In vitro study of baseline sensitivity of important fungi against different fungicides

Baseline sensitivity values of important phytopathogenic fungi were studied against fungicides. ED50, ED90 and MIC value of propiconazole for, Colletotrichum capsici, and Gloeosporium ampelophagum was in the range of 0.020-0.04 ?g/ml. ED50 values of tebuconazole for Alternaria alternata was 30.0 ?g/ml. Azoxystrobin was also tested for its ED50, ED90 and MIC values against Alternaria alternata, C. capsici, G. ampelophagum and Botrytis cinerea where the values were in the range of 0.019-50.0, 0.03-60.0 and 0.2-100.0 ?g/ml respectively. Baseline sensitivity values are important for the management of plant diseases and resistance development

Morphological and cultural characterization of Alternaria alternata (Fr.) Keissler blight of gerbera (Gerbera jamesonii H. Bolus ex J.D. Hook)

Fungal blights are among the major concern for limiting the cultivation and production of many ornamental and flowering plants. Gerbera is an important cut flower with great export potential. However, it is infected by many pathogens in the protected cultivation. The severe infection of fungal blight caused by Alternaria alternata (Fr.) Keissler was observed in the polyhouse condition. Hence, in this study, critical morphological and cultural studies were done to understand the pathogen behaviour. The fungus A. alternata produced profuse mycelium on Potato Dextrose Agar (PDA) with an average width of 4.42 ?m in diameter, conidiophores, conidia and intercalary chlamydospores measured as 42.26 x 4.29 ?m, 47.16 x 13.49 ?m and 7.22 ?m in diameter, respectively. The synthetic media viz., Leonions’s agar, Glucose-peptone agar and Sabourand’s agar and non-synthetic media, Oat meal agar and PDA were excellent for the mycelial growth and conidial production of A. alternata

Fungicidal management of Alternaria alternata (Fr.) Keissler causing blight of gerbera (Gerbera jamesonii H. Bolus ex J.D. Hook)

Alternaria, the fungal pathogen has wide host range generally attacks the aerial parts of plants causing leaf spots and blights. Gerbera is a genus of ornamental flower plants. Gerbera plants are infected by many diseases. Different disease management practices are adopted in gerbera cultivation. The fungicidal management of Alternaria blight is one of the important strategies for the disease management in gerbera in polyhouse condition. In this study, preventive and curative fungicidal sprays were adopted for the management of blight disease in polyhouse. This study revealed that preventive fungicidal sprays were significant over curative fungicidal sprays for the management of Alternaria alternata blight of gerbera (Gerbera jamesonii H. Bolus ex J.D. Hook) in polyhouse. The preventive sprays made of Bordeaux mixture (0.6 %), tricyclazole (0.1%) and iprodione + carbendazim (0.1%) fungicides were found effective with 95.85 %, 96.59 % and 95.88 % disease control respectively, under polyhouse condition

Characterization of a bacterial collar and rhizome rot of banana (Musa paradisiaca) caused by strains of Erwinia chrysanthemi pv. paradisiaca

A serious collar and rhizome rot disease of banana was observed in the north region of Maharashtra state in post rainy season. The disease was caused by the bacterial strains of Erwinia chrysanthemi pv. paradisiaca identified and characterized by morphological, physiological, biochemical and pathogenicity tests. The infection occurred on new banana plantation of one month old in poorly drained soil. In post rainy season, banana plantations of 8 to 10 weeks were found severely infected. E. chrysanthemi pv. paradisiaca produced soft rot symptom onhealthy banana rhizomes within three weeks. Two strains were isolated from the collar and rhizome rotted diseased samples which were similar in morphological, physiological and biochemical characteristics, however they differed in the virulence aggressiveness to cause the disease in banana. Strain II caused soft rot symptoms within 19 days, however strain I produced it within 23 days of inoculation with suspension of 3×108 CFU ml-1. The result of this study revealed that strain II was more aggressive as compared to strain I of E. chrysanthemi pv. paradisiaca

