Papers by Raguchander Thiruvengadam
The talc-based formulation of two Pseudomonas fluorescens strains (PF1 and FP7) and its mixture (... more The talc-based formulation of two Pseudomonas fluorescens strains (PF1 and FP7) and its mixture (with and without chitin) were tested against sheath blight and leaffolder in rice. The application of talc-formulation through seed, root, soil and foliar spray significantly reduced the sheath blight and leaffolder incidence both under greenhouse and field conditions. The mixture of two strains performed better than the individual strains. In field trials the maximum of 62.1% sheath blight and 47.7-56.1% reduction in leaffolder incidence was noticed in the mixture treatment containing chitin and its efficacy was equivalent to standard fungicide and insecticide treatments. Pseudomonas treated leaves altered the feeding behaviour of leaffolder larvae and reduced larval and pupal weight, increased larval mortality and incidence of malformed adults under in vitro. An increased population of natural enemies of leaffolder viz., hymenopterous parasitoids and predatory spider was noticed in Pseudomonas treated plots under field conditions, which, yielded 12-21% more rice.
Proteome …, 2009
Plant Growth Promoting Rhizobacteria (PGPR), Pseudomonas fluorescens strain KH-1 was found to exh... more Plant Growth Promoting Rhizobacteria (PGPR), Pseudomonas fluorescens strain KH-1 was found to exhibit plant growth promotional activity in rice under both in-vitro and in-vivo conditions. But the mechanism underlying such promotional activity of P. fluorescens is not yet ...
Physiological and Molecular Plant Pathology, 2013
ABSTRACT The bioformulation of Pseudomonas fluorescens (Pf1 and TDK1) and Beauveria bassiana (B2)... more ABSTRACT The bioformulation of Pseudomonas fluorescens (Pf1 and TDK1) and Beauveria bassiana (B2) strains was evaluated individually and in combinations with and without chitin for their efficacy against leafminer insect and collar rot disease and the effect of the interaction between Pseudomonas, Beauveria and groundnut leafminer insect and collar rot pathogen in the expression of defense enzymes and pathogenesis-related proteins (PR-proteins) in groundnut. Among the various bioformulations, B2 + TDK1 + Pf1 (amended with or without chitin) formulation significantly reduced the incidence of leafminer and collar rot disease when compared to untreated control. A significant increase in the enzymatic activity of phenylalanine ammonia-lyase, peroxidase, polyphenol oxidase, chitinase, β-1,3-glucanase, superoxide dismutase, catalase, lipoxygenase, and phenolics in groundnut plants treated with B2 + TDK1 + Pf1 bioformulation (amended with or without chitin) and challenge inoculated with Aproaerema modicella and Sclerotium rolfsii. Native gel electrophoresis also revealed the expression of more isoforms of pathogenesis-related proteins and other defense enzymes viz., polyphenol oxidase and superoxide dismutase in plants treated with B2 + TDK1 + Pf1 mixture challenged with A. modicella and S. rolfsii. The present study reveals that sustained and timely induction and accumulation of these defense enzymes and PR-proteins enhance the resistance in groundnut against leafminer insect and collar rot disease.
Journal of Phytopathology, 2015
Folia Microbiologica
... A taxonomic study. J.Gen.Microbiol. 43, 159-171 (1966). STICHER L., MAUCH-MANI B., ME'rR... more ... A taxonomic study. J.Gen.Microbiol. 43, 159-171 (1966). STICHER L., MAUCH-MANI B., ME'rRAUX JP: Systemic acquired resistance. Ann.Rev.Phytopathol. 35, 235-270 (1997). VAN HUYSTEE RB: Some molecular aspects of plant peroxidase biosynthetic studies. ...
Folia Microbiologica
Pseudomonas fluorescens (two native strains, one collection strain and their strain mixtures in a... more Pseudomonas fluorescens (two native strains, one collection strain and their strain mixtures in all possible combinations) when applied through seed, seedling dip, soil and on leaf significantly reduced the tomato spotted wilt virus (TSWV) disease. In P.fluorescens-treated plants, the peroxidase and phenylalanine ammonia-lyase activity increased. Accumulation of phenolic compounds and lignin were shown to be increased in the P. fluorescens-treated plants. Isoperoxidase native PAGE indicated that the peroxidase isoforms in tomato plants induced by fluorescent pseudomonads were different from the control plants; this suggests that the general phenylpropanoid pathway is probably stimulated in tomato plants treated which in turn led to significant reduction in TSWV.
