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 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 Biological Management of Colocasia Blight Incited by Phytophthora colocasiae using Native Strains of Antagonists in North Western Himalayas

2021 ◽  
Author(s):  
Divya Bhandhari ◽  
Amar Singh ◽  
J.V. Patel ◽  
D.K. Banyal
Keyword(s):  
Growth Inhibition ◽  
Disease Control ◽  
Pseudomonas Fluorescens ◽  
Mycelial Growth ◽  
Antagonistic Activity ◽  
Trichoderma Spp ◽  
Phytophthora Colocasiae ◽  
Biological Management

Background: Colocasia is cultivated globally for its edible corm and leaves. Leaf blight incited by Phytophthora colocasiae is the most destructive disease of colocasia. The current study aims at biological management of the disease. Methods: Nine Trichoderma isolates from the colocasia rhizosphere soil along with five designated isolates of Trichoderma spp. already available in the Department of Plant Pathology, CSK HPKV, Palampur were tested in vitro for antagonistic activity against P. colocasiae. Similarly, six unidentified bacterial strains isolated from colocasia phylloplane and available Pseudomonas fluorescens were evaluated for antagonistic activity against P. colocasiae under in vitro conditions. The bioagents found best under in vitro conditions were evaluated in vivo. Result: Trichoderma isolate Ti-6 was found significantly superior bioagent as it resulted in 72.9 per cent mycelial growth inhibition of P. colocasiae followed by Ti-5 (63.2%), Ti-4 (60.1%) and Ti-1 (54.5%). Amongst bacterial antagonists, Pseudomonas fluorescens gave maximum mycelial growth inhibition of 50.5 per cent followed by Pb-3 (31.4%) and Pb-6 (30.5%). The efficacy of five Trichoderma spp isolates viz., Ti-6, Ti-5, Ti-4, Ti-1, T. viride and one bacterial isolate of P. fluorescens found effective under in vitro were also evaluated in vivo using three delivery systems under net house condition. Corm treatment with bioagents was found superior for management of colocasia blight. Corm treatment with Ti-6 was found to be significantly superior to other treatments as 93.74 per cent of disease control was observed. For drenching, bioagent Ti-6 was proved best in managing blight disease (88.91%) followed by Ti-5 (88.90%). However, Ti-5 isolate of Trichoderma sp. as soil application was found superior with 90.02 per cent disease control.

Management of collar rot disease in chickpea by Trichoderma species

2020 ◽  
Vol 7 (03) ◽  
Author(s):  
PREM PANDEY ◽  
G. C. SAGAR ◽  
SUNDARMAN SHRESTHA2 ◽  
HIRAKAJI MANANDHAR ◽  
RITESH K. YADAV ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Mycelial Growth ◽  
Sclerotium Rolfsii ◽  
Maximum Growth ◽  
Pot Experiment ◽  
Trichoderma Spp ◽  
Trichoderma Species ◽  
Collar Rot ◽  
Rot Disease

Nine isolates of Trichoderma spp. were isolated from different agro- ecological regions of Nepal viz; Jumla, Palpa, Chitwan, Tarahara, Banke, Illam and Salyan and screened against Sclerotium rolfsii Sacc. Adreded soil borne phytopathogen causing collar rot of chickpea in chickpea; In-vitro efficacy of nine fungal antagonist (Trichoderma spp.) against Sclerotium rolfsii were screened. Pot experiment was done to find out the effective management of S. rolfsi through Tricoderma using different methods i.e. Seed treatment, soil drenching and soil application. All the tested isolates of Trichoderma spp. were found effective on mycelial growth inhibition and sclerotial parasitization of S. rolfsii. Trichoderma isolated from Palpa district showed maximum growth inhibition (%) of pathogen periodically after 48(93.78%), 72(96.00%), 96(97.96%) and 120(100.00%) hours of inoculation. Parasitized sclerotium showed minimum sclerotial germination on agar plates. Moreover, Trichoderma species isolated from Palpa districts showed second best percent mycelial growth inhibition periodically at 72(25.00%), 120(29.16%), 168(29.16%) and 216(29.16%).In pot experiment at 40 days after sowing, Seedling height was maximum in soil drenching with 30g per 100ml of water (22.27cm) and Mortality percentage of seedlings was least or highest disease control was observed in seed treated with 109cfu/ml (0.000%).

