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

自1985年以来，我们小组一直在研究发病机制相关（PR）蛋白的各个方面，包括它们的位置、它们在抗病中的功能和它们的合成。我们和其他几个实验室最近的工作强烈表明，水杨酸（SA）在植物疾病防御反应中起着重要的信号作用，包括诱导PR基因。我们建议继续进行几方面的研究，以帮助进一步确定SA的信号作用，并确定这一信号转导途径的组成部分。在烟草花叶病毒（TMV）侵染后的抗性栽培中，除了游离SA外，还发现了一种糖苷化形式（SAG）。这两种形式的SA在系统性获得性耐药（SAR）的发展和表现中的作用将被解决。第二项研究涉及到顺式元件(s)和反式作用因子的表征，这些因子介导sa诱导的烟草酸性PR-2（葡聚糖酶）基因的转录激活。在研究的第三条线拟南芥sa不敏感（SAIN）突变体将被分离和表征。SAIN突变体的阳性选择将利用农杆菌的tms2基因与SA诱导的烟草PR-1或PR-2启动子融合。这些研究将有助于更好地理解在防御反应中SA信号是如何产生、修改、感知和转导的。它们也可能提供对其他sa介导的生理变化的作用机制的见解，并应该提供一个机会来比较植物与微生物和动物的信号转导。* * *

9310371 Klessig Since 1985 our group has been studying various aspects of pathogenesis related (PR) proteins including their location, their function in disease resistance and their synthesis. Recent work in our, as well as several other, laboratories strongly suggests that salicylic acid (SA) plays an important signaling role in plant disease defense responses including the induction of PR genes. We propose to continue several lines of study to help further define SA's signaling role and identify components of this signal transduction pathway. In addition to free SA, a glucosidated form (SAG) is found in resistant cultivate of tobacco after infection with tobacco mosaic virus (TMV). The roles of these two forms of SA in the development and manifestation of systemic acquired resistance (SAR) will be addressed. The second line of study involves characterization of the cis element (s) and trans-acting factors which mediate SA-induced transcriptional activation of the acidic PR-2 (glucanase) gene of tobacco. In the third line of study SA-insensitive (SAIN) mutants of Arabidopsis will be isolated and characterized. Positive selection of SAIN mutants will utilize the tms2 gene of Agrobacterium tumefaciens fused to the SA- inducible tobacco PR-1 or PR-2 promoters. %%% These studies should lead to a better understanding of how the SA signal is generated, modified, perceived and transduced during defense responses. They may also provide insights into the mechanisms (s) of action of other SA-mediated physiological changes and should provide an opportunity to compare signal transduction in plants with that in microbes and animals. ***