Cloning, expression and activity of cry1Ia gene from Bacillus thuringiensis isolate

Abstract

A Full-length cry1Ia gene fragment, which obtained by PCR amplification with a pair of primers designed according to cryIa-type gene sequences and DNA from Bacillus thuringiensis Btc008 as template, was introduced into expression vector pET-21b and transformed into Escherichia coli BL21(DE3). Molecular weight of the induced express product was 81 kD. The encoded protein was composed of 719 amino acid residues and the predicted MW was 81.2 kD. The amino acid sequence of the Cry1Ia was very different from those of 12 known Cry1Ia-type proteins. This gene with accession number AF373207 was designated as cry1Ia8 by International Bt Insecticidal Gene Nomenclature Committee. The bioassay results indicated that the Cry1Ia toxin protein showed distinctly insecticidal activity against Ostrinia furnacalis and Plutella xylostella with LC50 of 0.268 μg/g and 2.227 μg/mL, respectively, while it also had insecticidal activity against Leguminivora glycinivorella,but no activity against Pyrrhalta aenescens. The novel cry1Ia8 gene will be new resource for the construction of genetically engineered bacterium and transgenic plant for biocontrol of insect pests. It is also available for screening gene stacks to delay the resistance produce of the pests.