摘 要 ：采用CTAB法提取经600 mmol·L-1 NaCl胁迫处理后的胡杨总RNA，利用SMART技术构建载体为λTriplEx2的盐胁迫条件下胡杨的表达型cDNA文库（SSL）。文库的滴度为1.2×106 pfu·ml-1，重组率约为90.6%，扩增后的滴度为3×109 pfu·ml-1，容量约为2.4×1011。插入片段长度均大于400 bp，平均长度约为790 bp。从文库中随机挑选32个阳性克隆进行3′端测序，并将测序结果通过NCBI (National Center for Biotechnology Information) 数据库进行比较，发现有23个EST序列与已知序列有明显的同源性，而其余的与NCBI中的已知序列相似性较低（e值>10-4）,可能是未知基因。其中序列SSL061、SSL179与脱水素序列有较高的序列一致性。同时合成引物，通过PCR扩增文库的方法，从中筛选获得存在于植物细胞膜上并在植物受盐胁迫时起重要作用的nhx基因，进一步验证了文库的质量。
Abstract:The total RNA was extracted from Populus euphratica under salt stress with the 600mmol·L-1 NaCl treatment, and then the cDNA library was constructed by SMART technique, which uses λTriplEx2 as a vector. The estimated titer and the percentage for the unamplified salt stress library (SSL) is 1.2×106 pfu·ml-1 and 90.6%. Selected cDNA clones randomly and the EST were obtained by 3′ sequenced, these sequences were compared in GenBank databases. 32 Expressed Sequence Taqs (ESTs) were gained from the SSL with high homologous sequences, 71.8% are assigned putative identities. The sequences from the remaining clones showed either significant similarity to protein or DNA sequences that were of unknown function or no significant similarity to any other sequences in the databases. Two of the SSL transcripts encoding dehydrin may be connected with salt stress. Meanwhile, two primers of nhx were synthesized and the full length nhx cDNA of Populus euphratica was successfully obtained from this library to identify the high quality library using PCR.