Antisense Expression of a Caffeic Acid O-methyltransferase of Stylosanthes humilis in Transgenic Poplar : Effect of Expression on O-methyltransferase Activity and Lignin Composition

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Poplar (Populus tremula) was transformed with a construct carrying an antisense caffeic acid O-methyltransferase (COMT) CDNA (pOMT8) from a tropical pasture legume, Stylosanthes humilis. pOMT8 shows 83% overall homology to the corresponding COMT gene (pPCL4) of poplar. Of the 200 putatively-transformed plants regenerated on selective media after co-cultivation of poplar stem explants with Agrobacterium tumefacfens harbouring a CaMV 35S-antisense pOMT8 construct, a subset of 20 plants were randomly chosen for further analysis. PCR and Southern blot analysis demonstrated the stable integration of T-DNA into the genome of these plants. Antisense expression of pOMT8 resulted in reductions in total COMT activity in the majority of the transgenic plants with the lowest total COMT activities (61-70% of untransformed control plants) being observed in four transgenic plants. The composition of lignin in transgenic plants was also changed, as detected by reductions in the content of syringyl units using infrared spectroscopy. However, no changes were found in the amount of insoluble lignin in transgenic plants as compared to untransformed control plants. These results indicate the potential of the pOMT8 gene to partially suppress COMT activity and modify the composition of lignin in transgenic poplar.
一般社団法人日本森林学会の論文
1999-05-16