Prevalence of cry2-type genes in Bacillus thuringiensis isolates recovered from diverse habitats in India and isolation of a novel cry2Af2 gene toxic to Helicoverpa armigera (cotton boll worm)

Deployment of cry1A-type genes from Bacillus thuringiensis (Bt) in first generation transgenic crops has led to development of resistance in lepidopteran insects. Novel cry2-type genes are required for gene pyramiding to delay evolution of resistance. Two PCR-based techniques were employed for screening of cry2-type genes in 129 Bt isolates from diverse habitats in India and 27 known Bt strains. The cry2Ab-type genes were more prevalent than cry2Aa- and cry2Ac-type genes. Correlation between source of isolates and abundance of cry2-type genes was not observed. Full length cry2A-type genes were amplified from nine Bt isolates and four Bt strains using specially designed primers. The genes from Bt isolates SK-758 from Sorghum grain dust and SK-793 from Chilli seeds warehouse, Andhra Pradesh, were cloned and sequenced. The gene from SK-758 (NCBI GenBank accession GQ866915) was novel while that from SK-793 (NCBI GenBank accession GQ866914) was identical to cry2Ab1 gene. Bacillus thuringiensis Nomenclature Committee (http://www.biols.susx.ac.uk/Home/Neil_Crickmore/BT/) named these genes as cry2Af2 and cry2Ab16 respectively. The cry2Af2 gene was expressed in Escherichia coli and found to be toxic towards Helicoverpa armigera. The cry2Af2 gene will be useful for pyramiding in transgenic crops.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author