scholarly journals Variations in the Sensitivity of Phytophthora infestans Isolates from Different Genetic Backgrounds to Dimethomorph

Plant Disease ◽  
2003 ◽  
Vol 87 (11) ◽  
pp. 1283-1289 ◽  
Author(s):  
J. M. Stein ◽  
W. W. Kirk
Keyword(s):  
Life Cycle ◽  
Phytophthora Infestans ◽  
Mycelial Growth ◽  
Hyphal Growth ◽  
Potato Leaf ◽  
Leaf Discs ◽  
Highly Sensitive ◽  
Significant Difference ◽  
Cyst Germination

The sensitivities of 11 isolates of Phytophthora infestans to dimethomorph were examined at all stages of the asexual life cycle and when inoculated onto potato leaf discs. In vitro zoospore encystment and cyst germination were highly sensitive to dimethomorph with 50% reduction of mycelial growth and cyst germination (EC50) values for most isolates <0.20 μg/ml, whereas direct sporangia germination and in vitro hyphal growth and sporulation were less sensitive (means of 0.45 and 0.22 μg/ml, respectively). Zoosporogenesis was not significantly inhibited at the maximum dimethomorph concentration examined, 10 μg/ml. Significant differences (Fisher's least significant difference, P = 0.05) in the EC50 values were present between isolates for all stages of the asexual life cycle, except direct sporangia germination and zoosporogenesis. Sensitivity ratios between the least- and most-sensitive isolates were 6.11, 12.14, 12.36, and 10.56 for hyphal growth, in vitro sporulation, zoospore encystment, and cyst germination, respectively. Application of dimethomorph at 1,000 μg/ml to potato leaf discs at 24 or 48 h before inoculation completely inhibited symptom incidence for most isolates, whereas application after inoculation generally was not significantly different from the untreated control, regardless of concentration. Sporulation from leaf discs treated with dimethomorph at 24 or 48 h after inoculation was completely inhibited for all isolates with dimethomorph at 1,000 μg/ml, even when symptom incidence was not significantly reduced.

scholarly journals Contribution of Hydrogen Cyanide to the Antagonistic Activity of Pseudomonas Strains Against Phytophthora infestans

2020 ◽  
Vol 8 (8) ◽  
pp. 1144
Author(s):  
Abhishek Anand ◽  
Delphine Chinchilla ◽  
Christopher Tan ◽  
Laurent Mène-Saffrané ◽  
Floriane L’Haridon ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Phytophthora Infestans ◽  
Hydrogen Cyanide ◽  
Mycelial Growth ◽  
Developmental Stages ◽  
Antagonistic Activity ◽  
Potato Leaf ◽  
Relative Contribution ◽  
Production Of Hydrogen

Plants face many biotic and abiotic challenges in nature; one of them is attack by disease-causing microbes. Phytophthora infestans, the causal agent of late blight is one of the most prominent pathogens of the potato responsible for multi-billion-dollar losses every year. We have previously reported that potato-associated Pseudomonas strains inhibited P. infestans at various developmental stages. A comparative genomics approach identified several factors putatively involved in this anti-oomycete activity, among which was the production of hydrogen cyanide (HCN). Here, we report the relative contribution of HCN emission to the overall anti-Phytophthora activity of two cyanogenic Pseudomonas strains, P. putida R32 and P. chlororaphis R47. To quantify this contribution, we generated HCN-negative mutants (Δhcn) and compared their activities to those of their respective wild types in different experiments assessing P. infestans mycelial growth, zoospore germination, and infection of potato leaf disks. Using in vitro experiments allowing only volatile-mediated interactions, we observed that HCN accounted for most of the mycelial growth inhibition (57% in R47 and 80% in R32). However, when allowing both volatile and diffusible compound-mediated interactions, HCN only accounted for 1% (R47) and 18% (R32) of mycelial growth inhibition. Likewise, both mutants inhibited zoospore germination in a similar way as their respective wild types. More importantly, leaf disk experiments showed that both wild-type and Δhcn strains of R47 and R32 were able to limit P. infestans infection to a similar extent. Our results suggest that while HCN is a major contributor to the in vitro volatile-mediated restriction of P. infestans mycelial growth, it does not play a major role in the inhibition of other disease-related features such as zoospore germination or infection of plant tissues.

scholarly journals Impact of Azoxystrobin, Dimethomorph, Fluazinam, Fosetyl-Al, and Metalaxyl on Growth, Sporulation, and Zoospore Cyst Germination of Three Phytophthora spp.

