Live Cell Molecular Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan; Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
Dev Cell. 2013 Nov 11;27(3):345-52. doi: 10.1016/j.devcel.2013.10.005.
Cytoplasmic streaming is active transport widely occurring in plant cells ranging from algae to angiosperms. Although it has been revealed that cytoplasmic streaming is generated by organelle-associated myosin XI moving along actin bundles, the fundamental function in plants remains unclear. We generated high- and low-speed chimeric myosin XI by replacing the motor domains of Arabidopsis thaliana myosin XI-2 with those of Chara corallina myosin XI and Homo sapiens myosin Vb, respectively. Surprisingly, the plant sizes of the transgenic Arabidopsis expressing high- and low-speed chimeric myosin XI-2 were larger and smaller, respectively, than that of the wild-type plant. This size change correlated with acceleration and deceleration, respectively, of cytoplasmic streaming. Our results strongly suggest that cytoplasmic streaming is a key determinant of plant size. Furthermore, because cytoplasmic streaming is a common system for intracellular transport in plants, our system could have applications in artificial size control in plants.
细胞质流动是一种广泛存在于藻类到被子植物等植物细胞中的主动运输方式。虽然已经揭示细胞质流动是由与细胞器相关的肌球蛋白 XI 沿着肌动蛋白束运动产生的，但在植物中的基本功能仍不清楚。我们通过分别用珊瑚藻肌球蛋白 XI 和人肌球蛋白 Vb 的马达结构域替换拟南芥肌球蛋白 XI-2 的马达结构域，生成了高速和低速嵌合肌球蛋白 XI。令人惊讶的是，表达高速和低速嵌合肌球蛋白 XI-2 的转基因拟南芥的植物大小分别大于和小于野生型植物。这种大小变化分别与细胞质流动的加速和减速相关。我们的结果强烈表明细胞质流动是植物大小的关键决定因素。此外，由于细胞质流动是植物细胞内运输的常见系统，我们的系统可应用于植物的人工大小控制。
