A team led by Dr. Yuki Nakamura, an Assistant Research Fellow at the Institute of Plant and Microbial Biology recently discovered that a flowering inducer florigen binds diurnally (day/night) oscillating phospholipid species and accelerates flowering. The study proposed a novel model of flowering time control by lipids, which provides a new direction for agricultural innovation such as improved crop yields or efficient bioenergy creation. The research was published in the British journal Nature Communications on April 4, 2014.

         Seed plants perceive seasonal changes of day length and flower at the right time for successful fertilization and subsequent propagation of the species. The existence of a flowering-inducing hormone, or florigen, was proposed by scholars about 80 years ago, which is a long-range mobile signal produced in leaves that acts to initiate flowering. Because of its critical role, florigen was studied intensively worldwide, and revealed to be small mobile protein acting as a complex which was named the "florigen activation complex". However, to date, what sort of molecules florigen interacts with to fulfill its role to initiate flowering is still poorly understood.

         Dr. Nakamura's team hypothesized, based on the 3D structure of florigen, that phospholipids (molecules containing fatty acid chains and a phosphate-containing head group) might represent novel binding partners of florigen to modulate its function. Through the screening of various phospholipid species present in plants, they found that phosphatidylcholine (PC) bound specifically to florigen. To investigate the role of PC in flowering, they developed a new technology to engineer PC levels in a specific part of floral tissue. They found that increases in PC where florigen acts, promote flowering, whereas decreases in PC delay flowering time. This effect was attenuated if florigen was genetically knocked out. They further discovered that PC molecular species oscillated diurnally (fluctuated between day and night), and night-dominant species were not the preferred ligands (binding partners) for florigen. Metabolic engineering to increase night species during the day time delayed the flowering time in the presence of florigen. Thus, Nakamura's team concluded that diurnally oscillating PC binds florigen to regulate flowering time.

         The research was funded by Academia Sinica and the Japan Science and Technology Agency, and was conducted in collaboration with Honor. Prof. Dr. George Coupland (Max-Planck-Institute for Plant Molecular Breeding, Germany) and Prof. Dr. Peter Dormann (Univ. Bonn, Germany).

         The complete list of authors is: Yuki Nakamura, Fernando Andres, Kazue Kanehara, Yu-chi Liu, Peter Dormann and George Coupland.

         The complete article entitled "Arabidopsis florigen FT binds to diurnally oscillating phospholipids that accelerate flowering" can be found at Nature Communications journal website at: http://www.nature.com/ncomms/2014/140404/ncomms4553/full/ncomms4553.html