Optimization of Epsps Gene and Development of Double Herbicide Tolerant Transgenic PGMS Rice

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The alternative use of non-selective herbicides in different years will reduce the possibility of weeds resistance to herbicide by avoiding the crops constant exposure to herbicide selection pressure. The photoperiod-sensitive genic male sterile (PGMS) rice with herbicide resistance will be convenient to the mechanization of hybrid seed production and weed control. In order to develop double herbicide tolerant transgenic PGMS rice, the optimized Epspsgene and the Bar gene were jointly introduced into 7001S, a japonica PGMS rice, by Agrobacterium-mediated transformation. The coding sequence of Epsps gene was optimized based on the codon usage of rice genes and the function of optimized Epspsgene was validated by real-time PCR analysis, enzyme-linked immunosorbent assay of EPSPS protein, and herbicide resistant assay in the obtained independent transformants. The highest relative expression level of EPSPS protein in leaf reached 9.02% of the total soluble proteins. The transformants of T2 generation withstood at least 3.332 g glyphosate /m2 at seedling stage, which was 2.7 times higher than that reported by Monsanto Company. The transformants harboring the optimized Epsps gene and Bar gene were also resistant to glyphosate and glufosinate simultaneously at seedling stage; the resistant dosages were 0.375 g glufosinate m-2 and 0.833 g glyphosate m-2.