scholarly journals A yceI Gene Involves in the Adaptation of Ralstonia solanacearum to Methyl Gallate and Other Stresses

2021 ◽  
Vol 9 (9) ◽  
pp. 1982
Author(s):  
Kai-Hao Wang ◽  
De-Hong Zheng ◽  
Gao-Qing Yuan ◽  
Wei Lin ◽  
Qi-Qin Li
Keyword(s):  
Ralstonia Solanacearum ◽  
Wild Type Strain ◽  
Methyl Gallate ◽  
Wild Type ◽  
Lower Growth ◽  
Tomato Plants ◽  
Over Expression ◽  
Virulence Potential ◽  
Significant Difference ◽  
Expression Strain

Ralstonia solanacearum is a plant-pathogenic bacterium causing plant bacterial wilt, and can be strongly inhibited by methyl gallate (MG). Our previous transcriptome sequencing of MG-treated R. solanacearum showed that the yceI gene AVT05_RS03545 of Rs-T02 was up-regulated significantly under MG stress. In this study, a deletion mutant (named DM3545) and an over-expression strain (named OE3545) for yceI were constructed to confirm this hypothesis. No significant difference was observed among the growth of wild-type strain, DM3545, and OE3545 strains without MG treatment. Mutant DM3545 showed a lower growth ability than that of the wild type and OE3545 strains under MG treatment, non-optimal temperature, or 1% NaCl. The ability of DM3545 for rhizosphere colonization was lower than that of the wild-type and OE3545 strains. The DM3545 strain showed substantially reduced virulence toward tomato plants than its wild-type and OE3545 counterpart. Moreover, DM3545 was more sensitive to MG in plants than the wild-type and OE3545 strains. These results suggest that YceI is involved in the adaptability of R. solanacearum to the presence of MG and the effect of other tested abiotic stresses. This protein is also possibly engaged in the virulence potential of R. solanacearum.

scholarly journals Trehalose Synthesis Contributes to Osmotic Stress Tolerance and Virulence of the Bacterial Wilt Pathogen Ralstonia solanacearum

2020 ◽  
Vol 33 (3) ◽  
pp. 462-473 ◽  
Author(s):  
April M. MacIntyre ◽  
John X. Barth ◽  
Molly C. Pellitteri Hahn ◽  
Cameron O. Scarlett ◽  
Stéphane Genin ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Xylem Sap ◽  
Wilt Disease ◽  
Wild Type ◽  
Tomato Plants ◽  
Trehalose Synthesis

The xylem-dwelling plant pathogen Ralstonia solanacearum changes the chemical composition of host xylem sap during bacterial wilt disease. The disaccharide trehalose, implicated in stress tolerance across all kingdoms of life, is enriched in sap from R. solanacearum–infected tomato plants. Trehalose in xylem sap could be synthesized by the bacterium, the plant, or both. To investigate the source and role of trehalose metabolism during wilt disease, we evaluated the effects of deleting the three trehalose synthesis pathways in the pathogen: TreYZ, TreS, and OtsAB, as well as its sole trehalase, TreA. A quadruple treY/treS/otsA/treA mutant produced 30-fold less intracellular trehalose than the wild-type strain missing the trehalase enzyme. This trehalose-nonproducing mutant had reduced tolerance to osmotic stress, which the bacterium likely experiences in plant xylem vessels. Following naturalistic soil-soak inoculation of tomato plants, this triple mutant did not cause disease as well as wild-type R. solanacearum. Further, the wild-type strain out-competed the trehalose-nonproducing mutant by over 600-fold when tomato plants were coinoculated with both strains, showing that trehalose biosynthesis helps R. solanacearum overcome environmental stresses during infection. An otsA (trehalose-6-phosphate synthase) single mutant behaved similarly to ΔtreY/treS/otsA in all experimental settings, suggesting that the OtsAB pathway is the dominant trehalose synthesis pathway in R. solanacearum.

scholarly journals Chemotaxis Is Required for Virulence and Competitive Fitness of the Bacterial Wilt Pathogen Ralstonia solanacearum

2006 ◽  
Vol 188 (10) ◽  
pp. 3697-3708 ◽  
Author(s):  
Jian Yao ◽  
Caitilyn Allen
Keyword(s):  
Host Plant ◽  
Plant Pathogen ◽  
Ralstonia Solanacearum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Random Motion ◽  
Wild Type ◽  
Tomato Plants ◽  
Swimming Motility ◽  
Directed Motility