Plant Disease ◽  
2000 ◽  
Vol 84 (4) ◽  
pp. 454-458 ◽  
Author(s):  
M. E. Matheron ◽  
M. Porchas
Keyword(s):  
Life Cycle ◽  
Disease Control ◽  
Mycelial Growth ◽  
Phytophthora Capsici ◽  
Effective Concentration ◽  
The Other ◽  
In Vitro Activity ◽  
Phytophthora Spp ◽  
Cyst Germination

In vitro activity of azoxystrobin, dimethomorph, and fluazinam on growth, sporulation, and zoospore cyst germination of Phytophthora capsici, P. citrophthora, and P. parasitica was compared to that of fosetyl-Al and metalaxyl. The 50% effective concentration (EC50) values for)inhibition of mycelial growth of the three pathogens usually were lowest for dimethomorph and (metalaxyl, ranging from <0.1 to 0.38 μg/ml. However, the 90% effective concentration (EC90) levels for dimethomorph always were lower than the other four tested compounds, with values ranging from 0.32 to 1.6 μg/ml. Mycelial growth of P. capsici, P. citrophthora, and P. parasitica was least affected by azoxystrobin and fluazinam, with estimated (EC90) values >3,000 μg/ml. Reduction of sporangium formation by P. capsici, P. citrophthora, and P. parasitica in the presence of dimethomorph at 1 μg/ml was significantly greater than that recorded for the same concentration of azoxystrobin, fluazinam, and fosetyl-Al. For the three species of Phytophthora, zoospore motility was most sensitive to fluazinam (EC50 and EC90 values of <0.001 μg/ml) and (least sensitive to fosetyl-Al, with (EC50 and EC90 values ranging from 299 to 334 and 518 to 680 μg/ml, respectively). Germination of encysted zoospores of P. capsici, P. citrophthora, and P. parasitica was most sensitive to dimethomorph (EC50 and EC90 values ranging from 3.3 to 7.2 and 5.6 to 21 μg/ml, respectively), intermediate in sensitivity to fluazinam (EC50 and EC90 from 18 to 108 and 67 to >1,000 μg/ml, respectively) and metalaxyl (EC50 and EC90 from 32 to 280 and 49 to 529 μg/ml, respectively), and lowest in sensitivity to azoxystrobin and fosetyl-Al (EC50 and EC90 from 256 to >1,000 μg/ml). The activity of azoxystrobin, dimethomorph, and fluazinam on one or more stages of the life cycle of P. capsici, P. citrophthora, and P. parasitica suggests that these compounds potentially could provide Phytophthora spp. disease control comparable to that of the established fungicides fosetyl-Al and metalaxyl.

Serum interspecies differences in metabolic pathways of bradykinin and [des-Arg9]BK: influence of enalaprilat

1996 ◽  
Vol 271 (4) ◽  
pp. H1340-H1347 ◽  
Author(s):  
A. Decarie ◽  
P. Raymond ◽  
N. Gervais ◽  
R. Couture ◽  
A. Adam
Keyword(s):  
Metabolic Pathways ◽  
Neutral Endopeptidase ◽  
Thrombin Inhibitor ◽  
Rat Serum ◽  
Highly Sensitive ◽  
Significant Difference ◽  
Hydrolysis Of

