Detection of transgenes in three genetically modified rice lines by fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) using T-DNA probes was applied to localize transgenes onto specific chromosomes and confirm the steady integration of transferred genes in three genetically modified (GM) rice lines, LS28 (event LS30-32-20-1), Cry1Ac1 (event C7-1-9-1) and LS28×Cry1Ac1 (event L/C1-1-3-1), which are a rice leaf blast-resistant single trait GM line, a leaf folder-resistant single trait GM line, and a rice leaf blast-resistant and leaf folder-resistant stacked GM hybrid line, respectively. The FISH signals were clearly detected on the arms of one homologous chromosome pair for LS28, and on the arms of another chromosome pair for Cry1Ac1 when using the transformation vector pSBM AtCK containing the rice leaf blast-resistant gene (LS28) and pMJ-RTB containing the leaf folder-resistant gene (mCry1Ac1) as a probe, respectively. As expected, we detected two pairs of FISH signals, each on the arms of different chromosome pairs in the stacked GM rice line LS28×Cry1Ac1 when using both pSBM AtCK and pMJ-RTB as probes. These results indicate that the transgenes are located at specific homologous loci and show position stability among generations in both single trait and stacked GM rice lines. The usefulness and the necessity of FISH to detect inserted genes in transformed plants will be discussed for the purpose of future studies to develop breeding programs and conduct risk assessment of GM plants.