Resistance of Solanaceous and non-Solanaceous species to Peronospora tabacina as shown by necrotrophic reactions

1971 ◽  
Vol 11 (48) ◽  
pp. 94 ◽  
Author(s):  
M Mandryk
Keyword(s):  
Leaf Disc ◽  
Peronospora Tabacina ◽  
Nicotiana Species ◽  
Leaf Discs ◽  
Solanaceous Species ◽  
Wide Range ◽  
Disc Area ◽  
Susceptibility Status

A necrotrophic reaction in leaf discs of a wide range of Nicotiana and other Solanaceous and non-Solanaceous species following infection by Peronospora tabacina Adam is described.With a few exceptions, species resistant to the pathogen developed water-soaking or gave no reaction, whereas susceptible species showed necroses affecting 60-100% of the leaf disc area. The degree if necrotrophic reaction is related to the resistance-susceptibility status of Nicotiana species, and it may be extended to detect susceptibility to the pathogen in Petunia, Capsicum, Lycopersicon, Hyoscyamus, Schizanthus, and other genera related ti Nicotiana.

scholarly journals A Necrotrophic Reaction in Nicotiana Species induced by Peronospora Tabacina Adam. II. Quantification of the Resistance-Susceptibility Status of Tobacco Breeding Lines

1967 ◽  
Vol 20 (6) ◽  
pp. 1161 ◽  
Author(s):  
OJ Shepherd ◽  
M Mandryk
Keyword(s):  
Intrinsic Resistance ◽  
Peronospora Tabacina ◽  
Breeding Lines ◽  
Nicotiana Species ◽  
Susceptibility Status

A comparison was made between the performances of a large.plant test, the cotyledon test, and a test based on the necrotrophic reaction for assessment of the resistance-susceptibility status of various tobacco species and breeding lines to infection by Perono8pora tabacina Adam. All three methods were shown to give similar assessments and it is suggested that the necrotrophy test gives an accurate measure of intrinsic resistance.

scholarly journals Toxin Production in Soybean (Glycine max L.) Plants with Charcoal Rot Disease and by Macrophomina phaseolina, the Fungus that Causes the Disease

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 645 ◽  
Author(s):  
Hamed K. Abbas ◽  
Nacer Bellaloui ◽  
Cesare Accinelli ◽  
James R. Smith ◽  
W. Thomas Shier
Keyword(s):  
Culture Media ◽  
Leaf Disc ◽  
Toxin Production ◽  
Macrophomina Phaseolina ◽  
Economic Losses ◽  
Limit Of Quantification ◽  
Charcoal Rot ◽  
Wide Range ◽  
Soybean Plants ◽  
Rot Disease

Charcoal rot disease, caused by the fungus Macrophomina phaseolina, results in major economic losses in soybean production in southern USA. M. phaseolina has been proposed to use the toxin (-)-botryodiplodin in its root infection mechanism to create a necrotic zone in root tissue through which fungal hyphae can readily enter the plant. The majority (51.4%) of M. phaseolina isolates from plants with charcoal rot disease produced a wide range of (-)-botryodiplodin concentrations in a culture medium (0.14–6.11 µg/mL), 37.8% produced traces below the limit of quantification (0.01 µg/mL), and 10.8% produced no detectable (-)-botryodiplodin. Some culture media with traces or no (-)-botryodiplodin were nevertheless strongly phytotoxic in soybean leaf disc cultures, consistent with the production of another unidentified toxin(s). Widely ranging (-)-botryodiplodin levels (traces to 3.14 µg/g) were also observed in the roots, but not in the aerial parts, of soybean plants naturally infected with charcoal rot disease. This is the first report of (-)-botryodiplodin in plant tissues naturally infected with charcoal rot disease. No phaseolinone was detected in M. phaseolina culture media or naturally infected soybean tissues. These results are consistent with (-)-botryodiplodin playing a role in the pathology of some, but not all, M. phaseolina isolates from soybeans with charcoal rot disease in southern USA.

