Analysis of breeding efficiency and application of insect-resistant and herbicide-tolerant maize LD05

Maize is one of the most important grain crops in China and suffers severe damage from lepidopteran pests, with annual yield losses reaching 15–20%. Long‑term reliance on chemical pesticides has led to increasing problems of resistance, environmental pollution, and food safety. Transgenic insect‑resistant maize offers a new approach for green pest management. Although insect-resistant and herbicide-tolerant maize LD05 carrying the fusion gene m2cryAb‑vip3A has been granted a biosafety certificate, its breeding efficiency and performance in elite maize hybrids have not been systematically investigated. In this study, the m2cryAb‑vip3A and bar genes from LD05 were successfully introgressed into two elite inbred lines, Qixi5101 and DH382, through backcrossing combined with marker‑assisted selection. Compared with LCV01, which carries two independent insect‑resistant genes, the fusion gene strategy significantly improved breeding efficiency. The genetically modified (GM) inbred lines exhibited high resistance to lepidopteran pests and tolerated four times the recommended medium dose of glufosinate. Developed from these GM inbred lines, the GM hybrids Ludan509 and Denghai605 maintained original yield levels while exhibiting excellent insect resistance and herbicide tolerance, thereby reducing field management costs and increasing economic benefits. This study presents the complete pre‑commercialization chain of GM maize, from LD05 transformation to hybrid combination and field validation, providing an efficient, simple and cost-effective technical pathway for multi-trait improvement. This strategy provides a practical and efficient alternative for multi-trait improvement in crop breeding and offers technical support for the sustainable development of modern agriculture.