ABSTRACT Ralstonia solanacearum, a soilborne plant pathogen of considerable economic importance, invades host plant roots from the soil. Qualitative and quantitative chemotaxis assays revealed that this bacterium is specifically attracted to diverse amino acids and organic acids, and especially to root exudates from the host plant tomato. Exudates from rice, a nonhost plant, were less attractive. Eight different strains from this heterogeneous species complex varied significantly in their attraction to a panel of carbohydrate stimuli, raising the possibility that chemotactic responses may be differentially selected traits that confer adaptation to various hosts or ecological conditions. Previous studies found that an aflagellate mutant lacking swimming motility is significantly reduced in virulence, but the role of directed motility mediated by the chemotaxis system was not known. Two site-directed R. solanacearum mutants lacking either CheA or CheW, which are core chemotaxis signal transduction proteins, were completely nonchemotactic but retained normal swimming motility. In biologically realistic soil soak virulence assays on tomato plants, both nonchemotactic mutants had significantly reduced virulence indistinguishable from that of a nonmotile mutant, demonstrating that directed motility, not simply random motion, is required for full virulence. In contrast, nontactic strains were as virulent as the wild-type strain was when bacteria were introduced directly into the plant stem through a cut petiole, indicating that taxis makes its contribution to virulence in the early stages of host invasion and colonization. When inoculated individually by soaking the soil, both nontactic mutants reached the same population sizes as the wild type did in the stems of tomato plants just beginning to wilt. However, when tomato plants were coinoculated with a 1:1 mixture of a nontactic mutant and its wild-type parent, the wild-type strain outcompeted both nontactic mutants by 100-fold. Together, these results indicate that chemotaxis is an important trait for virulence and pathogenic fitness in this plant pathogen.

scholarly journals Failure of Surface Ring Mutant Strains of Helicobacter mustelae To Persistently Infect the Ferret Stomach

2003 ◽  
Vol 71 (5) ◽  
pp. 2350-2355 ◽  
Author(s):  
M. M. Patterson ◽  
P. W. O'Toole ◽  
N. T. Forester ◽  
B. Noonan ◽  
T. J. Trust ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Gastric Body ◽  
Wild Type ◽  
Significant Difference ◽  
Specific Pathogen ◽  
Ring Structures ◽  
H Pylori ◽  
Successful Colonization ◽  
Persistently Infect

ABSTRACT Helicobacter mustelae, the gastric pathogen of ferrets, produces an array of surface ring structures which have not been described for any other member of the genus Helicobacter, including H. pylori. The unique ring structures are composed of a protein named Hsr. To investigate whether the Hsr rings are important for colonization of the ferret stomach, ferrets specific pathogen free for H. mustelae were inoculated with an Hsr-deficient mutant strain or the wild-type H. mustelae strain. Quantitative cultures from antral biopsy specimens obtained at 3, 6, and 9 weeks postinoculation demonstrated no significant difference in the levels of bacteria in the ferrets that received the Hsr-negative strain and the ferrets infected with the parent strain. However, when the ferrets were biopsied at 12 and 15 weeks and necropsied at 18 weeks after infection, the levels of bacteria of the Hsr-negative strain in the stomach antrum were significantly reduced. This decline contrasted the robust antral colonization by the wild-type strain. The Hsr-negative strain did not efficiently colonize the gastric body of the study ferrets. Histological examination at 18 weeks postinoculation revealed minimal gastric inflammation in the animals that received the mutant H. mustelae strain, a finding consistent with its waning infection status, whereas lesions characteristic of helicobacter infection were present in ferrets infected with the wild-type strain. Scant colonization by the Hsr-negative H. mustelae strain at the end of the 18-week study, despite initial successful colonization, indicates an inability of the mutant to persist, perhaps due to a specific host response.

scholarly journals Autoproteolysis of YscU of Yersinia pseudotuberculosis Is Important for Regulation of Expression and Secretion of Yop Proteins

2009 ◽  
Vol 191 (13) ◽  
pp. 4259-4267 ◽  
Author(s):  
Ann-Catrin Björnfot ◽  
Moa Lavander ◽  
Åke Forsberg ◽  
Hans Wolf-Watz
Keyword(s):  
Type Iii Secretion ◽  
Calcium Concentration ◽  
Wild Type Strain ◽  
Yersinia Pseudotuberculosis ◽  
Secretion System ◽  
Wild Type ◽  
Regulation Of Expression ◽  
Significant Difference ◽  
In The Wild ◽  
Needle Protein

