The Selaginella Genome Identifies Genetic Changes Associated with the Evolution of Vascular Plants

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Science  05 May 2011:
DOI: 10.1126/science.1203810


Vascular plants appeared ~410 million years ago, then diverged into several lineages, of which only two survive: the euphyllophytes(ferns and seed plants) and the lycophytes. Here, we report the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first nonseed vascular plant genome reported. By comparing gene content in evolutionary diverse taxa, we found that the transition from a gametophyte- to sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, while 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 tasiRNA pathway and extensive RNA editing of organellar genes.