scholarly journals Biocontrol Activity of Three Pseudomonas in a Newly Assembled Collection of Phytophthora infestans Isolates

2019 ◽  
Vol 109 (9) ◽  
pp. 1555-1565 ◽  
Author(s):  
Mout De Vrieze ◽  
Ramona Gloor ◽  
Josep Massana Codina ◽  
Stefano Torriani ◽  
Katia Gindro ◽  
...  
Keyword(s):  
Phytophthora Infestans ◽  
Leaf Disc ◽  
Potato Production ◽  
Biocontrol Activity ◽  
General Demand ◽  
Resistant Genotypes ◽  
Highly Virulent ◽  
Alternative Control Methods ◽  
Open Access Article

Late blight caused by the oomycete Phytophthora infestans constitutes the greatest threat to potato production worldwide. Considering the increasing concerns regarding the emergence of novel fungicide-resistant genotypes and the general demand for reducing inputs of synthetic and copper-based fungicides, the need for alternative control methods is acute. Several bacterial antagonists have shown anti-Phytophthora effects during in vitro and greenhouse experiments. We report the effects of three Pseudomonas strains recovered from field-grown potatoes against a collection of P. infestans isolates assembled for this study. The collection comprised 19 P. infestans isolates of mating types A1 and A2 greatly varying in fungicide resistance and virulence profiles as deduced from leaf disc experiments on Black’s differential set. The mycelial growth of all P. infestans isolates was fully inhibited when co-cultivated with the most active Pseudomonas strain (R47). Moreover, the isolates reacted differently to exposure to the less active Pseudomonas strains (S19 and R76). Leaf disc infection experiments with six selected P. infestans isolates showed that four of them, including highly virulent and fungicide-resistant ones, could be efficiently controlled by different potato-associated Pseudomonas strains. [Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Characterization of South African Isolates of Phytophthora infestans

Plant Disease ◽  
2001 ◽  
Vol 85 (3) ◽  
pp. 287-291 ◽  
Author(s):  
A. McLeod ◽  
S. Denman ◽  
A. Sadie ◽  
F. D. N. Denner
Keyword(s):  
Phytophthora Infestans ◽  
Mating Type ◽  
Coastal Region ◽  
Potato Production ◽  
Screening Tests ◽  
Sensitivity Testing ◽  
Fingerprint Pattern ◽  
Metalaxyl Sensitivity ◽  
Mitochondrial Dna Haplotype

Severe late blight epidemics in South Africa in 1995 and 1996 prompted an investigation into the mating type, genotype, and metalaxyl sensitivity of populations of Phytophthora infestans. A country-wide survey was conducted from 1996 to 1998 in which isolates were collected from 101 potato fields (656 isolates) and 16 tomato fields (57 isolates). Six hundred and fifty-seven isolates (600 potato and 57 tomato) were analyzed for mating type, while subsets of isolates were analyzed for genotype at the Glucose-6-phosphate isomerase locus (n = 148), DNA fingerprinting with probe RG-57 (n = 61) and mitochondrial DNA haplotype (n = 20). All isolates tested had the characteristics typical of the pre-1980 population (A1 mating type, 86/100 Gpi genotype, US-1 fingerprint pattern, and mtDNA haplotype I-b) previously found worldwide. Metalaxyl sensitivity testing of 656 potato isolates by the in vitro leaf disk method showed that the frequency of highly resistant isolates (50% effective concentration [EC50] > 200 μg a.i./ml) in potato production regions increased from 35% in 1996 to 51% in 1997. The high frequency of resistant isolates was confined to the southern coastal regions in 1996 and 1997, as well as the western Free State in 1997. Although phenylamides were withdrawn from the southern coastal region in December 1996, screening tests carried out in 1998 indicated that resistance levels remained high (≥83%). Sensitive isolates (EC50 < 40 μg a.i./ml) predominated in the remaining six potato production regions. Screening of 45 isolates collected from tomatoes indicated that no resistant strains were present in the sample tested.

scholarly journals Sensitivity to fungicides in the isolates of Phytophthora infestans (Mont.) de Bary in the Czech Republic from 2003 to 2008

2011 ◽  
Vol 47 (No. 1) ◽  
pp. 5-12 ◽  
Author(s):  
J. Mazáková ◽  
M. Zouhar ◽  
P. Ryšánek ◽  
V. Táborský ◽  
E. Hausvater ◽  
...  
Keyword(s):  
Czech Republic ◽  
Phytophthora Infestans ◽  
Mycelial Growth ◽  
Leaf Disc ◽  
The Czech Republic ◽  
Growing Seasons ◽  
Leaf Disc Assay ◽  
Disc Assay ◽  
Floating Leaf

