Z. Yu, H. Luo, J. Xiong, Q. Zhou, L. Xia, M. Sun, L. Li, Z. Yu
State Key Laboratory of Breeding Base of Microbial Molecular Biology, The Cooperative Innovation Center of Engineering and New Products for Developmental Biology of Hunan Province, College of Life Science, Hunan Normal University, Changsha, China.
The group of nematicidal crystal protein Cry6A shares very low identity and exhibits different structure with Cry5B, another well-studied group of nematicidal crystal protein produced by Bacillus thuringiensis. In this study, we assayed the susceptibility of bre mutants (Caenorhabditis elegans with resistance to Cry5B) to Cry6Aa2 and examined the synergistic activity between Cry6Aa2 and Cry5Ba2. Our results show that all bre mutants are susceptible to Cry6Aa2 on the lethal activity, growth inhibition, fertility and exhibit no cross-resistance to Cry6Aa2. Moreover, all combinations of Cry6Aa2 and Cry5Ba2 with serial ratios exhibit significant synergism to C. elegans, and the highest synergistic effect was observed when Cry6Aa2 and Cry5Ba2 were mixed with a ration of 4 : 1. The susceptibility of bre mutants to Cry6A and synergistic activity between Cry6A and Cry5B may be attributed to the diverse action mode, because of different structure of the two nematicidal crystal protein toxins.