中文摘要：

羊草具有耐寒、耐盐和耐旱等特点,是一种兼具经济价值和生态价值的多年生重要牧草。脯氨酸是植物在渗透胁迫下积累的主要渗透调节物质之一。Δ1-吡咯啉-5-羧酸合成酶（P5CS）是脯氨酸的谷氨酸合成途径中的关键酶。根据前期Solexa测序结果的数据,设计同源引物,从羊草中克隆了一个P5CS基因,该基因cDNA序列全长2 197bp,推断其编码730个氨基酸,根据序列比对将其蛋白命名为LcP5CS1。同源性分析表明：LcP5CS1与单子叶植物短柄草P5CS的同源性为95%,而与双子叶植物的P5CS同源性较低。表达模式分析表明,在叶鞘、叶和茎中,LcP5CS1均有较高表达;在冷、ABA、盐和干旱胁迫下,该基因明显受胁迫诱导,并随胁迫时间的延长,其表达量总体呈上调趋势。对羊草人工创伤处理后的Solexa测序差异表达数据分析表明：LcP5CS1在处理2和6h后表达量明显提高,推测羊草创伤处理后体内脯氨酸含量升高可能是其耐牧的一种适应性机制。

英文摘要：

Leymus chinensis is tolerant to high salinity, drought and cold stresses. It is an important perennial plant with economic and ecological value. Proline is one of the main regulators in many plants under osmotic stresses. Al-pyrroline-5-carboxylate synthetase （PSCS） is a key regulatory enzyme that plays a crucial role in proline biosynthesis by the glutamate pathway. Based on analysis of solexa sequencing data, a PSCS gene from L. chinensis was cloned by RT--PCR using homologous primers. The cDNA sequence was 2 197 bp in length and putatively translated to 730 amino acids. Based on the sequence alignment results, the protein was named LcP5CS1. The homology between LcPSCS1 and BdPSCS1 was 95%, but LcPSCS1 had low homology with PSCS from dicotyledons. Analysis expression profiles of LcPSCS1 revealed that LcPSCS1 was highly expressed in leaf sheaths, stems and leaves. In cold conditions, ABA, salt and drought stress, it was significantly in- duced with time, and the expression levels of LcPSCS1 were up-regulated. The results of Solexa sequencing for wounded L. chinensis showed that LcP5CS1 was up regulated, and the increased proline in L. chinensis may contribute to its stress tolerance.