Transgenic soybean expressing Cry1Ab-Vip3A fusion protein confers broad-spectrum resistance to lepidopteran pest.

Abstract

Key message: Transgenic soybean event CAL-16 expressing fusion Bt protein Cry1Ab-Vip3A was developed for conferring broad-spectrum resistance to lepidopteran pests Lepidopteran insect species are important soybean pests causing significant yield loss and quality degradation worldwide. Transgenic soybeans expressing crystal (Cry) insecticidal proteins have been utilized for insect pest management. However, the efficacy of currently adopted insect-resistant soybean is challenged by insect resistance evolution. Vegetative insecticidal proteins (Vips) are highly active against a broad spectrum of lepidopteran insects. They differ from Cry in modes of action, and show great potential for lepidopteran pest management. Here, we report the creation and characterization of a transgenic soybean event CAL-16 which expresses a fusion protein of Cry1Ab and Vip3A. CAL-16 is a single copy T-DNA insertion transgenic event highly resistant to a broad-spectrum of lepidopteran insects. Insect bioassays demonstrated that CAL-16 caused 100% mortality to neonates of Helicoverpa armigera, Spodoptera litura, Agrotis ipsilon, Spodoptera exigua and Spodoptera frugiperda. Field trial also demonstrated its excellent resistance to Leguminivora glycinivorella, a severe pest feeding on soybean seeds. The expression of the fusion protein was found to be constitutively high in CAL-16 throughout developmental stages, and highly stable over 12 generations. Moreover, there was no statistical difference in agronomic traits between CAL-16 and its non-transgenic recipient control plants in field trial. In conclusion, CAL-16 is an elite soybean event with high efficacy toward major lepidopteran pests. It is expected to be released for commercial cultivation in the near future in China as it has been deregulated in China in 2023.