Characterization of Systemin-responsive MAP Kinase Cascades

Systemin 响应 MAP 激酶级联的表征

• 批准号: 0321453
• 负责人: Johannes Stratmann
• 金额: $ 41.76万
• 依托单位: University South Carolina Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-15 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0321453&HistoricalAwards=false
• 关键词: Characterization; Systemin; responsive; MAP; Kinase

Insect pests cause huge losses to farmers in the U.S. and worldwide. Developing improved plants with increased resistance to herbivorous insects is important for increasing yields while reducing production costs and the use of environmentally harmful insecticides. A key for understanding plant defense responses to insects are the underlying signaling pathways that result in upregulation of defense genes. In tomato, potato and other solanaceous plants, the response to chewing insects is mediated by a hormone-like short signaling peptide, systemin. Systemin is essential for successful defense against insects, and its signaling pathway is well defined. A major advance was the recent identification of the systemin receptor SR160, a LRR-receptor kinase. Surprisingly, it was shown that SR160 is identical to tBRI1, the tomato brassinosteroid (BR) receptor. BRs play an important role in plant development. Thus, tomato provides a unique opportunity to study how interactions of the receptor SR160/tBRI1 with systemin and BRs result in either stress or developmental responses. Such dual ligand receptors had not been identified in plants before and may be an entirely new way of signaling.MAPKs are central for the relay of stress signals to defense genes. They are part of the MAPK cascade, which consists of three functionally linked kinases. The MAPK cascade is often activated in a receptor-dependent manner, but the components that link receptors and MAPK cascades are not known. The focus of the proposed research is to identify the components and mechanisms that connect the receptor SR160/tBRI1 to the systemin-responsive MAPKs. As a first step, systemin-responsive MAPK kinases (MAPKKs) will be identified by employing the yeast two-hybrid system. MAPKKs function directly upstream of MAPKs. Using mutant plants and a tomato protoplast transient transformation system, it will be tested in vivo if these MAPKKs activate MAPKs in response to systemin, and if this requires SR160/tBRI1. It will also be tested, if expression of constitutively active mutants of these MAPKKs results in upregulation of defense genes and increased resistance against herbivorous insects in transgenic plants. Manipulation of MAPK cascades has been realized to be a very promising tool to generate stress resistant crop plants. It is hypothesized that signal transduction for systemin and BRs diverges downstream of the receptor SR160/tBRI1, and that BRs do not activate MAPKs. If BRs do activate MAPKs, these MAPKs will be further characterized. Elucidating the unique mode of signaling via a dual ligand receptor will lead to new insights in signal perception and transduction that is likely to be more common than previously assumed. Taken together, this project will increase the understanding of how signaling mechanisms regulate plant stress responses.The project will involve a postdoctoral research associate, a graduate student and undergraduate students who will be trained in state-of-the-art methods in plant molecular biology. Access to hands-on research experience for undergraduate students is crucial for the development of their careers. Research related to this project will be incorporated in an upper level class for undergraduate and graduate students, taught by the PI. Underrepresented groups will be actively recruited to participate in the project.

害虫给美国和世界各地的农民造成巨大损失。开发对食草昆虫具有更高抗性的改良植物对于增加产量、同时降低生产成本和使用对环境有害的杀虫剂非常重要。理解植物对昆虫防御反应的关键是导致防御基因上调的潜在信号通路。在番茄、马铃薯和其他茄科植物中，对咀嚼昆虫的反应是由一种类似昆虫的短信号肽系统素介导的。系统素对于成功防御昆虫至关重要，其信号通路已明确定义。一个主要的进展是最近确定的系统素受体SR 160，LRR受体激酶。令人惊讶的是，SR 160与番茄油菜素类固醇（BR）受体tBRI 1相同。BR在植物发育中起着重要作用。因此，番茄提供了一个独特的机会来研究受体SR 160/tBRI 1与系统素和BR的相互作用如何导致应激或发育反应。这种双重配体受体以前从未在植物中发现过，可能是一种全新的信号传导方式。它们是MAPK级联的一部分，MAPK级联由三种功能性连接的激酶组成。MAPK级联通常以受体依赖性方式激活，但连接受体和MAPK级联的组分尚不清楚。该研究的重点是确定将受体SR 160/tBRI 1连接到系统蛋白反应性MAPK的组分和机制。作为第一步，系统蛋白反应性MAPK激酶（MAPKKs）将通过采用酵母双杂交系统进行鉴定。MAPKK直接在MAPKs的上游发挥作用。使用突变体植物和番茄原生质体瞬时转化系统，将在体内测试这些MAPKK是否响应于系统素激活MAPKs，以及这是否需要SR 160/tBRI 1。还将测试这些MAPKK的组成型活性突变体的表达是否导致转基因植物中防御基因的上调和对草食性昆虫的抗性增加。操纵MAPK级联已被认为是产生抗逆作物的非常有前途的工具。假设系统素和BR的信号转导在受体SR 160/tBRI 1的下游发散，并且BR不激活MAPK。如果BR确实激活MAPK，则将进一步表征这些MAPK。阐明通过双配体受体的信号传导的独特模式将导致信号感知和转导的新见解，这可能比以前假设的更常见。总的来说，该项目将增加对信号机制如何调节植物胁迫反应的理解。该项目将涉及一名博士后研究助理，一名研究生和一名本科生，他们将接受植物分子生物学最先进方法的培训。获得本科生的实践研究经验对他们的职业发展至关重要。与此项目相关的研究将被纳入由PI教授的本科生和研究生的上层课程。将积极招募代表性不足的群体参与该项目。