Talking Plant Science: Junko Kyozuka

The ARC Centre of Excellence for Plant Success in Nature and Agriculture is proud to bring you the next seminar in our Talking Plant Science series, presented by Distinguished Professor Junko Kyozuka.

Step by step evolution of strigolactone signalling pathway

Strigolactones (SLs) serve dual functions as hormones that regulate growth and development and as rhizosphere signalling molecules that promote symbiosis with arbuscular mycorrhizal fungi in flowering plants. How SLs acquired these dual roles remained unclear. We reported that the ancestral function of SLs was as rhizosphere signals, which were later co-opted as hormones through the gradual evolution of signalling components. SLs are perceived by DWARF14 (D14), which interacts with the F-box protein MAX2 and SMXL repressors; D14 arose via duplication of KARRIKIN INSENSITIVE2 (KAI2), a receptor for the unidentified ligand KL, in the common ancestor of seed plants. KAI2 itself likely originated via horizontal gene transfer prior to streptophyte evolution. Phylogenetic analysis indicates that KL signaling was established in the common ancestor of land plants.

To investigate the ancestral role of KL signaling, we analyzed its function in two bryophytes, the liverwort Marchantia polymorpha and the moss Physcomitrium patens. In both species, KL signaling modulates growth by regulating cytokinin accumulation. We propose that the functions of KL signalling in bryophytes may reflect its original role in optimizing growth and development.

Distinguished Professor Junko Kyozuka

Tohoku University