Fungicides for the control of tobacco blue mould in the field

1964 ◽  
Vol 4 (14) ◽  
pp. 236 ◽  
Author(s):  
RG Paddick
Keyword(s):  
Field Conditions ◽  
Peronospora Tabacina ◽  
Leaf Quality ◽  
Blue Mould ◽  
Wide Range ◽  
The Absolute

A wide range of fungicides and antibiotics was tested under field conditions for control of blue mould of tobacco (Peronospora tabacina Adam). Zineb and maneb, used at weekly intervals, have given consistently good results without adversely affecting leaf quality. Heavy atmospheric spore loads reduced the absolute affectiveness of the fungicides but the trend towards higher yields of saleable leaf was maintained. Best control throughout the season was obtained with zineb spray from transplanting to early January and subsequently zineb dust to the beginning of harvest. Results with maneb were not significantly different from those with zineb.

Resistance of seedlings of Nicotiana species to Peronospora tabacina Adam

1962 ◽  
Vol 2 (4) ◽  
pp. 12 ◽  
Author(s):  
AV Hill ◽  
M Mandryk
Keyword(s):  
Field Observations ◽  
Peronospora Tabacina ◽  
Nicotiana Species ◽  
Australian Species ◽  
Arid Habitat

Seedlings of Nicotiana species of Australian and American origin were tested for resistance to an Australian strain of P. tabacina. American species were less resistant than Australian species and differences in 12 results of similar tests in both countries could have been due to differences in the pathogen or in the seed lines tested. The data suggest that the pathogen would have difficult in surviving on the highly resistant Australian species of Nicotiana in their natural arid habitat. Field observations have shown that survival occurs on the introduced susceptible species N. tabacum and N. glauca.

scholarly journals Laboratory assays for selection of Botrytis suppressive microorganisms on necrotic grape leaf discs

2006 ◽  
Vol 59 ◽  
pp. 348-354
Author(s):  
M. Walter ◽  
S.M. Zydenbos ◽  
M.V. Jaspers ◽  
A. Stewart
Keyword(s):  
Leaf Disc ◽  
Field Evaluation ◽  
Saprophytic Fungi ◽  
Trichoderma Spp ◽  
Disc Area ◽  
Dual Plate ◽  
Biological Control Potential ◽  
Grape Leaf ◽  
Selection Of

Isolates of saprophytic fungi (n209) were evaluated for biological control potential against Botrytis cinerea using in vitro dual plate and necrotic grape leaf disc assays Interrupted wetness periods were introduced during the 40day assay to select for disease suppressive saprophytic fungi with a high tolerance to fluctuating dry and wet periods Leaf disc assays were highly reproducible with relative rankings of the test isolates being similar over three assays In the absence of antagonists B cinerea sporulation increased during the 40day incubation to cover over 90 of the leaf disc area in conidiophores However in the presence of antagonists B cinerea sporulation was heavily reduced with the top seven isolates having less than 10 coverage relative to the control Thirteen isolates representing four genera Alternaria spp Epicoccum spp Trichoderma spp and Ulocladium spp have been identified for further laboratory testing prior to selection of a limited number of isolates for field evaluation

scholarly journals Effect of Detergent on the Quantification of Grapevine Downy Mildew Sporangia from Leaf Discs

HortScience ◽  
2015 ◽  
Vol 50 (5) ◽  
pp. 656-660 ◽  
Author(s):  
Atsushi Kono ◽  
Akihiko Sato ◽  
Bruce Reisch ◽  
Lance Cadle-Davidson
Keyword(s):  
Downy Mildew ◽  
Leaf Disc ◽  
Plasmopara Viticola ◽  
Inhibitory Effect ◽  
Tween 20 ◽  
Infected Leaf ◽  
Grapevine Downy Mildew ◽  
Visual Rating ◽  
Leaf Discs ◽  
Highly Correlated

