Pathogen Of Wilt Disease Research Articles

Molecular probing of wilt etiology in Thuja orientalis, and pathogen confirmation through Koch’s Postulates

Thuja orientalis a monoecious widely grown ornamental plant in Pakistan. T. orientalis plants were observed being severely attacked by Fusarium wilt during a survey of the landscape areas of District Faisalabad. Infected plants had severe symptoms of leaves wilting, chlorosis, and necrosis. Wilt disease-affected samples of Thuja orientalis were collected from the University of Agriculture, Faisalabad, Pakistan, in 2017. The associated pathogen was identified based on morphological characters and molecular characterization by using ITS primers (ITS1-F/ITS4) specific to ITS regions of ribosomal RNA (rRNA) of the fungus. The morphologically characterized fungal isolates were used in pathogenicity. In the pathogenicity test, inoculated plants were compared with control plants (sprayed with distilled water). After 3-4 weeks, inoculated plants showed typical chlorosis symptoms. Pathogenicity test proved the F. solani as pathogen of wilt disease on Thuja. Keywords: Thuja orientalis, Morpankh, Fusarium solani, Fusarium wilt, pathogenicity.

Effectiveness of Endophytic Bacteria from Local Tomato Plants Against Wilt Disease Caused by Fusarium oxysporum

Fusarium wilt is a plant disease caused by <em>Fusarium oxysporum</em> that generates significant economic loss to crops. A method to sustainably control <em>F. oxysporum</em> is utilizing biological agents, such as endophytic bacteria. Therefore, this study aimed to isolate endophytic bacteria from tomato plant tissue, which could inhibit the pathogen of wilt disease (<em>F. oxysporum</em>). Endophytic bacteria were isolated from local tomato plants in Muna Regency, Indonesia. Morphological characteristics such as size, shape, color and height of bacterial colonies were then determined by Gram staining using potassium hydroxide (KOH). Endophytic bacterial isolates were evaluated for their ability to inhibit <em>F. oxysporum</em> through inhibition and hydrogen cyanide (HCN) production tests. Subsequently, analysis of variance was used to determine whether endophytic bacteria inhibited <em>F. oxysporum</em> growth, and if there was a significant effect, Duncan's test was conducted at 95% significance. HCN production was observed through qualitative methods. The results showed that four endophytic bacteria isolates, namely LBR I A03, SWR II B04, SDM II B05 and SWR I A02 inhibited the growth of <em>F. oxysporum</em> by more than 50%. It also revealed that four endophytic bacterial isolates were strong HCN producers and two were weak producers. Therefore, isolates showing antifungal activity in this study can be used as biopesticide agents to induce plant resistance to <em>F. oxysporum</em>.

Utilization of Rhizobacteria and Spent Mushroom Compost for the Management of Bacterial Wilt of Potato

Potato (Solanum tuberosum L.) is the fourth most important staple food in the world after wheat (Triticum aestivum L.), rice (Oryza sativa L.) and maize (Zea mays L.). In Pakistan, potato crop is cultivated over an area of 191.6 million hectares. On an average potato production in Pakistan is 20 tonnes per hectare.A target has set by The Government of Pakistan to produce about 4.871 million tons potatoes during Rabi Season 2020-21. (Federal Committee on Agriculture FCA) The potato production exceeds 376 million tonnes harvested from an area of 19.25 million hectares in the world (FAOSTAT 2018). Ralstonia solanacearum causing bacterial wilt is a major threat to potato production. Management through biocontrol agents is one of the best methods that can replace synthetic chemical-based formulations. In the current study combine effect of antagonist rhizobacteria as biocontrol agent and spent mushroom compost as biofertilizer were tested against bacterial wilt disease pathogen. Potato plant samples infected with R. solanacearum and rhizobacteria were collected from potato growing fields in Rawalpindi. Out of twenty tested antagonistic rhizobacterial isolates, only three viz., Rh10, Rh12 and Rh 15 showed maximum inhibitory effect against R. solanacearum. In another experiment different combinations of treatments containing rhizobacteria alone or combined with fresh and spent mushroom composts were also tested against the bacterial wilt pathogen under laboratory conditions. Combination of rhizobacteria along with weathered compost (T5) reduced the disease incidence to 15.92 % when compared against 77.81 % in control after six weeks. Significant increase in plant height up to 41.83 cm was also observed as compared to control viz., 35.5cm. Similarly, T2 (only fresh compost), T3 (containing fresh compost along with rhizobacteria) and T4 (rhizobacteria along with weathered compost) also showed better results as compared to against control (T0) where there was no application of rhizobacteria and compost. Application of rhizobacterial along with spent mushroom compost can significantly reduce the disease incidence along with the improvement in plant growth parameters.

