antagonistic Bacteria ◽

Bacterial Soft Rot ◽

Soft Rot Disease ◽

Wide Range ◽

Rot Disease ◽

And Control

Dickeya zeae is the causal agent of bacterial soft rot disease, with a wide range of hosts all over the world. At present, chemical agents, especially agricultural antibiotics, are commonly used in the prevention and control of bacterial soft rot, causing the emergence of resistant pathogens and therefore increasing the difficulty of disease prevention and control. This study aims to provide a safer and more effective biocontrol method for soft rot disease caused by D. zeae. The spot-on-lawn assay was used to screen antagonistic bacteria, and three strains including SC3, SC11 and 3-10 revealed strong antagonistic effects and were identified as Pseudomonas fluorescens, P. parafulva and Bacillus velezensis, respectively, using multi-locus sequence analysis (MLSA) based on the sequences of 16S rRNA and other housekeeping genes. In vitro antimicrobial activity showed that two Pseudomonas strains SC3 and SC11 were only antagonistic to some pathogenic bacteria, while strain 3-10 had broad-spectrum antimicrobial activity on both pathogenic bacteria and fungi. Evaluation of control efficacy in greenhouse trials showed that they all restrained the occurrence and development of soft rot disease caused by D. zeae MS2 or EC1. Among them, strain SC3 had the most impressive biocontrol efficacy on alleviating the soft rot symptoms on both monocotyledonous and dicotyledonous hosts, and strain 3-10 additionally reduced the occurrence of banana wilt disease caused by Fusarium oxysporum f. sp. cubensis. This is the first report of P. fluorescens, P. parafulva and B. velezensis as potential bio-reagents on controlling soft rot disease caused by D. zeae.

Download Full-text

Inactivation of pecS restores the virulence of mutants devoid of osmoregulated periplasmic glucans in the phytopathogenic bacterium Dickeya dadantii

Microbiology ◽

10.1099/mic.0.074484-0 ◽

2014 ◽

Vol 160 (4) ◽

pp. 766-777 ◽

Cited By ~ 7

Author(s):

Sébastien Bontemps-Gallo ◽

Edwige Madec ◽

Jean-Marie Lacroix

Keyword(s):

Plant Cell Wall ◽

Transcriptional Regulator ◽

Soft Rot ◽

Cellular Functions ◽

Cell Wall Degrading Enzymes ◽

Dickeya Dadantii ◽

Phytopathogenic Bacterium ◽

Wide Range ◽

Severe Reduction ◽

Rot Disease

Dickeya dadantii is a phytopathogenic enterobacterium that causes soft rot disease in a wide range of plant species. Maceration, an apparent symptom of the disease, is the result of the synthesis and secretion of a set of plant cell wall-degrading enzymes (PCWDEs), but many additional factors are required for full virulence. Among these, osmoregulated periplasmic glucans (OPGs) and the PecS transcriptional regulator are essential virulence factors. Several cellular functions are controlled by both OPGs and PecS. Strains devoid of OPGs display a pleiotropic phenotype including total loss of virulence, loss of motility and severe reduction in the synthesis of PCWDEs. PecS is one of the major regulators of virulence in D. dadantii, acting mainly as a repressor of various cellular functions including virulence, motility and synthesis of PCWDEs. The present study shows that inactivation of the pecS gene restored virulence in a D. dadantii strain devoid of OPGs, indicating that PecS cannot be de-repressed in strains devoid of OPGs.

Download Full-text

Identification of bacterial virulence factors based on an integration of experimental and in silico transcription factor target discovery

Abstract book of the 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology" PLAMIC2020 ◽

10.28983/plamic2020.278 ◽

2020 ◽

Author(s):

P. V. Vychyk ◽

Y. A. Nikolaichik

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Binding Sites ◽

In Silico ◽

Soft Rot ◽

Bacterial Virulence ◽

Dickeya Dadantii ◽

Soft Rot Disease ◽

Transcription Factor Target ◽

Rot Disease

In silico transcription factors binding sites analysis in Dickeya dadantii genome matches published experimental results and predicts new regulators for genes inducing soft-rot disease in plants.

Download Full-text

First Report of Soft Rot Disease on Pak Choi (Brassica chinensis) Caused by Dickeya dadantii subsp. dieffenbachiae in Malaysia

Plant Disease ◽

10.1094/pdis-07-14-0754-pdn ◽

2016 ◽

Vol 100 (1) ◽

pp. 209-209 ◽

Cited By ~ 3

Author(s):

E. Golkhandan ◽

S. Kamaruzaman ◽

M. A. Zainalabidin ◽

A. Nasehi

Keyword(s):

Soft Rot ◽

Dickeya Dadantii ◽

Pak Choi ◽

Brassica Chinensis ◽

First Report ◽

Soft Rot Disease ◽

Rot Disease

Download Full-text

Identification of Three Type II Toxin-Antitoxin Systems in Model Bacterial Plant Pathogen Dickeya dadantii 3937

International Journal of Molecular Sciences ◽

10.3390/ijms22115932 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5932

Author(s):

Lidia Boss ◽

Marcin Górniak ◽

Alicja Lewańczyk ◽

Joanna Morcinek-Orłowska ◽

Sylwia Barańska ◽

...

