Range Of Phytopathogenic Fungi Research Articles

ANTAGONISTIC ACTIVITY OF A NEW STRAIN OF TRICHODERMA VIRIDE AND ITS EFFECT ON MICROMYCETES POPULATIONS IN THE ROOT ZONE OF CORN PLANTS

Goal. To investigate the antagonistic activity of a new strain of Trichoderma viride F-100076and its effect on the formation of micromycetes populations in the root zone of corn plants underfield conditions. Methods. The antagonistic activity of T. viride F-100076 was studied by the method of mixed (counter) cultures on wort agar using phytopathogenic fungi, which were isolated andidentified in the Laboratory of Plant-Microbial Interactions. The appearance and type of relationship were registered using a scale modified by Symonian and Mamikonian. The number of micromycetes was determined by the method of soil dilutions. Isolation, accounting and cultivation of fungiwas carried out according to conventional methods. Micromycetes were identified according to thedeterminants appropriate for a specific systematic group of micromycetes. Results. It was foundthat T. viride IMB F-100076 is characterized by high antagonistic activity against a wide range ofphytopathogenic fungi, showing hyperparasitism as early as on the eighth day. The highest antagonistic activity of the strain was found against: Alternaria radicina, Acremonium strictum, Acremonium сucurbitacearum, Fusarium oxysporum var. orthoceras, Fusarium moniliforme var. lactis, Torula expansa (5 points on the corresponding Symonian and Mamikonian scale). Data from the mycological analysis of the sod-podzolic soil of the corn rhizosphere showed that the mycocenosis ofthe sod-podzolic soil of the corn rhizosphere was formed by micromycetes belonging to the generaAcremonium Link, Cladosporium Corda, Fusarium Link:Fr, Gliocladium Corda, Mucor Mich, Penicillium Link:Fr, Rhizopus Ehrenb, Trichoderma Hers, among which the most represented were micromycetes of the genus Penicillium (59 %). The total number of fungi in the control variant was291.00 ± 79.67 thousand CFU/g of soil. The introduction of straw affected both the total number ofmicromycetes and the genus composition of fungi. The total number of fungi in the variant withstraw increased 2.6 times and amounted to 744.00 ± 114.67 thousand CFU/g of soil. The number ofrepresentatives of all studied genera of micromycetes also increased. In addition, the introductionof straw provoked the development of fungi of Bipolaris and Fusarium genera, which can be considered a negative outcome since representatives of these species are commonly recognised as pathogens of root diseases. Application of the fungus antagonist T. viride IMB F-100076 to the soilalong with straw did not significantly affect the total number of micromycetes. At the same time, a displacement of fungi of the genus Bipolaris and Fusarium from the rhizosphere of corn was registered.The number of fusaria decreased from 96.00 ± 5.44 to 23.00 ± 2.32 thousand CFU/g of soil or almost4 times and reached the level of the control variant. Fungi of the genus Bipolaris in the variant withthe introduction of trichoderma were not detected. Conclusion. The antagonist fungus T. virideF-100076, introduced into the soil along with straw, strikes root in the soil and exhibits antagonisticactivity against micromycetes of the genera Bipolaris and Fusarium, which are commonly represented by root rot pathogens of many crops. Thus, the new strain T. viride F-100076 allows increasing theantagonistic potential of the rhizosphere soil of corn and protecting plants from pathogens.

A new method of synthesis of substituted 1-(1H-imidazole-4-yl)-1H-1,2,3-triazoles and their fungicidal activity

Based on the deoxygenation reaction of 1-(1-tert-butyl-3-nitroazetidine-3-yl)-1H-1,2,3-triazoles a new method for the synthesis of substituted 1-(1H-imidazole-4-yl)-1H-1,2,3-triazoles has been developed. Fungicidal activity of these compounds has been investigated at a range of phytopathogenic fungi.