scholarly journals Suppression of Stem-End Rot on Avocado Fruit Using Trichoderma spp. in the Central Highlands of Kenya

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
E. K. Wanjiku ◽  
J. W. Waceke ◽  
J. N. Mbaka
Keyword(s):  
Growth Inhibition ◽  
Fungal Pathogen ◽  
Mycelial Growth ◽  
Culture Technique ◽  
Global Market ◽  
Dual Culture ◽  
Postharvest Diseases ◽  
Trichoderma Spp ◽  
Lasiodiplodia Theobromae

Demand for organic avocado fruits, together with stringent food safety standards in the global market, has made producers to use alternative, safe, and consumer-friendly strategies of controlling the postharvest fungal disease of avocado fruits. This study assessed the in vitro efficacy of Trichoderma spp. (T. atroviride, T. virens, T. asperellum, and T. harzianum) against isolated avocado stem-end rot (SER) fungal pathogens (Lasiodiplodia theobromae, Neofusicoccum parvum, Nectria pseudotrichia, and Fusarium solani) using a dual culture technique. The Trichoderma spp. were also evaluated singly on postharvest “Hass” avocado fruits. Spore suspension at 5 × 104 conidial/ml of the Trichoderma spp. was applied on the avocado fruits at three time points, twenty-four hours before the fungal pathogen (preinoculation), at the same time as the fungal pathogen (concurrent inoculation), and 24 hours after the fungal pathogen (postinoculation). In the in vitro study, T. atroviride showed the highest mycelial growth inhibition against N. parvum (48%), N. pseudotrichia (55%), and F. solani (32.95%), while T. harzianum had the highest mycelial growth inhibition against L. theobromae. Trichoderma asperellum was the least effective in inhibiting the mycelial growth of all the pathogens. Similarly, T. virens showed the highest mycelial growth inhibition against N. pseudotrichia at 45% inhibition. On postharvest “Hass” fruits, T. atroviride showed the highest efficacy against N. parvum, N. pseudotrichia, and F. solani in all the applications. Trichoderma virens and T. harzianum were most effective against all the pathogens during postinoculation, while Lasiodiplodia theobromae was best controlled by T. virens, T. harzianum, and T. asperellum during postinoculation. Both T. atroviride and T. harzianum present a potential alternative to synthetic fungicides against postharvest diseases of avocado fruits, and further tests under field conditions to be done to validate their efficacy. The possibility of using Trichoderma spp. in the management of SER on avocado fruits at a commercial level should also be explored.

scholarly journals In-vitro evaluation of six bio-product against coriander stem gall disease

2020 ◽  
Vol 35 (1-2) ◽  
Author(s):  
Munish Leharwan ◽  
Meenu Gupta ◽  
Sanjeev Leharwan
Keyword(s):  
Growth Inhibition ◽  
Mycelial Growth ◽  
Significant Inhibition ◽  
Fresh Milk ◽  
Cent Concentration ◽  
Cow Urine ◽  
Stem Gall ◽  
Butter Milk ◽  
Poison Food Technique

Stem gall of coriander caused by Protomyces macrosporus Unger. is a highly devastating seed and soil borne pathogen in coriander and has emerged as one of the major disease causing substantial quantitative and qualitative losses. In the present studies, efficacy of six bio-products, namely, Neemazal, cow urine, butter milk, fresh milk, beejamrit and jeevamrit was screened against mycelial growth inhibition of P. macrosporus under in vitro conditions. Extracts of these bio-products were evaluated at three different concentrations (i.e 10, 20 and 30%) by poison food technique. Results revealed that that among the various bio-products evaluated against test pathogen, irrespective of concentration tested, all the bio-products resulted in significant inhibition in mycelial growth of test pathogen with neemazal giving the complete inhibition [100.00 % (90.00)] followed by fresh milk [30.66 % (28.44)] and butter milk [26.55 % (25.99)], though these treatments were statistically different from one another. Different concentrations (10 to 30 %) of bio-products, irrespective of the treatments showed that 30 per cent concentration of all bio-products was most efficacious in inhibiting the mycelial growth of the test pathogen giving 69.95 per cent (36.77) growth inhibition. This was followed 20 and 10 per cent concentration of bio-products resulting in 55.58 per cent (32.49) and 45.53 per cent (16.30) growth inhibition, respectively. The result regarding evaluation of bio-products under in vitro conditions against the P. macrosporus showed that Neemazal treatment was most effective at all concentrations and completely inhibited the test fungus followed by 30 per cent fresh milk resulting in the mycelial growth inhibition of 51.60 per cent.