Among the different enzymes responsible for the metabolism of bradykinin (BK), three peptidases look relevant in vivo: kininase I (KI), which transforms BK into its active metabolite, [des-Arg9]BK; kininase II (KII); and neutral endopeptidase, which inactivate BK and [des-Arg9]BK. The in vitro incubation of BK and [des-Arg9]BK in the serum of four species with or without enalaprilat and the quantification of the immunoreactivity of both peptides at different time intervals allowed the measurement of the kinetic parameters characterizing their metabolic pathways. Highly sensitive chemiluminescent enzyme immunoassays were used to measure the residual concentrations of BK and [des-Arg9]BK. Half-life (t1/2) of BK showed significant difference among species: rats (10 +/- 1 s) = dogs (13 +/- 1 s) < rabbits (31 +/- 1 s) < humans (49 +/- 2 s). t1/2 values of [des-Arg9]BK were also species dependent: rats (96 +/- 6 s) < < rabbits (314 +/- 6 s) = dogs (323 +/- 11 s) = humans (325 +/- 12 s). Enalaprilat significantly prevented the rapid BK and [des-Arg9]BK degradation in all species except that of [des-Arg9]BK in rat serum. Relative amount of BK hydrolyzed by serum KII was given as follows: rabbits (93.7 +/- 14.8%) = rats (83.6 +/- 6.7%) = humans (76.0 +/- 7.5%) > dogs (50.0 +/- 3.9%). Its importance in the hydrolysis of [des-Arg9]BK was 5.2 +/- 0.5% in rats < < 33.9 +/- 1.5% in humans < 52.0 +/- 1.1% in rabbits < 65.1 +/- 3.4% in dogs. The participation of serum KI in the transformation of BK into [des-Arg9]BK was dogs (67.2 +/- 5.3%) > > humans (3.4 +/- 1.2%) = rabbits (1.8 +/- 0.2%) = rats (1.4 +/- 0.3%). Finally, no significant difference on t1/2 values for BK and [des-Arg9]BK could be demonstrated between serum and plasma treated with either sodium citrate or a thrombin inhibitor. These results revealed striking species differences in the serum metabolism of kinins that could address at least partially some of the controversial data related to the cardioprotective role of kinins.

scholarly journals EVALUATION OF VARIOUS NATURAL DIETS FOR MASS REARING OF Spodoptera frugiperda J.E SMITH (LEPIDOPTERA: NOCTUIDAE)

2021 ◽  
Vol 21 (1) ◽  
pp. 43-48
Author(s):  
Sempurna Ginting ◽  
Tri Sunardi ◽  
Chaincin Buana Sari ◽  
Risky Hadi Wibowo
Keyword(s):  
Life Cycle ◽  
Spodoptera Frugiperda ◽  
Sugar Cane ◽  
Growth And Development ◽  
Mass Rearing ◽  
Cycle Period ◽  
Water Spinach ◽  
Potato Leaf ◽  
Lepidoptera Noctuidae

Evaluation of various natural diets for mass rearing of Spodoptera frugiperda J.E Smith (Lepidoptera: Noctuidae). Spodoptera frugiperda is one of the pests that attack corn in Indonesia. This study aimed to evaluate the most suitable diet for rearing of S. frugiperda from various natural diets. The study was conducted in vitro. The treatments were consisted of variation on S. frugiperda natural diets, such as maize leaf, green mustard leaf, water spinach, sweet potato leaf, sugar cane leaf, and soybeans leaf. The observed variables were life cycle period, pupa size, and pupa weight. The results showed that the shortest life cycle period was on corn leaves diet (40.92 days), and the longest was on sugarcane leaves (45.01 days). The longest size of pupa were S. frugiperda on mustard leaves diet (12.86 mm) and corn leaves (12.56 mm), The heaviest pupa weights were observed in S. frugiperda on mustard leaves diet (0.18 mg), and corn leaves (0.16 mg). Based on the data, it could be concluded that corn leaves were the most suitable type of diet for the growth and development of S. frugiperda.

scholarly journals In vitro Inhibition of Soilborn Phytopathogens Treated With Swine Wastewater

2018 ◽  
Vol 10 (5) ◽  
pp. 211
Author(s):  
Danielle Dutra Martinha ◽  
Cleonice Lubian ◽  
Cintia Koech ◽  
Roberto Luis Portz ◽  
Vivian Carré Missio ◽  
...  
Keyword(s):  
Organic Matter ◽  
Mycelial Growth ◽  
Sclerotium Rolfsii ◽  
Soil Condition ◽  
Swine Wastewater ◽  
Soil Conditions ◽  
Potato Dextrose Agar Medium ◽  
Suppression Effect ◽  
Significant Difference

