Researchers Study Traits of Field-Grown COMT-Downregulated Switchgrass

The downregulation of the caffeic acid O-methyltransferase (COMT) gene in the lignin biosynthesis pathway of switchgrass reduced the conversion recalcitrance of the biomass. However, lignin biosynthesis is extremely affected by environmental conditions, thus, knowing the consequences of the changes in field-grown plants is essential to evaluate the performance of lignin-altered plants.

Mi Li and a team of researchers from Oak Ridge National Laborator and the National Renewable Energy Laboratory investigated whether the traits and features of modified switchgrass are stable in the field over multiple years.

Field-grown COMT downregulated plants maintained both reduced cell wall recalcitrance and lignin content compared with the non-transgenic controls for at least 3 seasons. The transgenic switchgrass also yielded significantly higher in both total sugar release from a 72-hour enzymatic hydrolysis without pretreatment and in enzymatic sugar release after hydrothermal pretreatment.

The downregulation of COMT in switchgrass resulting in a reduced lignin content and biomass recalcitrance was found to be stable in field-grown trials for at least three seasons. This study suggests that lignin downregulation in lignocellulosic feedstock confers improved saccharification that translates from greenhouse to field trials.