A comparative study of transgenic canola (Brassica napus L.) harboring either chimeric or native Chit42 genes against phytopathogenic fungi

Canola (Brassica napus L.), an agro-economically important crop in the world, is sensitive to many fungal pathogens. One strategy to combat fungal diseases is genetic engineering through transferring genes encoding the pathogenesis-related (PR) proteins such as chitinase which cause the chitin degradation of fungal cell wall. Chitinase Chit42 from Trichoderma atroviride (PTCC5220) plays an important role in biocontrol and has high antifungal activity against a wide range of phytopathogenic fungi. This enzyme lacks a chitin binding domain (ChBD) which is involved in binding activity to insoluble chitin. In the present study, we investigated the effect of chitin binding domain fused to Chit42 when compared with native Chit42. These genes were over-expressed under the CaMV35S promoter in B. napus, R line Hyola 308. Transformation of cotyledonary petioles was achieved by pBISM2 and pBIKE1 constructs containing chimeric and native Chit42 genes respectively, via Agrobacterium method. The insertion of transgenes in T0 generation was verified through polymerase chain reaction (PCR) and Southern blot analysis. Antifungal activity of expressed chitinase in transgenic plants was also investigated by bioassays. The transgenic canola expressing chimeric chitinase showed stronger inhibition against phytopathogenic fungi that indicates the role of chitin binding domain.

Inhibition of agronomically relevant fungal phytopathogens by tyrocidines, cyclic antimicrobial peptides isolated from Bacillus aneurinolyticus.

The tyrocidines, a complex of analogous cyclic decapeptides produced by Bacillus aneurinolyticus, exhibited noteworthy activity against a range of phytopathogenic fungi, including Fusarium verticillioides, Fusarium solani and Botrytis cinerea. The activity of the tyrocidine peptide complex (Trc mixture) and purified tyrocidines exhibited minimum inhibition concentrations below 13 µg ml(-1) (~10 µM) and was significantly more potent than that of the commercial imidazole fungicide, bifonazole. Although the tyrocidines' activity was negatively influenced by the presence of Ca(2+), it remained unaffected by the presence of Mg(2+), Na(+) and K(+). Microscopic analysis revealed significant impact on the morphology of F. solani and Bot. cinerea including retarded germination and hyperbranching of hyphae. Studies with membrane-impermeable dyes, SYTOX green and propidium iodide suggested that the main mode of action of tyrocidines involves the disruption of fungal membrane integrity. Because of the tyrocidines' broad spectrum and potent antifungal activity, possible multiple targets reducing the risk of overt resistance and general salt tolerance, they are promising candidates that warrant further investigation as bio-fungicides.

English

Strain EGB3 was isolated from the gut of earthworm fed with sterile soil and identified as Pseudomonas stutzeri on the basis of biochemical tests and by comparison of 16S rDNA sequences. This bacterium exhibits a broad-spectrum antifungal activity towards soil borne phytopathogenic fungi (Fusarium oxysporum, Fusarium solani, Fusarium moniliformae, Fusarium udum, Macrophomena phaseolina, Rhizoctonia solani, Colletotrichum capsicii, Aspergillus flavus, and Aspergillus niger). The antifungal metabolite produced by EGB3 was extracted and characterized to determine the nature of the active molecules (volatile and non-volatile). The bioactive compound was thermostable upto 80°C for 10 min. The zone of inhibition was observed after 6 h of incubation and increased up to 36 h and there was no change in zone of inhibition after 36 h of incubation. EGB3 was an antagonist against a range of phytopathogenic fungi that infect groundnut plants. Key words: phytopathogenic fungi, EGB3, Pseudomonas stutzeri, antifungal metabolites.

