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-1α, 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 (<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.

scholarly journals Respuesta de biosurfactantes producidos por Pseudomonas fluorescens para el control de la gota de la papa Phytophthora infestans (Mont) de Bary, bajo condiciones controlada.

2010 ◽  
Vol 11 (1) ◽  
pp. 21
Author(s):  
Hugo F. Rivera ◽  
Erika P. Martínez ◽  
Jairo A. Osorio ◽  
Edgar Martínez
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Pseudomonas Fluorescens ◽  
Negative Impact ◽  
Potato Late Blight ◽  
Pathogen Resistance ◽  
Production Costs ◽  
In Vitro Assays

<p>Phytophthora infestans (Mont.) de Bary, agente causal de la gota de la papa, es considerado la principal limitante de la producción de este cultivo en Colombia. El control habitual del patógeno se realiza con fungicidas de tipo sistémico, que incrementan los costos de producción, pueden inducir la resistencia del patógeno y tiene un impacto negativo en el ambiente. Por tanto, se llevó a cabo este estudio con el propósito de buscar alternativas amigables con el ambiente, que hagan parte de un paquete tecnológico eficaz de control. Dos cepas nativas de Psedomonas fluorescens (039T y 021V), provenientes de cultivos de papa, fueron evaluadas contra P. infestans. Las suspensiones bacterianas y los biosurfactantes parcialmente purificados (BPP), producidos por éstas (obtenidos en medio mínimo de sales con querosén), fueron aplicados sobre foliolos desprendidos en ensayos in vitro y experimentos in vivo en plantas de papa, en condiciones controladas en casa de malla. Los resultados demostraron la capacidad que tienen los biosurfactantes y las suspensiones bacterianas para controlar al patógeno, ya que el BPP 039T logró reducir el nivel de severidad de la enfermedad en 79,9% in vitro y 38,5% in vivo, mientras que el BPP 021V redujo en 78,7% in vitro y 30,2% in vivo. Las suspensiones bacterianas redujeron el nivel de severidad en 72,4% (039T) y 66,1% (021V) en las evaluaciones in vitro y 35% en los experimentos in vivo. Los resultados de esta investigación muestran el potencial que tienen los biosurfactantes para el control de la gota en Colombia.</p><p> </p><p><strong>Evaluation of Biosurfactants Produced by Pseudomonas fluorescens for Potato Late Blight Control (Phytophthora infestans (Mont) de Bary) Under Controlled Conditions</strong></p><p>Phytophthora infestans (Mont.) de Bary, causal agent of potato late blight is considered the main limiting pathogen for the production of this crop in Colombia. The usual control of the disease has been performed with systemic fungicides which increase production costs, can induce pathogen resistance and have a negative impact on the environment. Therefore, this study was carried out in order to find effective and environmentally friendly control alternatives for potato late blight. Two Pseudomonas fluorescens native strains (039T and 021V) isolated from potato crops were evaluated against P. infestans. Bacterial suspensions (obtained from minimal salts medium added with kerosene) and partially purified biosurfactants (BPP) were applied on detached leaflets for in vitro assays and on potato plants in greenhouse, for in vivo assays and the measure of inhibitory effect of the disease was assessed. The results showed the ability of P. fluorescens biosurfactants and bacterial suspensions to control the pathogen. BPP 039T was able to reduce the level of severity disease by 79.9% in vitro and 38.5% in vivo, whereas BPP 021V decreased 78.7% in vitro and 30.2% in vivo. Bacterial suspensions reduced the severity level in 72.4% (039T) and 66.1% (021V) in vitro assessments and 35% in the in vivo experiment. These results show the potential of P. fluorescens biosurfactants to control the potato late blight in Colombia.</p>

In vitro synthesis of glycosaminoglycans in endocrine ophthalmopathy

1992 ◽  
Vol 127 (5) ◽  
pp. 397-402 ◽  
Author(s):  
G Kahaly ◽  
C Stover ◽  
J Beyer ◽  
E Otto
Keyword(s):  
Hyaluronic Acid ◽  
Acid Concentration ◽  
Cetylpyridinium Chloride ◽  
Acid Synthesis ◽  
Cell Mediated Immunity ◽  
Glycosaminoglycan Synthesis ◽  
In Vitro Synthesis ◽  
Significant Difference ◽  
Endocrine Ophthalmopathy

