Expression of Cry1Ac in transgenic Bt soybean lines and their efficiency in controlling lepidopteran pests.
BACKGROUND
Two transgenic lines of the soybean Glycine max, MON87701 expressing the Cry1Ac protein and MON87701RR2Y expressing Cry1Ac +  EPSPS proteins, were evaluated for their resistance to four lepidopteran pests in the laboratory using detached-leaf bioassays throughout the soybean growth seasons (before anthesis, during anthesis and after anthesis) in China. Enzyme-linked immunosorbent assays (ELISAs) were used to monitor the Cry1Ac expression in soybean leaves.


RESULTS
The bioassay results revealed that both transgenic soybean lines exhibited significantly high resistance against Helicoverpa armigera (Hübner) throughout the soybean growing seasons. The survival rates of H. armigera larvae ranged from 5.4 to 24.4% when feeding on the transgenic soybean leaves, significantly lower than the survival rates when feeding on control leaves (71.1-94.9%). Limited resistance was found for both transgenic soybean lines against Spodoptera litura (Fabricius), although the survival rates and weight of S. litura larvae as well as female fecundity were significantly decreased when feeding on Bt soybean leaves compared with feeding on control leaves. In contrast, both transgenic soybean lines provided almost no resistance to Spodoptera exigua (Hübner) and Agrotis ypsilon (Rottemberg). Cry1Ac expression in the leaves of both transgenic soybean lines was relatively stable throughout the soybean growing season, with a peak occurring at V6 -8 and V11 -12 before anthesis. The ELISA results were positively correlated with the results from the insect bioassays.


CONCLUSIONS
The results show that, while Cry1Ac-expressing Bt soybeans may provide good protection against H. armigera, alternative control measures are required to manage S. exigua, S. litura and A. ypsilon.
['Yu|Huilin|H|', 'Li|Yunhe|Y|', 'Li|Xiangju|X|', 'Romeis|Jörg|J|', 'Wu|Kongming|K|']
D000818:Animals D000083722:Bacillus thuringiensis Toxins D001426:Bacterial Proteins D002681:China D004731:Endotoxins D005260:Female D006460:Hemolysin Proteins D007915:Lepidoptera D008297:Male D010572:Pest Control, Biological D010935:Plant Diseases D030821:Plants, Genetically Modified D013025:Soybeans
Bt soybean ELISA Helicoverpa armigera Spodoptera litura Spodoptera exigua Agrotis ypsilon