딸기 위황병원균 Fusarium oxysporum f sp. fragariae의 살균제 감수성 평가

딸기 위황병원균 Fusarium oxysporum f sp. fragariae의 살균제 감수성 평가

Production of \u03b2-1,3-glucanase and chitosanase from clostridial strains isolated from the soil subjected to biological disinfestation

Biological soil disinfestation (BSD) or anaerobic (reductive) soil disinfestation (ASD/RSD) is a bioremediation method used to eliminate soil-borne plant pathogens by exploiting the activities of anaerobic bacteria in soil. In this study, two obligate anaerobic bacterial strains isolated from BSD-treated soil and identified as Clostridium beijerinckii were examined for their abilities to suppress the spinach wilt disease pathogen (Fusarium oxysporum f. sp. spinaciae) as a representative soil-borne fungal plant pathogen. Both strains degraded β-1,3-glucan and chitosan, two major polysaccharide components of ascomycetes fungal cell wall, supplemented in the medium. β-1,3-Glucanase was detected in the supernatants of cultures supplemented with different types of glucan. Similarly, chitosanase was detected in cultures supplemented with chitosan. Both the enzyme activities were also detected in cultures containing glucose as a substrate. Live cells of F. oxysporum f. sp. spinaciae that were co-incubated with each anaerobic strain under anaerobic conditions using glucose as a substrate died during incubation. Freeze-dried dead fungal biomass of the pathogen, when added to the culture, supported good growth of both anaerobes and production of both enzymes. Severe and nearly complete degradation of both live and dead fungal cells during incubation with anaerobic bacteria was observed by fluorescence microscopy. When individual anaerobic bacterial strain was co-incubated with live pathogenic fungal cells in wheat bran, a popular material for BSD-treatment, both the strains grew well and killed the fungal pathogen promptly by producing both enzymes. These results indicate that both the bacterial strains attack the fungal cells by releasing extracellular fungal cell wall-degrading enzymes, thereby eliminating the pathogen.

Evaluation of micronutrients for inhibition of Panama wilt disease pathogen (Fusarium oxysporum f. sp. cubense) of Banana

The major losses of banana at present by Panama wilt disease pathogen of banana and its management is very typical because it is caused by a soil-borne pathogen (Fusarium oxysporum f. sp. cubense). The micronutrients are used to manage the disease as well as it provide the healthiness of plant and increases the fertility. The mechanism of healthiness of plant is achieved with micronutrients applied in the soil. An experiment was conducted to evaluate the micronutrients viz. Zinc Sulfate, Ferrous Sulfate, Ammonium Sulfate, Copper Sulfate, Calcium Nitrate, Borax and Potassium Chloride against Fusarium oxysporum f.sp. cubense causing Panama wilt of banana. The results of the study revealed that among the micronutrients used, Borax @ 500 and 750 ppm completely inhibited the mycelial growth of FOC followed by Zinc Sulfate (45.7, 42.6, 39.2 and 18.5 mm at 100, 250, 500 and 750 ppm, respectively). The incorporation of borax in the solid medium at higher concentrations viz., 500 and 750 ppm was very effective for the management of Panama wilt disease of banana.

塩ストレスによる植物病原菌（青枯病菌）の抑制

塩ストレスによる植物病原菌（青枯病菌）の抑制

The Effect of Fusaric Acid Application on the Lignin and Suberin Formation as Resistance Indicator on Tomato

Fusaric acid (=FA) is a phytotoxin produced by Fusarium oxysporum, pathogen of wilt disease on tomato. A concentration of FA causes death of plant. However, low concentration will elicit various plant defense responses and inhibit pathogen growth. The research focused on the observation of lignin and suberin formation after application of FA on tomato in different concentration. This research was caried out at elementary laboratory of Agriculture Faculty of Muhammadiyah University of Parepare, Parepare and Micology Laboratory of Gadjah Mada University, Yogyakarta. Four concentrations of FA (sigma) 0, 25, 50, 75, and 100 ppm were used in this research, whereas inoculation with Fusarium oxysporum was served as control. Lignin and suberin formations in plant cell as structural resitantance response were analyzied by using microtechnique protocol. The result of histological analysis showed that treatment of F. oxysporum, 10 ppm, 50 ppm, 75 ppm, and 100 ppm of FA, caused a change in lignin content of tomato cell on 10 – 40 days after application and followed also by necrotitation. The application of 25 ppm FA increases the lignin and the suberin content without necrosis on 20 and 30 days after application.

Search for alternate hosts of the coconut Cape Saint Paul wilt disease pathogen

A thesis submitted to the Department of Biochemistry and Biotechnology in partial fulfilment of the Requirements for the award of a Master of Science in Biotechnology, 2009

Search for alternate hosts of the coconut Cape Saint Paul Wilt Disease pathogen

Lethal Yellowing disease locally called Cape Saint Paul wilt disease (CSPWD) is the bane of the coconut industry in Ghana and is caused by a phytoplasma. In Ghana, there are areas where the disease has re-infected re-plantings long after decimating all the palms in the area. This brings to the fore the possibility of alternate hosts in the spread of the disease because the pathogen is an obligate parasite. In this work, a number of plants were screened for their host status to the CSPWD pathogen. The presence of phytoplasmas in these plants was tested by polymerase chain reaction analysis using universal phytoplasma primers P1/P7 and CSPWD-specific primers G813/GAKSR. Although Desmodium adscendens tested positive to the CSPWD-specific primers, cloning and sequencing did not confirm it as an alternate host. The identification of alternate hosts will help us to evolve sound control strategies against the spread of the disease.

