Microtubules Make Tracks for Cellulose

摘要

In a remarkable series of biological transformations, green plants convert carbon dioxide into cellulose fibers stronger than steel. These thin threads of polymeric glucose are wrapped around growing cells, lending structural support to the plant as it extends further into the environment. The fibers are not simply secreted into the plant cell wall in a haphazard fashion but are deposited in ordered layers that still allow the cell to expand. For more than 40 years, it has been known that the alignment of these cellulose fibers (microfibrils) in the cell wall often coincides with cytoskeletal micio-tubules tethered to the cytoplasmic side of the plasma membrane (see the figure). Despite this coincidence, there has never been direct proof that microtubules provide a guidance mechanism for the alignment of cellulose microfibrils Now, on page 1491 of this issue, Paiedez et al. (l) provide that proof.