Characterization of the Salicylic Acid Signal Transduction Pathway in Plant Defense Responses

越来越多的证据表明，水杨酸（Salicylic Acid， SA）是激活和/或增强局部和全身抗性防御反应所需的重要内源信号。本研究将继续研究SA信号转导通路的成分，这些成分导致防御反应的激活，特别是致病相关（PR）基因的表达。将继续追求两个主要目标：1)表征SA信号转导改变的拟南芥突变体；2)表征可能参与SA反应的PR-2d启动子结合蛋白。遗传、分子和生化方法的结合正在被用于拟南芥和烟草（烟草）。遗传方法包括分离和鉴定拟南芥突变体以及构建转基因拟南芥和烟草植株，以鉴定和表征SA/防御信号通路的顺式和反式成分。分子方法包括克隆、DNA测序、Southern、northern和western blotting、酵母单杂交和双杂交筛选、定点诱变和重组蛋白的生产。蛋白质纯化、酶分析和蛋白质- dna或蛋白质-蛋白质相互作用的表征代表了一些生化工具，这些工具被用来进一步表征潜在的途径成分。病毒（烟草花叶病毒（TMV）和萝卜皱病毒（TCV））和细菌（丁香假单胞菌、番茄、黄斑菌或烟粉虱）病原体都被用来激活防御途径并研究其成分。抗性植物和易感植物之间的一个关键区别是及时识别入侵病原体和快速有效地激活宿主防御。因此，研究植物抗病性的主要目的之一是识别和表征对导致这些宿主防御激活的信号转导过程至关重要的植物成分。鉴定和表征这些成分对我们了解抗病机制至关重要。此外，通过遗传和分子方法对它们进行操纵，为增强植物抗病性提供了令人兴奋的前景。

Klessig 9723952 Characterization of the Salicylic Acid Signal Transduction Pathway in Plant Defense Responses An ever increasing body of evidence indicates that salicylic acid (SA) is an important endogenous signal required for activation and/or potentiation of defense responses in both local and systemic resistance. This research will continue studies to identify, clone, and characterize the components of the SA signal transduction pathway(s) which lead to activation of defense responses, in particular pathogenesis-related (PR) gene expression. Two major objectives will continue to be pursued: i) characterization of Arabidopsis mutants with altered SA signal transduction and ii) characterization of PR-2d promoter binding proteins potentially involved in SA responsiveness. A combination of genetic, molecular, and biochemical approaches are being utilized in Arabidopsis and Nicotiana tabacum (tobacco). Genetic approaches include isolation and characterization of Arabidopsis mutants and construction of transgenic Arabidopsis and tobacco plants to identify and characterize cis- and trans-acting components of the SA/defense signaling pathway(s). Molecular approaches include cloning, DNA sequencing, Southern, northern, and western blotting, yeast one- and two-hybrid screening, site-directed mutagenesis, and production of recombinant proteins. Protein purification, enzyme analysis, and characterization of protein-DNA or protein-protein interactions represent some of' the biochemical tools that are being used to further characterize potential pathway components. Both viral (tobacco mosaic virus TMV and turnip crinkle virus TCV ) and bacterial (Pseudomonas syringae pv tomato, maculicola, or tabaci) pathogens are being used to activate the defense pathway(s) and study its components. A key difference between resistant and susceptible plants is the timely recognition of the invading pathogen and the rapid and effective activation of host defenses. Thus, one of the major aims of stu dying plant disease resistance is to identify and characterize plant components which are crucial for the signal transduction processes leading to activation of these host defenses. Identification and characterization of these components are essential to our understanding of the mechanisms of disease resistance. Furthermore, their manipulation through genetic and molecular approaches offers the exciting prospect of enhancing plant disease resistance.