【作者】 李倩；

【导师】 王罡；

【作者基本信息】 天津大学 ， 遗传学， 2019， 博士

【摘要】 干旱等非生物胁迫是主要的环境因素,严重限制了植物的正常发育和全球农作物的生产力。水杨酸（Salicylic acid,SA）是一种植物激素,在植物的生长发育以及它们应对非生物胁迫的反应中起重要作用。为了深入探究内源SA在植物抗逆中的功能,本研究从中华枸杞中分离得到了SA代谢调控相关的水杨酸结合蛋白2（SA binding protein,SABP2）同源基因LcSABP及水杨酸羧基甲基转移酶（SA carboxyl methyltransferase,SAMT）同源基因LcSAMT,通过农杆菌介导的遗传转化方法分别获得了LcSABP与LcSAMT过表达的转基因烟草植株。对LcSABP过表达烟草植株进行生理生化指标检测,结果表明,干旱胁迫处理后,与对照组相比,转基因植株的SA含量、叶绿素含量、光合能力、抗氧化酶活性及胁迫应激相关基因的表达水平均显著升高,表明LcSABP介导的内源SA水平的升高在植物抵御干旱胁迫应答过程中发挥了积极的调节作用。另外,干旱胁迫条件下,与对照组相比,LcSAMT在烟草中的过表达下调了内源SA的水平,进一步降低了植物对干旱胁迫的耐受性;转基因植株中ROS的积累和MDA水平增加,脯氨酸含量和抗氧化酶活性降低,同时,转基因植株对干旱的敏感性增加,并伴随ABA的含量减少,以及胁迫应答相关基因的转录水平降低。以上结果表明,LcSABP和LcSAMT介导的植物内源SA水平的变化在植物抵御干旱胁迫的反应过程中发挥重要的调节作用。为进一步探究SA及其调控相关基因（SABP2、SAMT）在农业实际生产中农作物抵御非生物胁迫过程中的作用,本研究选用马铃薯作为目标植物,利用外源SA喷施处理,研究SA及其代谢调控相关基因（SABP2、SAMT）在马铃薯植株应对重金属Cd胁迫过程中发挥的作用。实验结果表明,外源SA处理Cd胁迫条件下的马铃薯后,植株体内内源SA含量、叶绿素、脯氨酸含量和抗氧化酶活性均显著升高,MDA、H₂O₂和O₂^-含量下降。此外,Cd胁迫下外源施用SA后,马铃薯植株胁迫应答相关基因及SA代谢调控相关基因（StSABP2、StSAMT）的表达水平显著增强,表明SA处理增强了马铃薯对Cd胁迫的耐受性,StSABP2、StSAMT基因参与了植物抵御Cd胁迫的反应过程。更多还原

【Abstract】 Abiotic stresses such as drought are the major environmental factors that severely limit the normal development of plants and the productivity of global crops.Salicylic acid（SA）is a plant hormone that plays an important role in the growth and development of plants and their response to abiotic stresses.In order to further study the function of endogenous SA in plant stress tolerance,the SA binding protein 2（SABP2）-like gene LcSABP and SA carboxyl methyltransferase（SAMT）-like gene LcSAMT which were related to SA metabolic regulation from Lycium chinense were isolated in our study.Then,transgenic tobacco plants with strong expression of LcSABP or LcSAMT were obtained via Agrobacterium-mediated genetic transformation method,respectively.The physiological and biochemical indexes of LcSABP overexpressing tobacco plants were tested.The results showed that the SA content,chlorophyll content,photosynthetic capacity,antioxidant enzyme activities and expression levels of stress-related genes in transgenic plants were significantly higher than those in wild-type（WT）plants after drought stress treatment.This suggested that LcSABP-mediated elevation of endogenous SA levels played positive regulatory role in plant responses to drought stress.In addition,under drought stress conditions,compared with the control group,overexpression of Lc SAMT in tobaccos down-regulated the endogenous SA levels,which further reduced plant tolerance to drought stress.And the LcSAMT transgenic plants showed the increased accumulation of ROS and MDA,decreased proline content and antioxidant enzyme activities.At the same time,the transgenic plants exhibited the increased sensitivity to drought stress which accompanied by a decrease both in the content of ABA and the transcription levels of genes involved in stress response.The above results demonstrated that LcSABP and LcSAMT-mediated changes in plant endogenous SA levels played an important regulatory role in plant responses to drought stress.In order to further explore the role of SA and its regulation-related genes（SABP2 and SAMT）in agricultural crops resistance to abiotic stresses,the potato plants were selected as the target plants to analyze the effects of SA and its metabolic regulation-related genes（SABP2 and SAMT）on plant response to heavy metal Cd stress through exogenous SA spraying.The results demonstrated that the contents of endogenous SA,chlorophyll,proline and antioxidant enzymes activity increased,and the contents of MDA,H₂O₂ and O₂^-decreased in potato plants with exogenous SA treatment under Cd stress.Additionally,the expression levels of stress-related genes and SA metabolism-related genes（StSABP2 and StSAMT）in potato plants were significantly increased after exogenous application of SA under Cd stress.This revealed that SA treatment enhanced the tolerance of potato to Cd stress,and StSABP2 and StSAMT genes involved in the process of plants response to Cd stress.更多还原