Defense related enzyme induction in coconut by endophytic bacteria (EPC 5)

Endophytic bacteria Bacillus subtilis (EPC 5) was isolated and tested in vitro along with Pseudomonas fluorescens (Pf1) and the fungus Trichoderma viride (Tv1) against Ganoderma lucidum (Leys) Karst, the causal agent of basal stem rot on coconut palm. The endophytic bacterial strains namely EPC 5 and EPC 8 showed higher vigor index (germination percentage, root and shoot length) and more inhibition against G. lucidum over un-inoculated control. These strains were confirmed as Bacillus subtilis by biochemical tests, cloning and sequencing of internal transcribed spacer (ITS) region. The Bacillus subtilis (EPC 5) along with Pseudomonas fluorescens (Pf1) and Trichoderma viride (Tv1) has been tried as bioconsortia against basal stem rot disease under greenhouse conditions. The soil application of bioconsortia enriched with farm yard manure (FYM) enhanced the coconut saplings growth under greenhouse conditions and showed higher induction of defense related enzymes like peroxidase, polyphenol oxidase, phenylalanine ammonia lyase and phenols when challenged with pathogen

Pre-Harvest Application of a New Biocontrol Formulation Induces Resistance to Post-Harvest Anthracnose and Enhances Fruit Yield in Mango

Pre-harvest application of biocontrol formulations consisting of 1. the two plant growth promoting rhizobacterial strains FP7 and Pf1 of Pseudomonas fluorescens; 2. a strain of Bacillus subtilis Bs-1; and 3. a strain (Sc-1) of the yeast Saccharomyces cerevisiae, given at fortnightly or monthly intervals and with or without a chitin amendment, were evaluated in two trials for their ability to reduce anthracnose in mango caused by Colletotrichum gloeosporioides. Growth of C. gloeosporioides in vitro was significantly reduced by strain FP7 and in both field trials the bacterial strain in combination with chitin significantly reduced infection. Pre-harvest application of these formulations at fortnightly intervals also significantly improved flower initiation, yield parameters (mean number of fruits and fruit yield) and fruit quality (total soluble solids, ascorbic acid, free acidity, total, reducing and non- reducing sugar content). The delay in latent symptom expression increased by 15 days under stored conditions. The highest levels of phenolic content, peroxidase and polyphenol oxidase on mango leaves, flowers and fruits were achieved with FP7 +chitin

Induction of systemic resistance in banana (Musa spp.) against Banana bunchy top virus (BBTV) by combining chitin with root-colonizing Pseudomonas fluorescens strain CHA0

Pseudomonas fluorescens strains CHA0 and Pf1 were investigated for their biocontrol efficacy against Banana bunchy top virus (BBTV) in banana (Musa spp.) alone and in combination with chitin under glasshouse and field conditions. Bioformulation of P. fluorescens strain CHA0 with chitin was effective in reducing the banana bunchy top disease (BBTD) incidence in banana under glasshouse and field conditions. In addition to disease control, the bioformulation increased the economic yield significantly compared to the untreated control. Increased accumulation of oxidative enzymes, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), pathogenesis-related (PR) proteins, chitinase, beta-1,3-glucanase and phenolics were observed in CHA0 bioformulation amended with chitin-treated plants challenged with BBTV under glasshouse conditions. Indirect ELISA indicated the reduction in viral antigen concentration in P. fluorescens strain CHA0 with chitin-treated banana plants corresponding to reduced disease ratings. The present study revealed that induction of defence enzymes by P. fluorescens with chitin amendment reduced the BBTD incidence and increased bunch yield in banana

Chemically and biologically mediated systemic resistance in cucumber (Cucumis sativus L.) against Pseudoperonospora cubensis and Erysiphe cichoracearum

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)

Production of secondary metabolites by strains of Pseudomonas spp. antagonistic to Colletotrichum falcatum causing red rot disease in sugarcane

Production of secondary metabolites such as siderophores, indole acetic acid, salicylic acid and antibiotics phenazine, pyocyanine and 2,4-diacetyl phloroglucinol by Pseudomonas spp. associated with induced systemic resistance (ISR) activity in sugarcane against red rot disease was assessed. Many of the strains have been found to produce these metabolites and antibiotics in the culture medium. The antibiotics were separated and identified by thin layer chromatography by running the purified metabolites from the reference strains. The bacterial strains varied in their capability to produce the metabolites. The purified compounds were tested for their antifungal activity against the red rot pathogen Colletotrichum falcatum. Most of the purified metabolites have completely arrested conidial germination and mycelial growth of the fungus. The results suggest that the metabolites production may play a role in antagonism/induced systemic resistance against the pathogen

