Convergence of Bar and Cry1Ac Mutant Genes in Soybean Confers Synergistic Resistance to Herbicide and Lepidopteran Insects

Tien Dung Nguyen; Van Hien La; Van Duy Nguyen; Tri Thuc Bui; Thi Tinh Nguyen; Yeon Ho Je; Young Soo Chung; Xuan Binh Ngo

doi:10.3389/fpls.2021.698882

Convergence of Bar and Cry1Ac Mutant Genes in Soybean Confers Synergistic Resistance to Herbicide and Lepidopteran Insects

Front Plant Sci. 2021 Oct 14:12:698882. doi: 10.3389/fpls.2021.698882. eCollection 2021.

Authors

Tien Dung Nguyen¹, Van Hien La¹, Van Duy Nguyen¹, Tri Thuc Bui¹, Thi Tinh Nguyen¹, Yeon Ho Je², Young Soo Chung³, Xuan Binh Ngo^{1

4}

Affiliations

¹ Department of Biotechnology and Food Technology, Thai Nguyen University of Agriculture and Forestry, Thai Nguyen, Vietnam.
² Department of Agricultural Biotechnology, College of Agriculture and Life Science, Seoul National University, Seoul, South Korea.
³ Department of Genetic Engineering, Dong A University, Busan, South Korea.
⁴ Department of Science and Technology for Economic Technical Branches, Ministry of Science and Technology, Ha Noi, Vietnam.

Abstract

Soybean is a globally important crop species, which is subject to pressure by insects and weeds causing severe substantially reduce yield and quality. Despite the success of transgenic soybean in terms of Bacillus thuringiensis (Bt) and herbicide tolerance, unforeseen mitigated performances have still been inspected due to climate changes that favor the emergence of insect resistance. Therefore, there is a need to develop a biotech soybean with elaborated gene stacking to improve insect and herbicide tolerance in the field. In this study, new gene stacking soybean events, such as bialaphos resistance (bar) and pesticidal crystal protein (cry)1Ac mutant 2 (M#2), are being developed in Vietnamese soybean under field condition. Five transgenic plants were extensively studied in the herbicide effects, gene expression patterns, and insect mortality across generations. The increase in the expression of the bar gene by 100% in the leaves of putative transgenic plants was a determinant of herbicide tolerance. In an insect bioassay, the cry1Ac-M#2 protein tested yielded higher than expected larval mortality (86%), reflecting larval weight gain and weight of leaf consumed were less in the T1 generation. Similarly, in the field tests, the expression of cry1Ac-M#2 in the transgenic soybean lines was relatively stable from T0 to T3 generations that corresponded to a large reduction in the rate of leaves and pods damage caused by Lamprosema indicata and Helicoverpa armigera. The transgenic lines converged two genes, producing a soybean phenotype that was resistant to herbicide and lepidopteran insects. Furthermore, the expression of cry1Ac-M#2 was dominant in the T1 generation leading to the exhibit of better phenotypic traits. These results underscored the great potential of combining bar and cry1Ac mutation genes in transgenic soybean as pursuant of ensuring resistance to herbicide and lepidopteran insects.

Keywords: Cry1Ac mutation 2; Lepidoptera insects; VX93; herbicide resistance; soybean transformation.