Lignocellulosic biomass is a promising renewable resource for the production of primary sugars to be fermented to biobased products. Lignin is the main factor limiting the enzymatic deconstruction of the biomass. To reduce the recalcitrance engendered by the lignin polymer, lignin structure can be engineered such that is is easier to degrade and remove from the lignocellulosic matrix. Through the simultaneous expression of FERULOYL-CoA 6'-HYDROXYLASE 1 (F6'H1) and COUMARIN SYNTHASE (COSY) in lignifying cells in Arabidopsis, the transgenic lines overproduced the coumarin scopoletin and incorporated it into the lignin polymer, without adversely affecting plant growth. About 3.3% of the lignin units in the transgenic lines were derived from scopoletin, thereby exceeding the levels of the traditional p-hydroxyphenyl units. Saccharification efficiency of alkali-pretreated scopoletin-overproducing lines was 40% higher than for wild type.