Diversity of culturable gut bacteria associated with the field populations of cotton leafhopper (Amrasca biguttula biguttula) in India

Field populations of cotton leafhopper [Amrasca biguttula biguttula (Ishida)] exposed to heavy applications of imidacloprid, acephate, acetamiprid and dimethoate were collected from the seven cotton (Gossypium spp ) growing areas of the country. Thirty culturable bacteria were isolated from the guts of 16 populations of leafhoppers and were characterized through morphological and molecular methods. A good diversity of microflora was recorded across the location and is unique with respect to the locations. None of them are repeated except the genera Bacillus and Enterobacter. There was more number of gut microflora associated with the leafhoppers collected from Dharwad where the insecticide usage pattern and the number of sprays were very high as compared to other locations. Various Bacillus spp. were reported in the Dharwad population. The association of Enterococcus asburiae, Enterobacter silesiacus from the guts of leafhoppers of Guntur which was exposed to nine rounds of sprays of acephate, imidacloprid and dimethoate as compared to Bangalore which was not exposed to insecticides at all. Enterococcus hormaechei was isolated from the insects of Bangalore. The predominant bacterial genera identified in A.biguttula biguttula were Serratia, Bacillus, Enterococcus, Enterobacter, Pantoea, Methylobacterium, Stenotrophomonas, Pseudomonas and Paenibacillus

Identification of Fluorescent Pseudomonas Isolates with Potential Biocontrol activity from the Rhizosphere of Crops

Native fluorescent Pseudomonas isolates from the rhizosphere of various crops grown in the state of Karnataka in southern India were isolated, identified and screened for their ability to act as biological control agents for economically important fungal plant pathogens. Ninety two Pseudomonas isolates were isolated from the rhizosphere soil of different crop plants from the farms of the University of Agricultural Sciences, Raichur (India) and surrounding villages, Dharwad and IIHR, Bangalore using specific medium. All the isolates were found to be gram-negative rods. Among these, 66 isolates produced the characteristic yellow pigmentation and showed fluorescence. The isolates were categorized into four groups based on siderophore production (high, moderate, low and no production) and evaluated for the presence of pvdA, phl and plt genes associated with siderophore production, DAPG and pyoluteorin respectively. None of them appeared to carry the pvdA and plt genes. However, one isolate RPF-13 was found to carry the phl gene based on gene specific PCR results. This DAPG+ve isolate was identified as Pseudomonas putida by 16s r DNA sequence analysis. This paper reports the identification of one of the few highly effective DAPG producing Pseudomonas isolates from southern India that can be used biological control in addition to the identification and characterization of several other fluorescent Pseudomonads with potential to serve as bio-control agents against a number of important pathogenic fungal species

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Not AvailableThe objective of this study was to assess the efficacy of native Pseudomonas spp., against root-knot nematode, Meloidogyne incognita and other soil borne fungal pathogens such as Fusarium oxysporum f. sp. Lycopersici and Sclerotium rolfsii. The eggs and second stage juveniles (J2) of M. incognita were exposed to each isolates of Pseudomonas spp., by diluting the standard culture filtrate to fifty percent and to undiluted culture filtrate (100%). Four isolates of Pseudomonas spp. (CRS3, CRS6, and CRS8 and CRS10) significantly induced inhibition of egg hatching and mortality of M. incognita juveniles. The per cent mortality was proportional to the concentration of culture filtrate and the duration of exposure period. The highest percentage of inhibition of egg hatching was recorded for CRS3 while mortality of second stage juveniles was found in the case of CRS10 in undiluted culture filtrate. The CRS6 caused 48% inhibition of Sclerotium rolfsii while CRS8 caused 58% inhibition of Fusarium oxysporum f. sp. lycopersici. Since meloidogyne infection can predispose plants to plant pathogens, these isolates show promise for management of nematode and disease complex of vegetable crops.Not Availabl

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Not AvailablePseudomonas putida (NBAII-RPF9) was identified as an abiotic stress tolerant bacterium capable of growing at 45 °C as well as in 1 M NaCl. The proteins expressed by this bacterium when subjected to these two stresses were analyzed by 2D gel and MALDI-TOF/MS. Two parameters viz., heat/saline shock (20 min at 45 °C/1 M solid NaCl added at mid log phase and incubated for 1 h) and heat/saline tolerance (24 h growth at 45 °C/in 1 M NaCl) were studied. Under heat shock 13 upregulated proteins and 1 downregulated protein were identified and under tolerance 6 upregulated proteins were identified. GroES and GroEL proteins were expressed under both tolerance and shock. Under saline shock 11 upregulated proteins were identified whereas under saline tolerance 6 upregulated proteins were identified and all these proteins had pI between 3 and 10 with molecular weights ranging from 14.3 to 97 kDa. Aspartate carbamoyltransferase was common under both the saline conditions studied. The analysis revealed involvement of heat stress responsive molecular chaperones and membrane proteins during heat stress. During salt stress, proteins involved in metabolic processes were found to be upregulated to favor growth and adaptation of the bacterium. Heat shock chaperones viz., DnaK and DnaJ were expressed under both saline and heat stress. This is the first report of protein profile obtained from a single bacterium under saline and heat stress and the studies reveal the complex mechanisms adapted by the organism to survive under high temperature or saline conditions.Not Availabl

