A LACCASE ASSOCIATED WITH LIGNIFICATION IN LOBLOLLY-PINE XYLEM

Peroxidase has been thought to be the only enzyme that oxidizes monoli gnol precursors to initiate lignin formation in plants. A laccase was purified from cell walls of differentiating xylem of loblolly pine and shown to coincide in time and place with lignin formation and to oxid ize monolignols to dehydrogenation products in vitro. These results su ggest that laccase participates in lignin biosynthesis and therefore c ould be an important target for genetic engineering to modify wood pro perties or to improve the digestibility of forage crops.