orm Wickett, Ph.D., a conservation scientist working in genomics and bioinformatics at the Chicago Botanic Garden, writes for National Geographic that we have known for quite some time that all land plants share a common ancestor with green algae. But, there has been some debate as to what form of algae is the closest relative, as well as how some of the major groups of land plants are related to each other.
Over the past four years, Dr. Wickett collaborated with an international team of researchers on a study of 103 plants, examining how major forms of land plants are related to each other and to aquatic green algae. Together, they gathered an enormous amount of genetic data and developed computer-based tools that allowed them to apply advanced DNA sequencing technologies to biodiversity research.
Recently their results – the first piece of the One Thousand Plants (1KP) research partnership – were published in the Proceedings of the National Academy of Sciences (PNAS) and GigaScience. With the publication of this research, they’ve enabled unprecedented access to natural events spanning some 500 million years.
The researchers dove into plant genetic data at a fine level of detail, looking deeply at each plant’s transcriptome, which represents those pieces of DNA that are responsible for essential biological functions at the cellular level. They selected 852 genes to identify patterns that reflect how species are related.
Despite earlier theories that land plants are more closely related to one of two different lineages of algae which share complex structures and life cycle characteristics with land plants, their research reinforced – with strong statistical support – recent work showing that land plants are actually more closely related to Zygnematophyceae, a much less complex group of freshwater algae. This may mean that the ancestor of all land plants was actually an alga with a relatively simple growth form.
Their new paper suggests that the order of events of early land plant evolution may have been different than what we thought previously. That order of events informs how scientists interpret when and how certain characteristics or processes, like desiccation tolerance, came to be. Their results may lead to subtle differences in how scientists group mosses, liverworts and hornworts, the lineage of plants (bryophytes) that descended from the earliest land plants.