Xu W, Purugganan M M, Polisensky D H, Antosiewicz D M, Fry S C, Braam J
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251-1892, USA.
Plant Cell. 1995 Oct;7(10):1555-67. doi: 10.1105/tpc.7.10.1555.
Adaptation of plants to environmental conditions requires that sensing of external stimuli be linked to mechanisms of morphogenesis. The Arabidopsis TCH (for touch) genes are rapidly upregulated in expression in response to environmental stimuli, but a connection between this molecular response and developmental alterations has not been established. We identified TCH4 as a xyloglucan endotransglycosylase by sequence similarity and enzyme activity. Xyloglucan endotransglycosylases most likely modify cell walls, a fundamental determinant of plant form. We determined that TCH4 expression is regulated by auxin and brassinosteroids, by environmental stimuli, and during development, by a 1-kb region. Expression was restricted to expanding tissues and organs that undergo cell wall modification. Regulation of genes encoding cell wall-modifying enzymes, such as TCH4, may underlie plant morphogenetic responses to the environment.
植物对环境条件的适应要求对外部刺激的感知与形态发生机制相联系。拟南芥的TCH（触觉）基因在响应环境刺激时表达迅速上调，但这种分子反应与发育变化之间的联系尚未确立。我们通过序列相似性和酶活性将TCH4鉴定为一种木葡聚糖内转糖基酶。木葡聚糖内转糖基酶很可能修饰细胞壁，而细胞壁是植物形态的一个基本决定因素。我们确定TCH4的表达受生长素和油菜素内酯调控，受环境刺激调控，且在发育过程中受一个1千碱基区域的调控。其表达局限于正在扩展且经历细胞壁修饰的组织和器官。像TCH4这样编码细胞壁修饰酶的基因的调控，可能是植物对环境的形态发生反应的基础。
