01/17/2012
New Type of Lignin Discovered in Vanilla Plant
Naturally biosynthesized from the unusual C monolignol, caffeyl alcohol.
The Science
Found within the plant cell wall, lignin is a complex polymeric compound that provides the plant with both mechanical support and protection from pests and pathogens. However, the structural rigidity of this compound also inhibits efficient conversion of the sugars within plant cell walls into biofuels, making lignin a major obstacle to the efficient production of biofuels from cellulosic feedstocks. Three types of lignin are usually found in nature: H-, G-, and S-lignins. They are synthesized by polymerization of their respective monolignol units. However, lignin biosynthesis can be relatively flexible, sometimes allowing different and more unusual monolignols to be incorporated. Researchers at the DOE BioEnergy Science Center (BESC) and DOE Great Lakes Bioenergy Research Center (GLBRC) report the identification and characterization of a new type of polymer, C-lignin, composed almost exclusively of caffeyl units. Detected in the Vanilla orchid, a few related orchids, and some cactus species, this unique new lignin was found only in the seed coats, with more conventional lignins observed in other plant tissues. This polymer (C-lignin) is deposited to high concentrations in the seed coat during the early stages of seed development in the vanilla orchid (Vanilla planifolia), and in several members of the Cactaceae. These results may lead to a greater understanding of the lignin biosynthetic pathway, as well as new approaches for engineering biomass that can be more easily and efficiently digested for conversion into biofuels.
BER Program Manager
Kari Perez
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]
References
Chen, F., Y. Tobimatsu, D. Havkin-Frenkeld, R. A. Dixon, and J. Ralph. 2012. “A Polymer of Caffeyl Alcohol in Plant Seeds,” Proceedings of the National Academy of Sciences of the United States of America 109(5), 1772-77. DOI: 10.1073/pnas.1120992109.