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Showing 6 results for Xanthomonas

Majid Amani, Nader Hassanzadeh, Saeid Rezaei,
Volume 1, Issue 1 (3-2012)

In 2005, Circular to elliptical brown necrotic leaf spots, were observed on young leaves of Banana(Musa acuminata L.) plantion under plastic cover in Mazandaran&Gorgan provinces. The rhizomes and pseudostems were not affected. A gram-negativebacterium with yellow mucoid colonies was isolated from the leaves on sucrose and glucose nutrient agar. All isolates were negative in oxidas, and positive in catalase reaction. Non of isolates did not produce green or blue pigment on KB medium. On the basia of phenotypic charachteristics pathogenicity test was confirmed with inocoulation of bacterial suspension to Banana plants. The causal agent of bacterial necrotic and leaf spot of banana was recognized asXanthomonascampestris. This is the first report ofbacterial necrotic and leaf spot of banana in Iran.
Rasool Rezaei,
Volume 4, Issue 1 (3-2015)

Rezaei R. 2015. Pathogenicity and virulence factors of plant pathogenic bacteria. Plant Pathology Science 4(1):23-33.
 Plant pathogenic bacteria have evolved specialized strategies to infect their hosts. In this regard, the key virulence factors are effector proteins, cell wall degrading enzymes, toxins, extracellular polysaccharides and phytohormones. The interactions between plant pathogenic bacteria and their hosts have resulted in an evolutionary system between host defense responses and pathogen virulence factors. Pathogenic bacteria are continually under pressure to diversify their mechanisms to prevent host defenses and optimize nutrient availability. In turn, these virulence mechanisms have shaped the evolution of plant innate immunity. In this paper, the pathogenicity and virulence factors of plant pathogenic bacteria are discussed.

Nahid Gerayeli, Sareh Baghaee Ravari,
Volume 5, Issue 2 (8-2016)

Gerayeli N. & Baghaee-Ravari S. 2016. The  biological  role of bacteriocins of gram-negative bacteria. Plant Pathology Science 5(2): 63-70.

Bacteriocins are a kind of antimicrobial peptides  or  proteins, produced by some gram-negative bacteria, for competition for space and resources, which can kill or inhibit  closely-related  bacteria. The producer bacterium is immune to these  material by specific immunity proteins. Bacteriocins vary in size, microbial targets, mode of action and immunity mechanism. So  far  lots of  bacteriocins  that produced by  specific isolates of gram-negative bacteria have been identified, which often have a high  molecular  weight. In this paper, mode of production,  and  mechanisms of  action of  bacteriocins, and  their  role  in  management  of  plants bacterial diseases, described.

Rasool Rezaei,
Volume 9, Issue 1 (3-2020)

Rezaei R (2020) Effect of eight essential oils on bacterial canker disease in citrus. Plant Pathology Science 9(1):30-39. DOI: 10.2982/PPS.9.1.30.
Introduction: Citrus bacterial canker caused by Xanthomonas citri subsp. citri is an economically important disease in many tropical and subtropical countries. Several pathotypes of this pathogen have been described which, in addition to certain genotypic features, are distinguished above all by their geographical origin and their host range. Citrus bacterial canker disease is wide spread in Iran and a major threat to the production of Mexican lime (Citrus aurantifolia). Therefore, management of citrus canker is inevitable in citrus growing areas where citrus canker has been established. Application of copper-based bactericides is a standard control measure for management of citrus canker worldwide. Therefore, their long-term use leads to the development of resistant isolates. Plant extracts and essential oils with an antimicrobial effect have become particularly important as an environmentally friendly method for the treatment of plant diseases. Many researchers have recently focused on studying plant extracts and essential oils that contain antimicrobial compounds. Material and Methods: The present study was carried out on the antibacterial effect of Common yarrow (Achillea millefolium), Ginger (Zingiber offcinale), Golden marguerite (Anthemis tinctoria), Fennel (Foeniculum vulgare), Common sage (Salvia officinalis), Gum tragacanth (Astaragalus gossypinus), Summer savory (Satureja hortensis) and True cardamom (Elettaria cardamomum) against two pathotype of Xanthomonas citri subsp. citri under laboratory and greenhouse conditions. Results: All essential oils have an inhibitory effect on multiplication of Xanthomonas citri subsp. citri. The antibacterial test results showed that the essential oils of Ginger and True cardamom strongly inhibited the growth of Xanthomonas citri subsp. citri pathotype, especially the pathotype A*, whereas other essential oils showed moderate to weak activities. Conclusion: The essential oils of these eight plants, especially ginger and cardamom, have good potential for the management of citrus bacterial canker.

Ali Asghar Dehghan, Reza Ghaderi,
Volume 9, Issue 1 (3-2020)

Dehghan AA, Ghaderi R (2020) Application of seaweeds in plant diseases management. Plant Pathology Science 9(1):101-107.         DOI: 10.2982/PPS.9.1.101.
Algae are the most important plant growth stimulants due to their high content of minerals, amino acids, vitamins and growth regulators such as auxin, cytokinin and gibberellin. Use of these stimuli in crops can improve rooting, yield, photosynthetic capacity and their resistance to pathogens. Application of algae (mainly seaweeds) against various plant diseases including bacterial, fungal, viral and nematode diseases as well as pests has been proven. Seaweeds are used as a powder or extract mixed with soil, or foliar spray to control of plant diseases. They are usually involved in controlling plant pathogens by inducing plant resistance, antagonistic activity by induced activity of other microorganisms, and enhancing plant growth. In general, seaweeds can be applied as biofertilizers, biostimulators and soil amendments in integrated plant diseases management programs.

Saeid Ghahari, Somayeh Ghahari, Sajjad Ghahari, Ghorban Ali Nematzadeh,
Volume 10, Issue 1 (2-2021)

Ghahari S, Ghahari S, Ghahari S Nematzadeh GH (2021) The impact of Chinaberry, Colocynth and Camelthorn extracts on eight bacteria and three fungi. Plant Pathology Science 10(1):14-26.  Doi: 10.2982/PPS.10.1.14.
Introduction: Antibacterial, antifungal and antioxidant activity of methanolic extracts of Colocynth (Citrullus colocynthis) seeds, Camelthorn  (Alhagi maurorum) fruit and Chinaberry (Melia azedarach) leaves on eight bacteria and three fungi, which usually cause damage to agricultural products examined in this research. Material and Methods: Antimicrobial activity of selected plants in six concentrations on 11 microorganisms including, three gram-positive bacteria vs. Bacillus subtilis, Staphylococcus aureus, and Rathayibacter toxicus, and five gram-negative bacteria vs. Escherichia coli, Pseudomonas aeruginosa, Pseudomonas syringae subsp. syringae, Pseudomonas viridiflava, and Xanthomonas campestris pv. campestris, as well as three fungi vs. Pyricularia oryzae, Fusarium oxysporum and Botrytis cinerea was measured using the disk diffusion method. Also, the antioxidant activity of the extracts of these  plants was evaluated by measuring the enzymes of catalase and guaiacol peroxidase and evaluating the ability to trap DPPH radicals. In addition, the amount of total phenols and flavonoids in these plants extracts were measured. Results: Methanolic extract of Colocynth seeds had the highest antibacterial activity, the highest activity of catalase and guaiacol peroxidase enzymes and the highest percentage of DPPH radical inhibition. Methanolic extracts of these plants had no effect on fungal colony growth. Conclusion: Methanolic extract of Colocynth seeds can be considered as potential sources of bactericides in agriculture.

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