In the growing seasons from 2003 to 2008, 547 isolates of Phytophthora infestans from five regions in the Czech Republic were collected and examined for their sensitivity to the active ingredients (metalaxyl, dimethomorph and propamocarb-HCl) of frequently used fungicides. The response of the isolates to each of these substances was examined using the in vitro amended-agar method; in 352 of these isolates, the sensitivity to metalaxyl was also assessed by the floating leaf-disc assay. The majority of the isolates were sensitive (89.8%) to metalaxyl. Resistant isolates were found only in two of the sample years (2003 and 2008); they represented 58% of the samples in 2003 and only 29% in 2008. Four isolates from 2004 were found to be intermediate for their level of resistance. All the isolates that were tested were sensitive to dimethomorph and propamocarb-HCl; these particular substances completely suppressed mycelial growth at 1 &micro;g a.i. per ml.

scholarly journals The Potency of Unassociated Trichoderma spp and the Fungicides Antagonistic of the Late Blight of Potato by Phytophthora infestans (Mont.) De-Bary

2021 ◽  
pp. 246-253
Author(s):  
Anuj Bansal ◽  
S. K. Biswas ◽  
Deepak Baboo ◽  
Vikram Singh
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Radial Growth ◽  
Potato Production ◽  
Dual Culture ◽  
Vegetable Crops ◽  
Culture Methods ◽  
Trichoderma Spp ◽  
Late Blight Of Potato

The potato (Solanum tuberosum) is one of the most important vegetable crops in the world, belonging to the family Solanaceae and is an important starchy food crop in both sub-tropical and temperate regions. Potato plants are subjected to attack by numerous diseases wherever the crop is grown. Among them, late blight of potato caused by Phytophthora infestans (Mont.) de-Bary is of major cause of concern in potato production at present. An experiment was conducted in the Department of Plant Pathology, College of Agriculture, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur. The antifungal activity of different fungicides was evaluated in-vitro through the food poison technique. The experimental finding showed that radial growth of mycelium of Phytophthora infestans was inhibited by fungicides over control. At 100 ppm, the minimum radial growth of mycelium was found in Equation Pro treatment as 5.3, 8.2, 11.4, 14.2, 16.2, 18.4 and 22.6 mm over control against 12.3, 19.1, 26.1, 35.9, 42.5, 51.4 and 64.8 mm at 1, 2, 3, 4, 5, 6 and 7 days after inoculation respectively. Similarly, at 500 and 1000 ppm the minimum radial growth of mycelium was found in Equation Pro treatment. Efficacy of bio-control agents on the radial growth of Phytophthora infestans was evaluated using Dual Culture Methods. Among the different concentrations, 1000 ppm was found most effective than 100 and 500 ppm. Among the different bio-agents, Trichoderma harzianum able to reduced maximum radial mycelial growth of fungus showing 4.6, 8.8, 10.1, 13.2, 15.6, 19.3 and 23.5 mm against 12.3, 19.1, 26.1, 35.9, 42.5, 51.4 and 64.8 mm at 1, 2, 3, 4, 5, 6 and 7 days after inoculation, respectively.

scholarly journals Multi-Trait Wheat Rhizobacteria from Calcareous Soil with Biocontrol Activity Promote Plant Growth and Mitigate Salinity Stress

2021 ◽  
Vol 9 (8) ◽  
pp. 1588
Author(s):  
Anastasia Venieraki ◽  
Styliani N. Chorianopoulou ◽  
Panagiotis Katinakis ◽  
Dimitris L. Bouranis
Keyword(s):  
Plant Growth ◽  
Salinity Stress ◽  
Calcareous Soil ◽  
In Vitro Studies ◽  
Pgp Traits ◽  
Biocontrol Activity ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Microbial Fertilizers

Plant growth promoting rhizobacteria (PGPR) can be functional microbial fertilizers and/or biological control agents, contributing to an eco-spirit and safe solution for chemical replacement. Therefore, we have isolated rhizospheric arylsulfatase (ARS)-producing bacteria, belonging to Pseudomonas and Bacillus genus, from durum wheat crop grown on calcareous soil. These isolates harbouring plant growth promoting (PGP) traits were further evaluated in vitro for additional PGP traits, including indole compounds production and biocontrol activity against phytopathogens, limiting the group of multi-trait strains to eight. The selected bacterial strains were further evaluated for PGP attributes associated with biofilm formation, compatibility, salt tolerance ability and effect on plant growth. In vitro studies demonstrated that the multi-trait isolates, Bacillus (1.SG.7, 5.SG.3) and Pseudomonas (2.SG.20, 2.C.19) strains, enhanced the lateral roots abundance and shoots biomass, mitigated salinity stress, suggesting the utility of beneficial ARS-producing bacteria as potential microbial fertilizers. Furthermore, in vitro studies demonstrated that compatible combinations of multi-trait isolates, Bacillus sp. 1.SG.7 in a mixture coupled with 5.SG.3, and 2.C.19 with 5.SG.3 belonging to Bacillus and Pseudomonas, respectively, may enhance plant growth as compared to single inoculants.

