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The synergistic activity between Cry1Aa and Cry1c from Bacillus thuringiensis against Spodoptera exigua and
1Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
Aims:
To investigate the interaction between two crystal proteins, Cry1Aa and Cry1C, for future development of biopesticides based on Bacillus thuringiensis, toxicities of the two individual proteins and in combinations have been determined against Spodoptera exigua and Helicoverpa armigera larvae, and synergism between the proteins has been evaluated using synergistic factor.
Methods And Results:
SDS-PAGE showed that Cry1Aa and Cry1C proteins could be expressed in acrystalliferous B. thuringiensis 4Q7 strain, with molecular weights of 135 and 130 kDa respectively. The bioassay results indicated a synergistic activity between Cry1Aa and Cry1C against S. exigua and H. armigera, and the highest toxicities could be observed in the combination of Cry1Aa and Cry1C at a ratio of 1 : 1.
Conclusion:
The two toxins, Cry1Aa and Cry1C, interact synergistically to exhibit higher toxicity against S. exigua and H. armigera.
Significance And Impact Of The Study:
This is the investigation on the synergistic activity between two B. thuringiensis Cry1 toxins. It can be applied to the rational design of new generations of B. thuringiensis biopesticides and to strategies for management of resistant insects.
Insights
Bacillus thuringiensis (Bt) Cry1Aa and Cry1C proteins show synergistic activity against Spodoptera exigua and Helicoverpa armigera. This interaction enhances biopesticide efficacy and aids in managing resistant insect populations.
Area of Science:
- Molecular biology
- Entomology
- Biotechnology
Background:
- Bacillus thuringiensis (Bt) produces crystal proteins toxic to insects.
- Understanding Cry protein interactions is crucial for developing effective biopesticides.
Purpose of the Study:
- To investigate the synergistic interaction between Bt Cry1Aa and Cry1C proteins.
- To evaluate their combined toxicity against Spodoptera exigua and Helicoverpa armigera larvae.
Main Methods:
- Expression of Cry1Aa and Cry1C proteins in an acrystalliferous Bt strain.
- SDS-PAGE to confirm protein expression and molecular weights.
- Bioassays to determine individual and combined toxicities and synergistic factors.
Main Results:
- Cry1Aa (135 kDa) and Cry1C (130 kDa) proteins were successfully expressed.
- Synergistic activity was observed between Cry1Aa and Cry1C against both S. exigua and H. armigera.
- Optimal toxicity was achieved with a 1:1 ratio of Cry1Aa to Cry1C.
Conclusions:
- Cry1Aa and Cry1C proteins exhibit synergistic interaction, leading to enhanced toxicity.
- This synergy can be leveraged for designing next-generation Bt biopesticides.
- Findings support strategies for managing insecticide resistance in key agricultural pests.
