Overexpression of the scopoletin biosynthetic pathway enhances lignocellulosic biomass processing
Lennart Hoengenaert, Marlies Wouters, Hoon Kim, Barbara De Meester, Kris Morreel, Steven Vandersyppe, Jacob Pollier, Sandrien Desmet, Geert Goeminne, John Ralph, Wout Boerjan, Ruben Vanholme
Abstract
Lignin is the main factor limiting the enzymatic conversion of lignocellulosic biomass into fermentable sugars. To reduce the recalcitrance engendered by the lignin polymer, the coumarin scopoletin was incorporated into the lignin polymer 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 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.