African journal of microbiology research
Although many Bacillus species are known to be good antibiotic producers capable of acting as bio... more Although many Bacillus species are known to be good antibiotic producers capable of acting as biocontrol agents, the underlying antimicrobial mechanisms are often poorly understood. In this study, 3 Bacillus strains out of 30, demonstrating over 55% mycelial inhibition against Mycosphaerella musicola as well as significant control in plate assays, were examined for the presence of antibiotic biosynthetic genes. The use of 16S rRNA revealed that the three strains belonged to Bacillus amyloliquefaciens (BB30), Bacillus atrophaeus (BB15) and Bacillus subtilis (BB13). Sequence analysis of purified PCR products revealed homology with corresponding genes from other Bacillus sp. in the GenBank database. Primers specific for iturin D, surfactin, bacillomycin D, bacillomycin A, fengycin and zwittermycin A were used to amplify biosynthetic genes from these Bacillus strains using polymerase chain reaction (PCR). This study reveals the equivalent capability of different Bacillus strains from various microhabitats to produce the above-mentioned antibiotics and highlights the possibility of using some strains as potential biocontrol agents under different microhabitats distant from their original habitat. Furthermore, it will enable researchers to develop rational strategies for the application of the antagonists and their metabolites within an agroecosystem.
Biochemical and Cellular Archives
ABSTRACT
Subhendu Jash, Surajit Khalko, Shaonli Bose, Manisha Roy and Sitansu Pan Department of Plant Path... more Subhendu Jash, Surajit Khalko, Shaonli Bose, Manisha Roy and Sitansu Pan Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia - 741 252, India ABSTRACT Two wild and five mutant isolates of Gliocladium virens were tested for morphological and ...
Azoxystrobin at concentrations of 0.25, 0.5 and 1.0 ml l -1 , mancozeb at 2 g l -1 and Pseudomona... more Azoxystrobin at concentrations of 0.25, 0.5 and 1.0 ml l -1 , mancozeb at 2 g l -1 and Pseudomonas fl uorescens at 10 g l -1 were evaluated in cucumber for their effi cacy in inducing defense enzymes against Pseudoperonospora cubensis and Erysiphe cichoracearum. The activity of the defense enzymes peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), ß-1,3-glucanase, chitinase, catalase and defense-inducing chemicals (total phenols) increased in the azoxystrobin and P. fl uorescens treated cucumber plants. Increased expression of specifi c isoforms of PO and PPO was observed due to induced systemic resistance (ISR).
Basal Stem Rot (BSR) disease caused by Ganoderma lucidum (Leys) Karst. is the most destruc-tive d... more Basal Stem Rot (BSR) disease caused by Ganoderma lucidum (Leys) Karst. is the most destruc-tive disease and a major constraint in coconut production. Fifty five endophytic strains of bacteria were isolated from coconut roots of different regions. Among the isolates, EPC5 (Endophytes coconut), EPC8, EPC15, EPC29, EPC52 and Pf1 (Plant growth promoting rhizobacteria) promoted the rice seed-ling growth in roll towel and pot culture method. EPC5 (Plant growth promoting endophytic bacteria), Pf1 and Trichoderma viride (Plant growth promoting fungus) effectively inhibited the G. lucidum growth in vitro. When bioagents along with farm yard manure (FYM) were heaped for different days interval the population was increased in twenty days both in sterilized and unsterilized conditions.
Basal stem rot disease in coconut is caused by the white-rot fungus Ganoderma lucidum, which is s... more Basal stem rot disease in coconut is caused by the white-rot fungus Ganoderma lucidum, which is soil-borne in nature. Its degree of virulence is governed by the activity of the laccase enzyme. Of twenty-fi ve isolates belonging to the genus Ganoderma obtained from different host species, the isolate from Silent Valley (SV) showed the greatest laccase activity in vitro, followed by the isolate from Veppankulam (CRS-1). These two isolates also reacted positively in the laccase assay in vitro. The laccase-positive SV and CRS-1 isolates were further amplifi ed by polymerase chain reaction (PCR) using degenerate primers for the partial sequence, which showed the fragment size of 200 bp. The highly virulent SV isolate was cloned in a plasmid vector and sequenced. It was confi rmed as a partial-length laccase gene and submitted to the GenBank database. The nucleotide sequence of the DNA of this isolate showed high homology with those of the laccase genes of other basidiomycetes.
