Esmon C Alex, Pedmale Ullas V, Liscum Emmanuel
University of Missouri-Columbia, Division of Biological Sciences, Columbia, Missouri 65211, USA.
Int J Dev Biol. 2005;49(5-6):665-74. doi: 10.1387/ijdb.052028ce.
In an attempt to compensate for their sessile nature, plants have developed growth responses to deal with the copious and rapid changes in their environment. These responses are known as tropisms and they are marked by a directional growth response that is the result of differential cellular growth and development in response to an external stimulation such as light, gravity or touch. While the mechanics of tropic growth and subsequent development have been the topic of debate for more than a hundred years, only recently have researchers been able to make strides in understanding how plants perceive and respond to tropic stimulations, thanks in large part to mutant analysis and recent advances in genomics. This paper focuses on the recent advances in four of the best-understood tropic responses and how each affects plant growth and development: phototropism, gravitropism, thigmotropism and hydrotropism. While progress has been made in deciphering the events between tropic stimulation signal perception and each characteristic growth response, there are many areas that remain unclear, some of which will be discussed herein. As has become evident, each tropic response pathway exhibits distinguishing characteristics. However, these pathways of tropic perception and response also have overlapping components - a fact that is certainly related to the necessity for pathway integration given the ever-changing environment that surrounds every plant.
为了弥补自身固着生长的特性，植物进化出了生长响应机制，以应对其环境中大量且迅速的变化。这些响应被称为向性运动，其特征是定向生长响应，这是细胞在诸如光、重力或触摸等外部刺激下差异生长和发育的结果。尽管向性生长及其后续发育的机制已争论了一百多年，但直到最近，研究人员才在理解植物如何感知和响应向性刺激方面取得进展，这在很大程度上要归功于突变分析和基因组学的最新进展。本文重点关注四种最被深入理解的向性响应的最新进展，以及每种向性响应如何影响植物的生长和发育：向光性、向重力性、向触性和向水性。虽然在解读向性刺激信号感知与每种特征性生长响应之间的事件方面已取得进展，但仍有许多领域尚不清楚，本文将讨论其中一些领域。显而易见，每种向性响应途径都具有独特的特征。然而，这些向性感知和响应途径也有重叠的部分——鉴于围绕每株植物的环境不断变化，这一事实无疑与途径整合的必要性相关。