ABSTRACT YscU of Yersinia can be autoproteolysed to generate a 10-kDa C-terminal polypeptide designated YscUCC. Autoproteolysis occurs at the conserved N↓PTH motif of YscU. The specific in-cis-generated point mutants N263A and P264A were found to be defective in proteolysis. Both mutants expressed and secreted Yop proteins (Yops) in calcium-containing medium (+Ca2+ conditions) and calcium-depleted medium (−Ca2+ conditions). The level of Yop and LcrV secretion by the N263A mutant was about 20% that of the wild-type strain, but there was no significant difference in the ratio of the different secreted Yops, including LcrV. The N263A mutant secreted LcrQ regardless of the calcium concentration in the medium, corroborating the observation that Yops were expressed and secreted in Ca2+-containing medium by the mutant. YscF, the type III secretion system (T3SS) needle protein, was secreted at elevated levels by the mutant compared to the wild type when bacteria were grown under +Ca2+ conditions. YscF secretion was induced in the mutant, as well as in the wild type, when the bacteria were incubated under −Ca2+ conditions, although the mutant secreted smaller amounts of YscF. The N263A mutant was cytotoxic for HeLa cells, demonstrating that the T3SS-mediated delivery of effectors was functional. We suggest that YscU blocks Yop release and that autoproteolysis is required to relieve this block.

scholarly journals Pyramiding Unmarked Deletions in Ralstonia solanacearum Shows That Secreted Proteins in Addition to Plant Cell-Wall-Degrading Enzymes Contribute to Virulence

2005 ◽  
Vol 18 (12) ◽  
pp. 1296-1305 ◽  
Author(s):  
Huanli Liu ◽  
Shuping Zhang ◽  
Mark A. Schell ◽  
Timothy P. Denny
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Ralstonia Solanacearum ◽  
Plant Cell Wall ◽  
Secreted Proteins ◽  
Cellulolytic Enzymes ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes ◽  
Tomato Plants ◽  
Degrading Enzymes

Ralstonia solanacearum, like many phytopathogenic bacteria, makes multiple extracellular plant cell-wall-degrading enzymes (CWDE), some of which contribute to its ability to cause wilt disease. CWDE and many other proteins are secreted to the milieu via the highly conserved type II protein secretion system (T2SS). R. solanacearum with a defective T2SS is weakly virulent, but it is not known whether this is due to absence of all the CWDE or the loss of other secreted proteins that contribute to disease. These alternatives were investigated by creating mutants of wild-type strain GMI1000 lacking either the T2SS or up to six CWDE and comparing them for virulence on tomato plants. To create unmarked deletions, genomic regions flanking the target gene were polymerase chain reaction (PCR)-amplified, were fused using splice overlap extension PCR, were cloned into a suicide plasmid harboring the sacB counter-selectable marker, and then, were site-specifically introduced into the genome. Various combinations of five deletions (δpehA, δpehB, δpehC, δpme, and δegl) and one inactivated allele (cbhA::aphA-3) resulted in 15 mutants missing one to six CWDE. In soil-drench inoculation assays, virulence of mutants lacking only pectic enzymes (PehA, PehB, PehC, and Pme) was not statistically different from GMI1000, but all the mutants lacking one or both cellulolytic enzymes (Egl or CbhA) wilted plants significantly more slowly than did the wild type. The GMI-6 mutant that lacks all six CWDE was more virulent than the mutant lacking only its two cellulolytic enzymes, and both were significantly more virulent than the T2SS mutant (GMI-D). Very similar results were observed in wounded-petiole inoculation assays, so GMI-6 and GMI-D appear to be less capable of colonizing tomato tissues after invasion. Because the T2SS mutant was much less virulent than the sixfold CWDE mutant, we conclude that other secreted proteins contribute substantially to the ability of R. solanacearum GMI1000 to systemically colonize tomato plants.

scholarly journals Competition with the Wild-type Strain and a Phenotypic Conversion Strain of Ralstonia solanacearum in the Soil and Plants

2016 ◽  
Vol 28 (3) ◽  
pp. 133-141 ◽  
Author(s):  
Hiroki NAKAHARA ◽  
Taro MORI ◽  
Hiromi MATSUSAKI ◽  
Naotaka MATSUZOE
Keyword(s):  
Ralstonia Solanacearum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type

scholarly journals Characteristic Observation of Cordyceps Militaris (L) Wild Type Strain from Five Oil Palm Plantation in Muara Wahau East Borneo

2021 ◽  
Vol 29 (3) ◽  
pp. 167-175
Author(s):  
Edwin Aprianda ◽  
Gunawan Djajakirana ◽  
Darmawan Darmawan
Keyword(s):  
Oil Palm ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Colony Diameter ◽  
Virulence Potential ◽  
Rich Media ◽  
High Virulence ◽  
Incubation Method

