scholarly journals The RSc0454-Encoded FAD-Linked Oxidase Is Indispensable for Pathogenicity in Ralstonia solanacearum GMI1000

2019 ◽  
Vol 32 (6) ◽  
pp. 697-707
Author(s):  
Xun Hu ◽  
Zhiwen Zhao ◽  
Tao Zhuo ◽  
Xiaojing Fan ◽  
Huasong Zou

Ralstonia solanacearum is the causal agent of bacterial wilt disease. Here, we report that a large FAD-linked oxidase encoded by RSc0454 in GMI1000 is required for pathogenicity. The FAD-linked oxidase encoded by RSc0454 is composed of 1,345 amino acids, including DUF3683, lactate dehydrogenase (LDH), and succinate dehydrogenase (SDH) domains. The RSc0454 protein showed both LDH and SDH activities. To investigate its role in pathogenicity, a deletion mutant of the RSc0454 gene was constructed in GMI1000, which was impaired in its ability to cause bacterial wilt disease in tomato. A single DUF3683, LDH, or SDH domain was insufficient to restore bacterial pathogenicity. Mutagenesis of the RSc0454 gene did not affect growth rate but caused cell aggregation at the bottom of the liquid nutrient medium, which was reversed by exogenous applications of lactate, fumarate, pyruvate, and succinate. qRT-PCR and promoter LacZ fusion experiments demonstrated that RSc0454 gene transcription was induced by lactate and fumarate (both substrates of LDH). Compared with the downregulation of the succinate dehydrogenase gene sdhBADC and the lactate dehydrogenase gene ldh, RSc0454 gene transcription was enhanced in planta. This suggests that the oxidase encoded by RSc0454 was involved in a redox balance, which is in line with the different living conditions of R. solanacearum.

2019 ◽  
Vol 3 (2) ◽  
pp. 103
Author(s):  
Arika Purnawati ◽  
Wiwik Harjani ◽  
Herry Nirwanto

<p>Wilt disease of <em>Solanaceae</em> caused by <em>Ralstonia solanacearum</em> reduce the crop quality and negatively affect the crop product. The objective of this research was to discover of endophytic bacteria formulation that effectively decreases bacterial which cause wilt disease on <em>Solanaceae</em>. The research consisted of purification of <em>Ralstonia solanacearum</em>, endophytic bacteria were obtained from the sample and the screening of endophytic bacteria using this following assay: antagonist assay, seedling assay and <em>in planta</em> assay. The results showed that in antagonist assay, the bacterial isolate code PS<sub>1</sub>, PS<sub>2</sub>, and PS<sub>8 </sub>could inhibit growth of <em>R. solanacearum. </em>From the seedling assay, it obtained that all of the isolates increased of percentage of germination, seed coating and powder formulation can decrease disease incidence of bacterial wilt disease.</p>


2001 ◽  
Vol 183 (12) ◽  
pp. 3597-3605 ◽  
Author(s):  
Julie Tans-Kersten ◽  
Huayu Huang ◽  
Caitilyn Allen

ABSTRACT Ralstonia solanacearum, a widely distributed and economically important plant pathogen, invades the roots of diverse plant hosts from the soil and aggressively colonizes the xylem vessels, causing a lethal wilting known as bacterial wilt disease. By examining bacteria from the xylem vessels of infected plants, we found thatR. solanacearum is essentially nonmotile in planta, although it can be highly motile in culture. To determine the role of pathogen motility in this disease, we cloned, characterized, and mutated two genes in the R. solanacearum flagellar biosynthetic pathway. The genes for flagellin, the subunit of the flagellar filament (fliC), and for the flagellar motor switch protein (fliM) were isolated based on their resemblance to these proteins in other bacteria. As is typical for flagellins, the predicted FliC protein had well-conserved N- and C-terminal regions, separated by a divergent central domain. The predicted R. solanacearum FliM closely resembled motor switch proteins from other proteobacteria. Chromosomal mutants lackingfliC or fliM were created by replacing the genes with marked interrupted constructs. Since fliM is embedded in the fliLMNOPQR operon, the aphAcassette was used to make a nonpolar fliM mutation. Both mutants were completely nonmotile on soft agar plates, in minimal broth, and in tomato plants. The fliC mutant lacked flagella altogether; moreover, sheared-cell protein preparations from the fliC mutant lacked a 30-kDa band corresponding to flagellin. The fliM mutant was usually aflagellate, but about 10% of cells had abnormal truncated flagella. In a biologically representative soil-soak inoculation virulence assay, both nonmotile mutants were significantly reduced in the ability to cause disease on tomato plants. However, the fliC mutant had wild-type virulence when it was inoculated directly onto cut tomato petioles, an inoculation method that did not require bacteria to enter the intact host from the soil. These results suggest that swimming motility makes its most important contribution to bacterial wilt virulence in the early stages of host plant invasion and colonization.


