Abstract
In 2017, various orange coloured petunia on the market turned out to be genetically modified (GM) without an official authorization for commercialization. Sequence analysis suggested these undeclared plants most probably originated from a plant transformation experiment performed in the 1980s. For a deeper understanding how GM petunia entered classical breeding programmes worldwide, and whether they originated from a single source or not, we undertook a molecular genetic characterization of the T-DNA integration sites in different GM petunia cultivars and breeding lines. By means of genome walking, we isolated different T-DNA sequences, which are located at the junctions between the T-DNA(s) and the petunia DNA. Based on the results obtained we conclude that there are at least two T-DNA copies of different lengths. This is supported by Southern blot analysis. For T-DNA1, the 3′-junction sequence was isolated, whereas the 5′-junction remained unclear. In contrast, for T-DNA2, the 5′-junction sequence was isolated, whereas the sequence isolated from the 3′-region consists only of T-DNA, but did not include the junction from the T-DNA to the petunia DNA. We developed primers for event-specific PCRs and screened a set of three orange GM petunia cultivars and 126 GM offspring from a commercial breeding program. We show that both T-DNA copies are present in all our tested GM petunia samples, which underpins the assumption of a single transgenic origin of the undeclared GM petunia. Most likely, the two T-DNAs are integrated in close proximity into the petunia genome.
Highlights
Petunias are economically important balcony and bedding plants, which are available in many different growing shapes and flower colours
For a deeper understanding how genetically modified (GM) petunia entered classical breeding programmes worldwide and whether they originated from a single source or not, we aimed for the molecular genetic characterization of the T-DNA integration sites in different GM petunia cultivars and breeding lines
Genome walking technology was used to isolate the T-DNA junction sequences between the known T-DNA sequences MF521566 and KY964325, which are available at the database of the National Center for Biotechnology Information (NCBI), and the petunia genome in the orange GM petunia cv
Summary
Petunias are economically important balcony and bedding plants, which are available in many different growing shapes and flower colours. Like some other species (e.g. cyclamen, African violet, Cymbidium, Angelonia), petunia do not naturally produce orange/bright-red flowers because they lack the ability to synthesize pelargonidin-type anthocyanin pigments (Forkmann and Ruhnau 1987; Gosch et al 2014; Johnson et al 1999). This is because of the substrate specificity of petunia dihydroflavonol 4-reductase (DFR), which does not accept the essential pelargonidin-precursor dihydrokaempferol as a substrate during anthocyanin biosynthesis. The cultivars, which were identified as GM, were removed from the market with some exceptions like e.g. Canada (CFIA 2020)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
