Microtubule severing at crossover sites by katanin generates ordered cortical microtubule arrays in Arabidopsis.

摘要: The noncentrosomal cortical microtubules (CMTs) of land plants form highly ordered parallel arrays that mediate cell morphogenesis by orienting cellulose deposition. Since new CMTs initiate from dispersed sites at random orientations, array organization is hypothesized to require selective pruning are not in the dominant orientation. Severing crossover proposed be a potential mechanism; however, parameters and molecular mechanisms underlying this activity unknown. Here, using live-cell imaging, we show severing preferentially targets overlying leads their depolymerization about 85% time. In addition, probability has sigmoidal relationship dwell time, indicating strong bias for longer-lived severed. We found CMT was completely abolished Arabidopsis katanin mutant. Consistent with finding, GFP-tagged driven its native promoter localizes prior severing. Furthermore, recovery experiments showed fail become conclude solely responsible essential generate arrays.