2020 ◽  
Vol 14 (1) ◽  
pp. 8-20
Author(s):  
Fery Abdul Choliq ◽  
Mintarto Martosudiro ◽  
Istiqomah Istiqomah ◽  
Muhammad Fanhash Nijami

Tomato is the top priority in the development of horticultural crops. The obstacle which mostly encountered is Ralstonia solanacearum pathogen attack. Bacteriophage can cause bacterial lysis after they they develop themselves inside the bacteria. The specific of the bacteriophage can provide result quickly, accurately, and efficiently so that it can be used as an alternative to control bacterial wilt disease R. solanacearum environmentally friendly. This study aims to find out the effectiveness of bacteriophage to control the bacterial wilt disease R. solanacearum. The testing method are plaque assay, bacteriophage infections test in various dilutions, bacteriophage infection test in a liquid medium, and transmission electron microscopy test. In the greenhouse scale testing using a Completely Randomized Design (CRD) with 6 treatments and 4 replications. Quantitative data were analyzed using analysis of variance 5% error level and followed by least significant different  test level of 5%. The results showed that bacteriophages can infect R. solanacearum. Bacteriophage can infect bacteria R. solanacearum indicated by the appearance of plaques in NA media, the declining value of absorbance spectophotometer, and can lyse bacterial cells from dilutions 10-1 to 10-9. The morphology of bacteriophages that infect R. solanacearum have hexagonal head structure and it have which is with a size of 200 nm. In the greenhouse scale showed that the symptoms of R. solanacearum appear at 29 days after inoculation. Application of bacteriophages can control R. solanacearum with lower percentage than the control treatment.


2019 ◽  
Vol 2 (3) ◽  
pp. 89-96 ◽  
Author(s):  
Rachmad Saputra ◽  
Triwidodo Arwiyanto ◽  
Arif Wibowo

Streptomyces sp. bacteria have the potential to produce antibiotic compounds, which are one of the mechanisms that are widely used in biological control. However, in general, biological control mechanisms also occur through competition, cell wall degradation and induced resistance. This study was aimed to determine the physiological, biochemical and molecular characteristics of two isolates of Streptomyces sp. (S-4 and S16 isolates) isolated from the tomatoes roots, and to find out their ability to control Ralstonia solanacearum, which causes bacterial wilt disease on a wide range of hosts. The results showed both Streptomyces sp. isolates had several different physiological and biochemical characteristics and had a different ability to inhibit R. solanacearum in vitro. Streptomyces sp. S-16 isolate had a high similarity with Streptomyces diastaticus subsp. ardesiacus strain NRRL B-1773T based on the molecular identification results. Further research needs to be done to see the potential inhibition of the two Streptomyces isolates in inhibiting the development of bacterial wilt disease in tomato plants caused by R. solanacearum.


Plant Science ◽  
2019 ◽  
Vol 280 ◽  
pp. 197-205 ◽  
Author(s):  
Tâmara P. Morais ◽  
Paulo A. Zaini ◽  
Sandeep Chakraborty ◽  
Hossein Gouran ◽  
Camila P. Carvalho ◽  
...  

2010 ◽  
Vol 23 (8) ◽  
pp. 1042-1052 ◽  
Author(s):  
Jennifer Colburn-Clifford ◽  
Caitilyn Allen

Ralstonia solanacearum race 3 biovar 2 (R3bv2) is an economically important soilborne plant pathogen that causes bacterial wilt disease by infecting host plant roots and colonizing the xylem vessels. Little is known about R3bv2 behavior in the host rhizosphere and early in bacterial wilt pathogenesis. To explore this part of the disease cycle, we used a novel taxis-based promoter-trapping strategy to identify pathogen genes induced in the plant rhizosphere. This screen identified several rex (root exudate expressed) genes whose promoters were upregulated in the presence of tomato root exudates. One rex gene encodes an assembly protein for a high affinity cbb3-type cytochrome c oxidase (cbb3-cco) that enables respiration in low-oxygen conditions in other bacteria. R3bv2 cbb3-cco gene expression increased under low-oxygen conditions, and a cbb3-cco mutant strain grew more slowly in a microaerobic environment (0.5% O2). Although the cco mutant could still wilt tomato plants, symptom onset was significantly delayed relative to the wild-type parent strain. Further, the cco mutant did not colonize host stems or adhere to roots as effectively as wild type. These results suggest that R3bv2 encounters low-oxygen environments during its interactions with host plants and that the pathogen depends on this oxidase to help it succeed in planta.


2013 ◽  
Vol 14 (1) ◽  
pp. 32
Author(s):  
Jonathan M. Jacobs ◽  
Caitilyn Allen

The bacterial wilt pathogen Ralstonia solanacearum causes major agricultural losses on many crop hosts worldwide. Resistance breeding is the best way to control bacterial wilt disease, but the biological basis for bacterial wilt resistance is unknown. We found that R. solanacearum uses an AvrE-family, Type III-secreted effector called PopS to overcome plant defenses and cause disease on tomato. Orthologs of PopS are widely conserved across distinct classes of plant pathogenic bacteria and could provide novel, durable targets for resistance. Accepted for publication 25 September 2013. Published 25 November 2013.


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