Theoretical Biology Laboratory MOCHIZUKI Lab.

Properly patterned cell-wall deposition is essential for plant cell development. Xylem vessel cells deposit rigid secondary cell walls in distinct patterns such as annular, spiral, reticulate, and pitted patterns to form water-conducting vessels. In differentiating xylem vessel cells, cortical microtubules are arranged into specific patterns to direct the secondary cell wall deposition. However, little is known about the regulatory mechanism of the cortical microtubule behavior in xylem vessel cells. We have revealed that the plant Rho GTPase, ROP11, is activated to form plasma membrane domains to promote local cortical microtubule disassembly through MIDD1-Kinesin-13A complex, which in trun directs secondary cell wall pit formation in metaxylem vessel cells [1-3]. We recently found that two novel microtubule-associated proteins, IQD13 and CORD1, regulate the stability of the cortical microtubules surrounding the ROP11-activated domains to shape the oval secondary cell wall pits [4,5]. We also found that ROPGEFs and ROPGAPs, activators and inactivators of ROP11, respectively, mediate the local activation of ROP11 by reaction-diffusion system. Our study revealed how cell-wall patterns are cell-autonomously generated by Rho GTPase signling in association with cortical cytoskeleton.

1. Oda Y, Iida Y, Kondo Y, Fukuda H (2010) Wood cell-wall structure requires local 2D-microtubule disassembly by a novel plasma membrane-anchored protein. Curr Biol 20:1197-1202.
2. Oda Y, Fukuda H (2013) Rho of plant GTPase signaling regulates the behavior of Arabidopsis kinesin-13A to establish secondary cell wall patterns. Plant Cell 25:4439-4450.
3. Oda Y, Fukuda H (2012) Initiation of cell wall pattern by a Rho- and microtubule-driven symmetry breaking. Science 337:1333-1336.
4. Sugiyama Y, Wakazaki M, Toyooka K, Fukuda H, Oda Y (2017) A Novel Plasma Membrane-Anchored Protein Regulates Xylem Cell-Wall Deposition through Microtubule-Dependent Lateral Inhibition of Rho GTPase Domains. Curr Biol 27:2522-2528.
5. Sasaki T, Fukuda H, Oda Y (2017) CORTICAL MICROTUBULE DISORDERING1 is required for secondary cell wall pattens in xylem vessels. Plant Cell in press.