Production, Purification, and Characterization of Antifungal Metabolite from Pseudomonas aeruginosa SD12, a New Strain Obtained from Tannery Waste Polluted Soil

A new strain, SD12, was isolated from tannery waste polluted soil and identified as Pseudomonas aeruginosa on the basis of phenotypic traits and by comparison of 16S rRNA sequences. This bacterium exhibited broad-spectrum antagonistic activity against phytopathogenic fungi. The strain produced phosphatases, cellulases, proteases, pectinases, and HCN and also retained its ability to produce hydroxamate-type siderophore. A bioactive metabolite was isolated from P. aeruginosa SD12 and was characterized as 1-hydroxyphenazine ((1-OH-PHZ) by nuclear magnetic resonance (NMR) spectral analysis. The strain was used as a biocontrol agent against root rot and wilt disease of pyrethrum caused by Rhizoctonia solani. The stain is also reported to increase the growth and biomass of Plantago ovata. The purified compound, 1-hydroxyphenazine, also showed broad-spectrum antagonistic activity towards a range of phytopathogenic fungi, which is the first report of its kind.

The distribution and symptomatology of grapevine trunk disease pathogens are influenced by climate

Grapevine trunk diseases, caused by a range of phytopathogenic fungi, represent a serious impediment to wine and table grape production wherever these crops are cultivated. Previous studies have shown that the distribution of these pathogens is influenced by climate and that they are associated with a variety of internal wood decay symptoms. Little was known, however, about the influence of climate on the disease symptomatology of the different pathogens in a specific area. To address this, a survey was conductedin 30 wine and table grape vineyards in summer, marginal and winter rainfall regions of South Africa. Apart from Eutypa lata , which occurred only in the winter rainfall region, Phaeomoniella chlamydospora , species of Phaeoacremonium , Botryosphaeriaceae and Phomopsis occurred in all regions surveyed. The incidence of the fungal genera and species associated with trunk disease varied between regions, with overlapping symptom profiles that differed based on the climatic region. These findings suggest that symptom-based disease diagnosis alone is unreliable and that distribution and symptomatology of grapevine trunk pathogens are strongly influenced by climatic conditions in a specific production region.

Temporal susceptibility of grapevine pruning wounds to trunk pathogen infection in South African grapevines.

Grapevine trunk diseases, caused by a range of phytopathogenic fungi, represent a serious impediment to wine and table grape production wherever these crops are cultivated. Previous studies have shown that the distribution of these pathogens is influenced by climate and that they are associated with a variety of internal wood decay symptoms. Little was known, however, about the influence of climate on the disease symptomatology of the different pathogens in a specific area. To address this, a survey was conducted in 30 wine and table grape vineyards in summer, marginal and winter rainfall regions of South Africa. Apart from Eutypa lata , which occurred only in the winter rainfall region, Phaeomoniella chlamydospora , species of Phaeoacremonium , Botryosphaeriaceae and Phomopsis occurred in all regions surveyed. The incidence of the fungal genera and species associated with trunk disease varied between regions, with overlapping symptom profiles that differed based on the climatic region. These findings suggest that symptom-based disease diagnosis alone is unreliable and that distribution and symptomatology of grapevine trunk pathogens are strongly influenced by climatic conditions in a specific production region.

Disease suppression and crop improvement in moong beans (Vigna radiata) through Pseudomonas and Burkholderia strains isolated from semi arid region of Rajasthan, India

Pseudomonas fluorescens BAM-4, Burkholderia cepacia BAM-6 and B. cepacia BAM-12 isolated from the rhizosphere of moong bean (Vigna radiata L.) showed significant growth-inhibitory activity against a range of phytopathogenic fungi. Light and scanning electron microscopic (SEM) studies showed morphological abnormalities such as fragmentation, swelling, perforation and lysis of hyphae of pathogens by Pseudomonas and Burkholderia. Two of the strains (BAM-4 and BAM-6) produced siderophore in CAS agar plates, whereas all three strains produced chitinase. Bacterization of seeds of moong bean with pseudomonads has been reported as a potential method for enhancing plant growth and yield, and for providing protection against Macrophomina phaseolina. Seed bacterization with these plant growth-promoting rhizobacteria (PGPR) showed a significant increase in seed germination, shoot length, shoot fresh and dry weight, root length, root fresh and dry weight, leaf area and rhizosphere colonization. Yield parameters such as pods, number of seeds, and grain yield per plant also enhanced significantly in comparison to control. The disease suppression and plant growth enhancement along with the positive rhizosphere colonization by these strains indicate their possible use as PGPR/biocontrol agents against charcoal rot.