scholarly journals Penapisan Cendawan Trichoderma spp. untuk Pengendalian Phytophthora infestans secara in vitro

2016 ◽  
Vol 12 (3) ◽  
pp. 96
Author(s):  
Susiana Purwantisari ◽  
Achmadi Priyatmojo ◽  
Retno Peni Sancayaningsih ◽  
Rina Sri Kasiamdari
Keyword(s):  
Growth Inhibition ◽  
Phytophthora Infestans ◽  
Pathogenic Fungus ◽  
Culture Method ◽  
Inhibition Zone ◽  
Dual Culture ◽  
Trichoderma Spp ◽  
Suppressive Soil ◽  
Blight Disease

Late blight disease on potato caused by a plant pathogenic fungus (Phytophthora infestans)  is the most important disease in Indonesia.  The use of antagonist fungi Trichoderma is an environmentally friendly technology to control the potato disease. The purpose of this study was to determine the ability of Trichoderma spp. to control P. infestans in vitro. Trichoderma spp. have been isolated from suppressive soil at central potato areas in district of Lembang, Bandung, West Java Province. To determine the inhibition ability of Trichoderma spp against P. infestans, a dual culture method was performed.  Variable observed was inhibition zone of Trichoderma spp. against P. infestans. The results showed that 9 isolates of Trichoderma were successfuly isolated from suppressive soil, i.e. T. viride (2 isolates), T. atroviride (1 isolate), T. harzianum (1 isolate) and T. aureoviride (5 isolates). All the Trichoderma isolates revealed growth inhibition abality against P. infestans and. The highest growth inhibition (68.6%) was observed by T. viride isolate ( Ti 9).

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 Iodothyronine deiodinase structure and function: from ascidians to humans

2012 ◽  
Vol 215 (2) ◽  
pp. 189-206 ◽  
Author(s):  
Veerle M Darras ◽  
Stijn L J Van Herck
Keyword(s):  
Developmental Stages ◽  
The Body ◽  
Thyroid Status ◽  
Iodothyronine Deiodinase ◽  
Relative Contribution ◽  
Iodothyronine Deiodinases ◽  
Different Types ◽  
And Function ◽  
The Impact

Iodothyronine deiodinases are important mediators of thyroid hormone (TH) action. They are present in tissues throughout the body where they catalyse 3,5,3′-triiodothyronine (T3) production and degradation via, respectively, outer and inner ring deiodination. Three different types of iodothyronine deiodinases (D1, D2 and D3) have been identified in vertebrates from fish to mammals. They share several common characteristics, including a selenocysteine residue in their catalytic centre, but show also some type-specific differences. These specific characteristics seem very well conserved for D2 and D3, while D1 shows more evolutionary diversity related to itsKm, 6-n-propyl-2-thiouracil sensitivity and dependence on dithiothreitol as a cofactorin vitro. The three deiodinase types have an impact on systemic T3levels and they all contribute directly or indirectly to intracellular T3availability in different tissues. The relative contribution of each of them, however, varies amongst species, developmental stages and tissues. This is especially true for amphibians, where the impact of D1 may be minimal. D2 and D3 expression and activity respond to thyroid status in an opposite and conserved way, while the response of D1 is variable, especially in fish. Recently, a number of deiodinases have been cloned from lower chordates. Both urochordates and cephalochordates possess selenodeiodinases, although they cannot be classified in one of the three vertebrate types. In addition, the cephalochordate amphioxus also expresses a non-selenodeiodinase. Finally, deiodinase-like sequences have been identified in the genome of non-deuterostome organisms, suggesting that deiodination of externally derived THs may even be functionally relevant in a wide variety of invertebrates.

scholarly journals Baseline Sensitivity of Fusarium virguliforme to Fluopyram Fungicide

