Transgenic cotton co-expressing chimeric Vip3AcAa and Cry1Ac confers effective protection against Cry1Ac-resistant cotton bollworm
- 416 Downloads
Wide planting of transgenic Bt cotton in China since 1997 to control cotton bollworm (Helicoverpa armigera) has increased yields and decreased insecticide use, but the evolution of resistance to Bt cotton by H. armigera remains a challenge. Toward developing a new generation of insect-resistant transgenic crops, a chimeric protein of Vip3Aa1 and Vip3Ac1, named Vip3AcAa, having a broader insecticidal spectrum, was specifically created previously in our laboratory. In this study, we investigated cross resistance and interactions between Vip3AcAa and Cry1Ac with three H. armigera strains, one that is susceptible and two that are Cry1Ac-resistant, to determine if Vip3AcAa is a good candidate for development the pyramid cotton with Cry1Ac toxin. Our results showed that evolution of insect resistance to Cry1Ac toxin did not influence the sensitivity of Cry1Ac-resistant strains to Vip3AcAa. For the strains examined, observed mortality was equivalent to the expected mortality for all the combinations of Vip3AcAa and Cry1Ac tested, reflecting independent activity between these two toxins. When this chimeric vip3AcAa gene and the cry1Ac gene were introduced into cotton, mortality rates of Cry1Ac resistant H. armigera larvae strains that fed on this new cotton increased significantly compared with larvae fed on non-Bt cotton and cotton producing only Cry1Ac. These results suggest that the Vip3AcAa protein is an excellent option for a “pyramid” strategy for pest resistance management in China.
KeywordsBacillus thuringiensis Vegetative insecticidal protein (Vip3AcAa) Helicoverpa armigera Cross resistance Transgenic cotton
The authors are grateful for the supported by the National Natural Science Funds (Grant No. 31321004) and the Key Project for Breeding Genetic Modified Organisms (Grant Nos. 2014ZX0800912B and 2016ZX0812-004).
Compliance with ethical standards
Conflicts of interest
The authors declare no conflict of interest.
- Abdelkefi-Mesrati L, Boukedi H, Dammak-Karray M, Sellami-Boudawara T, Jaoua S, Tounsi S (2011) Study of the Bacillus thuringiensis Vip3Aa16 histopathological effects and determination of its putative binding proteins in the midgut of Spodoptera littoralis. J Invertebr Pathol 106:250–254CrossRefPubMedGoogle Scholar
- Barkhade UP, Thakare AS (2010) Protease mediated resistance mechanism to Cry1C and Vip3A in Spodoptera litura. Egypt Acad J Biol Sci 3:43–50Google Scholar
- Bernardi O, Amado D, Sousa RS, Segatti F, Fatoretto J, Burd AD, Omoto C (2014) Baseline Susceptibility and Monitoring of Brazilian Populations of Spodoptera frugiperda (Lepidoptera: Noctuidae) and Diatraea saccharalis (Lepidoptera: Crambidae) to Vip3Aa20 Insecticidal Protein. J Econ Entomol 107:781–790CrossRefPubMedGoogle Scholar
- James C (2015) Global status of commercialized biotech/GM Crops: 2015 ISAAA Briefs 51 Ithaca. International Service for the Acquisition of Agri-biotech Applications, NYGoogle Scholar
- Liang G, Tan W, Guo Y (1999) An improvement in the technique of artificial rearing cotton bollworm. Plant Protect 25:15–17Google Scholar
- Russell RM, Robertson JL, Savin NE (1977) POLO: a new computer program for probit analysis. Bull Entomol Soc Am 23:209–213Google Scholar
- Wolfersberger MG, Luethy P, Maurer A, Parenti P, Sacchi VF, Giordana B, Hanozet GM (1987) Preparation and partial characterization of amino acid transporting brush border membrane vesicles from the larval midgut of the cabbage butterfly (Pieris brassicae). Comp Biochem Physiol 86:301–308CrossRefGoogle Scholar