Lignans are phenylpropane dimers that are biosynthesized via the phenylpropanoid pathway, in which
pinoresinol lariciresinol reductase (PLR) catalyzes the last steps of
lignan production. Our previous studies demonstrated that the contents of
lignans in various wheat cultivars were significantly associated with anti-
tumor activities in APC(Min) mice. To enhance
lignan biosynthesis, this study was conducted to transform wheat cultivars ('Bobwhite', 'Madison', and 'Fielder', respectively) with the Forsythia intermedia PLR gene under the regulatory control of maize
ubiquitin promoter. Of 24 putative transgenic wheat lines, we successfully obtained 3 transformants with the inserted
ubiquitin-PLR gene as screened by PCR. Southern blot analysis further demonstrated that different copies of the PLR gene up to 5 were carried out in their genomes. Furthermore, a real-time PCR indicated approximately 17% increase of PLR gene expression over the control in 2 of the 3 positive transformants at T(0) generation. The levels of
secoisolariciresinol diglucoside, a prominent
lignan in wheat as determined by HPLC-MS, were found to be 2.2-times higher in one of the three positive transgenic sub-lines at T(2 )than that in the wild-type (117.9 +/- 4.5 vs. 52.9 +/- 19.8 mug/g, p <0.005). To the best of our knowledge, this is the first study that elevated
lignan levels in a transgenic wheat line has been successfully achieved through genetic engineering of over-expressed PLR gene. Although future studies are needed for a stably expression and more efficient transformants, the new wheat line with significantly higher SDG contents obtained from this study may have potential application in providing additive health benefits for
cancer prevention.