Antagonistic effects of Streptomyces violaceusniger strain G10 on Fusarium oxysporum f.sp. cubense race 4: indirect evidence for the role of antibiosis in the antagonistic process.

Fusarium oxysporum f.sp. cubense is the causal pathogen of wilt disease of banana. A cost-effective measure of control for this disease is still not available. Streptomyces violaceusniger strain G10 acts as an antifungal agent antagonistic towards many different phytopathogenic fungi, including different pathogenic races of the Fusarium wilt pathogen. In an attempt to understand the mode of action of this antagonist in nature, the interaction between S. violaceusniger strain G10 and F. oxysporum f.sp. cubense was first studied by paired incubation on agar plates. Evidence for the in vitro antibiosis of strain G10 was demonstrated by inhibition zones in the "cross-plug" assay plates. Microscopic observations showed lysis of hyphal ends in the inhibited fungal colonies. Culture of strain G10 in liquid media produces antifungal metabolites, which showed in vitro antagonistic effects against F. oxysporum f.sp. cubense such as swelling, distortion and excessive branching of hyphae, and inhibition of spore germination. An indirect method was used to show that antibiosis is one of the mechanisms of antagonism by which strain G10 acts against F. oxysporun f.sp. cubense in soil. This study suggests the potential of developing strain G10 for the biological control of Fusarium wilt disease of banana.

An Antimicrobial Substance Produced byPseudomonas cepaciaB5 against the Bacterial Wilt Disease Pathogen,Pseudomonas solanacearum

An antimicrobial substance produced by Pseudomonas cepacia B5 (B5) against the bacterial wilt disease pathogen, Pseudomonas solanacearum, was isolated and identified in order to clarify the mechanism for disease suppression by B5. A filtrate of the B5 culture showed high inhibitory activity against this pathogen. The active substance was isolated in pure form by chromatography with a Diaion HP20 column and by high-performance liquid chromatography with a Jaigel GS220 column. On the basis of IR, NMR, and mass spectra, the antimicrobial substance was identified as 2-keto-d-gluconic acid (2KGA). The production of 2KGA and the destruction of the disease pathogen in a contaminated soil suspension to which the B5 strain was added, together with wheat bran, suggested that 2KGA might be involved in disease suppression by P. cepacia B5.

An Antimicrobial Substance Produced by Pseudomonas cepacia B5 against the Bacterial Wilt Disease Pathogen, Pseudomonas solanacearum

An antimicrobial substance produced by Pseudomonas cepacia B5 (B5) against the bacterial wilt disease pathogen, Pseudomonas solanacearum, was isolated and identified in order to clarify the mechanism for disease suppression by B5. A filtrate of the B5 culture showed high inhibitory activity against this pathogen. The active substance was isolated in pure form by chromatography with a Diaion HP20 column and by high-performance liquid chromatography with a Jaigel GS220 column. On the basis of IR, NMR, and mass spectra, the antimicrobial substance was identified as 2-keto-d-gluconic acid (2KGA). The production of 2KGA and the destruction of the disease pathogen in a contaminated soil suspension to which the B5 strain was added, together with wheat bran, suggested that 2KGA might be involved in disease suppression by P. cepacia B5.

The Elegans fusaria causing wilt disease of carnation. I. Taxonomy

The distinction of the wilt disease pathogen of carnationFusarium (oxysporum var.)redolens fromF. oxysporum (var.oxysporum) is considered. Previous reports that isolates of both taxa cause indistinguishable diseases in carnation are confirmed.F. (oxysporum var.)redolens andF. oxysporum were found to form one variable complex on morphological criteria. Apparently, host specialization rather than morphological variation reflects the evolutionary relationships in theFusarium sectionElegans. The distinction ofF. redolens fromF. oxysporum does therefore not seem justified, neither at specific nor at varietal level.

A wilt disease of coconuts from Trinidad associated with Phytomonas sp., a sieve tube‐restricted protozoan flagellate

SUMMARYA wilt disease of coconut palms in Trinidad has been responsible for the death of more than 15 000 palms in the last 2 years. Symptoms of the disease include: loss of nuts, premature browning of successively younger leaves, necrosis of open and unopened inflorescences and of the young unexpanded leaves at the centre of the crown; rotting of the growing point, stem apex and roots.Samples from each of 10 diseased palms contained flagellates which were classified as trypanosomatid protozoans of the genus Phytomonas. The protozoans, which by squeezing could be expressed easily from tissues for observation by phase contrast light microscopy, were 1–1.5 μm wide and 27 μm long including the flagellum which was approximately 7 μm long.Sections of inflorescence rachillae from diseased palms revealed that the phytomonads were restricted to the sieve tubes. Phytomonas was always associated with diseased palms but it was never found in healthy palms.A brief description of the ultrastructure of the presumed pathogen of wilt disease is also given.