Plant Disease ◽  
2017 ◽  
Vol 101 (4) ◽  
pp. 576-582 ◽  
Author(s):  
Jie Wang ◽  
Carl A. Bradley ◽  
Olivia Stenzel ◽  
Dianne K. Pedersen ◽  
Ursula Reuter-Carlson ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Mycelial Growth ◽  
Soybean Seed ◽  
Inhibition Assay ◽  
Baseline Sensitivity ◽  
Growth Inhibition Assay ◽  
Fusarium Virguliforme ◽  
Fungicide Sensitivity ◽  
Conidia Germination

Fluopyram, a succinate dehydrogenase inhibitor (SDHI) fungicide, was recently registered for use as a soybean seed treatment for management of sudden death syndrome (SDS) caused by Fusarium virguliforme. Although registered and now used commercially, in vitro baseline fungicide sensitivity of F. virguliforme to fluopyram has not yet been established. In this study, the baseline sensitivity of F. virguliforme to fluopyram was determined using in vitro growth of mycelium and germination of conidia assays with two collections of F. virguliforme isolates. A total of 130 and 75 F. virguliforme isolates were tested using the mycelial growth and conidia germination assays, respectively, including a core set of isolates that were tested with both assays. In the mycelial growth inhibition assay, 113 out of 130 isolates (86.9%) were inhibited 50% by effective concentrations (EC50) less than 5 µg/ml with a mean EC50 of 3.35 µg/ml. For the conidia germination assay, 73 out of 75 isolates (97%) were determined to have an estimated EC50 of less than 5 µg/ml with a mean EC50 value of 2.28 µg/ml. In a subset of 20 common isolates that were phenotyped with both assays, conidia germination of F. virguliforme was determined to be more sensitive to fluopyram (mean EC50 = 2.28 µg/ml) than mycelial growth (mean EC50 = 3.35 µg/ml). Hormetic effects were observed in the mycelial growth inhibition assay as 22% of the isolates demonstrated more growth on medium amended with the lowest fluopyram concentration (1 µg/ml), as compared with the nonfluopyram amended control. It was not possible to determine EC50 values for nine out of 185 isolates (4.8%), as those isolates were not inhibited by 50% even at the highest fluopyram concentrations of 100 µg/ml for mycelial growth and 20 µg/ml for conidia germination inhibition assays. On the whole, the F. virguliforme population appears to be sensitive to fluopyram, and this study enables future monitoring of fungicide sensitivity.

scholarly journals Efficacy of botanicals and fungicides against Rhizoctonia solani inciting sheath blight disease on Rice (Oryza sativa L.)

2017 ◽  
Vol 9 (4) ◽  
pp. 1916-1920
Author(s):  
Vipin Kumar ◽  
V.P. Chaudhary ◽  
Dharmendra Kumar ◽  
Ajay Kumar ◽  
Sushma Sagar ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Mycelial Growth ◽  
Allium Sativum ◽  
Oryza Sativa L ◽  
Fungal Growth ◽  
Sheath Blight ◽  
Ocimum Sanctum ◽  
Sheath Blight Disease ◽  
Fungal Growth Inhibition

Among the fungal diseases, sheath blight, caused by multinucleate Rhizoctoniasolani Kuhn (teleomorph: Thanatephorus cucumeris Donk), a ubiquitous pathogen, is an important fungal disease of rice ranking only after blast and often rivalling it. The potential losses due to sheath blight alone in India has been up to 51.3%. In this study an attempt was made to investigate the antifungal efficacy of botanicals viz., neem (Azadirachtaindica), tulsi (Ocimum sanctum), garlic (Allium sativum), onion (Allium cepa), ginger (Zingiberofficinale) and various fungicides namely mancozeb, propiconazole, hexaconazole, carbendazim, and copper oxychlorideagainst Rhizoctoniasolani in vitro by poison food technique. R. solani was allowed to grow at 5%, 10% concentrations of botanicals and at 200, 500, 1000ppm of fungicides amended potato dextrose agar (PDA) medium. The effect of botanicals and fungicides on mycelial growth inhibition was recorded after 36, 48 and 72 post hrs inoculation (phi). It was observed that bulb extract of Allium sativum and rhizome extract of Zingier officinal suppressed the mycelial growth (80.19 and 76.32, respectively) @ 10% followed by leaf extract of Azadirachtaindica (72.78 %) after 72 phi. Among the fungicides, the complete fungal growth inhibition was observed in propiconazole and carbendazim fungicides amended medium.

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