【作者】 桂国春；

【导师】 彭友良；

【作者基本信息】 中国农业大学 ， 植物病理学， 2004， 硕士

【摘要】 植物在受到病原物侵染时可以产生一系列复杂的生理生化反应，这些反应大多数是由一系列植物基因的转录活化所介导的，其中包括许多植物的防卫基因及其它一些可能涉及植物与病原物识别，信号转导和防卫基因转录起始等相关的基因。这些基因包括植保素合成途径的关键酶基因。研究这些基因在植物与病原物互作过程中的功能及诱导表达特性，有助于揭示植物-病原物的互作机理；同时，分离这些基因可为植物抗病基因工程提供必要的操作材料。 植保素是植物抵抗外来生物或非生物因素的侵袭而产生的低分子量抗菌活性物质，是植物体内的次生代谢产物，具有侵染可诱导性和体外抗菌性的特点，其在受病原菌侵染的植物体内的诱导合成与积累被认为是重要的抗病机理之一。彭友良(1996)在非亲和性稻瘟菌接种的稻叶中发现两种新的色胺类植保素P1(N-苯甲酰基色胺)和P2(N-肉桂酰基色胺)，根据化学结构推测，苯甲酰类化合物是这两种植保素的前体之一，在非亲和性稻瘟菌侵染的稻叶中可能有苯甲酰转移酶(Benzoyltransferase)的诱导。 在本研究中，作者以一个与其它物种苯甲酰基转移酶基因具有同源性的cDNA片段为探针，筛选非亲和性稻瘟菌侵染诱导的稻叶cDNA文库，获得的了一个苯甲酰基转移酶基因全长cDNA。 苯甲酰基转移酶基因的cDNA全长为1610bp，其中完整的开放阅读框为1335bp(82-1419)，编码一条具有446个氨基酸残基的多肽。而且该多肽含有一个保守的苯甲酰基转移酶催化区HXXXDG，该基因推定的氨基酸序列与来自于大麦。紫杉 康乃馨 长春花的中的苯甲酰基转移酶基因的氨基酸序列一致性高达41.69％。在大肠杆菌中能诱导表达，SDA-PAGE结果显示在74kDa有一差异表达带。并初步测定具有酶的活性。 Northern杂交分析表明：非亲和性稻瘟菌小种能诱导苯甲酰基转移酶转录物的积累；而亲和性稻瘟菌小种不能诱导苯甲酰基转移酶转录物的累积。 以上结果证明：苯甲酰基转移酶与水稻抗稻瘟病相关，能够体外催化合成植保素P1，可以作为抗病基因工程的侯选材料。更多还原

【Abstract】 Plants show a series of complex physiological and biochemical changes in response to pathogen attack. Most of these responses are mediated by activation of plant genes including various defense genes and those involved in the process of pathogen recognition, signal transduction and initiation of transcription. The functional identification and expressing characterization of plant genes that are induced during interaction with pathogen will be a great help to reveal the mechanism of plant-pathogen interaction; isolation of these genes may provide a good choice for engineering plant disease resistance.Phytoalexin is utilized by plant to resist biological or none biological invading factors, which is secondary metabolic product. It is an important fungi resistant material that have activity in vitro and can be inducible by invading factors. It is thought to be an important mechanism for its induced synthesis in plant after infected by pathogen. Fan and Peng(1996) isolated two phytoalexin in rice inoculated with incompatible race of Magnaporthe grisea. They accumulate in rice after 48 hours. According to their chemical structure, benzoc acid and cinnamic acid is precursor of this two phytoalexin. The density of JA immediately increase after elicitor., is correspondent with process of phytoalexin induction. It can be inferred that Benzoyltransferase involved in rice resistance reaction to Magnaporthe grisea.The author characterized one full-length cDNA. Sequencing result showed that the full-length cDNA which consists of 1610bp has an intact ORF (82-1419) that encodes an 446-amino-acid protein. BLAST search indicated that the deduced amino acid sequence shares 41.69% identity with that transferase of from Hordeum, Taxus chinensis,.Catharanthus, Diabnthus caryophyllus respectively. Then there is a different band with 74kDa in the SDA-PAGE , after indued with IPTG .the result of expressing Benzoyltransferase in E. coli showed Benzoyltransferase has the transferase activity. Benzoyltransferase transcript in rice leaves can be induced by blast fungus infection.更多还原