Journal of Phytopathology
Công bố khoa học tiêu biểu
* Dữ liệu chỉ mang tính chất tham khảo
Sắp xếp:
Gas Exchange and Emission of Chlorophyll Fluorescence during the Monocycle of Rust, Angular Leaf Spot and Anthracnose on Bean Leaves as a Function of their Trophic Characteristics Measurements related to gas exchange and chlorophyll fluorescence emission were taken from healthy and diseased bean leaves with rust, angular leaf spot, and anthracnose during lesion development for each disease. The experiments were performed at different temperatures of plant incubation, and using two bean cultivars. The main effect of temperature of plant incubation was in disease development. There was no significant difference between cultivars in relation to disease development and in magnitude of physiological alterations when disease severity was the same for each cultivar. These diseases reduced the net photosynthetic rate and increased the dark respiration of infected leaves after the appearance of visible symptoms and the differences between healthy and diseased leaves increased with disease development. The transpiration rate and stomatal conductance were stable during the monocycle of rust, however, these two variables decreased in leaves with angular leaf spot and anthracnose beginning with symptom appearance and continuing until lesion development was complete. Carboxylation resistance was probably the main factor related to reduction of photosynthetic rate of the apparently healthy area of leaves with rust and angular leaf spot. Reduction of the intercellular concentration of CO2 , due to higher stomatal resistance, was probably the main factor for leaves with anthracnose. Chlorophyll fluorescence assessments suggested that there was no change in electron transport capacity and generation of ATP and NADPH in apparently healthy areas of diseased leaves, but decreases in chlorophyll fluorescence emission occurred on visibly lesioned areas for all diseases. Minimal fluorescence was remarkably reduced in leaves with angular leaf spot. Maximal fluorescence and optimal quantum yield of photosystem II of leaves were reduced for all three diseases. Bean rust, caused by a biotrophic pathogen, induced less damage to the regulation mechanisms of the physiological processes of the remaining green area of diseased leaves than did bean angular leaf spot or anthracnose, caused by hemibiotrophic pathogens. The magnitude of photosynthesis reduction can be related to the host–pathogen trophic relationships.
Journal of Phytopathology - Tập 150 Số 1 - Trang 37-47 - 2002
Untersuchungen über den Einfluß der endotrophen Mycorrhiza auf die TMV-Läsionenbildung in Nicotiana tabacum L. var. Xanthi-nc.
Journal of Phytopathology - Tập 73 Số 1 - Trang 78-80 - 1972
Scanning Electron Microscopy of <i>Pseudomonas syringae</i> pv, <i>morsprunorum</i> on Sweet Cherry Leaves Abstract Scanning electron microscopy indicated that sub‐stomatal cavities on sweet cherry leaves are “protected sites” which shelter resident populations of Pseudomonas syringae pv. morsprunorum . Bacteria entered the stomata, multiplied in the cavities and emerged in a mass 6 days after inoculation. There were no visible symptoms, suggesting that the pathogen colonized the host in “sub‐clinical” numbers to generate populations which were then released onto the leaf surface under suitable conditions.
Journal of Phytopathology - Tập 108 Số 1 - Trang 18-25 - 1983
Resistance to Pyrimethanil and other Fungicides in <i>Botrytis cinerea</i> Populations Collected on Vegetable Crops in Spain Abstract Forty‐seven greenhouses of vegetable crops were surveyed in south‐eastern Spain at the beginning of the epidemic (January 2000) to compare sensitivity of Botrytis cinerea populations to pyrimethanil (an anilinopyrimidine fungicide) after 4 years of treatment with an unexposed population from a 1992 collection. A standard method to test the sensitivity of B. cinerea to pyrimethanil in a defined minimal medium (1.75 g/l of KH2 PO4 , 0.75 g/l of MgSO4 , 4 g/l of glucose and 4 g/l of gelatine) was used to establish frequency distributions of pyrimethanil sensitivity in both populations. Two different distributions for sensitive and resistant isolates were obtained. ED50 of sensitive isolates in 1992 ranged from 0.05 to 0.5 mg a.i./l (mean ± SE, 0.23 ± 0.02), and 0.04–0.4 mg a.i./l in 2000 (0.11 ± 0.01). ED50 for resistant isolates ranged from 1 to 10 mg a.i./l in both surveys (5 ± 2.64 and 4.25 ± 2.14, in 1992 and 2000, respectively). No resistance build‐up to pyrimethanil was developed in B. cinerea populations after exposition of 4 years to the fungicide. An in vitro monitoring procedure was developed based on testing on one single discriminatory dose of pyrimethanil (established at 0.7 mg a.i./l). Isolates resistant to pyrimethanil in the in vitro assay caused visible lesions on cucumber leaf discs treated with the fungicide. No significant differences in fitness (growth or sporulation) between resistant and sensitive isolates were obtained. The 307 isolates collected in January 2000 were tested in vitro using discriminatory doses to estimate the frequencies of resistance of B. cinerea to benzimidazoles (carbendazim), dicarboximides (procymidone), N ‐phenylcarbamates (diethofencarb), and anilinopyrimidines (pyrimethanil). Of the 307 isolates collected, 90% were resistant to benzimidazoles, 77% to dicarboximides, 23% to N ‐phenylcarbamates and 12% to anilinopyrimidines (in this case of 165 isolates). Dicarboximide and benzimidazole cross‐resistant isolates were found in each of the surveyed greenhouses and accounted for 65.8%. Fourteen percentage of the population were resistant to dicarboximides, benzimidazoles and N ‐phenylcarbamates, and 3% were also resistant to anilinopyrimidines.
