Abstract DBI-9803949 Bonnie C. McCaig This action funds an NSF/Alfred P. Sloan Postdoctoral Research Fellowship in Molecular Evolution for 1998. These fellowships support studies involving the theoretical, comparative, computational, and/or experimental analyses of biological patterns and processes at the molecular level within the framework of organismic evolutionary change and adaptation. These studies also include the use of molecular data to address broader evolutionary questions. Each fellowship supports a research and training plan to be carried out in a sponsoring laboratory. The research and training plan for this fellowship is entitled evolution of structural components of plants. The lignin in conifers arises from the polymerization of one precursor, whereas that in flowering plants arises from two. The question being addressed is did a second laccase gene family coincide with the origin of syringyl lignin in angiosperms? The two classes of lignin-polymerizing laccases have different substrate preferences, and these classes may be expressed differentially during plant development. This project examines the molecular evolution of genes encoding laccases, the enzymes catalyzing lignin polymerization, to determine whether a separate biosynthetic pathway evolved to supply the syringyl component of angiosperm lignin. Gene phylogenies and expression studies are used to determine whether the classes diverged in parallel with changes in lignin and cell composition during plant evolution.
