Genetic Dissection of Systemic Acquired Resistance in Arabidopsis

9419301羔羊试图感染非病原体或无毒病原体，不仅会导致局部的过敏性抗性，还会导致系统获得性抗性的发展，在这种抗性中，对通常毒力强的病原菌的抗性会在整个植物中产生。SAR的建立与细胞壁羟脯氨酸水平和过氧化物酶活性的增加以及一系列防御基因的系统表达有关，但这些防御机制在SAR中的功能意义尚未确定。全身信号的诱导与局部过敏性坏死相关，水杨酸是SAR机制的一个组成部分，尽管它似乎不是全身信号。已建立了一种通过预先接种遗传上明确定义的细菌病原体来诱导拟南芥(A.thaliana)SAR的生物诱导系统。该系统显示了烟草和黄瓜中具有良好特性的SAR的许多特征，并且已经开发了一个易于处理的突变筛选，在初步研究中，从11,000株诱变植株中分离出10个证实的突变体，这些突变体表现出局部超敏抗性，但未能产生SAR。现在建议利用拟南芥现有的工具来进行SAR的遗传解剖，具体目标如下：1.进一步研究生物诱导的拟南芥SAR的生理特性。2.对抗性缺陷突变体进行分析，以确定局部过敏性坏死在SAR生物诱导中的作用。3.进一步从拟南芥生态型Col-O诱变种子和生态型Wassilewski ja T-DNA标记系中筛选出SAR突变体。4.关于显性、互补性和图谱位置的这一发展中的突变体集合的特征。5.利用这些突变体，通过对基因作用序列的遗传和生理分析，描绘出生物诱导SAR的信号通路。6.SAR基因的分子克隆，重点放在已确定T-DNA标记等位基因的关键基因上。

9419301 Lamb Attempted infection by a non-pathogen or an avirulent form of a pathogen can result not only in localized hypersensitive resistance, but also in the development of systemic acquired resistance (SAR) in which resistance to normally virulent pathogens develops throughout the plant. Establishment of SAR is associated with increases in cell wall hydroxyproline levels and peroxidase activity, together with the system expression of a subset of defense genes, but the functional significance of these defenses in SAR has not been established. Induction of the systemic signals is correlated with localized hypersensitive necrosis, and salicylic acid is a component of the SAR mechanism although it does not appear to be the systemic signal. A system has been extablished for biological induction of SAR in Arabidopsis (A. thaliana) by pre-challenge inoculation with genetically well-defined bacterial pathogens. This system exhibits many of the features of well-characterized SAR in tobacco and cucumber, and a tractable mutant screen has been developed that in preliminary studies resulted in the isolation, from a population of 11,000 mutagenized plants, of 10 confirmed mutants that exhibit local hypersensitive resistance but fail to develop SAR. It is now proposed to exploit the tools available with Arabidopsis for genetic dissection of SAR with the following specific objectives: 1. Further physiological characterization of biologically induced SAR in Arabidopsis. 2. Analysis of hypersensitive resistance-defective mutants to define the role of localized hypersensitive necrosis in the biological induction of SAR. 3. Further develop the collection of SAR mutants from mutagenized seeds of Arabidospsis ecotype Col-O and T- DNA taggd lines of ecotype Wassilewskija. 4. Characterization of this developing collection of mutants with respect to dominance, complementation, and map position. 5. Use these mutants to delineate the signal pathway for biological induction of SAR by genetic and physiological analysis of the sequence of gene action. 6. Molecular cloning of SAR genes with an initial emphasis on key genes for which T-DNA tagged alleles have been identified.