Location: Crop Improvement & Utilization Research
Project Number: 5325-21000-020-07
Start Date: Oct 01, 2013
End Date: Sep 30, 2014
The suppression of both the Fad2-1 and Fad3 genes has previously been demonstrated to increase oleate concentration in soybeans. A set of pEXCH-1 vectors designed to suppress Fad2-1 and Fad3 via RNA interference (RNAi) and containing expression cassettes for CinH and Bxb1 recombinases will be assembled using standard molecular biology cloning techniques. The various expression cassettes will be tested for functionality through transient assays for either recombinase activity or RNAi expression. Agrobacterium-mediated transformation will be used to perform site-specific gene integration into previously constructed founder lines that contain target sites for Bxb1 recombinase. Molecular analyses will be performed to confirm targeted transgene integration of the Fad2-1 and Fad3 RNAi transgenes and selectable marker gene removal. The unidirectional activity of these recombinase enzymes will produce stable transgene loci. Thus, the GE soybean lines produced are expected to have predictable and stable levels of expression of the high oleate trait. These lines will be propagated and their seed oil composition characterized. This will complete the first round of Recombinase-mediated Cassette Exchange (RMCE). In parallel, a second set of EXCH vectors (pEXCH-2) designed to improve seed meal composition will be constructed. These will be tested for recombinase functionality using transient assays. They will be introduced via Agrobacterium transformation into one or more of the high oleic GE soybean lines. This will comprise the second round of RMCE. Molecular analyses will be performed to confirm targeted transgene integration of the pEXCH-2 transgenes and selectable marker gene removal.