Biological control of phytopathogenic fungi of vanilla through lytic action of Trichoderma species and Pseudomonas fluorescens

Trichoderma, soil-borne filamentous fungi, are capable of parasitising several plant pathogenic fungi. Secretion of lytic enzymes, mainly glucanases, proteases and chitinases, is considered the most crucial step of the mycoparasitic process. The lytic enzymes degrade the cell walls of the pathogenic fungi, enabling Trichoderma to utilise both their cell walls and cellular contents for nutrition. Twenty-one strains of Trichoderma spp. were isolated from vanilla rhizosphere and suppressive soils from different regions of Tamil Nadu. The antagonistic effect of Trichoderma was studied towards a range of phytopathogenic fungi; Fusarium oxysporum f.sp. vanillae, P. meadii and Colletotrichum vanillae in vanilla. Coculture of the phytopathogens and Trichodema under laboratory conditions clearly showed dominance of the Trichoderma species. In all cases, Trichoderma overgrew the phytopathogens and subsequently developed a conidial lawn over the surface. The percent inhibition of pathogen growth by isolates T1 and T17 were significantly high by 49.5 and 48.2% respectively. In these studies the lytic action of the pathogen was clearly apparent and the inhibition of growth appears directly related to its ability to hydrolyse the cell walls of the tested microorganisms. Protease, chitinase and β-1,3-glucanase activities were determined in the extracellular fluid of Trichoderma. The data imply that the nature of Trichoderma antagonism is based on mycoparasitism (lysis) and appears to optimalize with contact between the mycelia. Six of them (Tricho1, Tricho6, Tricho10, Tricho12, Tricho15 and Tricho17) were prioritized for further evaluation to utilize different substrates by chitinase production. T. viride isolates T1 and T17 produced more extracellular protease, chitinase and β-1,3 glucanase, which cause disruption of the cell wall and membrane structure of pathogen. The increase in mycelial weight, inhibition behaviour and production of extracellular enzymes by these isolates suggest that the isolates can be used as biological control agents in vanilla plantations. In vanilla field evaluation with microbial consortia involving P. fluorescens strains and Trichoderma isolates, the combinations viz., Pf1 + FP7 + chitin (soil and foliar), Pf1 + Tricho1 + chitin (soil) + Pf1 + chitin (foliar) and Pf1 + Tricho17 + chitin (soil) + Pf1 + chitin (foliar) performed well in reducing the disease incidence.

Axial addition in diastereoisomeric [Cu(Me814ane)](ClO4)2 complexes: antifungal and antibacterial activities

A series of diastereoisomeric square planar copper(II) perchlorate complexes, [Cu(Me8[14]ane)](ClO4)2, undergo axial addition reactions with H2O, NCS− and to yield the octahedral species trans-[CuL1X2](ClO4) n (L1 = isomeric Me8[14]ane; X = H2O, NCS, NO2 or NO3; n = 2 when X = H2O; n = 0 when X = NCS, NO2 or NO3). The products have been characterized on the basis of analytical, spectroscopic, magnetic and conductance data. Some derivatives are unstable in open air and may react with adventious H2O to form diaquo complexes. Antifungal and antibacterial activities of the uncomplexed ligands, the square planar copper(II) complexes and their axial addition products have been investigated against a range of phytopathogenic fungi and bacteria.

