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Speaker: Junko KYOZUKA
Professor
Graduate School of Life Sciences
Tohoku University
Title:
Origin and evolution of strigolactones as a class of plant hormone
Time：27th October 2022, 10:00 am [Japan] 9:00 am [PK]
ZOOM Meeting：819 3531 0360
Passcode：900723
Join Zoom meeting:
https://adelaide.zoom.us/j/81935310360?pwd=cE1iTWlwdjRzTWRVZ283M21tb0hFdz09
Host: Dabing Zhang
Basic Information:
Land plants evolved from an algal ancestor more than 450 million years ago. The mutualistic symbiosis formed with arbuscular mycorrhizal (AM) fungi was critical for the initial colonization of the terrestrial environment. Symbiosis with AM fungi is observed in more than 80% of extant land plant species, including the bryophytes that diverged from the vascular plant lineage more than 400 million years ago. In flowering plants, the establishment of the AM symbiosis requires stimulation of hyphal branching by plant root-derived strigolactones (SLs). In addition to their role as rhizosphere signaling molecules, SLs also function as a class of plant hormones and regulate various aspects of growth and development in flowering plants.
The origin and evolution of the dual function of SLS have been largely unknown. The receptor of SLs, DWARF14 (D14), was generated by duplication of KARRIKIN INSENSITIVE 2 (KAI2) that occurred in the common ancestor of seed plants. Thus, D14 is absent in the bryophytes. We identified an ancestral SL, bryosymbiol (BSB), present in diverse bryophytes such as Marchantia paleacea, and vascular plants. In M. paleacea, BSB is secreted from the plants and is required for AM symbiosis but not for development. We show that BSB is not perceived by M. paleacea cells due to the absence of cognate SL receptors. Our findings revealed that the ancestral function of SLs is as AM symbiosis-inducing rhizosphere signaling molecules and that this function was already present in the most recent common ancestor of land plants (1).
KAI2-dependent signaling controls growth and development in flowering plants. All components in the KAI2-dependent signaling are present in bryophytes (2). We show that KAI2-dependent signaling in M. polymorpha regulates vegetative reproduction in a nutrient condition-dependent manner (3).
1. Kodama et al. Nature Communications. 13:3974 (2022).
2. Mizuno et al., Plant Cell. 33, 2395-2411 (2021).
3. Komatsu et al. (under revision)
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