烟草水通道蛋白NtTIP1基因的克隆及其在干旱胁迫下的表达分析

Cloning of an aquaporin gene NtTIP1 from tobacco and its expression under drought stress

为明确烟草水通道蛋白在干旱胁迫下的表达特性，利用RT—PCR方法从烟草中克隆了一个水通道蛋白NtTIP1的全长eDNA编码区．序列分析表明，NtTIP1开放阅读框长756bp，编码251个氨基酸．对该基因编码氨基酸的保守结构域进行分析，NtTIP1包含6个保守的跨膜结构域．系统进化分析显示，NtTIP1与3种茄科植物、拟南芥TIP同源性较高，相似性为80％～97％．荧光定量PCR分析表明，NtTIP1在烟草的根、茎、叶等营养器官中表达量较高．20％PEG6000诱导的干旱胁迫条件下，NtTIP1在耐旱、干旱敏感品种中表现出不同的响应模式，在耐旱品种中显著上调表达，而在干旱敏感品种中显著下调表达．这一结果表明了NtTIP1的表达丰度与烟草的抗旱性密切相关．

To clarify expression property of aquaporins （AQPs） under drought stress in tobacco, we cloned the coding sequence of the NtTIP1 by RT - PCR. Sequence analysis has shown that the open reading frame of NtTIP1 is 756 bp and encodes a protein with 251 aa. The structure prediction has also found that NtTIP1 contains six conserved transmembrane domains. Phylogenetic tree of TIPs based on different species has demonstrated that NtTIP1 has quite high similarities （80% - 97% ） to TIP proteins from Solanaceae and Arabidopsis species. Quantitative real-time RT - PCR has revealed that the NtTIP1 transcript levels were higher in vegetative organs of tobacco, including stems, leaves and roots. Upon PEG 6000-induced drought stress, NtTIP1 showed contrasting expression patterns between the tolerant and sensitive varieties. The transcript levels of NtTIP1 were up-regulated significantly in the tolerant variety LJ 851, but down-regulated in the sensitive one JX 6007, indicating that the expression abundance of the NtTIP1 is tightly correlated to drought tolerance and NtTIP1 may play an important role in drought adaption in tobacco.