Grapevine downy mildew (DM), caused by the oomycete Plasmopara viticola (Berk. & Curt.) Berlese & de Toni, is a major disease, especially in humid viticultural areas. Development of resistant cultivars is an important objective for grapevine breeding. To establish a reliable and inexpensive quantitative method to aid in breeding for DM resistance, we improved the method for counting the number of sporangia on leaf discs, and developed a method for counting the number of sporangia in solution. To prevent the loss of DM sporangia from adhesion onto plastic ware, we found as little as 0.01% Tween 20 was effective. On the other hand, this detergent was shown to have a severe inhibitory effect upon DM infection of leaves. We developed a sporangia counting method using dried droplets of DM suspensions, and the method was highly correlated with counting by hemacytometer (R2 > 0.96). The nonparametric Spearman’s rank correlations between visual rating and the number of the sporangia were as high as ρ = 0.82 to 0.91, suggesting that evaluation by the visual rating could provide a good estimate of the sporangia numbers on leaf discs. We established a high-throughput and inexpensive method with acceptable accuracy for DM resistance evaluation based on a leaf disc assay, and our results suggested that visual ratings of infected leaf discs provide a good estimate of sporangia numbers.

Assessment of two nondestructive assays for detecting glyphosate resistance in horseweed (Conyza canadensis)

Weed Science ◽  
2005 ◽  
Vol 53 (4) ◽  
pp. 438-445 ◽  
Author(s):  
Clifford H. Koger ◽  
Dale L. Shaner ◽  
W. Brien Henry ◽  
Talia Nadler-Hassar ◽  
Walter E. Thomas ◽  
...  
Keyword(s):  
Leaf Disc ◽  
Glyphosate Resistance ◽  
Conyza Canadensis ◽  
Dependent Manner ◽  
Leaf Discs ◽  
Plant Sensitivity ◽  
Soybean Plants ◽  
Nondestructive Assays ◽  
Dose Dependent

Two rapid, nondestructive assays were developed and tested for their potential in differentiating glyphosate-resistant from glyphosate-susceptible biotypes of horseweed. In one assay, leaves of glyphosate-resistant and -susceptible corn, cotton, and soybean plants, as well as glyphosate-resistant and -susceptible horseweed plants, were dipped in solutions of 0, 300, 600, and 1,200 mg ae L−1glyphosate for 3 d, and subsequent injury was evaluated. In the second assay, plant sensitivity to glyphosate was evaluated in vivo by incubating excised leaf disc tissue from the same plants used in the first assay in 0.7, 1.3, 2.6, 5.3, 10.6, 21.1, 42.3, and 84.5 mg ae L−1glyphosate solutions for 16 h and measuring shikimate levels with a spectrophotometer. The leaf dip assay differentiated between glyphosate-resistant and -susceptible crops and horseweed biotypes. The 600 mg L−1rate of glyphosate was more consistent in differentiating resistant and susceptible plants compared with the 300 and 1,200 mg L−1rates. The in vivo assay detected significant differences between susceptible and glyphosate-resistant plants of all species. Shikimate accumulated in a glyphosate dose–dependent manner in leaf discs from susceptible crops, but shikimate did not accumulate in leaf discs from resistant crops, and levels were similar to nontreated leaf discs. Shikimate accumulated at high (≥ 21.1 mg ae L−1) concentrations of glyphosate in leaf discs from all horseweed biotypes. Shikimate accumulated at low glyphosate concentrations (≤ 10.6 mg L−1) in leaf discs from susceptible horseweed biotypes but not in resistant biotypes. Both assays were able to differentiate resistant from susceptible biotypes of horseweed and could have utility for screening other weed populations for resistance to glyphosate.

scholarly journals Alkaloid Composition of the Nicotiana Species

1990 ◽  
Vol 14 (6) ◽  
pp. 327-339 ◽  
Author(s):  
VA Sisson ◽  
RF Severson
Keyword(s):  
Total Alkaloid ◽  
Dry Weight ◽  
Glass Capillary ◽  
Nicotiana Species ◽  
Alkaloid Composition ◽  
Total Alkaloids ◽  
Freeze Dried ◽  
Wide Range ◽  
Field Samples ◽  
Highly Correlated

