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Root rot

About: Root rot is a(n) research topic. Over the lifetime, 7078 publication(s) have been published within this topic receiving 83068 citation(s). more


Open accessJournal ArticleDOI: 10.1002/J.1460-2075.1989.TB03384.X
01 Feb 1989-The EMBO Journal
Abstract: Pseudomonas fluorescens CHA0 suppresses black root rot of tobacco, a disease caused by the fungus Thielaviopsis basicola. Strain CHA0 excretes several metabolites with antifungal properties. The importance of one such metabolite, hydrogen cyanide, was tested in a gnotobiotic system containing an artificial, iron-rich soil. A cyanidenegative (hcn) mutant, CHA5, constructed by a gene replacement technique, protected the tobacco plant less effectively than did the wild-type CHA0. Complementation of strain CHA5 by the cloned wild-type hcn+ genes restored the strain's ability to suppress disease. An artificial transposon carrying the hcn+ genes of strain CHA0 (Tnhcn) was constructed and inserted into the genome of another P.fluorescens strain, P3, which naturally does not produce cyanide and gives poor plant protection. The P3::Tnhcn derivative synthesized cyanide and exhibited an improved ability to suppress disease. All bacterial strains colonized the roots similarly and did not influence significantly the survival of T.basicola in soil. We conclude that bacterial cyanide is an important but not the only factor involved in suppression of black root rot. more

Topics: Thielaviopsis (56%), Pseudomonas fluorescens (55%), Hydrogen cyanide (55%) more

631 Citations

Journal ArticleDOI: 10.1094/PHYTO-84-139
01 Feb 1994-Phytopathology
Abstract: Pseudomonas fluorescens strain CHA0, which suppresses various plant diseases caused by soilborne pathogens, also can restrict leaf disease. Plants of Nicotiana glutinosa and of two cultivars of N. tabacum were grown in autoclaved natural soil previously inoculated with strain CHA0. After 6 wk, all the plants tested showed resistance in leaves to infection with tobacco necrosis virus (TNV) to the same extent as plants previously immunized with TNV (induced resistance control). Polyacrylamide gel electrophoresis and enzyme assays showed that the same amount of PR proteins (Pr-1 group proteins, beta-1,3-glucanases, and endochitinases) was induced in the intercellular fluid of leaves of plants grown in the presence of strain CHA0 as in the intercellular fluid of leaves of plants immunized by a previous TNV inoculation on a lower leaf. Strain CHA0 was reisolated from the roots but could not be detected in stems or leaves. Strain CHA96, a gacA (global activator)-negative mutant of strain CHA0 defective in the production of antibiotics and in the suppression of black root rot of tobacco, had the same capacity to induce PR proteins and resistance against TNV as did the wild-type strain. CHA400, a pyoverdine-negative mutant of strain CHA0 with the same capacity to suppress black root rot of tobacco and take-all of wheat as the wild-type strain, was able to induce PR proteins but only partial resistance against TNV. P3, another P. fluorescens wild-type strain, does not suppress diseases caused by soilborne pathogens and induced neither resistance nor PR proteins in tobacco leaves. Root colonization of tobacco plants with strain CHA0 and its derivatives as well as leaf infection with TNV caused an increase in salicylic acid in leaves. These results show that colonization of tobacco roots by strain CHA0 reduces TNV leaf necrosis and induces physiological changes in the plant to the same extent as does induction of systemic resistance by leaf inoculation with TNV more

Topics: Tobacco necrosis virus (56%), Necrovirus (54%), Nicotiana tabacum (54%) more

552 Citations

Open accessJournal ArticleDOI: 10.1111/J.1364-3703.2009.00538.X
Caroline B. Michielse1, Martijn Rep1Institutions (1)
Abstract: Taxonomy: Kingdom Fungi; Phylum Ascomycota; Class Sordariomycetes; Order Hypocreales; Family Nectriaceae; genus Fusarium. Host range: Very broad at the species level. More than 120 different formae speciales have been identified based on specificity to host species belonging to a wide range of plant families. Disease symptoms: Initial symptoms of vascular wilt include vein clearing and leaf epinasty, followed by stunting, yellowing of the lower leaves, progressive wilting, defoliation and, finally, death of the plant. On fungal colonization, the vascular tissue turns brown, which is clearly visible in cross-sections of the stem. Some formae speciales are not primarily vascular pathogens, but cause foot and root rot or bulb rot. Economic importance: Can cause severe losses in many vegetables and flowers, field crops, such as cotton, and plantation crops, such as banana, date palm and oil palm. Control: Use of resistant varieties is the only practical measure for controlling the disease in the field. In glasshouses, soil sterilization can be performed. Useful websites:;; more

Topics: Fusarium oxysporum (54%), Fusarium (53%), Root rot (52%)

450 Citations

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Topic's top 5 most impactful authors

Timothy C. Paulitz

17 papers, 786 citations

Krishnapillai Sivasithamparam

17 papers, 510 citations

Giancarlo Polizzi

15 papers, 151 citations

Dalia Aiello

15 papers, 151 citations

Wade H. Elmer

15 papers, 352 citations

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