Movement of a factor in tobacco infected with Peronospora tabacina Adam which systemically protects against blue mold

Peronospora tabacina is an obligate plant pathogen that causes blue mold of tobacco. The disease is difficult to diagnose before the appearance of symptoms and can be easily spread in nonsymptomatic tobacco seedlings. We developed a real-time polymerase chain reaction (PCR) assay for P. tabacina that uses 5′ fluorogenic exonuclease (TaqMan) chemistry to detect and quantify pathogen DNA from diseased tissue. The primers and probe were designed using 5.8S ribosomal DNA sequences from 12 fungal and oomycete tobacco pathogens and 24 Peronospora spp. The PtabBM TaqMan assay was optimized and performed with a final concentration of 450 nM primers and 125 nM probe. The real-time TaqMan assay was assessed for sensitivity and the lower detection limit was 1 fg of DNA. The assay was specific for P. tabacina. None of the DNA from other tobacco pathogens, nonpathogens, or the host were amplified. The PtabBM TaqMan assay was useful for detection of P. tabacina in field samples, artificially inoculated leaves, roots, and systemically infected tobacco seedlings. The assay was used to quantify host resistance and it was possible to detect the pathogen 4 days postinoculation in both medium-resistant and susceptible tobacco cultivars. The real-time PCR assay for P. tabacina will be a valuable tool for the detection of the pathogen and of use to regulatory agencies interested in preventing the spread of blue mold.

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Effects of β-ionone and abscisic acid on the growth of tobacco and resistance to blue mold. Mimicry of effects of stem infection by Peronospora tabacina Adam

Physiological and Molecular Plant Pathology ◽

10.1016/s0048-4059(86)80071-6 ◽

1986 ◽

Vol 28 (2) ◽

pp. 287-297 ◽

Cited By ~ 42

Author(s):

S.D. Salt ◽

S. Tuzun ◽

J. Kuć

Keyword(s):

Abscisic Acid ◽

Blue Mold ◽

Peronospora Tabacina ◽

Stem Infection

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Cocultures of Peronospora tabacina and Nicotiana Species to Study Host-Pathogen Interactions

Phytopathology ◽

10.1094/phyto.2001.91.12.1224 ◽

2001 ◽

Vol 91 (12) ◽

pp. 1224-1230 ◽

Cited By ~ 3

Author(s):

E. P. Heist ◽

W. C. Nesmith ◽

C. L. Schardl

Keyword(s):

Nicotiana Tabacum ◽

Total Darkness ◽

Blue Mold ◽

Peronospora Tabacina ◽

Genetic Studies ◽

Free System ◽

Light Regimes ◽

Intact Plants ◽

Reliable Source

Long-term cocultures of the tobacco blue mold pathogen, Peronospora tabacina, with Nicotiana tabacum and N. repanda callus were derived from infected host plant tissue. In this apparently contaminant-free system, sporulation occurred under similar conditions as in intact plants. Sporangia were collected from cocultures and used to complete Koch's postulates. The cocultures were grown under two light regimes. One consisted of 23 h of light followed by 1 h of darkness and the second comprised total darkness. Sporulation occurred frequently in the 23 h light-grown cocultures but resulted in production of abnormal sporangiophores and sporangia. Production of normal sporangiophores and sporangia was achieved by transferring light-grown cocultures to overnight darkness and resulted in necrosis of the callus. Cocultures of Peronospora tabacina with either host species, grown in total darkness, frequently sporulated with minimal necrosis over the course of 1 year. Thus, cocultures should prove useful as a source of Peronospora tabacina over extended periods of time at low risk of pathogen release, for studying the physiology of Peronospora tabacina- Nicotiana interactions, maintaining Peronospora tabacina lines for genetic studies, and providing a reliable source of axenic inoculum for research.

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Evaluation of the Efficacy of CGA 245704 Combined or Not with CGA 329 351 (Mefenoxam) for the Control of Tobacco Blue Mold (Peronospora Tabacina): Results of Four Years of Experiments

Beiträge zur Tabakforschung International/Contributions to Tobacco Research ◽

10.2478/cttr-2013-0670 ◽

1998 ◽

Vol 18 (2) ◽

pp. 55-62

Author(s):

R Delon ◽

B Cailleteau ◽

JL Verrier ◽

MN Tanne ◽

M Sylvestre

Keyword(s):

Active Ingredient ◽

Pesticide Residues ◽

Foliar Application ◽

Foliar Spray ◽

Systemic Resistance ◽

Blue Mold ◽

Peronospora Tabacina ◽

Tobacco Plants ◽

Tobacco Leaves ◽

Chemical Class

AbstractA compound for activating systemic resistance (CGA 245 704), in the chemical class of benzothiadiazoles, was studied since 1993 for the control of tobacco blue mold (Peronosporatabacina A.) in seedbeds and in the field. One foliar application of CGA 245 704 at 1.6 g active ingredient/hl every 14 days protected tobacco plants against blue mold but protection was not total. Mixed with mefenoxam (CGA 329 351) at 16 g active ingredient/hl the protection is equivalent to standard Acylon¯ TC (25 % metalaxyl, 50 % maneb) applied as foliar spray at 0.160 kg/hl (40 g active ingredient metalaxyl per hl). This allows a reduction in the quantity of fungicides dispersed in the environment and the pesticide residues on the tobacco leaves. At the rate applied, no phytotoxic effects were observed in seedbeds or in the field.

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