Location: Crop Genetics and Breeding ResearchTitle: Cytotoxicity and binding profiles of activated Cry1Ac and Cry2Ab to three insect cell lines
|WEI, JIZHEN - Chinese Academy Of Agricultural Sciences|
|LIANG, GEMEI - Chinese Academy Of Agricultural Sciences|
|WU, KONGMING - Chinese Academy Of Agricultural Sciences|
|GU, SHAOHUA - Chinese Academy Of Agricultural Sciences|
|GUO, YUYUAN - Chinese Academy Of Agricultural Sciences|
|LI, XIANCHUN - University Of Arizona|
Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2017
Publication Date: 8/1/2018
Citation: Wei, J., Liang, G., Wu, K., Gu, S., Guo, Y., Ni, X., Li, X. 2018. Cytotoxicity and binding profiles of activated Cry1Ac and Cry2Ab to three insect cell lines. Insect Science. 25:655-666.
Interpretive Summary: In insect larvae, fat body is one of the most abundant not-gut tissues that may serve as the potential target tissues of bacterial toxins, but nothing is known about its susceptibility to any Bt toxins that have been used in transgenic crops. To estimate the susceptibilities to Bt toxins of insect fat body, we measured cellular toxicity of Bt toxins 1 and 2 (i.e., Cry1Ac and Cry 2Ab) against three insect cell lines that were derived from larval midgut and fat body tissues of corn earworm and pupal ovary tissue of fall armyworm, respectively. The experiment showed that the descending order of toxicity of Bt toxin 1 against the three cell lines was midgut and fat body of the corn earworm, and ovarian tissue of fall armyworm. In contrast, the fat body cell was twice more susceptible to Bt toxin 2 than the midgut cell line, which was not significantly greater than that of fall armyworm cell line. Further bioassays showed that number and abundance of the binding proteins in the three cell lines was closely correlated to the relative potency of the two Bt toxins against the three cell lines. The findings indicate that fat body is an important potential target tissue for Bt toxins in caterpillars.
Technical Abstract: While Cry1Ac has been known to bind with larval midgut proteins cadherin, APN (amino peptidase N), ALP (alkaline phosphatase) and ABCC2 (ATP-binding cassette transporter subfamily C2), little is known about the receptors of Cry2Ab. To provide a clue to the receptors of Cry2Ab, we tested the baseline cytotoxicity of activated Cry1Ac and Cry2Ab against the midgut and fat body cell lines of Helicoverpa zea and the ovary cell line of Spodoptera frugiperda (SF9). As expected, the descending order of cytotoxicity of Cry1Ac against the three cell lines in terms of LC50 was midgut (31.0 µg/ml) > fat body (59.0 µg/ml) and SF9 cell (99.6 µg/ml). By contrast, the fat body cell line (LC50 =7.55 µg/ml) was about 2 times more susceptible to Cry2Ab than the midgut cell line (16.0 µg/ml), whose susceptibility was not significantly greater than that of SF9 cell (27.0 µg/ml). And ligand blot showed the binding differences between Cry1Ac and Cry2Ab in three cell lines. These results indicated that the receptors of Cry2Ab were enriched in fat body cells and thus largely different from the receptors of Cry1Ac, which were enriched in midgut cells.