Johnson K A, Sistrunk M L, Polisensky D H, Braam J
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005-1892, USA.
Plant Physiol. 1998 Feb;116(2):643-9. doi: 10.1104/pp.116.2.643.
Plants exposed to repetitive touch or wind are generally shorter and stockier than sheltered plants. These mechanostimulus-induced developmental changes are termed thigmomorphogenesis and may confer resistance to subsequent stresses. An early response of Arabidopsis thaliana to touch or wind is the up-regulation of TCH (touch) gene expression. The signal transduction pathway that leads to mechanostimulus responses is not well defined. A role for ethylene has been proposed based on the observation that mechanostimulation of plants leads to ethylene evolution and exogenous ethylene leads to thigmomorphogenetic-like changes. To determine whether ethylene has a role in plant responses to mechanostimulation, we assessed the ability of two ethylene-insensitive mutants, etr1-3 and ein2-1, to undergo thigmomorphogenesis and TCH gene up-regulation of expression. The ethylene-insensitive mutants responded to wind similarly to the wild type, with a delay in flowering, decrease in inflorescence elongation rate, shorter mature primary inflorescences, more rosette paraclades, and appropriate TCH gene expression changes. Also, wild-type and mutant Arabidopsis responded to vibrational stimulation, with an increase in hypocotyl elongation and up-regulation of TCH gene expression. We conclude that the ETR1 and EIN2 protein functions are not required for the developmental and molecular responses to mechanical stimulation.
与处于庇护环境中的植物相比，遭受反复触碰或风吹的植物通常更矮且更粗壮。这些机械刺激诱导的发育变化被称为形态建成，可能会赋予植物对后续胁迫的抗性。拟南芥对触碰或风吹的早期反应是TCH（触碰）基因表达上调。导致机械刺激反应的信号转导途径尚不清楚。基于植物的机械刺激会导致乙烯释放以及外源乙烯会导致类似形态建成的变化这一观察结果，有人提出乙烯在其中发挥作用。为了确定乙烯在植物对机械刺激的反应中是否起作用，我们评估了两个乙烯不敏感突变体etr1 - 3和ein2 - 1进行形态建成和TCH基因表达上调的能力。乙烯不敏感突变体对风吹的反应与野生型相似，表现为开花延迟、花序伸长率降低、成熟的初生花序变短、莲座叶旁枝增多以及TCH基因表达发生适当变化。此外，野生型和突变型拟南芥对振动刺激也有反应，表现为下胚轴伸长增加和TCH基因表达上调。我们得出结论，ETR1和EIN2蛋白功能对于植物对机械刺激的发育和分子反应并非必需。
