Spikemoss Genome Aids Biofuels Researchers

The Science

The genome of a small plant is providing biofuels researchers with information that could influence the development of candidate biofuel feedstock plants and offering botanists long-awaited insights into plant evolution. A team of researchers, including from DOE’s Joint Genome Institute (JGI), used a comparative genomics approach on Selaginella moellendorffii and 14 other plants up and down the phylogenetic tree to identify the core genes likely to be present in a common ancestor to land plants.

“When you burn coal, you’re burning Selaginella’s ancestors,” said Purdue University botanist Jody Banks, who led the 2005 DOE JGI Community Sequencing Program project. The Selaginella research community has grown up around the availability of the genome since 2009 through the DOE JGI’s plant portal Phytozome. The spikemoss genome has revealed the transition from mosses to plants with vascular systems involving fewer genes than going from a non flower-producing vascular plant to one that does.

Selaginella moellendorffii, like all lycophytes, has features typical of vascular plants, including a dominant and complex sporophyte generation having vascular tissues with lignified cell types. Lycophytes also share traits with nonseed plants, most notably the release of haploid spores from the sporophyte and a gametophyte generation that develops independently of the sporophyte.

The spikemoss genome is already proving useful for biofuels researchers. For example, Banks’ colleague Clint Chapple, a coauthor on the paper and a Purdue colleague, has been using the Selaginella genome to study the pathways by which the three different types of lignin are synthesized in plants. He and his team have used enzymes from the lignin-synthesizing pathway in Selaginella to modify the canonical lignin-producing pathway in Arabidopsis to produce the polymer.

Summary

Researchers sequenced the Selaginella genome to provide a resource for identifying genes that may have been important in the early evolution of developmental and metabolic processes specific to vascular plants. By comparing gene content in evolutionarily diverse taxa, researchers found that the transition from a gametophyte- to a sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, whereas secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in posttranscriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the trans-acting small interfering RNA pathway, and extensive RNA editing of organellar genes.

Principal Investigator

Jo Ann Banks
Purdue University

BER Program Manager

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]

References

Banks, J. A., et al. 2011. “The Selaginella Genome Identifies Genetic Changes Associated with the Evolution of Vascular Plants,” Science 332, 960–63. P DOI:10.1126/science.1203810.