Antosiewicz D M, Purugganan M M, Polisensky D H, Braam J
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005-1892, USA.
Plant Physiol. 1997 Dec;115(4):1319-28. doi: 10.1104/pp.115.4.1319.
A gene family encoding xyloglucan endotransglycosylase (XET)-related proteins exists in Arabidopsis. TCH4, a member of this family, is strongly up-regulated by environmental stimuli and encodes an XET capable of modifying cell wall xyloglucans. To investigate XET localization we generated antibodies against the TCH4 carboxyl terminus. The antibodies recognized TCH4 and possibly other XET-related proteins. These data indicate that XETs accumulate in expanding cell, at the sites of intercellular airspace formation, and at the bases of leaves, cotyledons, and hypocotyls. XETs also accumulated in vascular tissue, where cell wall modifications lead to the formation of tracheary elements and sieve tubes. Thus, XETs may function in modifying cell walls to allow growth, airspace formation, the development of vasculature, and reinforcement of regions under mechanical strain. Following wind stimulation, overall XET levels appeared to decrease in the leaves of wind-stimulated plants. However, consistent with an increase in TCH4 mRNA levels following wind, there were regions that showed increased immunoreaction, including sites around cells of the pith parenchyma, between the vascular elements, and within the epidermis. These results indicate that TCH4 may contribute to the adaptive changes in morphogenesis that occur in Arabidopsis following exposure to mechanical stimuli.
拟南芥中存在一个编码木葡聚糖内转糖基酶（XET）相关蛋白的基因家族。该家族成员之一TCH4受环境刺激强烈上调表达，并编码一种能够修饰细胞壁木葡聚糖的XET。为了研究XET的定位，我们制备了针对TCH4羧基末端的抗体。这些抗体可识别TCH4以及可能的其他XET相关蛋白。这些数据表明，XET在正在扩展的细胞、细胞间气腔形成部位以及叶、子叶和下胚轴基部积累。XET也在维管组织中积累，在维管组织中细胞壁修饰导致管状分子和筛管的形成。因此，XET可能在修饰细胞壁以促进生长、气腔形成、维管系统发育以及机械应变区域的强化方面发挥作用。风刺激后，风刺激植株叶片中的总体XET水平似乎下降。然而，与风刺激后TCH4 mRNA水平升高一致，有一些区域显示免疫反应增强，包括髓薄壁组织细胞周围、维管束之间以及表皮内的部位。这些结果表明，TCH4可能有助于拟南芥在受到机械刺激后发生的形态发生适应性变化。
