Arabidopsis thaliana Myosin XI is Necessary for Cell Fate Determination in Root Epidermis

Root hairs are specialized epidermal cells with important functions, such as absorbing water and nutrients from soil. In Arabidopsis thaliana, root hairs de-velop in a strict position-dependent mechanism that results in alternating lon-gitudinal hair and non-hair cell files along the surface of the root. This invari-ant pattern is determined, in large part, by a complex network of transcription factors in the epidermis. However, epidermal cells are also highly plastic and have the ability to promote root hair growth even after the hairless cell fate has been determined by transcriptional control. Recently, it has been observed that the mutants of a specific isoform of class XI myosins, mya1, grow ectopic root hairs in Arabidopsis. Since class XI myosin proteins are actin-based molecular motors that transport intracellular organelles or protein complexes, it is pos-sible that MYA1 also has a role in the trafficking of those transcription factors and their upstream regulators that are involved in cell-type patterning. Here, three promoter-GUS (beta-glucuronidase) constructs were utilized to deter