University of Rhode Island, 120 Flagg Road, Kingston, Rhode Island, 02881, USA.
The Pennsylvania State University, 201 Huck Life Science Building, University Park, Pennsylvania, 16802, USA.
Sci Rep. 2018 Jan 15;8(1):735. doi: 10.1038/s41598-017-18994-4.
Results from live cell imaging of fluorescently tagged Cellulose Synthase (CESA) proteins in Cellulose Synthesis Complexes (CSCs) have enhanced our understanding of cellulose biosynthesis, including the mechanisms of action of cellulose synthesis inhibitors. However, this method has been applied only in Arabidopsis thaliana and Brachypodium distachyon thus far. Results from freeze fracture electron microscopy of protonemal filaments of the moss Funaria hygrometrica indicate that a cellulose synthesis inhibitor, 2,6-dichlorobenzonitrile (DCB), fragments CSCs and clears them from the plasma membrane. This differs from Arabidopsis, in which DCB causes CSC accumulation in the plasma membrane and a different cellulose synthesis inhibitor, isoxaben, clears CSCs from the plasma membrane. In this study, live cell imaging of the moss Physcomitrella patens indicated that DCB and isoxaben have little effect on protonemal growth rates, and that only DCB causes tip rupture. Live cell imaging of mEGFP-PpCESA5 and mEGFP-PpCESA8 showed that DCB and isoxaben substantially reduced CSC movement, but had no measureable effect on CSC density in the plasma membrane. These results suggest that DCB and isoxaben have similar effects on CSC movement in P. patens and Arabidopsis, but have different effects on CSC intracellular trafficking, cell growth and cell integrity in these divergent plant lineages.
活细胞成像技术对荧光标记的纤维素合酶（CESA）蛋白在纤维素合成复合物（CSC）中的研究，增强了我们对纤维素生物合成的理解，包括纤维素合成抑制剂的作用机制。然而，迄今为止，这种方法仅在拟南芥和短柄草中得到了应用。对藓类植物水绵的原丝体进行冷冻断裂电子显微镜研究的结果表明，纤维素合成抑制剂 2,6-二氯苯腈（DCB）会使 CSC 片段化并从质膜中清除。这与拟南芥不同，在拟南芥中，DCB 会导致 CSC 在质膜中积累，而另一种纤维素合成抑制剂异恶唑草酮则会从质膜中清除 CSC。在这项研究中，对藓类植物小立碗藓的活细胞成像表明，DCB 和异恶唑草酮对原丝体的生长速度几乎没有影响，只有 DCB 会导致尖端破裂。mEGFP-PpCESA5 和 mEGFP-PpCESA8 的活细胞成像显示，DCB 和异恶唑草酮会显著降低 CSC 的运动，但对质膜中 CSC 的密度没有可测量的影响。这些结果表明，DCB 和异恶唑草酮对 P. patens 和拟南芥中 CSC 的运动有相似的影响，但对 CSC 的细胞内运输、细胞生长和细胞完整性有不同的影响，这在这些不同的植物谱系中。
