Identification, Cloning and Expression of an Insecticide <b><i>cry8</i></b> Gene from <b><i>Bacillus</i></b><b><i>thuringiensis </i></b>INTA Fr7-4

Abstract

Insecticidal activity of Bacillus thuringiensis is attributed largely to the crystal proteins. These were found with specific toxic activity against insects in different orders. A novel cry8 gene from B. thuringiensis strain INTA Fr7-4 from Argentina was characterized. The encoded protein, Cry8Qa2, is 1184 amino acids long and its sequence is more similar to those of Cry8F class. We cloned and expressed the protein in an acrystalliferous strain of B. thuringiensis using two differentially regulated promoters. The recombinant strains produced ovoid crystals with low toxicity against larvae of Anticarsia gemmatalis (Lepidoptera: Noctuidae). The morphology and insecticidal properties of these crystals resembled those produced by the native strain INTA Fr7-4.

Sequence and Expression of Two <b><i>cry8</i></b> Genes from <b><i>Bacillus thuringiensis</i></b> INTA Fr7-4, a Native Strain from Argentina

“…The sizes of both gene products are within the range calculated for other Cry8 proteins [e.g. Amadio et al, 2013;Ogiwara et al, 1995;Shu et al, 2009]. Alignment of the amino acid sequences of Cry8Kb3 and Cry8Pa3 shows that their sequences share an overall 63% sequence identity (online suppl.…”

“…However, the crystals were smaller and refracted light differently. These differential properties were also observed in crystals formed upon expression of cry8Qa2 , the other cry8 gene cloned from INTA Fr7-4, in strain 4Q7 [Amadio et al, 2013]. These differences in crystal appearances may be attributed to the lower level of expression of cry8 genes in 4Q7.…”

“…We have previously reported that B. thuringiensis strain INTA Fr7-4 encodes the cry8Qa2 gene [Amadio et al, 2013]. This gene was sequenced from a cloned PCR product of 3,555 bp amplified with cry8 -specific primers C8F01 and C8R01 (table 1).…”

“…Anomala cuprea [Asano et al, 2003], Holotrichia parallela [Shu et al, 2009], Anthonomus grandis [Oliveira et al, 2011], and also to some lepidopteran pests, e.g. Anticarsia gemmatalis [Amadio et al, 2013].…”

“…We have previously reported the sequence and characterization of three plasmids carried by the B. thuringiesis strain INTA Fr7-4 [Amadio et al, 2009]. We have further studied the same B. thuringiesis strain at the phenotypic and genotypic levels and found the cry8Qa2 gene, which codes for a protein with low toxicity against A. gemmatalis (Lepidoptera) [Amadio et al, 2013].…”