Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2002
Publication Date: 3/20/2003
Citation: DREXLER,H.H., SCHEFFLER,J.A., HEINZ,E., EVALUATION OF PUTATIVE SEED-SPECIFIC PROMOTERS FOR LUNUM USITATISSIMUM, MOLECULAR BREEDING, 2003. Interpretive Summary: Oil from linseed (Linum usitatissimum L.)is high in linolenic acid (18:3) which makes the oil preferred for many different industrial applications, including production of paints and linoleum. Because of this versatility, linseed oil is a good candidate for further development as a renewable resource. However, some of these improvements will only be possible by transfer of foreign genes into linseed. Genetic modifications of linseed will also depend on our ability to limit expression of the foreign gene to the seed. One of the most widely used seed-specific promoters is the napin promoter from canola (Brassica napus). Other possible promoters include KCS from canola, LeB4 and USP both from Vicia faba. Unfortunately, previous studies have found that promoters may not function when transferred to other plant species. In order to test the expression of these four promoters in linseed, each promoter was fused to the reporter gene GUS and transferred via Agrobacterium mediated transformation into linseed. Seeds from the transformed plants were analyzed using an assay that stains seeds blue when the promoter activates the GUS gene. Activity was also measured using a fluorimetric assay. Based on our results, we concluded that the USP and LeB4 promoters could be used successfully in linseed whereas KCS and napin would not be expressed at high enough levels to be useful promoters. In addition, we observed that there was variability in the level of GUS expression among transformed plants. This highlights the need for generating large numbers of plants followed by careful selection to identify those with the desired level of expression and stability.
Technical Abstract: The GUS reporter gene was used to test the expression of four different seed-specific promoters in embryos from linseed flax (Linum usitatissimum). All four promoters (KCS, LeB4, napin and USP) and the positive control, a constitutive promoter,35S showed activity, but only 35S, LeB4 and USP exhibited an expression level high enough to be useful in linseed. Variability in the level of GUS expression was observed among transformed plants containing the same promoter-GUS construct. This highlights the need for generating large numbers of plants followed by careful evaluation and selection to identify those with the desired level of expression and stability.