LAUSR

The migration of nuclei during growth and development processes is a conserved phenomenon among man karyotic species. In Arabidopsis thaliana, the movement of the nucleus is important for root hair growth, but the detailed mechanism behind this nuclear movement is still not well known. Previous studies in different cell types have reported that the myosin XI-I motor protein is responsible for this nuclear movement by attaching to the nuclear transmembrane protein complex WIT1/WIT2. Here, we analyzed nuclear movement in growing A. thaliana root hairs of wild-type, myosin xi-i, and wit1 wit2 mutants in the presence of actin and microtubule disrupting inhibitors to determine the individual effects that actin filaments and microtubules have on nuclear movement. We discovered that forward nuclear movement during root hair growth can occur in the absence of myosin XI-I, suggesting the presence of an alternative actin-based mechanism that mediates rapid nuclear displacements. By quantifying nuclear movements with high temporal resolution during the initial phase of inhibitor treatment, we determined that microtubules work to dampen erratic nuclear movements during root hair growth. In addition, we discovered microtubule-dependent backwards nuclear movement when actin filaments were impaired in the absence of myosin XI-I, indicating the presence of complex interactions between the cytoskeletal arrays during nuclear movements in growing root hairs.