AbstractPlants from 64 Nicotiana species were sampled in the greenhouse in 1983 and 1984 and from the field in 1985 and 1986 for the purpose of developing a chemical profile of each species. Mature green leaves were harvested at flowering, freeze-dried and ground to pass a 1 mm screen prior to chemical analysis. In this study we report the type and amounts of nicotinoid alkaloids. Alkaloid values were determined by glass-capillary gas chromatography and were averaged over the two years for each environment. Both total alkaloids (mg g-1 dry weight) and the distribution (percentage composition) of nicotine, nornicotine, anabasine, and anatabine were highly correlated between years for greenhouse and field samples. Greenhouse and field data were highly correlated, although total-alkaloid levels were significantly higher from field-grown plants. All of the Nicotiana species tested contained a measurable alkaloid fraction (at least 10 µg g-1). There was a wide range in total-alkaloid levels with nearly a 200-fold difference among greenhouse-grown samples and a 400-fold difference among field-grown species. In general, total-alkaloid levels among the species were found to be relatively low. Eleven species were found to have a different alkaloid composition when green leaf and air-dried samples were compared. Evidence is presented for the association between alkaloid characteristics and the phylogenetic classification of the species in the genus.

COMPARISON OF LEAF DISC AND PETRI DISH ASSAYS FOR THE ASSESSMENT OF DICOFOL RESISTANCE IN POPULATIONS OF EUROPEAN RED MITE FROM SOUTHERN ONTARIO

1989 ◽  
Vol 121 (9) ◽  
pp. 771-776 ◽  
Author(s):  
D.J. Pree ◽  
K.J. Cole ◽  
P.A. Fisher
Keyword(s):  
Leaf Disc ◽  
Petri Dish ◽  
Wild Populations ◽  
Low Frequencies ◽  
Southern Ontario ◽  
Leaf Discs ◽  
Field Type ◽  
European Red Mite ◽  
Petri Dishes

AbstractTwo bioassay methods using leaf discs and Petri dishes as the treated medium were compared. Resistance levels were approximately 11-fold with the leaf disc method and 7-fold using the Petri dish assay. Comparisons of the two methods on six wild populations indicated that the Petri dish assay was more sensitive in identifying low frequencies of resistance. Advantages of the Petri dish assay over the previously used leaf disc method for rapid, field-type surveys are discussed.Surveys of populations from the Simcoe and Niagara areas, using the Petri dish assay, indicated resistance to dicofol in 11 of 22 samples. Resistance was generally correlated with sites where dicofol had been used at least once a year for 2–3 consecutive years. The data indicate a resurgence of dicofol resistance since 1984 when resistance was detected at 4% of the surveyed sites.

The role of temperature in the development of blue mould (Peronospora tabacina Adam) disease in tobacco seedlings. I. In leaves

1965 ◽  
Vol 16 (4) ◽  
pp. 597 ◽  
Author(s):  
AV Hill ◽  
S Green
Keyword(s):  
Narrow Range ◽  
Peronospora Tabacina ◽  
Progressive Development ◽  
Blue Mould ◽  
Temperature Conditions ◽  
Strong Trend ◽  
Slow Development ◽  
Wide Range ◽  
Tobacco Seedlings

In tests over a wide range of temperature conditions the number of days from inoculation of plants of cv. Virginia Gold with conidia of Peronospora tabacina to appearance of blue mould symptoms in leaves varied from 4 to 12 days with conidia of strain APT1 and from 5 to 15 days with strain APT2. It was 4 to 14 days with strain APT2 on plants of cv. SO1. Initial death of leaves of cv. Virginia Gold occurred at 5–6 days after inoculation with APT1 but 3–4 days later when similar plants or cv. SO1 were inoculated with APT2. For each strain there was a strong trend toward similar leaf loss, and similar progressive development of leaf loss in treatments with the same night temperatures. For both strains, leaf losses developed most rapidly and were most severe at night temperatures of 16–24°C. The relatively slow development of APT2, except over a narrow range of temperatures, would limit its capacity for competing with APT1 and for producing epiphytotics.

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