Journal of Phytopathology - Tập 152 Số 8-9 - Trang 484-490 - 2004
Phenylpyrrole Fungicides: Mitotic Instability in <i>Aspergillus nidulans</i> and Resistance in <i>Botrytis cinerea</i> The somatic recombinogenic activity of the phenylpyrrole fungicide fludioxonil, in diploid Aspergillus nidulans was found similar to that caused by aromatic hydrocarbon and dicarboximide fungicides (AHDFs), such as iprodione, chlozolinate and tolclofos–methyl. All these fungicides not only increased the number of mitotic recombinants but also provided similar appearance, small sectors, of white and yellow mitotic recombination products. Fludioxonil highly resistant strains (resistant factor approximately 5000) of Botrytis cinerea were isolated at high frequency (1.08 × 10−5 ). Study of cross‐resistance patterns of mutant strains to other fungicides, revealed cross‐resistance of fludioxonil with dicarboximides (iprodione, procymidone, and chlozolinate) and aromatic hydrocarbons, such as tolclofos–methyl, pentachloronitrobenzene (PCNB), tecnazene and chloroneb. The positive cross‐resistance relationships found between phenylpyrroles and members of the AHDFs and their ability to increase mitotic instability in diploid A. nidulans , indicate that phenylpyrroles should be included with AHDFs. A study of fitness parameters in wild‐type and representative fludioxonil‐resistant mutants of B. cinerea , showed that the mutation(s) leading to fludioxonil resistance may or may not affect some fitness‐determining characteristics, such as sensitivity to high osmolarity, growth rate, conidial germination and germ‐tube elongation. Pathogenicity tests on cucumber seedlings showed that an osmosensitive representative strain of B. cinerea , resistant to fludioxonil, was as virulent as the wild‐type strain. The phenylpyrrole fungicide was ineffective, even in high concentrations, to control grey mould caused by this isolate.
Journal of Phytopathology - Tập 149 Số 6 - Trang 301-308 - 2001
Isozyme Patterns of <i>Fusarium</i> Species and their Significance in Taxonomy
Journal of Phytopathology - Tập 74 Số 2 - Trang 115-125 - 1972
Potential Biological Control of Damping‐off Pathogens in Emerging Sugar Beet by <i>Pythium oligandrum</i> Drechsler
Journal of Phytopathology - Tập 90 Số 2 - Trang 113-115 - 1977
Control of Rhizoctonia solani and Cotton Seedling Disease by Laetisaria arvalis and a Mycophagous Insect Proisotoma minuta (Collembola) Abstract Laetisaria arvalis and a mycophagous, rhizosphere‐inhabiting collembolan, Proisotoma minuta , were evaluated in sterilized and nonsterilized soil for suppression of Rhizoctonia solani in a greenhouse environment. R. solani was applied to soil at rates between 10 and 150 mg of colonizedoat inoculum/kg soil. L. arvalis was applied directly to soil at 100 mg/kg or as a seed dressing, either alone or in combination with a population of P. minuta at 1000/kg soil. L. arvalis significantly reduced incidence and severity of cotton seedling disease caused by R. solani; the seed treatment provided better suppression than when L. arvalis was applied to soil. Combination of the fungal agent with P. minuta enhanced suppression of R. solani more than with either agent used alone. Control benefit was linearly increased when increased numbers of insects were applied with L. arvalis .
Journal of Phytopathology - Tập 133 Số 2 - Trang 89-98 - 1991
Antifungal Activity of a Bowman–Birk‐type Trypsin Inhibitor from Wheat Kernel A trypsin inhibitor from wheat kernel (WTI) was found to have a strong antifungal activity against a number of pathogenic fungi and to inhibit fungal trypsin‐like activity. WTI inhibited in vitro spore germination and hyphal growth of pathogens, with protein concentration required for 50% growth inhibition (IC50 ) values ranging from 111.7 to above 500 μg/ml. As observed by electron microscopy, WTI determined morphological alterations represented by hyphal growth inhibition and branching. One of the fungal species tested, Botrytis cinerea produced a trypsin‐like protease, which was inhibited by the trypsin inhibitor. WTI, as well as other seed defence proteins, appear to be an important resistance factor in wheat kernels during rest and early germination when plants are particularly exposed to attack by potential soil‐borne pathogens.
Journal of Phytopathology - Tập 148 Số 7-8 - Trang 477-481 - 2000
The Hydroxyproline Content in Cell Wall of Resistant and Susceptible Alfalfa Plants Inoculated with Wilt Pathogens Abstract The changes of hydroxyproline (Hyp) content in cell wall after inoculation with Corynebacterium michiganense pv. insidiosum or Verticillium albo‐atrum in 8 cultivars of alfalfa (Medicago sativa) were studied. In our experiments cultivars ‘Trek’ and ‘Vernal’– resistant, ‘Du Puits’ and ‘Vertus’– susceptible to C. michiganense; ‘Vela’ and ‘Maris Kabul’– resistant to V. albo‐atrum , ‘Sabilt’ and ‘Lahontan’– susceptible to V. albo‐atrum were used. In resistant plants inoculated with C. michiganense none or a small increase of Hyp content in comparison with control plants was registered. On the other hand, inoculated susceptible plants showed markedly increase of Hyp content in comparison with the control plants. The differences in Hyp content between control and inoculated resistant and susceptible plants with V. albo‐atrum were not markedly expressed in comparison with the alfalfa –C. michiganense pair. The changes had similar tendency both in C. michiganense and V. albo‐atrum. –alfalfa pairs.
Journal of Phytopathology - Tập 117 Số 1 - Trang 65-70 - 1986
Tổng số: 23
- 1
- 2
- 3