Braam Janet
Biochemistry and Cell Biology, Rice University, 6100 Main St, Houston, TX 77005-1892, USA.
New Phytol. 2005 Feb;165(2):373-89. doi: 10.1111/j.1469-8137.2004.01263.x.
Perception and response to mechanical stimuli are likely essential at the cellular and organismal levels. Elaborate and impressive touch responses of plants capture the imagination as such behaviors are unexpected in otherwise often quiescent creatures. Touch responses can turn plants into aggressors against animals, trapping and devouring them, and enable flowers to be active in ensuring crosspollination and shoots to climb to sunlit heights. Morphogenesis is also influenced by mechanical perturbations, including both dynamic environmental stimuli, such as wind, and constant forces, such as gravity. Even individual cells must sense turgor and wall integrity, and subcellular organelles can translocate in response to mechanical perturbations. Signaling molecules and hormones, including intracellular calcium, reactive oxygen species, octadecanoids and ethylene, have been implicated in touch responses. Remarkably, touch-induced gene expression is widespread; more than 2.5% of Arabidopsis genes are rapidly up-regulated in touch-stimulated plants. Many of these genes encode calcium-binding, cell wall modifying, defense, transcription factor and kinase proteins. With these genes as tools, molecular genetic methods may enable elucidation of mechanisms of touch perception, signal transduction and response regulation.
在细胞和机体水平上，对机械刺激的感知和反应可能至关重要。植物精妙且令人印象深刻的触觉反应激发了人们的想象力，因为在通常较为静止的生物中，这样的行为是出乎意料的。触觉反应能使植物转变为对动物的攻击者，捕获并吞噬它们，还能使花朵积极确保异花授粉，使茎蔓攀爬到有阳光的高处。形态发生也受机械干扰的影响，这包括动态的环境刺激，如风，以及恒定的力，如重力。甚至单个细胞都必须感知膨压和细胞壁完整性，并且亚细胞器能够响应机械干扰而发生移位。信号分子和激素，包括细胞内钙、活性氧、十八碳酸和乙烯，都与触觉反应有关。值得注意的是，触摸诱导的基因表达很普遍；在受到触摸刺激的拟南芥植物中，超过2.5%的基因会迅速上调。这些基因中有许多编码钙结合、细胞壁修饰、防御、转录因子和激酶蛋白。以这些基因作为工具，分子遗传学方法或许能够阐明触觉感知、信号转导和反应调节的机制。
