Regulation of secondary cell wall patterns

Plant cells have evolved cortical microtubules, in a two-dimensional space beneath the plasma membrane, that regulate patterning of cellulose deposition. Although recent studies have revealed that several microtubule-associated proteins facilitate self-organization of transverse cortical microtubules, it is still unknown how diverse patterns of cortical microtubules are organized in different xylem cells, which are the major components of wood. Using our newly established in vitro xylem cell differentiation system, we found that a novel microtubule-associated protein, microtubule depletion domain 1 (MIDD1), was anchored to distinct plasma membrane domains and promoted local microtubule disassembly, resulting in pits on xylem cell walls. This picture shows the typical behavior of MIDD1 (green) in the differentiating xylem cell. Note that MIDD1 is associated with the cortical MTs in the distinct area where the secondary wall deposition (pink) is inhibited.
Photo by Yoshihisa Oda