European Journal of Plant Pathology
A liquid based Pseudomonas fluorescens (Pf1) bioformulation was found to contribute the restricti... more A liquid based Pseudomonas fluorescens (Pf1) bioformulation was found to contribute the restriction of Fusarium oxysporum f. sp. lycopersici in tomato roots by inducing defence enzymes. Induction of defence enzymes such as phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenoloxidase (PPO), catalase, β-1,3 glucanase and super oxide dismutase (SOD), was studied in tomato plants pretreated with liquid as well as a talc based formulation of Pf1 challenged with F. oxysporum f. sp. lycopersici in glasshouse vegetable production systems. There were increased activities of PAL, PO, PPO, catalase and β-1 3-glucanases in tomato plants treated with a combined application of seedling dip + soil application + foliar spray of liquid and talc formulation of Pf1 when compared to pathogen inoculated and untreated healthy controls. The activities of the above enzymes started to increase at 3rd day, reached maximum levels on 8-9th day and thereafter declined gradually. Similarly, native polya...
Forty bacterial endophytes were isolated from different plant sources and tested for their effica... more Forty bacterial endophytes were isolated from different plant sources and tested for their efficacy against Xanthomonas oryza pv. oryzae inciting bacterial leaf blight disease in rice. Out of these, isolates viz., Bacillus subtilis var. amyloliquefaciens (FZB 24), EPB 9, EPB10, EPCO 29 and EPCO 78 recorded a significantly higher inhibition of X. oryzae pv. oryzae over control in vitro. Among these efficient endophytes EPB 18, EPB 11, EPCO 74, FZB24 and EPB 10 were promote the plant growth of rice seedlings significantly over the other isolates and control. In the present study, rice plants (cv. ADT39) applied with FZB 24 through seed treatment @ 4g/kg + seedling dip @ 4g/l + soil application @ 500g/ha + foliar application @ 500g/ha recorded the lowest severity of bacterial leaf blight (31.36 %) with a per cent reduction of 40 over control under glasshouse conditions. In addition, the B. subtilis (FZB 24) treated rice plants registred higher induction of defence related enzymes viz., peroxidase, polyhenol oxidase and phenylalanine ammonia lyase and resulted in higher accumulation of total phenols compared to untreated control plants. The endophytes treated rice plots registered a significantly lower intensity of bacterial leaf blight (2.80%) compared to untreated control plots (19.82%), which also recorded a higher grain and straw yield.
In Pigeonpea ( Cajanus cajan L. Millsp.), legume podborer (Maruca vitrata) and gram podborer (Hel... more In Pigeonpea ( Cajanus cajan L. Millsp.), legume podborer (Maruca vitrata) and gram podborer (Helicoverpa armigera) are considered to be a major insect pests leading to significant reduction in yield. Biological method of insect pest management is gaining momentum in recent years due to their advantages over chemical methods. Thus, in the present study, the objective was formulated to isolate the entomopathogenic fungus (Beauveria bassiana) and PGPR strains (Pseudomonas fluorescens) and to investigate the effect of talc and liquid based formulation these bioagents against podborer complex under glass house and field conditions individually and in combinations. The results revealed that all the isolates of B. bassiana were found pathogenic to larvae of M. vitrata and H. armigera. Among which, the B10 isolate showed higher per cent mortality (71.0%) followed by B2 (66.0%) against H. armigera. Whereas, the isolate B2 showed the higher per cent mortality (68.0%) against M. vitrata follo...
Anthracnose caused by Colletotrichum gloeosporioides is a major disease in many parts of the worl... more Anthracnose caused by Colletotrichum gloeosporioides is a major disease in many parts of the world where the climate is suitable for mango production to be the most important field and post harvest phase. The aim of the present work was to analyze virulence nature of C. gloeosporioides in the differentiation of isolates obtained from mango fruits and their potential to cause disease in different varieties. Survey was conducted in ten different districts of Tamil Nadu at post harvest phase. From the survey twenty six isolates of C. gloeosporioides were isolated and identified using morphological characters. Among the five artificial inoculation methods tested, pinprick plus spore suspension spray was the best suitable method. By this method out of twenty six isolates used, MCG 16 was identified as virulent isolate based on lesion diameter, per cent disease incidence and virulence index produced on inoculated fruits. MCG 16 was further used to test the varietal susceptibility of twelv...
Acta Phytopathologica et Entomologica Hungarica, 2015
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Papers by Raguchander Thiruvengadam