First Report of Bacterial Wilt Caused by Ralstonia solanacearum Biovar 2 Race 1 on Tomato in Egypt

Development of antibody to virulence factor flagellin and its evaluation in screening Ralstonia pseudosolanacearum

The bacterial wilt disease caused by Ralstonia pseudosolanacearum presents a notable economic risk to a variety of crucial crops worldwide. During preliminary isolation of this phytopathogen, several colonies of other saprophytic bacteria may be mistaken with it. So, the present study aims to address this issue by proposing the application of immunogenic proteins, particularly flagellin (FliC), to enable a rapid and early identification of bacterial wilt. In this study, a novel approach is unveiled for the early detection of R. pseudosolanacearum. The study exploits the immunogenic attributes of flagellin (FliC), by generating polyclonal antibodies against recombinant FliC within model organisms-rabbits and mice. The efficacy of these antibodies is meticulously assessed through discerning techniques, including DAS-ELISA and Western blot analyses, which elucidate their remarkable specificity in identifying various R. pseudosolanacearum strains. Furthermore, the introduction of antibody-coated latex agglutinating reagents offers an additional layer of confirmation, substantiating the feasibility of establishing a laboratory-based toolkit for swift screening and unambiguous identification of the bacterial wilt pathogen. This study presents a significant stride toward enhancing early diagnostic capabilities, potentially revolutionizing agricultural practices by safeguarding crop yield and quality through proactive pathogen detection and mitigation strategies.

Low cost and renewable H2S-biofilter inoculated with Trichoderma harzianum

The use of biogas to produce hydrogen is currently gaining more attention. One of the drawbacks for the valorization of biogas is the presence of H2S, a hazardous molecule that can cause damage in the metallic internal structures of industries. In this study, the H2S-removal performance of a fungi-based biofilter was investigated. First, an H2S-resistant fungal species was isolated from an industrial digestate and identified as Trichoderma harzianum. The capacity of this microorganism to metabolize H2S in a mineral medium was confirmed. Then, a bioreactor was constructed and put in place to monitor the elimination of gaseous H2S. A mix of cardboard, perlite, woodchips, and wood pellets was used as filling. Microbial development and the outlet gas composition were monitored during a 60-day experimental process during which H2S was completely removed. 97% of the introduced sulphur was detected in the used filling material (fungal species + packing material) by elemental analysis. 24% of the detected sulphur was identified by ion-exchange chromatography as SO42-. Elemental analysis, gas chromatography, and ion-exchange chromatography were used to determine the bioreactor sulphur balance. Metagenomic analysis underlined that H2S elimination was due to the presence of Trichoderma harzianum with a H2S-specific bacterial consortium.

Screening microbial inoculants and their interventions for cross-kingdom management of wilt disease of solanaceous crops- a step toward sustainable agriculture

Microbial inoculants may be called magical bullets because they are small in size but have a huge impact on plant life and humans. The screening of these beneficial microbes will give us an evergreen technology to manage harmful diseases of cross-kingdom crops. The production of these crops is reducing as a result of multiple biotic factors and among them the bacterial wilt disease triggered by Ralstonia solanacearum is the most important in solanaceous crops. The examination of the diversity of bioinoculants has shown that more microbial species have biocontrol activity against soil-borne pathogens. Reduced crop output, lower yields, and greater cost of cultivation are among the major issues caused by diseases in agriculture around the world. It is universally true that soil-borne disease epidemics pose a greater threat to crops. These necessitate the use of eco-friendly microbial bioinoculants. This review article provides an overview of plant growth-promoting microorganisms bioinoculants, their various characteristics, biochemical and molecular screening insights, and modes of action and interaction. The discussion is concluded with a brief overview of potential future possibilities for the sustainable development of agriculture. This review will be useful for students and researchers to obtain existing knowledge of microbial inoculants, their activities, and their mechanisms, which will facilitate the development of environmentally friendly management strategies for cross-kingdom plant diseases.

Molecular identification and biological control of Ralstonia solanacearum from wilt of papaya by natural compounds and Bacillus subtilis: An integrated experimental and computational study

Ralstonia solanacearum is a harmful pathogen that causes severe wilt disease in several vegetables. In the present study, we identified R. solanacearum from wilt of papaya by 16S rRNA PCR amplification. Virulence ability of R. solanacearum was determined by amplification of approximately 1500 bp clear band of hrpB gene. Further, in-vitro seed germination assay showed that R. solanacearum reduced the germination rate up to 26.21%, 34% and 33.63% of cucumber, bottle guard and pumpkin seeds, respectively whereas shoot and root growth were also significantly decreased. Moreover, growth inhibition of R. solanacearum was recorded using antibacterial compound from medicinal plant and antagonistic B. subtilis. Petroleum ether root extract of Rauvolfia serpentina showed highest 22 ± 0.04 mm diameter of zone of inhibition where methanolic extract of Cymbopogon citratus and ethanolic extract of Lantana camara exhibited 20 ± 0.06 mm and 20 ± 0.01 mm zone of inhibition against R. solanacearum, respectively. In addition, bioactive compounds of B. subtilis inhibited R. solanacearum growth by generating 17 ± 0.09 mm zone of inhibition. To unveil the inhibition mechanism, we adopted chemical-protein interaction network and molecular docking approaches where we found that, rutin from C. citratus interacts with citrate (Si)-synthase and dihydrolipoyl dehydrogenase of R. solanacearum with binding affinity of -9.7 kcal/mol and -9.5 kcal/mol while quercetin from B. subtillis interacts with the essential protein F0F1 ATP synthase subunit alpha of the R. solancearum with binding affinity of -6.9 kcal/mol and inhibit the growth of R. solanacearum. Our study will give shed light on the development of eco-friendly biological control of wilt disease of papaya.