From Plant Press, Vol. 12, No. 1 from January 2009.
By Liz Zimmer, Research Botanist & Curator
The synthesis of genetics and evolutionary biology, initially forged in the 1950s and 1960s with the advent of molecular methods for comparing proteins, has been greatly enhanced by subsequently emerging nucleic acid approaches. Automated DNA amplification and sequencing, in particular, have provided systematic and evolutionary biologists with the tools to compare specific genes across a range of taxa, from both newly collected specimens, as well as archival ones. As a result of this, molecular laboratories have expanded beyond universities’ facilities to many botanical gardens and museums, including the Smithsonian.
Meanwhile, first using plant model systems such as Arabidopsis and rice, scientists have examined functional changes and differential gene expression in multigene families, identified genes contributing to complex phenotypic traits, and sequenced entire nuclear and organellar genomes. Subsequently, for more complex genomes, such as those of maize and tomato, and where much of the genome resides in heterochromatin, enrichment techniques have been developed in order to make the expressed genome regions accessible to cloning and sequencing. New model systems also are emerging, including Populus (cottonwood), a model tree species, and Aquilegia (columbines) and Mimulus (monkey-flower), two genera shown to exhibit adaptations to pollinators and to environmental variables. Beyond the angiosperms, there are now genome projects for key place holder taxa of land plants (mosses-Physcomitrella; lycophytes-Selaginella; ferns-Ceratopteris) as well as exemplars of green, red and brown algae. And now, next-generation sequencing technologies promise a new era of “evolutionary genomics” by substantially increasing sequencing rates and lowering costs, allowing increasingly finer-scale genomic comparisons across all plants.
With this year’s annual Smithsonian Botanical Symposium, our invited speakers will highlight recent advances in comparative molecular genetics, including studies of genome structure and fluidity, of the role of gene families in the evolution of new functions, of the nature of “speciation genes,” and of the ways in which gene and genome studies are influencing phylogenetics. We also will hear about the influence of genomics on evolutionary studies of systems other than those of plants. Emerging techniques in both complete genome sequencing and bioinformatics will also be discussed as they offer the promise of “complete genome bar coding” in the foreseeable future. Many of the projects to be discussed, as well as our symposium, have been underwritten by the National Science Foundation, in large part by its Plant Genome Program. A new initiative of the NSF, the iPlant Collaborative <http://iplantcollaborative.org/home>, has just been established; its goal is to provide a cyberinfrastructure platform for addressing “grand challenges” across all of plant biology. Among the initial workshops already held to delineate specific challenges are one to address the ways in which plants adapt to their environments and one to implement the assembly of a green plant tree of life that enables comparative plant biology.
During this bicentennial celebration of Charles Darwin’s birth, it is worth noting that many of his contributions to biology arose from his study of plants. Besides his depiction of an evolutionary tree, the single illustration in the Origin of Species, Darwin wrote at least six other books about the nature of botanical systems, including works on plant floral dimorphism, effects of different plant fertilization modes, plant domestication, plant movement, and insectivorous plants and orchids. Darwin’s particular interest in orchids will be highlighted by the National Museum of Natural History’s hosting of the 15th annual orchid show, this year entitled “Orchids Through Darwin’s Eyes,” which opened January 24th. We hope to see you there and at the Symposium on March 28th.