丁安明 陈志华 杨懿德 余祥文 杨洋 鄢敏 杨兴有 王卫锋 孙玉合

摘 要：细胞壁松弛因子膨胀素在调控植物生长发育和响应非生物胁迫等方面发挥重要作用，克隆烟草膨胀素基因并研究其功能可为烟草叶片发育调控和抗逆育种提供理论依据。本研究从普通烟草K326中克隆了一个膨胀素基因NtabEXPA12及其启动子ProNtabEXPA12，通过实时荧光定量PCR、亚细胞定位和过表达等对该基因进行了功能研究，分析了启动子包含的顺式作用元件和活性。结果表明，NtabEXPA12在烟草叶片中具有较高的表达量;ProNtabEXPA12中包含多个响应高盐、干旱和植物激素的顺式元件，并且其活性受到高盐、干旱和ABA等的诱导;过表达NtabEXPA12通过调控细胞扩展促进转基因烟草叶片的生长发育，并可以提高转基因K326对高盐和干旱的抗性。因此，NtabEXPA12在烟草叶片发育调控及抗逆育种中具有潜在的应用前景。

关键词：膨胀素;基因功能;叶片发育;耐盐;抗旱性

Abstract： Expansins play important roles in plant growth and development and plants responses to abiotic stresses. Cloning and studying the functions of tobacco expansin genes will provide a theoretical basis for regulation of tobacco leaf development and tobacco resistance breeding. In this study， we cloned NtabEXPA12 with its promoter ProNtabEXPA12 from tobacco variety K326， studied its function by qPCR， subcellular localization and gene overexpression assays， and analyzed cis-regulatory elements in ProNtabEXPA12 and its promoter activity. The results showed that NtabEXPA12 was highly expressed in tobacco leaves. Various cis-elements in ProNtabEXPA12 were identified which were related to plants responses to salt， drought and plant hormones. And indeed， the activity of ProNtabEXPA12 was strongly induced by NaCl， ABA and drought treatments. We also found that overexpression of NtabEXPA12 promoted cell and leaf expansion， and enhanced abiotic stress tolerance in transgenic K326 plants. Therefore， NtabEXPA12 has potential application values in manipulating tobacco leaf development and tobacco resistance breeding.

Keywords： expansin; gene function; leaf development; slat tolerance; drought resistance

細胞壁为植物生长发育提供基础支撑，也是植物响应环境变化的一道防御屏障，其主要由纤维素、半纤维素和果胶质多糖构成，还包含少量的离子和细胞壁蛋白如膨胀素等[1-3]。植物生长包括细胞数目增加和细胞体积扩展两个方面，细胞体积的扩展受其内部膨胀压力和细胞壁可塑性的协同调控。事实上，细胞壁在为植物细胞提供支撑和保护作用的同时，也是限制细胞生长的主要因素之一[4-5]。因此，植物通过松弛细胞壁多糖之间的相互交联对细胞壁进行结构重塑，是其调控细胞生长的关键环节。……