Weng, Jing-Ke , Chapple, Clint .
Independent origins of syringyl lignin in vascular plants.
The lycophyte Selaginella moellendorffii is a member of one of the oldest lineages of vascular plants on Earth. Fossil records show that the lycophyte clade arose 400 million years ago, 150-200 million years earlier than angiosperms, a group of plants that includes the well-studied flowering plant Arabidopsis thaliana. The recent whole-genome sequencing project on S. moellendorffii further makes this species a target of extreme interest for research into comparative plant genomics, biochemistry, and development. Our interest in Selaginella was piqued by the observation that although syringyl lignin is often regarded as being restricted to angiosperms, it is found in lycophytes as well. To gain insight into the evolution of lignin biosynthesis and phenylpropanoid in general, we cloned candidates for the S. moellendorffii homologs of the three phenylpropanoid P450s that play essential roles in determining the lignin composition in angiosperms. To date, we have characterized one of the S. moellendorffii phenylpropanoid P450 candidates. Cross-species complementation experiments, gene expression data, and comparative enzyme assays indicate that this S. moellendorffii P450 is a ferulate 5-hydroxylase (F5H), which functionally can take the place of its angiosperm counterpart in syringyl monolignol biosynthesis. Phylogenetic analysis suggests that the identified Selaginella F5H is very divergent from all known plant P450s in sequence and might have been evolved independently from angiosperm F5Hs. This project will provide important information for better understanding the evolution of phenylpropanoid pathway in vascular plants.
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1 - Purdue University, Department of Biochemistry, 175 South University Street, west lafayette, IN, 47907, U. S. A.
2 - Purdue University, Department of Biochemistry
Presentation Type: ASPB Minisymposium
Location: Continental C/Hilton
Date: Tuesday, July 10th, 2007
Time: 4:10 PM