Establishment of an Efficient Transformation Protocol for Soybean Using Glyphosate As Selective Agent and the Development of Glyphosate-Tolerant Transgenic Soybean Lines

Abstract

Herbicide-tolerant soybean can significantly reduce the weed control cost, thus has great potential applications in agriculture. In a previous study, we described an efficient soybean transformation protocol using glufosinate as selective agent. The transformation efficiency was up to 4%. In this study, we attmpted to establish a transformation system using the newly isolated EPSPS genes, G6-EPSPS and G10-EPSPS as the selective marker gene. By optimization of the factors affecting each step of the transformation process, we were able to achieve a stable transformation system with efficiency higher than 1%. While the high glyphosate concentration (100 mg/L) signficantly reduced the numbers of proliferated shootlets in the cotyledonary nodes of soybean explants, the final transformation efficiency was not affected. Molecular analyses using Southern blot, reverse transcription PCR (RT-PCR), and Western blot verfied the insertions of the transgene in the transgenic soybean lines. The transgenic soybean plants were able to tolerant to spray of Roundup® up to 6 kg/hectares, which is 4.9 folds of the recommended field application rate. These results are valuable for soybean trangenic research and development of transgenic soybean for field application.