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Singh A.K.,Banaras Hindu University | Singh M.,Indian Institute of Vegetable Research | Dubey S.K.,Banaras Hindu University
BMC Microbiology | Year: 2013

Background: The global area under brinjal cultivation is expected to be 1.85 million hectare with total fruit production about 32 million metric tons (MTs). Brinjal cultivars are susceptible to a variety of stresses that significantly limit productivity. The most important biotic stress is caused by the Brinjal fruit and shoot Borer (FSB) forcing farmers to deploy high doses of insecticides; a matter of serious health concern. Therefore, to control the adverse effect of insecticides on the environment including the soil, transgenic technology has emerged as the effective alternative. However, the reports, regarding the nature of interaction of transgenic crops with the native microbial community are inconsistent. The effect of a Bt transgenic brinjal expressing the bio-insecticidal protein (Cry1Ac) on the rhizospheric community of actinomycetes has been assessed and compared with its non-transgenic counterpart. Results: Significant variation in the organic carbon observed between the crops (non-Bt and Bt brinjal) may be due to changes in root exudates quality and composition mediated by genetic attributes of Bt transgenic brinjal. Real time quantitative PCR indicated significant differences in the actinomycetes- specific 16S rRNA gene copy numbers between the non-Bt (5.62-27.86) × 1011 g-1 dws and Bt brinjal planted soil (5.62-24.04) × 1011 g-1 dws. Phylogenetic analysis indicated 14 and 11, actinomycetes related groups in soil with non-Bt and Bt brinjal crop, respectively. Micrococaceaea and Nocardiodaceae were the dominant groups in pre-vegetation, branching, flowering, maturation and post-harvest stage. However, Promicromonosporaceae, Streptosporangiaceae, Mycobacteriaceae, Geodermatophilaceae, Frankiaceae, Kineosporaceae, Actisymmetaceae and Streptomycetaceae were exclusively detected in a few stages in non-Bt brinjal rhizosphere soil while Nakamurellaceae, Corynebactericeae, Thermomonosporaceae and Pseudonocardiaceae in Bt brinjal counterpart. Conclusion: Field trails envisage that cultivation of Bt transgenic brinjal had negative effect on organic carbon which might be attributed to genetic modifications in the plant. Changes in the organic carbon also affect the actinomycetes population size and diversity associated with rhizospheric soils of both the crops. Further long-term study is required by taking account the natural cultivar apart from the Bt brinjal and its near-isogenic non-Bt brinjal with particular reference to the effects induced by the Bt transgenic brinjal across different plant growth stages. © 2013 Singh et al.; licensee BioMed Central Ltd.

Soni D.K.,Banaras Hindu University | Singh M.,Indian Institute of Vegetable Research | Singh D.V.,Institute of Life science | Dubey S.K.,Banaras Hindu University
BMC Microbiology | Year: 2014

Background: Listeria monocytogenes, a foodborne pathogen is ubiquitous to different environments including the agroecosystem. The organism poses serious public health problem. Therefore, an attempt has been made to gain further insight to their antibiotic susceptibility, serotypes and the virulence genes. Results: Out of the 10 vegetables selected, 6 (brinjal, cauliflower, dolichos-bean, tomato, chappan-kaddu and chilli), 20 isolates (10%) tested positive for L. monocytogenes. The prevalence of the pathogen in the respective rhizosphere soil samples was 5%. Noticeably, L. monocytogenes was absent from only cabbage, broccoli, palak and cowpea, and also the respective rhizospheric soils. The 30 isolates + ve for pathogenicity, belonged to serogroup 4b, 4d or 4e, and all were positive for inlA, inlC, inlJ, plcA, prfA, actA, hlyA and iap gene except one (VC3) among the vegetable isolates that lacked the plcA gene. ERIC- and REP-PCR collectively revealed that isolates from vegetables and their respective rhizospheric soils had distinct PCR fingerprints. Conclusions: The study demonstrates the prevalence of pathogenic L. monocytogenes in the selected agricultural farm samples. The increase in the number of strains resistant to ciprofloxacin and/or cefoxitin seems to pose serious public health consequences. © 2014 Soni et al.; licensee BioMed Central Ltd.