scholarly journals Cross-talk among flesh-eating Aeromonas hydrophila strains in mixed infection leading to necrotizing fasciitis

2016 ◽  
Vol 113 (3) ◽  
pp. 722-727 ◽  
Author(s):  
Duraisamy Ponnusamy ◽  
Elena V. Kozlova ◽  
Jian Sha ◽  
Tatiana E. Erova ◽  
Sasha R. Azar ◽  
...  
Keyword(s):  
Necrotizing Fasciitis ◽  
Mixed Infection ◽  
Aeromonas Hydrophila ◽  
Case Fatality ◽  
Host Immune System ◽  
Complex Interactions ◽  
Solid Media ◽  
Multiple Strains ◽  
Highly Virulent

Necrotizing fasciitis (NF) caused by flesh-eating bacteria is associated with high case fatality. In an earlier study, we reported infection of an immunocompetent individual with multiple strains of Aeromonas hydrophila (NF1–NF4), the latter three constituted a clonal group whereas NF1 was phylogenetically distinct. To understand the complex interactions of these strains in NF pathophysiology, a mouse model was used, whereby either single or mixed A. hydrophila strains were injected intramuscularly. NF2, which harbors exotoxin A (exoA) gene, was highly virulent when injected alone, but its virulence was attenuated in the presence of NF1 (exoA-minus). NF1 alone, although not lethal to animals, became highly virulent when combined with NF2, its virulence augmented by cis-exoA expression when injected alone in mice. Based on metagenomics and microbiological analyses, it was found that, in mixed infection, NF1 selectively disseminated to mouse peripheral organs, whereas the other strains (NF2, NF3, and NF4) were confined to the injection site and eventually cleared. In vitro studies showed NF2 to be more effectively phagocytized and killed by macrophages than NF1. NF1 inhibited growth of NF2 on solid media, but ExoA of NF2 augmented virulence of NF1 and the presence of NF1 facilitated clearance of NF2 from animals either by enhanced priming of host immune system or direct killing via a contact-dependent mechanism.

Corrigendum to: Integrated transcriptomics and metabolomics reveal induction of hierarchies of resistance genes in potato against late blight

2016 ◽  
Vol 43 (12) ◽  
pp. 1205 ◽  
Author(s):  
Kalenahalli N. Yogendra ◽  
Ajjamada C. Kushalappa
Keyword(s):  
Late Blight ◽  
Resistance Genes ◽  
Quantitative Resistance ◽  
Potato Production ◽  
Metabolic Reprogramming ◽  
Specific Gene ◽  
Molecular Events ◽  
Pathway Regulation ◽  
Molecular And Biochemical Mechanisms ◽  
Resistant Genotypes

Late blight caused by Phytophthora infestans is a devastating disease affecting potato production worldwide. The quantitative resistance is durable, but the underlying molecular and biochemical mechanisms are poorly understood, limiting its application in breeding. Integrated transcriptomics and metabolomics approach was used for the first time to study the hierarchies of molecular events occurring, following inoculation of resistant and susceptible potato genotypes with P. infestans. RNA sequencing revealed a total of 4216 genes that were differentially expressed in the resistant than in the susceptible genotype. Genes that were highly expressed and associated with their biosynthetic metabolites that were highly accumulated, through metabolic pathway regulation, were selected. Quantitative real-time PCR was performed to confirm the RNA-seq expression levels. The induced leucine-rich repeat receptor-like kinases (LRR-RLKs) are considered to be involved in pathogen recognition. These receptor genes are considered to trigger downstream oxidative burst, phytohormone signalling-related genes, and transcription factors that regulated the resistance genes to produce resistance related metabolites to suppress the pathogen infection. It was noted that several resistance genes in metabolic pathways related to phenylpropanoids, flavonoids, alkaloids and terpenoid biosynthesis were strongly induced in the resistant genotypes. The pathway specific gene induction provided key insights into the metabolic reprogramming of induced defence responses in resistant genotypes.

scholarly journals In Vitro Micropropagation of the Medicinal Plant Physalis angulata L.

