中文摘要：

利用已经分离的植物半胱氨酸蛋白酶抑制剂（cystatin）基因的cystatin结构域为检索序列在基因组水平上对拟南芥和水稻中的cystatin基因家族的成员进行分析；同时利用这些基因编码的蛋白质序列构建系统发生树，并对这些蛋白序列的保守序列进行分析；最后在GenBank的EST数据库中查找这些基因的ESTs表达序列。结果表明：①结合结构域的鉴定、多序列联配以及MEME分析最终确定了7个拟南芥和11个水稻的cystatin基因。②系统发生分析表明，cystatin基因的基本特征很可能是在拟南芥和水稻的分离之前就已经形成。③cystatin结构域在蛋白质间高度保守。④拟南芥和水稻的cystatin基因主要在花、叶、根、种子和愈伤组织中表达，这有助于植物避免昆虫的侵害。

英文摘要：

Plant cystatins or phytocystatins are cysteine proteinase inhibitors, which exist widely in different plant species. Because these genes can kill insects and pathogens by inhibiting the digestive function of the cysteine proteinase in gut, they are believed to play an important role in plant defense against pests and pathogens. In this study, we used the cystatin domain sequences identified from the cystatin genes in plants as queries to search for cystatin genes in both Arabidopsis and rice genomes. A polygenetic tree was then constructed based on the corresponding cystatin proteins from Arabidopsis and rice and the conserved sequences of these proteins were analyzed. Finally we searched the GenBank EST database to get the expression information of these genes. The results showed that： （1） Seven non-redundant cystatin genes in Arabidopsis and eleven in rice were identified based on identifying the cystatin domains and combining the results with the analysis of alignment and MEME. （2） The polygenetic analysis of these sequences indicated that the main character for cystatin genes might have been existent before the split of Arabidopsis and rice. （3） The cystatin domains among these proteins were highly conserved. （4）The Arabidopsis and rice cystatin genes were expressed mainly in flower, leaf, root, seed and callus, which was important for plant to defend the insects.