Characterization of the High Affinity Salicylic Acid-Binding Protein 2 in Plant Disease Resistance

智力优势：对一系列病原体的广谱抗药性，称为系统获得性抗药性(SAR)，可通过感染病原体或使用导致SAR的天然化学物质如水杨酸(SA)及其合成功能类似物INA或BTH来激活。水杨酸(SA)是一种重要的内源信号，激活与植物天然免疫相关的各种局部和系统防御反应所需。为了研究SA信号是如何传递的，已鉴定出一种与SA高亲和力结合的烟草SA结合蛋白(SABP)2。SABP2对其首选底物甲基SA(MESA)具有很强的酯酶活性。SA是这种催化的有效抑制剂。这些观察结果与晶体结构分析相一致，晶体结构分析表明，MESA很容易与SABP_2的S活性中心结合，SA也与该活性中心结合。由于SABP2的沉默抑制了抗病，特别是SAR，SABP2可能作为激活SAR和局部防御反应的信号转导途径的一部分，将生物上非活性的MESA转化为活性SA。这一建议的长期目标是破译SABP_2的S(S)在抗病中的作用及其作用机制(S)，从而验证上述假说。为了实现这些目标，正在确定SABP2表达变化对抗病的影响，并正在评估MESA是否是SABP2‘S的天然底物。利用一种新的互补方法并结合突变分析，将探讨SABP_2的S酯酶和SA结合活性的重要性。此外，还将评估SABP2是否参与了移动SAR信号的产生/传输或对该信号的响应。广泛影响：植物病害每年在全球造成约1000亿美元的损失。人们正在开发各种策略来保护植物免受疾病的侵袭。一种方法是诱导植物自身的自然防御。这一策略很有吸引力，因为它可以提供对广泛病原体的保护。开发通过操纵内源植物防御反应来控制疾病的策略对于维持农业生产、改善我们的环境和健康将是非常重要的。这项拟议的研究将为研究生和博士后提供一个刺激的培训环境，让他们接触到大量的生化、分子、遗传、药理学和生理学方法，以解决复杂的生物学问题。此外，该项目将继续为本科生提供机会，在博士后研究员、研究助理或研究生的密切指导下，或在BTI/康奈尔大学暑期实习计划中，亲身体验发现的兴奋。它还使这些研究生和研究生能够发展他们的教学和指导技能。

Intellectual Merit: Broad-spectrum resistance to a wide array of pathogens, know as systemic acquired resistance (SAR), can be activated by infection with a pathogen or treatment with SAR-inducing natural chemicals such as salicylic acid (SA) and its synthetic functional analogues, INA or BTH. Salicylic acid (SA) is an important endogenous signal required for the activation of various local and systemic defense responses associated with plant innate immunity. To investigate how the SA signal is transduced, a tobacco SA-binding protein (SABP)2 that binds SA with high affinity has been identified. SABP2 shows strong esterase activity for methyl SA (MeSA), its preferred substrate. SA is a potent inhibitor of this catalysis. These observations are consistent with crystal structure analyses showing that MeSA readily fits into SABP2's active site and that SA also binds this site. Since silencing of SABP2 suppresses disease resistance, particularly SAR, SABP2 likely functions to convert biologically inactive MeSA into active SA as part of the signal transduction pathways that activate SAR and perhaps also local defense responses. The long-term objectives of this proposal are to decipher SABP2's role(s) in disease resistance and its mechanism(s) of action, thereby testing the above hypothesis. To achieve these objectives, the effect of altered SABP2 expression on disease resistance is being determined and whether or not MeSA is SABP2's natural substrate is being assessed. Using a novel complementation approach together with mutational analysis the importance of SABP2's esterase and SA-binding activities will be addressed. In addition, whether SABP2 is involved in producing/transmitting the mobile SAR signal or responding to this signal will be assessed.Broader Impacts: Plant disease causes an estimated loss worldwide of $100B annually. A variety of strategies are being developed to protect plants against disease. One approach is to induce the plant's own natural defenses. This strategy is attractive since it can provide protection against a broad spectrum of pathogens. The development of strategies that control disease by manipulating endogenous plant defense responses will be very important for sustaining agricultural production and improving our environment and health. The proposed research will provide a stimulating training environment for graduate and postdoctoral students, where they are exposed to a large repertoire of biochemical, molecular, genetic, pharmacological, and physiological approaches to address a complex biological question. In addition, this project will continue to provide undergraduates with opportunities to experience first-hand the excitement of discovery under the close mentorship of a postdoctoral fellow, research associate or graduate student during the academic year or in the BTI/Cornell Summer Internship Program. It also enables these graduate and postgraduate students to develop their teaching and mentoring skills.