scholarly journals Differential Activity of Carboxylic Acid Amide Fungicides Against Various Developmental Stages of Phytophthora infestans

2007 ◽  
Vol 97 (10) ◽  
pp. 1274-1283 ◽  
Author(s):  
Yigal Cohen ◽  
Ulrich Gisi
Keyword(s):  
Carboxylic Acid ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Developmental Stages ◽  
Acid Amide ◽  
Intrinsic Activity ◽  
Dependent Manner ◽  
Carboxylic Acid Amide ◽  
In Planta ◽  
Mycelium Growth

Three carboxylic acid amide (CAA) fungicides, mandipropamid (MPD), dimethomorph (DMM) and iprovalicarb (IPRO) were examined for their effects on various asexual developmental stages of Phytophthora infestans in vitro and in planta. Germination of cystospores and direct germination of sporangia were inhibited with nanomole concentrations of MPD (0.005 μg/ml) and micromole concentrations of DMM (0.05 μg/ml) or IPRO (0.5 μg/ml). A temporary exposure of 1 h to CAAs was not detrimental to germination and infectivity of sporangia or cystospores. CAAs applied to cystospores at 1 h after the onset of germination did not prevent the emergence of germ tubes, but inhibited their further growth and deformed their shape. None of the fungicides affected discharge of zoospores from sporangia or the encystment (cell wall formation/assembly) of the zoospores. Mycelium growth in solid or liquid media was inhibited with micromole concentrations. CAAs mixed with sporangia and drop inoculated onto detached leaves strongly suppressed infection. Curative application at 1 day postinoculation (dpi) required higher concentrations of CAAs than preventive application to inhibit infection and lost its effectiveness at 2 dpi. When sprayed on established late blight lesions 4 days after inoculation, CAAs reduced sporangial production in a dose-dependent manner. Trans-laminar protection of potato or tomato leaves, although achieved with higher doses, was more effective with MPD than with DMM or IPRO. Shade house studies demonstrated superior control of late blight epidemics by MPD compared with the other molecules. The data suggest that germ tube formation by cystospores or sporangia is the most sensitive stage in the life cycle of P. infestans to CAAs. Of the three CAAs, MPD had the highest intrinsic activity against spore germination. This property, together with its better trans-laminar activity, makes MPD more effective than DMM or IPRO in controlling epidemics caused by P. infestans.

scholarly journals Mutagenesis of Phytophthora infestans for Resistance Against Carboxylic Acid Amide and Phenylamide Fungicides

Plant Disease ◽  
2008 ◽  
Vol 92 (5) ◽  
pp. 675-683 ◽  
Author(s):  
Avia (Evgenia) Rubin ◽  
Dror Gotlieb ◽  
Ulrich Gisi ◽  
Yigal Cohen
Keyword(s):  
Carboxylic Acid ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Uv Light ◽  
Acid Amide ◽  
Late Blight Resistance ◽  
Plasmopara Viticola ◽  
Carboxylic Acid Amide ◽  
In Planta

The carboxylic acid amide (CAA) fungicides mandipropamid, dimethomorph, iprovalicarb, and the phenylamide fungicide mefenoxam (MFX, the active enantiomer of metalaxyl) are anti-oomycete fungicides effective against downy mildews and late blight. Resistance against MFX was reported in nature in several oomycetes including Phytophthora infestans and Plasmopara viticola, whereas resistance against CAAs was reported in P. viticola but not in P. infestans. In this study the mutability of P. infestans for resistance against CAAs and MFX (as a control) was explored under laboratory conditions. UV light or chemical mutagens (e.g., ethyl methan sulfonate [EMS]) were applied to sporangia, and the emergence of mutants resistant to CAAs or MFX, or with altered mating type, was followed. Many mutants resistant to CAAs developed at generation 0 after mutagenesis, but all showed erratic, instable resistance in planta, diminishing after 1 to 8 asexual infection cycles, and failed to grow on CAA-amended medium. In contrast, 19 mutants resistant to MFX were obtained: 6 with UV irradiation (in isolates 28 or 96) and 13 with EMS (in isolates 408, 409, and 410). In three experiments, a shift in mating type, from A1 to A2, was detected. To elucidate whether or not resistance to CAAs is recessive and therefore might emerge only after sexual recombination, A1 and A2 mutants were crossed and the F1 and F2 progeny isolates were tested for resistance. Offspring isolates segregated for resistance to MFX, with resistant isolates maintaining stable resistance in vitro and in planta, whereas all progeny isolates failed to show stable resistance to CAAs in planta or in vitro. The data suggest that P. infestans could be artificially mutated for resistance against MFX, but not against CAAs.

scholarly journals Phenazine-1-Carboxylic Acid Production by Pseudomonas fluorescens LBUM636 Alters Phytophthora infestans Growth and Late Blight Development

