Evolutionary developmental biology of nonflowering land plants

Current phylogenetic studies indicate that the closest relatives to land plants are among the charophycean green algae, which have a gametophyte-dominant life cycle and lack a multicellular sporophyte generation. Land plants evolved a multicellular sporophyte generation and organs with complex tissue and cell differentiation. A number of genes in nonflowering plants homologous to the developmental genes in flowering plants have been isolated, and their roles during evolution have been hypothesized from expression patterns. Genetic manipulation is necessary to show the gene function implicated by expression patterns. In addition to studies in established model organisms, such as Physcomitrella patens, the development of genetic manipulation techniques in more taxa should be addressed. Genomics has accelerated the identification of genes and enabled the determination of the presence/absence of homologous genes, which would be the basis for the detection of gene losses and acquisitions. The process of phenotypic evolution should ultimately be explained by gene acquisitions and losses and changes in gene functions.