Department of Biology, Santa Clara University, Santa Clara, CA 95053, USA.
Mol Plant. 2012 May;5(3):716-25. doi: 10.1093/mp/sss033. Epub 2012 Apr 5.
Radially arranged cortical microtubules are a prominent feature of guard cells. We observed guard cells expressing GFP-tubulin (GFP-TUA6) with confocal microscopy and found recognizable changes in the appearance of microtubules when stomata open or close (Eisinger et al., 2012). In the present study, analysis of fluorescence distribution showed a dramatic increase in peak intensities of microtubule bundles within guard cells as stomata open. This increase was correlated with an increase in the total fluorescence that could be attributed to polymerized tubulin. Adjacent pavement cells did not show similar changes in peak intensities or integrated fluorescence when stomatal apertures changed. Imaging of RFP-tagged end binding protein 1 (EB1) and YFP-tagged α-tubulin expressed in the same cell revealed that the number of microtubules with growing ends remained constant, although the total amount of polymerized tubulin was higher in open than in closed guard cells. Taken together, these results indicate that the changes in microtubule array organization that are correlated with and required for normal guard cell function are characterized by changes in microtubule clustering or bundling.
呈放射状排列的皮层微管是保卫细胞的一个显著特征。我们通过共聚焦显微镜观察到表达 GFP-微管蛋白（GFP-TUA6）的保卫细胞，发现当气孔开放或关闭时，微管的外观有明显变化（Eisinger 等人，2012 年）。在本研究中，荧光分布分析显示，气孔开放时，保卫细胞中微管束的峰值强度显著增加。这种增加与聚合微管蛋白的总荧光强度的增加相关。当气孔孔径发生变化时，相邻的铺石细胞的峰值强度或积分荧光没有显示出类似的变化。在同一细胞中表达的红色荧光蛋白（RFP）标记的末端结合蛋白 1（EB1）和黄色荧光蛋白（YFP）标记的α-微管的成像显示，虽然在开放的保卫细胞中聚合的微管蛋白的总量高于关闭的保卫细胞，但具有生长末端的微管数量保持不变。综上所述，这些结果表明，与正常保卫细胞功能相关且必需的微管阵列组织的变化特征是微管聚集或束状的变化。