Axial ligand substitution in diastereoisomeric trans-[Co(Me814ane)Cl2]+ complexes and their anti-fungal activities

Three isomeric Me814anes, LA, LB and LC, on aeration with cobalt(II) acetate tetrahydrate and subsequent treatment with concentrated HCl and HClO4, give green trans-[CoLCl2]ClO4 diastereoisomers. Whereas the macrocyclic ligands LA and LB yield two N-chiral diastereoisomers, LC gives one isomer. The complexes undergo axial ligand substitution with small ligands such as , SCN−, OH− and H2O to produce corresponding trans products. Anti-fungal activities of the complexes against a range of phytopathogenic fungi have been investigated.

Characterization of antifungal metabolite produced by a new strain Pseudomonas aeruginosa PUPa3 that exhibits broad-spectrum antifungal activity and biofertilizing traits

To study the antifungal activity and plant beneficial traits of a broad-spectrum antagonistic fluorescent pseudomonad strain, PUPa3. Strain PUPa3 was isolated from the rhizosphere soil of rice and identified as Pseudomonas aeruginosa on the basis of biochemical tests and by comparison of 16S rDNA sequences. This bacterium exhibits a broad-spectrum antifungal activity towards phytopathogenic fungi. The antifungal metabolite by PUPa3 was extracted, purified and characterized using nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Production of indole-3-acetic acid (IAA), siderophores, phosphatase and protease in PUPa3 was determined. Strain PUPa3 did not produce hydrogen cyanide, cellulase and pectinase. The antifungal metabolite produced by PUPa3 has been identified as phenazine-1-carboxamide (PCN) on the basis of NMR and MS data. Strain PUPa3 showed a broad-spectrum antifungal activity towards a range of phytopathogenic fungi. This bacterium also showed several plant growth-promoting traits but did not show the traits attributed to deleterious rhizobacteria. Present study reports the production of PCN as well as IAA for the first time by a saprophytic P. aeruginosa strain PUPa3. Because of the production of siderophore, growth hormone, protease and phosphatase and its innate fungicidal potential, this strain can be used as biofertilizer and antagonist against a range of phytopathogenic fungi that infect rice, groundnut, tobacco, chili, mango, sugarcane, tea, cotton and banana.

Identification of conserved traits in fluorescent pseudomonads with antifungal activity.

A collection of 29 fluorescent pseudomonads, some with known biological control activity against a range of phytopathogenic fungi, were characterized phenotypically and genotypically by comparing carbon source utilization patterns, suppression of Pythium ultimum both in planta and in vitro and the potential to produce known secondary metabolites. Fatty acid profiling and restriction fragment length polymorphism (RFLP) analysis of the ribosomal DNA operon (ribotyping) were used to determine the diversity of isolates. A small group of genetically related Pseudomonas spp. with similar properties was identified; each isolate produced a diffusible bioactive product in vitro and was active against Pythium ultimum in planta. However, other isolates that were able to suppress damping off disease but did not inhibit hyphal extension in vitro clustered outside this group. Phenotypic analyses revealed that the accumulation of C17:0 cyclopropane fatty acid (17CFA) and the production of hydrogen cyanide correlated significantly with biological control activity and with the antagonism of fungal development. The potential of 17CFA as a marker for the selection of fluorescent pseudomonads with biocontrol agent (BCA) potential was demonstrated by the isolation of a novel active strain. This was selected after the screening of 13 clonal groups of fluorescent pseudomonads identified from 500 isolates from the phytosphere of sugar beet. Levels of 17CFA synthesis possibly reflect the efficacy of the rpoS allele in particular strains.

Synthesis, Characterisation and Anti-Fungal Activities of Some New Copper(II) Complexes of Octamethyl Tetraaza-Cyclotetradecadiene

The ligand Me8[14]diene, L, in its free state as well as in the dihydroperchlorate form, L.2HClO4, coordinates copper(ll) in different salts to yield a series of [CuLXx] Xy(H2O)z complexes where X = NO3, ClO4, NCS, Cl and Br; x and y may have values of 0 or 2 and z = 0, 1 or 2. The complex, [CuL(ClO4)2].2H2O is found to undergo axial ligand substitution reactions with SCN-, NO3 and Cl- to give a variety of substitution derivatives: [CuL(ClO4)m Xn] where X = NCS, NO3 and Cl; m = 0 or 1, and n = 1 or 2. The complexes .have been characterised on the basis of analytical, spectroscopic, magnetic and conductance data. The anti-fungal activities of the ligand and its complexes have been investigated against a range of phytopathogenic fungi.