2017 ◽  
Vol 107 (3) ◽  
pp. 273-279 ◽  
Author(s):  
Christopher K. Morrison ◽  
Tanya Arseneault ◽  
Amy Novinscak ◽  
Martin Filion
Keyword(s):  
Carboxylic Acid ◽  
Late Blight ◽  
Plant Defense ◽  
Phytophthora Infestans ◽  
Pseudomonas Fluorescens ◽  
Quantitative Polymerase Chain Reaction ◽  
Direct Interaction ◽  
Wild Type ◽  
In Planta

Phytophthora infestans causes late blight of potato, one of the most devastating diseases affecting potato production. Alternative approaches for controlling late blight are being increasingly sought due to increasing environmental concerns over the use of chemical pesticides and the increasing resistance of P. infestans to fungicides. Our research group has isolated a new strain of Pseudomonas fluorescens (LBUM636) of biocontrol interest producing the antibiotic phenazine-1-carboxylic acid (PCA). Wild-type LBUM636 was shown to significantly inhibit the growth of Phytophthora infestans in in vitro confrontational assays whereas its isogenic mutant (phzC−; not producing PCA) only slightly altered the pathogen’s growth. Wild-type LBUM636 but not the phzC− mutant also completely repressed disease symptom development on tubers. A pot experiment revealed that wild-type LBUM636 can significantly reduce P. infestans populations in the rhizosphere and in the roots of potato plants, as well as reduce in planta disease symptoms due to PCA production. The expression of eight common plant defense-related genes (ChtA, PR-1b, PR-2, PR-5, LOX, PIN2, PAL-2, and ERF3) was quantified in tubers, roots, and leaves by reverse-transcription quantitative polymerase chain reaction and revealed that the biocontrol observed was not associated with the induction of a plant defense response by LBUM636. Instead, a direct interaction between P. infestans and LBUM636 is required and PCA production appears to be a key factor for LBUM636’s biocontrol ability.

The molecular mechanisms of Phytophthora infestans in response to reactive oxygen species (ROS) stress

2021 ◽  
Author(s):  
Xiumei Luo ◽  
Tingting Tian ◽  
Maxime Bonnave ◽  
Xue Tan ◽  
Xiaoqing Huang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Molecular Mechanisms ◽  
Reactive Oxygen ◽  
Microbial Pathogens ◽  
Dependent Manner ◽  
Oxygen Species ◽  
Tor Signaling ◽  
Potato Resistance

Reactive oxygen species (ROS) are critical for the growth, development, proliferation, and pathogenicity of microbial pathogens; however, excessive levels of ROS are toxic. Little is known regarding the signaling cascades in response to ROS stress in oomycetes such as Phytophthora infestans, the causal agent of potato late blight. Here, P. infestans was used as a model system to investigate the mechanism underlying the response to ROS stress in oomycete pathogens. Results showed severe defects in sporangium germination, mycelial growth, appressorium formation, and virulence of P. infestans in response to H2O2 stress. Importantly, these phenotypes mimic those of P. infestans treated with rapamycin, the inhibitor of target of rapamycin (TOR, 1-phosphatidylinositol-3-kinase). Strong synergism occurred when P. infestans was treated with a combination of H2O2 and rapamycin, suggesting that a crosstalk exists between ROS stress and the TOR signaling pathway. Comprehensive analysis of transcriptome, proteome and phosphorylation omics showed that H2O2 stress significantly induced the operation of the TOR-mediated autophagy pathway. Monodansylcadaverine (MDC) staining showed that in the presence of H2O2 and rapamycin, the autophagosome level increased in a dosage-dependent manner. Furthermore, transgenic potatoes containing double-stranded RNA of PiTOR (TOR in P. infestans) displayed high resistance to P. infestans. Taken together, TOR is involved in the ROS response and is a potential target for control of oomycete diseases, as host-mediated silencing of PiTOR enhances potato resistance to late blight.

Rhodium catalyzed one-step hydroamidation of cyclopentadiene and dicyclopentadiene

2015 ◽  
Vol 5 (5) ◽  
pp. 2783-2787 ◽  
Author(s):  
Arno Behr ◽  
Denys Levikov ◽  
Edward Nürenberg
Keyword(s):  
Carboxylic Acid ◽  
Acid Amide ◽  
Amide Group ◽  
Carboxylic Acid Amide ◽  
Direct Route ◽  
One Step ◽  
Pharmaceutical Industries

The carboxylic acid amide group is of great importance in the contemporary chemical and pharmaceutical industries. A one-step rhodium catalyzed direct route from alkene to amide is presented via the hydroamidation reaction of cyclopentadiene and dicyclopentadiene.

Solvent- and catalyst-free, quantitative protection of hydroxyl, thiol, carboxylic acid, amide and heterocyclic amino functional groups

2016 ◽  
Vol 18 (23) ◽  
pp. 6209-6214 ◽  
Author(s):  
Mia L. Jawor ◽  
Basil M. Ahmed ◽  
Gellert Mezei
Keyword(s):  
Carboxylic Acid ◽  
Functional Groups ◽  
Acid Amide ◽  
Waste Materials ◽  
Carboxylic Acid Amide ◽  
Catalyst Free

Various substrates are quantitatively protected by 3,4-dihydro-2H-pyran at 125 °C in the absence of any additional chemicals, without generating any waste materials.

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