Not Available

Not AvailableSoil and plant samples from black rot infected fields were processed to isolate wild type Xanthomonas campestris pv. campestris (Xcc) bacteriophages by overlay agar method. Various Xcc strains were employed as indicator hosts. The aim of this study was to isolate and purify potential bacteriophages for their ability to lyse plant pathogenic strains of Xcc in vitro. Bacteriophages were purified and selected for further characterization based on their ability to produce clear lysis on plaque assay. Seventeen strains of pathogenic Xcc were tested for sensitivity to 31 phages isolated during the study. Lysis was graded subjectively as per standard. A virulent phage Xcc9SH3 isolated from soil sample from Lucknow was found to lyse all tested strains of Xcc in vitro. Characterization of Xcc9SH3 was done based on plaque morphology, phage titre, organic solvent sensitivity, effect of temperature and transmission electron microscopy. The size of long noncontractile tail of the phage was 100 nm in length and 10 nm in width with 20 nm diameter of head. The isometric head of the phage predicted to belong to Siphoviridae (dsDNA viruses) family of bacteriophages. These phages may be useful tool in specific and efficient detection and control of Xcc causing black rot disease in cole crops.Not Availabl

Not Available

Not Available.Not Availabl

Not Available

Not Available.Not Availabl

Not Available

Not AvailablePolyGalacturonase Inhibiting Proteins (PGIPs) are leucine rich repeat pathogenesis-related (PR) cell wall proteins, which interact and inhibit the PolyGalacturonase (PG), an enzyme secreted by the pathogen to degrade pectin. Interaction of PGIP with PG limits the vulnerability of PG by the activation of host defense response against pathogenic attack. Erwinia is gram-negative soft rot bacteria responsible for rhizome rot disease in banana and many other crop plants. The interaction of PG with PGIP is one of the crucial steps for plant-pathogen interaction. To study the molecular mechanism of PR proteins, we employed molecular modelling, protein-protein docking and molecular dynamics simulations of banana PGIP (bPGIP) with Erwinia carotovora PG (ecPG). Further, insilico site-directed mutagenesis was performed in Phaseolus vulgaris PGIP (pvPGIP2) to elucidate the interaction with ecPG. Docking and simulation studies divulge that binding of bPGIP and PvPGIP2 with active site residues of EcPG induces structural changes and thereby inhibit the enzyme. This study provides a unique insight into PG-PGIP interaction, which may help in the development of bacterial soft-rot resistant banana cultivars.Not Availabl

Biocomputational Assessment of Natural Compounds as a Potent Inhibitor to Quorum Sensors in Ralstonia solanacearum

Ralstonia solanacearum is among the most damaging bacterial phytopathogens with a wide number of hosts and a broad geographic distribution worldwide. The pathway of phenotype conversion (Phc) is operated by quorum-sensing signals and modulated through the (R)-methyl 3-hydroxypalmitate (3-OH PAME) in R. solanacearum. However, the molecular structures of the Phc pathway components are not yet established, and the structural consequences of 3-OH PAME on quorum sensing are not well studied. In this study, 3D structures of quorum-sensing proteins of the Phc pathway (PhcA and PhcR) were computationally modeled, followed by the virtual screening of the natural compounds library against the predicted active site residues of PhcA and PhcR proteins that could be employed in limiting signaling through 3-OH PAME. Two of the best scoring common ligands ZINC000014762512 and ZINC000011865192 for PhcA and PhcR were further analyzed utilizing orbital energies such as HOMO and LUMO, followed by molecular dynamics simulations of the complexes for 100 ns to determine the ligands binding stability. The findings indicate that ZINC000014762512 and ZINC000011865192 may be capable of inhibiting both PhcA and PhcR. We believe that, after further validation, these compounds may have the potential to disrupt bacterial quorum sensing and thus control this devastating phytopathogenic bacterial pathogen