Cordycep militaris (L) is known in oil palm plantations as a natural enemy of nettle caterpillars.  This fungus infects the caterpillars that descend down to become pupae around the palm circle, so that the pupae do not develop into imago and the pest's life cycle will be interrupted. This fungus is one of the 3 main entomopathogenic fungi used as bioinsecticides to control pests in oil palm plantations. In this study, the characteristics of C. militaris were observed from 5 oil palm plantations cultured in vitro using two types of media and two incubation methods. The results showed that there were mycelium pigmentation in nutrient-rich media Sabouraud Dextrose Agar plus Yeast extract (SDAY) when incubated with lighting.  Only one of five mycelium cultures using SDAY media showed pigmentation on the no-light incubation method. Pigmentation did not occur in nutrient-poor media such as agar (WA), either incubated with lighting or with no-light. The growth of isolates was generally higher on SDAY media than on WA media. This study showed that C. militaris is a facultative phagotrophic fungus. The highest growth of isolates cultured on SDAY media incubated with lighting was found in isolates A and C, with colony diameter 90 mm, high mycelium density (+++) and hairy texture like cotton at the end of the 3rd week after inoculation.  In the no-light incubation method, the highest growth was found in isolates B and C with colony diameter 90 mm, high mycelium density (+++) and hairy texture like cotton at the end of the 3rd week after inoculation. Isolates A and C showed high virulence potential to be used as bioinsecticides.

scholarly journals Positive regulation of MarR-type regulator slnO and improving salinomycin production of Streptomyces albus by multiple transcriptional regulations

2022 ◽  
Author(s):  
Hongrui Zhang ◽  
Weiwei Chen ◽  
Xinyi Wang ◽  
Yongquan Li ◽  
Zhenhong Zhu
Keyword(s):  
Gene Deletion ◽  
High Yield ◽  
Specific Gene ◽  
Wild Type ◽  
Yield Strain ◽  
Positive Regulation ◽  
Over Expression ◽  
Streptomyces Albus ◽  
Regulation Strategies ◽  
Expression Strain

The purpose of this study is to explore the function of MarR-family regulator slnO. In addition, the high-yield strain of salinomycin was constructed by using combined regulation strategies. Firstly the slnO gene over-expression strain (GO) was constructed in Streptomyces albus. Compared to wild type (WT) strain，salinomycin production in GO strain was increased about 28%. Electrophoretic mobility gel shift assays (EMSAs) confirmed that SlnO protein can bind specifically to the intergenic region of slnN-slnO, slnQ-slnA1 and slnF-slnT. qRT-PCR experiments also showed that slnA1, slnF, and slnT1 were significantly up-regulated, while the expression level of the slnN gene was down-regulated in GO strain. Secondly, slnN gene deletion strain (slnNDM) was used as the starting strain, and the pathway specific gene slnR in salinomycin gene cluster was over expressed in slnNDM. The new strain was named ZJUS01. The yield of salinomycin in ZJUS01 strain was 25% and 56% higher than that in slnNDM strain and WT strain. Above results indicate that the slnO gene has a positive regulation effect on the biosynthesis of salinomycin. Meanwhile, the yield of salinomycin could be greatly increased by manipulating multiple transcriptional regulations.

scholarly journals Role of aspartate ammonia-lyase in Pasteurella multocida

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Zui Wang ◽  
Li Li ◽  
Peng Liu ◽  
Chen Wang ◽  
Qin Lu ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Bacterial Growth ◽  
Type Strain ◽  
Pasteurella Multocida ◽  
Wild Type Strain ◽  
Luria Bertani ◽  
Economic Losses ◽  
Wild Type ◽  
Mueller Hinton ◽  
Significant Difference

Abstract Background Pasteurella multocida is responsible for a highly infectious and contagious disease in birds, leading to heavy economic losses in the chicken industry. However, the pathogenesis of this disease is poorly understood. We recently identified an aspartate ammonia-lyase (aspA) in P. multocida that was significantly upregulated under iron-restricted conditions, the protein of which could effectively protect chicken flocks against P. multocida. However, the functions of this gene remain unclear. In the present study, we constructed aspA mutant strain △aspA::kan and complementary strain C△aspA::kan to investigate the function of aspA in detail. Result Deletion of the aspA gene in P. multocida resulted in a significant reduction in bacterial growth in LB (Luria-Bertani) and MH (Mueller-Hinton) media, which was rescued by supplementation with 20 mM fumarate. The mutant strain △aspA::kan showed significantly growth defects in anaerobic conditions and acid medium, compared with the wild-type strain. Moreover, growth of △aspA::kan was more seriously impaired than that of the wild-type strain under iron-restricted conditions, and this growth recovered after supplementation with iron ions. AspA transcription was negatively regulated by iron conditions, as demonstrated by quantitative reverse transcription-polymerase chain reaction. Although competitive index assay showed the wild-type strain outcompetes the aspA mutant strain and △aspA::kan was significantly more efficient at producing biofilms than the wild-type strain, there was no significant difference in virulence between the mutant and the wild-type strains. Conclusion These results demonstrate that aspA is required for bacterial growth in complex medium, and under anaerobic, acid, and iron-limited conditions.

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