English

Most of the "plants" we see in life are belong to so-called land plants (taxonomically called Embryophytes).  Recent phylogenetic analysis revealed that land plants originate from a single ancestor diverged from green algae 4 - 5 million years ago. We would like to reveal the common the molecular mechanisms of land plant development and their changes during the course of evolution. To this end, we utilize model plants such as the liverwort Marchantia polymoprha. M. polymorpha is a relatively new experimental model, which has many advantages for molecular genetic studies. 

In the previous studies, we focused on the plant hormone auxin and revealed that M. polymorpha has a common but minimal auxin signaling system among land plant models. Instead of its simple auxin system, auxin regulates many aspects of growth and development of M. polymorpha. These results suggest that the origin of the auxin signaling system dates back to at least the common ancestor of land plants, and highlight usefulness of M. polymorpha in the study of auxin biology (Research Paper: 1-4). 

To investigate precise origin of the auxin signaling system, we utilized OneKP database containing transcriptome data from more than 1,000 plant species. Complehensive phylogenomic approaches revealed that ARF transcription factors were first established in the ancestor of charophycean algae, and then auxin perception system was established and integrated to the ARF pathway in the common ancestor of land plants (Research paper: 5, Press release)

ARF transcription factors are phylogenetically divided into the three major clades, A, B, and C. Past studies mainly investigated A-ARF whose primarily function as transcription al activator, and thus precise role of B- and C-ARF in auxin signaling remained unclear. We utilized the advantage of M. polymorpha which has only a single gene for each type of ARF, and revealed the functional specificity of each type of ARF proteins by combining various genetic and biochemical experiments. Based on these data, we proposed a basic model for three types of ARF proteins in land plants (Research paper: 8, Press release).

Given the origin and importance of auxin signaling in land plants, we speculated the downstream pathway is conserved across the evolution of land plants. We performed comparative transcriptome analysis using several species from byrophytes and ferns, and identified some gene families which are commonly regulated by auxin in the non-seed plants and flowering plants (Research paper: 5). We are currently investigating the function of these genes to unveil the common genetic network supporting complex body plan of land plants.