A novel trimeric complex in plant cells that contributes to the lamina inclination of rice.

The architecture determining grain production in rice is mainly affected by factors such as lamina angle, tillering, plant height and panicle morphology. In particular, leaf angle, the degree of bending between the leaf blade and leaf sheath directly affects crop architecture and grain yields. Balancing activities between the 2 antagonistic groups of proteins, atypical helix-loop-helix (HLH) and basic HLH (bHLH) proteins have been regarded as one of the major molecular machineries regulating lamina angles through the control of cell elongation in the lamina joint of rice. Recently, formation of a complex consisting of atypical HLH protein, OsBUL1, a KxDL motif-containing protein, LO9-177 and a bHLH protein, OsBC1 has been reported to play a positive role in lamina inclination of rice unraveling a novel layer of cell elongation control in rice lamina joint. Here, we demonstrate a trimeric complex formation in rice cells by a combination of BiFC and FRET-FLIM assays.