Screening and Characterization of Dipteran Specific cry Genes from Native Bacillus thuringiensis Isolates of Western Ghats, India

Abstract

Many studies have been done to control lepidopteran by the biological insecticide Bacillus thuringiensis crystal protein (Bt protein). But in the current study, we concentrated more on identification and characterization of cry genes specific to dipteran insects from twenty native Bacillus thuringiensis strains isolated from Western Ghats of Kerala, India. Genomic DNA of the twenty native isolates were subjected to PCR using specific primers for cry2, cry4, cry10, cry11, cry16, cry17, cry19 and cry21 genes to find out the cry genes content. Profiling of cry genes showed that cry4 was most predominant by 69 per cent in eleven isolates (Bt-23, Bt-133, Bt-242, Bt-245, Bt-250, Bt-326, Bt-411, Bt-420, Bt-447 and reference strain 4Q1). This was followed by cry11, which was present in 13 per cent and cry10 in 12 per cent. Combinations of cry4 and cry11 genes were present in Bt-23 and Bt-242 while cry21 was present only in isolate Bt-245. None of the isolates carried cry2, cry16, cry17 and cry19 genes. Partial cry4 gene was cloned around 800 bp from Bt-23 and sequenced from Bt-133, Bt-190 and Bt-242 showing homology with cry4 and cry4A genes in the NCBI database.