Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.
J Plant Physiol. 2010 Sep 15;167(14):1165-71. doi: 10.1016/j.jplph.2010.04.001. Epub 2010 May 6.
The effects of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, on growth, orientation of cortical microtubules, and the transcript levels of gamma-tubulin complex (VaTUG and VaGCP3) and katanin (VaKTN1) genes in azuki bean (Vigna angularis) epicotyls were examined. ACC inhibited elongation growth and stimulated lateral growth of epicotyls dose dependently. It also reduced the percentage of cells with transverse microtubules and increased the percentage of cells with longitudinal microtubules. A significant change in elongation and lateral growth was detected within 1 and 1.5 h after the start of 10(-5) M ACC treatment, respectively. On the other hand, the reorientation of cortical microtubules from transverse to longitudinal direction began within 0.5 h, and continued until 2 h after the start of ACC treatment. ACC at 10(-5) M increased the transcript level of VaTUG, VaGCP3 and VaKTN1 within 0.5 h, and the levels of VaTUG and VaGCP3 became maximum at 1h and that of VaKTN1 at 1.5 h, followed by a decrease to the control level. These results suggest that ACC transiently increases the transcript levels of gamma-tubulin complex and katanin genes, which may facilitate reorientation of cortical microtubules and modification of growth anisotropy from elongation to lateral growth in azuki bean epicotyls.
1-氨基环丙烷-1-羧酸（ACC）是乙烯的直接前体，研究了其对赤豆（Vigna angularis）上胚轴生长、皮层微管取向以及γ-微管复合物（VaTUG 和 VaGCP3）和katanin（VaKTN1）基因转录水平的影响。ACC 浓度依赖性地抑制上胚轴伸长生长并刺激其侧向生长。它还降低了具有横向微管的细胞百分比，并增加了具有纵向微管的细胞百分比。在 10^-5 M ACC 处理开始后 1 和 1.5 小时分别检测到伸长和侧向生长的显著变化。另一方面，皮层微管从横向到纵向的重定向在 ACC 处理开始后 0.5 小时内开始，并持续到 2 小时。10^-5 M 的 ACC 在 0.5 小时内增加了 VaTUG、VaGCP3 和 VaKTN1 的转录水平，VaTUG 和 VaGCP3 的水平在 1 小时达到最大值，VaKTN1 的水平在 1.5 小时达到最大值，随后降至对照水平。这些结果表明，ACC 会短暂增加 γ-微管复合物和 katanin 基因的转录水平，这可能有助于赤豆上胚轴皮层微管的重定向，并改变从伸长到侧向生长的生长各向异性。