The effects of humoral and cell-mediated immunity on the glycosaminoglycan synthesis of retrobulbar fibroblasts was evaluated in patients with endocrine ophthalmopathy. After incubation with IgG and sera, secreted glycosaminoglycans, radiolabeled with D-6-3H-glucosamine and 35sulfate, were precipitated with cetylpyridinium chloride and ethanol. Hyaluronic acid synthesis of human retrobulbar fibroblasts after incubation with sera and IgG and after co-culture with lymphocytes was assessed by means of a radiometric test. Patients' IgG, compared to controls', accounted for a higher secretory stimulation of porcine retrobulbar fibroblasts (as measured by cetylpyridinium chloride precipitation) after 24 and 48 h. Contrasting with 24 h incubation time, glycosaminoglycan values after 48 h were increased two to threefold. Patients' and controls' sera caused earlier and stronger, yet indistinguishable glycosaminoglycan production. Non-sulfated hyaluronic acid was the preponderant glycosaminoglycan secreted into the media by retrobulbar fibroblasts. As assessed with the radiometric test, incubation with patients' and controls' sera and IgG did not reveal a significant difference in stimulating the hyaluronic synthesis of patients' and controls' retrobulbar fibroblasts. When measuring the hyaluronic acid synthesis of controls' and patients' retrobulbar fibroblasts after co-cultivation of lymphocytes, however, patients' lymphocytes had a marked ability to increase the hyaluronic acid concentration compared to controls' lymphocytes. The hyaluronic acid concentration after incubation of a patient's retrobulbar fibroblasts with autologous lymphocytes was markedly more elevated than the intrinsic hyaluronic acid production of retrobulbar fibroblasts. In conclusion, though a significant in vitro influence of patients' IgG and sera on the glycosaminoglycan release of both porcine and human (patients' as well as controls') retrobulbar fibroblasts could not be observed in this study, the indications of a marked stimulatory influence of lymphocytes on the hyaluronic acid secretion of retrobulbar fibroblasts demand further investigation.

scholarly journals Comparison of Assays for Measuring Sensitivity of Phytophthora infestans Isolates to Fungicides

Plant Disease ◽  
1999 ◽  
Vol 83 (12) ◽  
pp. 1167-1169 ◽  
Author(s):  
M. Sedegui ◽  
R. B. Carroll ◽  
A. L. Morehart ◽  
R. A. Hamlen ◽  
R. J. Power
Keyword(s):  
Late Blight ◽  
Potato Tuber ◽  
Phytophthora Infestans ◽  
Systemic Fungicides ◽  
Detached Leaf ◽  
Significant Difference ◽  
The World ◽  
Assay Methods ◽  
Laboratory Assay

Pathogenic strains of Phytophthora infestans insensitive to phenylamide have been reported from around the world and are responsible for a lack of late blight control in both potatoes and tomatoes. In vivo laboratory assay methods used to determine the sensitivity of P. infestans to fungicides include floating of leaflet disks on fungicide suspension and the use of potato tuber disks. In our study, these two methods were compared with a new detached-leaf assay. The fungicides chlorothalonil (protective), oxadixyl and metalaxyl (systemic), and cymoxanil (locally systemic) were utilized. Phenylamide-insensitive and -sensitive genotypes of P. infestans were used as inoculum. Significant differences between preventive and systemic fungicides were found, and all assay methods differentiated between phenylamide-sensitive and -insensitive genotypes of P. infestans. Differences among assays were significant when comparing mean inhibitory values. There was no significant difference between the detached leaf and the tuber disk assay, but both methods were significantly different from the floating-leaflet disk assay.