A 2-year field study was conducted to develop an eco-friendly field application method for controlling root-knot disease of eggplant (Solanum melongena). The test sites were heavily infested with the root-knot nematode, Meloidogyne incognita. The efficacy of neem cake (1.5 t ha-1), talc-based preparations of Pseudomonas fluorescens (10 kg ha-1) and Trichoderma harzianum (10 kg ha-1) as soil application and seed treatment (10 g (kg seed)-1) were tested to develop an integrated nematode management module against M. incognita infecting eggplant. Neem cake, P. fluorescens and T. harzianum alone and in combinations significantly reduced the incidence of root-knot disease of eggplant. Fresh and dry weight of shoots were higher in the plant where neem cake, P. fluorescens and T. harzianum had been applied, than in both M. incognita-infected plants and other treatments. The best protection of disease, in terms of reduction in number of galls (81%) and reproductive factor (Pfâ̂•Pi < 0.5) of the nematode, was achieved through this treatment. It also enhanced yield of eggplant by up to 70%. It is suggested that integrated approach using organic amendment with bio-control agents to manage root-knot disease of eggplant under natural infestation is not only environmentally friendly but also more beneficial to growers. This approach also has potential for overcoming some of the efficacy problems that occur with application of individual biological control agent. © 2013 Koninklijke Brill NV, Leiden.

Venkataravanappa V.,Indian Institute of Horticultural Research | Venkataravanappa V.,Indian Institute of Vegetable Research | Jalali S.,Indian Institute of Horticultural Research | Krishna Reddy M.,Indian Institute of Horticultural Research
Virus Genes | Year: 2012

Yellow vein mosaic disease of okra is a whitefly transmitted begomovirus causing heavy economic loss in different parts of India. The okra isolate (OY131) of this virus from a bhendi plant [(Abelmoschus esculentus L.) Moench] showing yellow vein mosaic, vein twisting, reduced leaves, and a bushy appearance in the Palem region, New Delhi, India, was characterized in the present study. The complete DNA-A and DNA-B sequences have been determined and are comprised of 2,746 and 2,703 nucleotides, respectively. The betasatellite (DNA-β) component was absent in the sample. The genome organization was typically of biparite begomoviruses, which were characterized earlier. Comparison of DNA-A component with other known begomoviruses suggest that this virus, being only distantly related (<85.9% similarity with its nearest relative, BYVMV) to other known begomoviruses, is a new species. We have tentatively assigned the genome to a novel geminivirus species Bhendi yellow vein mosaic Delhi virus [BYVDV-IN (India: Delhi: okra)]. DNA-B showed highest sequence identity (87.8% identical) to that of a ToLCNDV (AY158080). The phylogenetic analysis of the present isolate is distinct from all other viruses; however clusters with ToLCNDV group infect different crops. The recombination analysis revealed that this isolate has sequences originated from ToLCNDV. This is the first known bhendi yellow vein mosaic disease associated bipartite begomovirus from India. © Springer Science+Business Media, LLC 2012.

Singh A.K.,Banaras Hindu University | Singh M.,Indian Institute of Vegetable Research | Dubey S.K.,Banaras Hindu University
Journal of Applied Microbiology | Year: 2014

Aims: The objective of this study was to investigate the influence of Cry1Ac gene expressing brinjal (VRBT-8) on the rhizospheric fungal community structure. Methods and Results: qPCR indicated variations in the fungal ITS rRNA copy numbers of non-Bt (1·43-4·43) × 109 g-1 dws and Bt (1·43-3·32) × 109 g-1 dws plots. Phylogenetic analysis of ITS rRNA clones indicated fungal-related group majority of being Ascomycota compared to that of Basidiomycota and Zygomycota in non-Bt- and Bt-planted soils. Sordariomycetes was the dominant class detected in all the stages. Conclusions: Despite the variations in the population size and the distribution pattern observed across the non-Bt and Bt brinjal, plant-growth-dependent variability was more prominent compared with genetic modification. Therefore, this study concludes that genetic modification of brinjal crop has minor effect on the fungal community. Significance and Impact of the Study: Brinjal, the important solanaceous crop, is also prone to attack by many insect pests, especially by Leucinoides orbonalis, resulting in significant losses in the crop yield. However, the reports on the effect of transgenic crops and the associated microbial community are inconsistent. The present communication takes into account for the first time the possible interactions between Bt brinjal and the associated fungal community; the latter playing a significant role in maintaining soil fertility. As this study is limited to the structural diversity of fungal community, additional information regarding the functional diversity of the group seems imperative before recommending the commercialization of GM crops. © 2014 The Society for Applied Microbiology.

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