Expression and Synergistic Effect of Bacillus thuringiensis Cry1Ac in Lepidopteran Toxic Strain to Plutella xylostella

• Published in: International Journal of Industrial Entomology 2007-03, Vol.14 (1), p.33
• Main Authors: Joong Nam Kang, Jong Yul Roh, Sang Chul Shin, Sang Hyun Ko, Yeong Jin Chung, Yang Su Kim, Yong Wang, Hee Kyu Choi, Ming Shun Li, Jae Young Choi, Yeon Ho Je
• Format: Article
• Language: Korean
• Subjects: Bacillus thuringiensis; Bt 2385-1; cry1Ac gene; synergistic effect
• ISSN: 1598-3579

To improve insecticidal activity of B. thuringiensis 2385-1 (Bt 2385-1), a recombinant plasmid, pHT1K-1Ac, was introduced into lepidopteran toxic Bt 2385-1 by electroporation. The presence of the recombinant plasmid in Bt 2385-1 after electroporation was confirmed by PCR. Bt 2385-1 transformant was named as Bt pHT1K-1Ac/2385-1 (lK-1Ac/2385-1). The 1K-1Ac/2385-1 transformant produced bipyramidal-shaped parasporal inclusion as like the wild-type strain, Bt 2385-1, and showed an 130 kDa band of Cry1Ac protein. The insecticidal activity of 1K-1Ac/2385-1 against S. exigua was similar to that of Bt 2385-1 but the LC50 value of transformant against P. xylostella was 1.8 times lower. Through these bioassay results, it was confirmed that toxicity of Bt 2385-1 transformant showed synergistic effect by introducing Cry1Ac. These results suggested that the multiple expressions of Cry proteins in a promising Bt strain may interact synergistically in insect midgut, resulting in increase of toxicity and expansion of host spectrum.