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Not AvailableStudies were conducted to systematically isolate Metarhizium isolates from the insect cadavers and soils of South India. Morphological and PCR amplified sequences of 5.8S ITS regions and RNA polymerase II largest subunit (RPB1) gene regions were used to identify the isolates at species level. Eight Metarhizium isolates were isolated and initially identified by morphological and microscopic studies. Further identification was confirmed through 5.8SrRNA ITS and RPB1 analysis. They were identified as three isolates of M. robertsii J.F. Bisch., Rehner & Humber sp. nov. (ArMz3R, ArMz3S and ArMz6W), one isolate of M. majus (J.R. Johnst.) J.F. Bisch., Rehner & Humber (VjMz1W) and four isolates of M. anisopliae (WnMz1S, NlMz2S, BgMz2S and DhMz4R). Topical conidial suspensions (TCS) and powder based formulations (PBF) of the eight indigenous isolates of Metarhizium spp. that were isolated from insect cadavers and soils of South India were tested against coleopteran pests Holotricha serrata L. and Oryctes rhinoceros L. that cause serious damage to sugarcane and palm trees respectively. Against H. serrata TCS of M. robertsii (ArMz6W) was the most effective with an LC50 of 6.893×105 cfu/ml and caused 100% mortality against the 3rd instar larvae in 5 days; PBF elicited an LC50 of 7.502×105 cfu/ml with 96% mortality in 10 days. Against O. rhinoceros TCS (LC50 of 9.75×105 cfu/ml) of M. majus (VjMz1W) caused 90% mortality in 7 days and the PBF (LC50 of 9.57×105 cfu/ml) caused 86% mortality in 14 days. The results establish that M. robertsii is highly effective against H. serrata and against O. rhinoceros, M. majus was the most effective. The TCS formulations of these two strains can be readily deployed for field applicationsNot Availabl

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Not AvailableHCry gene and plasmid profiling of indigenous Bacillus thuringiensis isolates from North East India and Andaman were carried out. A total of 29 isolates were screened and HD-1 was used as reference. Plasmid profiling showed distinct bands of different sizes with unique patterns for each strain. Twenty one isolates had plasmids above 33500 bp and only 14 had plasmids of the same size. One isolate NBAII-TRBT17 showed presence of four plasmids having sizes of 2500bp, 7000bp, 7500bp and 33500bp.Six of them had three plasmids of different sizes. The isolates NBAII-BT5, NBAII-TRBT9, NBAII-TRBT18, NBAII-ASBT15, NBAII-ASBT11 andNBAII-AGBT5 showed similar band migration with three plasmids between 7000 to 9000 bp and 33500 megaplasmid each. Strain NBAII-BTN3 showed two different plasmids but plasmid size ranged as 9000 bp and 33, 500 bp which had similar pattern with NBAIIASBT1, but NBAII-ASBT1 also harbored plasmid above 33500 bp. The isolates NBAII-TRBT10, NBAII-TRBT16, NBAII-TRBT8, NBAII-BTAN$,NBAII-BTAN5, NBAII-ASBT20, NBAII-ASBT2, NBAII-ASBTN1, NBAII-BTEG1, NBAII-AGBT13,NBAII-AGBT6, NBAII-AGBT1 and NBAII-ASBT21 showed presence of a single plasmid above 33500bp. The isolates NBAII-ASBT24, NBAII-BT3 and NBAII-AGBT25 showed similar migration of plasmids ranging between 15000-33500 bp. The plasmids were probed for Cry1, Cry2 and Cry3 genes with universal primers and isolates showed differential expression of the genes. Six of the isolates namely NBAII-ASBT20, NBAII-ASBT24, NBAII-TRBT10, NBAII-TRBT17, NBAII-BTAN4 and NBAII-BTAN5 showed presence of Cry3 gene also apart from Cry1 which could indicate that it could be active against coleopterans also. Plasmid DNA profiles and cry protein characterization provided information on diversity among the isolates and the cry gene diversity.Not Availabl

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Not AvailableField populations of cotton leafhopper [Amrasca biguttula biguttula (Ishida)] exposed to heavy applications of imidacloprid, acephate, acetamiprid and dimethoate were collected from the seven cotton (Gossypium spp ) growing areas of the country. Thirty culturable bacteria were isolated from the guts of 16 populations of leafhoppers and were characterized through morphological and molecular methods. A good diversity of microflora was recorded across the location and is unique with respect to the locations. None of them are repeated except the genera Bacillus and Enterobacter. There was more number of gut microflora associated with the leafhoppers collected from Dharwad where the insecticide usage pattern and the number of sprays were very high as compared to other locations. Various Bacillus spp. were reported in the Dharwad population. The association of Enterococcus asburiae, Enterobacter silesiacus from the guts of leafhoppers of Guntur which was exposed to nine rounds of sprays of acephate, imidacloprid and dimethoate as compared to Bangalore which was not exposed to insecticides at all. Enterococcus hormaechei was isolated from the insects of Bangalore. The predominant bacterial genera identified in A.biguttula biguttula were Serratia, Bacillus, Enterococcus, Enterobacter, Pantoea, Methylobacterium, Stenotrophomonas, Pseudomonas and Paenibacillus.Not Availabl

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Not AvailableBiological control of charcoal root rot disease caused by Macrophomina phaseolina in chickpea was studied by using Streptomyces sp. S160. This biocontrol agent (BCA) inhibited the mycelial growth of M. phaseolina by 50 % in vitro and significantly reduced charcoal rot incidence in the greenhouse by 33.3 %. The greenhouse experiment revealed that seed treatment along with soil application supported the highest germination (88.6 %), vigor index (7326.91) and reduced root rot incidence (12.5 %) in comparison to seed treatment and soil application alone. BCA enhanced the growth and helped in inducing resistance against charcoal rot disease of chickpea caused by M. phaseolina by increasing activity of defense-related enzymes in chickpea plants, leading to the synthesis of defense chemicals in plants. BCA (Streptomyces sp. S160) was also characterized and identified by using polyphasic approaches including 16S rDNA sequencing.Not Availabl