title: Molecular and insecticidal characterization of Vip3A protein producing Bacillus thuringiensis strains toxic against Helicoverpa armigera (Lepidoptera: Noctuidae).
abstract: Vegetative insecticidal proteins (Vip) represent the second generation of insecticidal proteins produced by Bacillus thuringiensis (Bt) during the vegetative growth stage of growth. Bt-based biopesticides are recognized as viable alternatives to chemical insecticides; the latter cause environmental pollution and lead to the emergence of pest resistance. To perform a systematic study of vip genes encoding toxic proteins, a total of 30 soil samples were collected from diverse locations of Kashmir valley, India, and characterized by molecular and analytical methods. Eighty-six colonies showing Bacillus-like morphology were selected. Scanning electron microscopy observations confirmed the presence of different crystal shapes, and PCR analysis of insecticidal genes revealed a predominance of the lepidopteran-specific vip3 (43.18%) gene followed by coleopteran-specific vip1 (22.72%) and vip2 (15.90%) genes in the isolates tested. Multi-alignment of the deduced amino acid sequences revealed that vip3 sequences were highly conserved, whereas vip1 and vip2 showed adequate differences in amino acid sequences compared with already reported sequences. Screening for toxicity against Helicoverpa armigera larvae was performed using partially purified soluble fractions containing Vip3A protein. The mortality levels observed ranged between 70% and 96.6% in the isolates. The LC50 values of 2 of the native isolates, JK37 and JK88, against H. armigera were found to be on par with that of Bt subsp. kurstaki HD1, suggesting that these isolates could be developed as effective biopesticides against H. armigera.
authors.affiliation: a Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, Uttar Pradesh 202002, India.|b Biotechnology and Climate Change Group, National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi 110012, India.
authors.forename: Showkat Ahmad
authors.initials: SA
authors.lastname: Lone
authors.affiliation: b Biotechnology and Climate Change Group, National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi 110012, India.
authors.forename: Radha
authors.initials: R
authors.lastname: Yadav
authors.affiliation: a Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, Uttar Pradesh 202002, India.
authors.forename: Abdul
authors.initials: A
authors.lastname: Malik
authors.affiliation: b Biotechnology and Climate Change Group, National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi 110012, India.
authors.forename: Jasdeep Chatrath
authors.initials: JC
authors.lastname: Padaria
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000494:pharmacology*; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D008969:Molecular Sequence Data; D009036:Moths / Q000502:physiology*; D012988:Soil Microbiology
chemical_list: D001426:Bacterial Proteins; D007306:Insecticides; C447139:Vip3A protein, Bacillus thuringiensis
keywords: Bacillus thuringiensis; Helicoverpa armigera; Vip proteins; microscopie électronique à balayage (MEB); protéines Vip; scanning electron microscopy (SEM); toxicity assay; épreuve de toxicité