Keyword(s):

Soft Rot ◽

Type Ii ◽

Experimental Proof ◽

Dickeya Dadantii ◽

Genetic Elements ◽

Bacterial Cell Death ◽

Wide Range ◽

Rot Disease

Type II toxin-antitoxin (TA) systems are genetic elements usually encoding two proteins: a stable toxin and an antitoxin, which binds the toxin and neutralizes its toxic effect. The disturbance in the intracellular toxin and antitoxin ratio typically leads to inhibition of bacterial growth or bacterial cell death. Despite the fact that TA modules are widespread in bacteria and archaea, the biological role of these systems is ambiguous. Nevertheless, a number of studies suggests that the TA modules are engaged in such important processes as biofilm formation, stress response or virulence and maintenance of mobile genetic elements. The Dickeya dadantii 3937 strain serves as a model for pathogens causing the soft-rot disease in a wide range of angiosperm plants. Until now, several chromosome-encoded type II TA systems were identified in silico in the genome of this economically important bacterium, however so far only one of them was experimentally validated. In this study, we investigated three putative type II TA systems in D. dadantii 3937: ccdAB2Dda, phd-docDda and dhiTA, which represents a novel toxin/antitoxin superfamily. We provide an experimental proof for their functionality in vivo both in D. dadantii and Escherichia coli. Finally, we examined the prevalence of those systems across the Pectobacteriaceae family by a phylogenetic analysis.

Download Full-text

Osmoregulated Periplasmic Glucan Synthesis Is Required for Erwinia chrysanthemi Pathogenicity

Journal of Bacteriology ◽

10.1128/jb.183.10.3134-3141.2001 ◽

2001 ◽

Vol 183 (10) ◽

pp. 3134-3141 ◽

Cited By ~ 65

Author(s):

Frederic Page ◽

Silvia Altabe ◽

Nicole Hugouvieux-Cotte-Pattat ◽

Jean-Marie Lacroix ◽

Janine Robert-Baudouy ◽

...

Keyword(s):

Pectate Lyase ◽

Soft Rot ◽

Erwinia Chrysanthemi ◽

Plant Host ◽

Wide Range ◽

Homologous Locus ◽

Glucan Synthesis ◽

Rot Disease ◽

High Level ◽

Periplasmic Glucan

ABSTRACT Erwinia chrysanthemi is a phytopathogenic enterobacterium causing soft rot disease in a wide range of plants. Osmoregulated periplasmic glucans (OPGs) are intrinsic components of the gram-negative bacterial envelope. We cloned the opgGHoperon of E. chrysanthemi, encoding proteins involved in the glucose backbone synthesis of OPGs, by complementation of the homologous locus mdoGH of Escherichia coli. OpgG and OpgH show a high level of similarity with MdoG and MdoH, respectively, and mutations in the opgG or opgHgene abolish OPG synthesis. The opg mutants exhibit a pleiotropic phenotype, including overproduction of exopolysaccharides, reduced motility, bile salt hypersensitivity, reduced protease, cellulase, and pectate lyase production, and complete loss of virulence. Coinoculation experiments support the conclusion that OPGs present in the periplasmic space of the bacteria are necessary for growth in the plant host.

Download Full-text

Relationship of Resistance-Related Enzyme activity and Salicylic Acid content in Phalaenopsis Species with different levels of resistance to DIckeya Dadantii

Journal of Horticultural Research ◽

10.2478/johr-2021-0018 ◽

2022 ◽

Vol 0 (0) ◽

Author(s):

I Putu Wahyu SANJAYA ◽

Dewi SUKMA ◽

Sudarsono SUDARSONO ◽

Ming-Tsair CHAN

Keyword(s):

Salicylic Acid ◽

Lignin Content ◽

Soft Rot ◽

Disease Assessment ◽

Post Inoculation ◽

Necrotrophic Pathogen ◽

Dickeya Dadantii ◽

Soft Rot Disease ◽

Resistant Species ◽

Rot Disease

ABSTRACT Orchids (Phalaenopsis) are ornamental plants that are cultivated commercially and in great demand in the market. Soft-rot disease (SRD) caused by the necrotrophic pathogen Dickeya dadantii is a cause of considerable economic loss to cultivators of many orchid species. Our previous experiment identified a limited number of species that were resistant to D. dadantii. This study aimed to validate the resistance level of four Phalaenopsis species in a detached leaf inoculation protocol to identify the resistance mechanism(s) involved. Soft-rot symptom diameter was measured from 6 to 18 hours post-inoculation (HPI) with D. dadantii. Disease assessment confirmed that P. amboinensis is a resistant species, P. pantherina is a susceptible species, and P. amabilis and P. schilleriana are very susceptible species. There was no difference in the lignin content between the resistant and very susceptible species. Detailed observation of resistant and very susceptible species, P. amboinensis vs. P. amabilis, revealed higher phenylalanine ammonia-lyase (PAL) and peroxidase (POD) in P. amabilis than in P. amboinensis. In contrast, there was higher salicylic acid (SA) content in P. amboinensis than in P. amabilis. These results suggest that POD and PAL activities may not be effective in defense against soft-rot disease, while SA plays an important role in the resistance of P. amboinensis to D. dadantii. Low PAL activity in P. amboinensis implies that the SA contents from the isochorismate pathway may be involved in the mechanism of P. amboinensis resistance to D. dadantii. Therefore, endogenous SA content may be a good indicator for screening resistant species in Phalaenopsis.

Download Full-text