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Not AvailableStudies were conducted on the possible role of siderophores and iron nutrient status in the medium on the antagonism of different strains of Pseudomonas against Colletotrichum falcatum, which causes red rot disease in sugarcane. In iron deficient medium, most of the bacterial strains produced siderophores and exhibited strong antagonism against C. falcatum. In field studies, Pseudomonas strains CHAO, EP1, KKM1 and VPT4 induced systemic resistance against red rot pathogen in disease susceptible cultivar. These strains were also effective in suppressing red rot disease development in sugarcane from the pathogen propagules surviving in the soil.Not Availabl

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Not AvailableIsolates of Pseudomonas spp. collected from the rhizosphere of sugarcane and cane stalks were screened for their antagonistic activity against Colletotrichum falcatum causing red rot disease in sugarcane. Talc formulations of the selected Pseudomonas spp. isolates improved the sugarcane vegetative sett germination and sugarcane growth under field conditions. Optimal talc formulations were assessed for their effect on induction of systemic resistance against the pathogen in the canes under artificial inoculation. All the four isolates CHAO, EP1, KKM1 and VPT4 were effective in inducing systemic resistance against C. falcatum in two seasons. In other studies, the bacterial formulations were assessed to induce resistance in sugarcane in a sick plot situation. In pathogen-infested soil the isolates KKM1 and CHAO suppressed the red rot disease development in susceptible sugarcane cultivar. Pseudomonas strains also protected sugarcane in a disease-endemic location. Pseudomonas spp treatment substantially improved the cane juice quality parameters affected by the pathogen infection. Standardization of talc formulations and application methods in the field offers potential for large-scale application of biocontrol formulations for the management of red rot disease in sugarcane growing regionsNot Availabl

Variation in resistance to tospoviruses in different tomato genotypes bearing the Sw 5 gene

The tomato spotted wilt disease caused by tospoviruses in tomato is an important viral disease. Artificial screening of tomato wild species and cultivars for resistance to tospoviruses revealed the wild species Lycopersicon peruvianum to be resistant to tospovirus infection. The protein profile in L. peruvianum showed additional proteins of molecular sizes of 45kDa, 34kDa and 26kDa and an additional 55kDa protein was detected in L. pimpinellifolium . The peroxidase isozyme pattern was also found to be distinct in L. peruvianum . cDNAs of R genes coding for tospovirus resistance were isolated from the wild species, L. peruvianum (TNAU T). The partial cDNAs were cloned in the vector pTZ57R/T, sequenced and characterized. The tomato varieties, hybrid and wild species L. pimpinellifolium selected in this study were susceptible to tospovirus infection and did not show presence of R genes. Sequence analysis of the partial cDNAs corresponding to the R genes isolated from the wild species L. peruvianum showed considerable homology on the protein level with already available resistance proteins like late blight resistance protein, root knot nematode resistance protein, potato disease resistance protein, Hero protein confirming resistance against potato cyst nematode, and Prf protein confirming resistance against Pseudomonas syringae pv. tomato . In the present study, R genes effective against tospoviruses were isolated and characterized from a wild species of tomato. These results have important impact in terms of transformation strategies to develop tospovirus resistant transgenic plants

A combination of biocontrol agents improves the management of dry root rot (<em>Macrophomina phaseolina</em>) in greengram

The biocontrol agents Trichoderma viride (strains Tv1 and Tv13), Pseudomonas fluorescens (Pf1 and Py15) and Bacillus subtilis (Bs16) were tested individually and in combination for their effectiveness against root rot of greengram caused by Macrophomina phaseolina. As regards the compatibility of the biocontrol agents with each other, T. viride strains were not compatible with B. subtilis (Bs16), but P. fluorescens strains were compatible with B. subtilis and T. viride. Of the biocontrol agents tested in vitro against M. phaseolina, combinations of P. fluorescens+T. viride (Pf1+Tv1, Pf1+Tv13 and Py15+Tv1) inhibited mycelial growth of the pathogen and they also promoted the growth of the greengram seedlings. A combination of Pf1+Tv1 was most effective in reducing root rot incidence under glass-house and field conditions as compared with other single or combined treatments or the untreated control. The activity of the defense-related enzymes peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase was significantly greater in greengram plants treated with a talc based formulation containing Pf1+Tv1 followed by Pf1+Tv13 and Py15+Tv1, than in plants receiving other treatments or the untreated control. Moreover, a combination of Pf1+Tv1 followed by Pf1+Tv13 and Py15+Tv1 significantly increased yield under glass house and field conditions