Synthesis, Characterisation and Antifungal Activities of Some New Copper(II) Complexes of Isomeric 3,5,7,7,10,12,14,14-Octamethyl-1,4,8,11-Tetraazacyclotetradecanes

Three isomeric Me8[14]anes, LA, LB and LC, undergo complexation with copper(II) salts to form a series of [CuLXn(H2O)x]Xy.(H2O)z complexes where L = LA, LB and LC; X = Cl, Br, NO3; n, x, y and z may have values of 0, 1 or 2. The complexes have been characterised on the basis of analytical, spectroscopic, magnetic and conductance data. Further, the X-ray crystal structure of one complex, [CuLB(OH2)2](NO3)2, has been determined. The antifungal activity of all three isomeric ligands and their complexes has been investigated against a range of phytopathogenic fungi.

Antifungal activity in culture filtrates of the ectomycorrhizal fungus Pisolithus tinctorius

The ectomycorrhizal fungus Pisolithus tinctorius secreted a metabolite that lysed hypha and conidia and inhibited the germination of conidia in a range of phytopathogenic fungi. The optimum incubation period for the production of the metabolite by P. tinctorius in liquid culture was 42–56 days. Dilutions of the culture filtrate with fresh medium caused a gradient of inhibitory effects. For hyphal lysis the minimum ratio of culture filtrate to medium for complete growth inhibition was 5:1 for Rhizoctonia praticola and Truncatella hartigii and 3:1 for Sphaerosporella brunnea. At higher dilutions, the hyphae that formed were short celled and highly branched; many hyphae lysed. Conidial germination was completely inhibited at a ratio of 5:1 for both Fusarium solani and T. hartigii, 3:1 for a North American isolate of Brunchorstia pinea (NA), 1:1 for a European isolate of B. pinea (EU), and 1:3 for two strains of Cochliobolus sativus (0910, 0912). Conidial lysis was seen for T. hartigii at a ratio of 5:1 and at a ratio of 1:1 for B. pinea (EU) and C. sativus (0910). Characterization of the cell-free culture filtrate through the separate additions of D-glucose and an adsorbent, activated charcoal, showed that hyphal lysis and conidia germination inhibition did not result from a depletion of carbohydrates from the growth medium but from the presence of some substance adsorbed by charcoal. Key words: Pisolithus tinctorius, allelopathy, antifungal metabolite, hyphal lysis, mycorrhizosphere.

Biological control of phytopathogenic fungi through lytic action ofTrichodermaspecies

The antagonistic effect of Trichoderma reesei and Trichoderma harzianum was studied towards a range of phytopathogenic fungi; Alternia solani, Botrytis fabae, Cladosporium cucumerinum, Fusarium oxysporum, Fusarium tricintum. Coculture of the phytopathogens and Trichodema under laboratory conditions clearly showed dominance of the Trichoderma species. In all cases, Trichoderma overgrew the phytopathogens and subsequently developed a conidial lawn over the surface. In these studies the lytic action of the pathogen was clearly apparent and the inhibition of growth appears directly related to its ability to hydrolyze the cell walls of the tested microorganisms rather than through the inhibitory action of antibiotics or toxins. Proteinase, mannanase, laminarinase and chitinase activities were determined in the extracellular fluid of Trichoderma. Glucose and laminaribiose were detected after the in vitro hydrolysis of the cell walls of the phytopathogens. The data imply that the nature of T. reesei and T. harzianum antagonism is based on mycoparasitism (lysis) and appears to optimalize with contact between the mycelia.