Isolation and characterization of two promoters from linseed for genetic engineering

Linseed (Linum usitatissimum L.) is an important oilseed crop worldwide and is cultivated for the high le, el of linolenic acid (18:3) in its seed oil . Currently, there is a concerted effort to improve linseed by genetic engi neering. This will require appropriate transgenes and tissue-specific or co nstitutive promoters. We report the isolation and characterization of two l inseed promoters from a two-member gene family encoding the enzyme stearogl -acyl carrier protein desaturase (SAD). The SAD1 and SAD2 gene promoter wer e each fused transcriptionally with the reporter gene for P-glucuronidase ( uidA; GUS) and were transferred to linseed to study their expression patter n. In transgenic linseed, GUS activity mediated by the SAD2 promoter appear ed to be constitutive and was detected in leaves, apices, stem, roots, newe r buds, flowers, and seeds. In contrast, GUS activity mediated by the SAD1 promoter appeared to be root- and seed-specific. In developing seeds, both the promoters exhibited a temporal expression pattern concomitant with prot ein and lipid biosyntheses. The GUS activity could be detected as early as 4 days after pollination (dap) and in mature seeds (similar to 50 dap) with the highest activities around mid-development. The first pair of linseed p romoters will be useful for manipulating the expression of indigenous as we ll as transgenes in linseed to create value-added cultivars.