Plant Physiology, Biochemistry, Molecular Biology Program, Department of Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky 40546, USA.
Plant Cell. 2011 Sep;23(9):3412-27. doi: 10.1105/tpc.111.089920. Epub 2011 Sep 27.
The dynamic instability of cortical microtubules (MTs) (i.e., their ability to rapidly alternate between phases of growth and shrinkage) plays an essential role in plant growth and development. In addition, recent studies have revealed a pivotal role for dynamic instability in the response to salt stress conditions. The salt stress response includes a rapid depolymerization of MTs followed by the formation of a new MT network that is believed to be better suited for surviving high salinity. Although this initial depolymerization response is essential for the adaptation to salt stress, the underlying molecular mechanism has remained largely unknown. Here, we show that the MT-associated protein SPIRAL1 (SPR1) plays a key role in salt stress-induced MT disassembly. SPR1, a microtubule stabilizing protein, is degraded by the 26S proteasome, and its degradation rate is accelerated in response to high salinity. We show that accelerated SPR1 degradation is required for a fast MT disassembly response to salt stress and for salt stress tolerance.
皮层微管（MTs）的动态不稳定性（即它们在生长和收缩相之间快速交替的能力）在植物生长和发育中起着至关重要的作用。此外，最近的研究揭示了动态不稳定性在应对盐胁迫条件中的关键作用。盐胁迫反应包括 MTs 的快速解聚，随后形成新的 MT 网络，据信该网络更适合在高盐度下生存。尽管这种初始的解聚反应对于适应盐胁迫至关重要，但潜在的分子机制在很大程度上仍然未知。在这里，我们表明与微管相关的蛋白 SPIRAL1（SPR1）在盐胁迫诱导的 MT 解聚中发挥关键作用。SPR1 是一种微管稳定蛋白，可被 26S 蛋白酶体降解，并且其降解速度在高盐度下会加快。我们表明，加速的 SPR1 降解对于快速的 MT 解聚反应以及对盐胁迫的耐受性是必需的。