Swine wastewater (SWW) is a residue from pig farming that presents a high load of nutrients and organic matter. The appliance of organic matter in soil alters the microbial dynamic and may suppress soilborn phytopathogens. This study aimed at evaluating the inhibition on mycelial growth of Sclerotinia sclerotiorum and Sclerotium rolfsii in vitro under SWW doses. Hereupon, three kilograms of a soil classified as red dystroferric latosol was collected and sieved. Half of it was autoclaved. SWW was incorporated at doses of 0 mL, 2.5 mL, 5 mL, 10 mL and 20 mL in both soil conditions, autoclaved and not autoclaved. Afterwards, 130 grams of each soil was separately put into Petri plates above what a thin layer (≅ 5 mL) of Water-Agar (2%) medium was carefully spread over. Above this agar layer, one disk (6 mm diameter) of pure mycelium from each fungal grown in Potato Dextrose Agar medium was individually placed on the center of each plate. Daily evaluations on mycelial growth measuring were taken and ended when mycelium in control plates (without SWW addition) reached plate borders. Results indicated that in autoclaved soil condition, the inhibition was proportional to the dose, what is to say that the higher the dose the less the mycelial growth. In not autoclaved soil there was no significant difference among treatments, suggesting stimuli on suppression effect for both pathogens caused by SWW. In addition, the confirmed potential of SWW as a suppressor of S. sclerotiorum and S. rolfsii leads to promising investigations on other phytopathogens hard to control.

scholarly journals In vitro antifungal activities of 26 plant extracts on mycelial growth of Phytophthora infestans (Mont.) de Bary

2011 ◽  
Vol 10 (14) ◽  
pp. 2625-2629 ◽  
Author(s):  
Yanar Yusuf ◽  
Kadioğlu Izzet ◽  
Gouml kccedil e Ayhan ◽  
Demirtaş İbrahim ◽  
Gouml ren Nezhun ◽  
...  
Keyword(s):  
Phytophthora Infestans ◽  
Plant Extracts ◽  
Mycelial Growth ◽  
Antifungal Activities

scholarly journals Benomyl Sensitivity of Isolates of Colletotrichum acutatum and C. gloeosporioides from Citrus

Plant Disease ◽  
2004 ◽  
Vol 88 (2) ◽  
pp. 125-130 ◽  
Author(s):  
N. A. R. Peres ◽  
N. L. Souza ◽  
T. L. Peever ◽  
L. W. Timmer
Keyword(s):  
Mycelial Growth ◽  
Colletotrichum Acutatum ◽  
Nucleotide Substitutions ◽  
Partial Sequencing ◽  
Research Fields ◽  
Fruit Drop ◽  
Highly Sensitive ◽  
Sensitive Isolate ◽  
Moderately Resistant

Postbloom fruit drop (PFD) of citrus, caused by Colletotrichum acutatum, produces orange-brown lesions on petals and results in premature fruit drop and the retention of calyces. C. gloeosporioides is common in groves and causes postharvest anthracnose on fruit. Both diseases are controlled effectively by the fungicide benomyl in research fields and commercial orchards. Highly sensitive and resistant isolates of C. gloeosporioides were found, whereas all isolates of C. acutatum tested were moderately resistant. In preliminary studies conducted in vitro with three isolates of each, mycelial growth of sensitive isolates of C. gloeosporioides was inhibited completely by benomyl (Benlate 50 WP) at 1.0 μg/ml, whereas resistant isolates grew well at 10 μg/ml. Growth of all isolates of C. acutatum was inhibited by about 55% at 0.1 μg/ml and by 80% at 1.0 μg/ml. Spore germination of C. acutatum was inhibited more at 0.1 μg/ml than at 1.0 μg/ml or higher concentrations. In all, 20 isolates of C. acutatum from 17 groves and 20 isolates of C. gloeosporioides from 7 groves were collected from locations with different histories of benomyl usage in São Paulo, Brazil, and Florida, United States. Benomyl at 1.0 μg/ml completely inhibited growth of 133 isolates of C. gloeosporioides, with the exception of 7 isolates that were highly resistant to the fungicide, whereas all isolates of C. acutatum were only partially inhibited at 0.1 and 1.0 μg/ml. Analysis of variance indicated that the sensitivity of the isolates of C. acutatum was not affected by benomyl usage or grove of origin, and country of origin had only minor effects. No highly resistant or sensitive isolate of C. acutatum was recovered. Partial sequencing of the β-tubulin gene did not reveal nucleotide substitutions in codons 198 or 200 in C. acutatum that usually are associated with benomyl resistance in other fungi.