2016 ◽  
Vol 8 (2) ◽  
pp. 161-163
Author(s):  
Owk ANIEL KUMAR ◽  
Songa RAMESH ◽  
Sape SUBBA TATA
Keyword(s):  
Large Scale ◽  
Leaf Disc ◽  
Basal Medium ◽  
Shoot Proliferation ◽  
Shoot Multiplication ◽  
Medicinal Herb ◽  
Root Induction ◽  
Survival Percentage ◽  
Physalis Angulata

Physalis angulata L. is an important medicinal herb. An efficient direct adventitious plant regeneration protocol was developed for large scale propagation using leaf disc as explants. The explants were cultured on MS basal medium supplemented with 0.25-3.0 mg/L 6-benzyl amino purine (BAP) for primary shoot proliferation. Inclusion of indole-3-acetic acid (IAA) and gibberellic acid (GA3) in the culture medium along with BAP promoted a higher rate of shoot multiplication. The maximum number of shoots was produced in MS + BAP (1.0 mg/L) + IAA (0.5 mg/L) + GA3 (0.20 mg/L) after the third subculture. An average of 152.8 ± 0.40 shoots were produced from each leaf disc. For root induction the shootlets were transferred to MS medium supplemented with different concentrations of indole-3-butyric acid (IBA). The highest percentage of root induction was observed in 1.0 mg/L (IBA). Rooted plants were successfully established in the soil after hardening. The survival percentage of rooted plants on soil was found to be 85%. This result will facilitate the conservation and propagation of the important medicinal herb Physalis angulata L.

scholarly journals Distribution and pathogenicity of Pseudomonas cichorii (Swingle) Stapp in coffee in Puerto Rico

1969 ◽  
Vol 87 (3-4) ◽  
pp. 123-135 ◽  
Author(s):  
Luis Sánchez ◽  
Mildred Zapata ◽  
Rocío del P. Rodríguez ◽  
James S. Beaver
Keyword(s):  
Puerto Rico ◽  
Leaf Age ◽  
Coffea Canephora ◽  
Resistance Mechanisms ◽  
Pseudomonas Cichorii ◽  
Inoculation Methods ◽  
Young Leaves ◽  
Resistant Genotypes ◽  
Coffee Species

Seventeen pathogenic strains of Pseudomonas cichorii were isolated from leaf samples of coffee (Coffea arabica) collected from nurseries in eight municipalities of Puerto Rico. Two different inoculation methods were evaluated under in vitro conditions: inoculation of plant-attached old and young leaves grown under greenhouse conditions, and plant-detached young coffee leaves grown under field conditions. Pseudomonas cichorii was more virulent in older leaves, thus indicating that resistance mechanisms differ according to leaf age. Both inoculation methods were reliable in identifying resistant genotypes. Three commercial varieties of coffee (Borbón, Pacas and Caturra) were susceptible to bacterial leaf blight, whereas coffee species Coffea liberica var. Excelsa and Coffea canephora var. Robusta were resistant.

scholarly journals Evaluation of powdery mildew resistance in various melon (Cucumis melo L.) genotypes

2018 ◽  
Vol 10 (4) ◽  
pp. 279-284
Author(s):  
Zh. Ivanova ◽  
K. Vasileva ◽  
N. Velkov ◽  
S. Grozeva
Keyword(s):  
Powdery Mildew ◽  
Genetic Resistance ◽  
Leaf Disc ◽  
Breeding Program ◽  
Vegetable Crops ◽  
Plant Materials ◽  
South Central ◽  
Leaf Disc Assay ◽  
Disc Assay

Abstract. Powdery mildew, caused by Podosphaera xanthii and Golovinomyces cichoracearum, is an economically important disease in melon worldwide. Genetic resistance is one of the most suitable strategies to control powdery mildew. During the last few years several races of the pathogens have been reported. The need to develop resistant varieties is a challenge for each breeding program. Leaf disc assay was used in phytopathology and breeding programs as a rapid and reliable method for evaluation of disease resistance in a large number of plant materials. The purpose of this study was to establish species and races of powdery mildew in Plovdiv region, South Central Bulgaria; to develop a suitable system of pathogen isolation and cultivation; to determine the resistance levels in different melon genotypes available in Maritsa Vegetable Crops Research Institute (MVCRI) - Plovdiv collection by the leaf disc assay. Fifty-three melon genotypes, including lines, varieties, hybrids and ten differential lines were tested. The data showed that causal agent of powdery mildew was race 1 of P. xanthii in Plovdiv region. Our experimental results indicated that for the long-term storage of powdery mildew it is preferable to keep a whole plant under in vitro conditions. This allows the preservation of powdery mildew for two months before transferring on a new tissue. Thirty-four of the tested melon genotypes reacted as immune or resistant and nineteen as susceptible. Resistant melon genotypes are a suitable source in initiating a new breeding program aimed to increase resistance to powdery mildew.

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