Abstract
Recently, gene knockouts of myosin XIs that are responsible for the cytoplasmic streaming showed stunted growth of Arabidopsis plants. However, conventional methods give us only limited understanding of this phenomenon. We genetically constructed high speed Chara-Arabidopsis chimeric myosin by replacing motor domains of Arabidopsis myosin XI with those of Chara myosin, the fastest motor protein in the world. This hyperactive myosin XI gives us a new methodology for integrated understanding about relationships between plant development and the cytoplasmic streaming generated by myosin motor activity.
Hyperactive chimera was constructed by using XI-2 that is ubiquitously expressed in plant. The velocity of this chimera was 2.3 times faster than the XI-2 in in vitro motility assay. GFP fused chimeric myosin XI was expressed in cultured cells of Arabidopsis. Live cell imaging revealed that they distributed on membranous structures which are actively moving faster than the velocity of cytoplasmic streaming. Transgenic Arabidopsis plants expressing chimeric myosin XI was developed. Effects of myosin hyperactivation on the phenotype especially on development was examined and discussed.