scholarly journals EVALUATION OF VARIOUS NATURAL DIETS FOR MASS REARING OF Spodoptera frugiperda J.E SMITH (LEPIDOPTERA: NOCTUIDAE)

2021 ◽  
Vol 21 (1) ◽  
pp. 43-48
Author(s):  
Sempurna Ginting ◽  
Tri Sunardi ◽  
Chaincin Buana Sari ◽  
Risky Hadi Wibowo
Keyword(s):  
Life Cycle ◽  
Sweet Potato ◽  
Spodoptera Frugiperda ◽  
Growth And Development ◽  
Mass Rearing ◽  
Cycle Period ◽  
Water Spinach ◽  
Potato Leaf ◽  
Lepidoptera Noctuidae

Evaluation of various natural diets for mass rearing of Spodoptera frugiperda J.E Smith (Lepidoptera: Noctuidae).Spodoptera frugiperda is one of the pests that attack corn in Indonesia. This study aimed to evaluate the most suitable dietfor rearing of S. frugiperda from various natural diets. The study was conducted in vitro. The treatments were consisted ofvariation on S. frugiperda natural diets, such as maize leaf, green mustard leaf, water spinach, sweet potato leaf, sugar caneleaf, and soybeans leaf. The observed variables were life cycle period, pupa size, and pupa weight. The results showed thatthe shortest life cycle period was on corn leaves diet (40.92 days), and the longest was on sugarcane leaves (45.01 days). Thelongest size of pupa were S. frugiperda on mustard leaves diet (12.86 mm) and corn leaves (12.56 mm), The heaviest pupaweights were observed in S. frugiperda on mustard leaves diet (0.18 mg), and corn leaves (0.16 mg). Based on the data, it couldbe concluded that corn leaves were the most suitable type of diet for the growth and development of S. frugiperda.

scholarly journals Spraying of dsRNA Molecules Derived from Phytophthora Infestans, as a Plant Protection Strategies for the Management of Potato Late Blight

2021 ◽  
Author(s):  
Sundaresha S. ◽  
Sanjeev Sharma ◽  
Aarti Bairwa ◽  
Maharishi Tomar ◽  
Ravinder Kumar ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Disease Severity ◽  
Plant Protection ◽  
Early Stage ◽  
Microscopy Imaging ◽  
In Vitro Synthesis ◽  
Significant Difference ◽  
Nano Clay

Phytophthora. infestans is a well known late blight causing oomycetes pathogen. It evolves and adapts to the host background and new fungicide molecules rapidly within a few years of their release, may be due to the predominance of transposable elements in its genome. Frequent and huge applications of fungicides cause environmental concerns. Here we developed target specific RNA interference based molecules, that are capable of effectively reducing the late blight infection. cDNA microarray expression data was used for the selection of genes involved in the early stage of infection process, sporulation etc. The in vitro synthesis of double stranded RNA molecule, targeting SDH, EF-1&alpha;, GPI-HAM344, PLD-3 and HSP-90 encoding genes revealed the reduction in growth, sporulation and symptom expression, which were subsequently assessed by culture bioassay, detached leaf assay and topical application methods. The multiple genes targeted dsRNA nano clay sprayed plants showed enhanced disease resistance (4% disease severity) and least sporulation (&lt;1x103), compared to naked dsRNA spray. Use of nano clay was assumed to be involved in the effective delivery, protection and boosting the action of RNAi in potato plants. A significant difference in the growth, sporulation count, disease severity and reduced expression of the genes and confocal microscopy imaging authenticates the effects of SIGS on late blight disease progression. Our research demonstrated that topical dsRNA nano clay spray under the open-air environment could be an alternative to chemical fungicides and transgenic approaches as a novel plant protection strategy for late blight in an environmentally friendly manner.

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