Molecular characterization of lepidopteran pest-resistant transgenic rice events expressing synthetic Cry1Ac

The insecticidal toxin gene of Bacillus thuringiensis (Bt) is one of the most commonly used in the development of genetically modified (GM) crops. In this research, we analyzed Bt rice showing lepidopteran pest-resistance. The Bt gene is a synthetic Cry1Ac composed of optimal codons for plants, and the Bt protein is targeted to the chloroplast by a transit peptide. Three Cry1Ac rice events (C103-3, C127-1, and C7-1) were analyzed for molecular characterization. C103-3 contains two copies of T-DNA where the left border (LB) region is truncated. Both C7-1 and C127-1 have a single copy of T-DNA, but a part of the vector backbone DNA is inserted into the genome of C127-1; thus, only C7-1 had intact T-DNA. Progenies of C7-1 crossed with the original cultivar, Nakdong, and double-haploid lines from anther culture of lines crossed with the elite cultivar, Dongjin, were analyzed for T-DNA flanking genomic DNA and genotyping. Results showed that an intact T-DNA region without the vector backbone was inserted into the genome and was stably inherited through generations. The C7-1 homozygous event could be used as breeding material to develop GM rice with pest resistance.