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 Infection of Potatoes by Oospores of Phytophthora infestans in Soil

Plant Disease ◽  
1999 ◽  
Vol 83 (9) ◽  
pp. 876-876 ◽  
Author(s):  
A. Strömberg ◽  
L. Persson ◽  
M. Wikström
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Potato Crop ◽  
Selective Medium ◽  
Day Length ◽  
Talcum Powder ◽  
Soil P ◽  
Nodal Cuttings

Phytophthora infestans (Mont.) de Bary, causing late blight on potatoes and considered to be a typical airborne disease, was found to be infective also by oospores in the soil. P. infestans is heterothallic, and is known to reproduce asexually in Sweden since only one mating type, A1, was present until 1986. Since the 1970s, the other mating type, A2, of P. infestans has migrated to most parts of the world from its original location in central Mexico (2). When A1 and A2 meet, they may form oospores, which are thick-walled, resting structures, giving the pathogen a possibility to recombine as well as survive without its host, for instance in the soil. The soil stages of the pathogen are now therefore under intense investigation. Oospores of P. infestans were produced from two Scandinavian A1 and A2 isolates in Rye A broth mixed with talcum powder and dried for 7 weeks. The inoculum was mixed with sterile, standardized soil in concentrations of 10, 150, 250, and 400 oospores per ml of soil. Cv. Bintje plants cultivated in vitro from nodal cuttings on Murashige and Skoog medium were transplanted to the soil after rooting. Brown discolorations were obtained on the underground stems and tubers on potato plants grown in the two highest concentrations of oospores for 1 month at 15°C and 16-h day length. After 3 days of incubation on P. infestans-selective medium (3), sporangia covered the tissue from plants grown in 250 and 400 oospores per ml of soil and the pathogen was reisolated. This shows that germinating oospores of P. infestans can infect underground stems and tubers of potatoes in soil and further explains the early attack of late blight as observed in a potato crop in Sweden 1996 and 1997 (1). References: (1) B. Andersson et al. Potato Res. 41:305, 1998. (2) D. Andrivon. Phytopathology 85:1053, 1995. (3) G. W. Griffith et al. Mycologist 9:87, 1995.

Comparison of the spine kinematics by defining lumbar as single and multi-segmental in completing critical daily task

2020 ◽  
Vol 14 (4) ◽  
pp. 7600-7608
Author(s):  
W. A. A Saad ◽  
Mohd Azuwan Mat Dzahir ◽  
Yamamoto Shinichirou ◽  
Mohamed Hussein ◽  
Maziah Mohamad ◽  
...  
Keyword(s):  
Independent Living ◽  
Early Stage ◽  
In Vitro Study ◽  
Spinal Curvature ◽  
Invasive Approach ◽  
Motion Patterns ◽  
Non Invasive ◽  
Spine Kinematics ◽  
Significant Difference

The change of the spinal curvature in completing a variety of daily tasks is essential to independent living. There is still a lack of studies highlighting the lumbar segmental contribution during sit-to-stand (STS) and stand-to-flexion (STF) using non-invasive study. The purpose of this study is to compare the spine kinematics by defining lumbar as a single and multi-segmental during continuous daily motion in healthy Asian adults using a non-invasive approach. During STS, most subjects implemented kyphotic lumbar curve during the early stage of motion which revealed poor posture implementation and significant differences in the lumbar kinematics which were only noticeable at specific phases between both approaches. A significant difference in multi-segmental behaviour was observed only at the end of the motion. All three segments displayed different time responses during the transition from kyphotic to lordotic curve. Passive/delayed behavior within the lower lumbar segment was observed between 0-50% of motion completion. During STF, statistically significant differences were found between assuming lumbar as a single and multi-segment in all phases. This in vitro study identified characteristic motion patterns in the lumbar spine during daily motions. The results provided a clear description of the healthy spinal condition of adults and may serve to identify specific multi-segmental contribution.

Accumulation of hypoxanthine in potato leaves and its effect on spore germination in Phytophthora infestans

1968 ◽  
Vol 46 (3) ◽  
pp. 267-270 ◽  
Author(s):  
M. C. Clark ◽  
O. T. Page
Keyword(s):  
Aqueous Solution ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Spore Germination ◽  
Detached Leaves ◽  
Whole Plants

The accumulation of hypoxanthine (6-hydroxypurine) in blighted potato leaves and its effect on spore germination in the late blight organism, Phytophthora infestans, were investigated. Preliminary experiments on the translocation of this compound in whole plants and detached leaves were also conducted.Under in vitro and in vivo conditions, hypoxanthine had a pronounced stimulatory effect on the indirect germination of sporangia. Studies on the movement of this base indicate that it is freely translocated, but fails to be exported from detached leaves into aqueous solution. These observations, coupled with the finding that hypoxanthine readily accumulated in blighted leaves, suggest that this compound could be of importance in predisposing uninfected portions of the host to invasion by the pathogen.

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