Synergistic improvement of high glyphosate resistance and high yield with environmental safety assessment.

Glyphosate, one of the most widely used and effective herbicides worldwide, plays a critical role in weed management. However, its application can indirectly compromise crop yield and fiber quality while controlling weeds. Consequently, breeding crop varieties that simultaneously exhibit high herbicide tolerance, high yield, and excellent quality has become a major goal in current crop breeding. To address this critical gap, we successfully developed a transgenic upland cotton line, designated as L397-1, by co-transforming the elite cultivar ZM24 with two functional genes: the herbicide-resistant g10evo-epsps and the high-yield csRRM2. Phenotypic analysis showed that L397-1 plants exhibited significantly enhanced tolerance to glyphosate, as well as increased yield and fiber length, indicating that this strategy effectively pyramids high-yield, high-quality, and high-herbicide-resistance traits. Furthermore, comprehensive environmental safety assessments were conducted on the transgenic plants, covering their competitive fitness in both wasteland and cultivated habitats, field arthropod community structure, incidence of major diseases, and the population density and species richness of harmful pests. The results revealed no significant differences between the transgenic L397-1 and its recipient ZM24 across all evaluated ecological parameters, supporting the ecological safety and application potential of L397-1 for future breeding utilization. In summary, this study establishes an integrated chain from "trait pyramiding technology development-germplasm innovation-multidimensional evaluation of breeding value", providing new insights for the synergistic improvement of multiple traits and their utilization in crop breeding.