RUI: Function of Lipoxygenase in the Arabidopsis Pathogen Defense Response

脂氧合酶具有生物学意义，因为该反应的主要产物脂肪酸氢过氧化物酶通常被代谢成已知或可疑的调节活性分子，这些分子可能在应激反应中起作用。本研究的目的是了解脂氧合酶在拟南芥对致病性假单胞菌的防御反应中的作用。本实验验证了一种假说，即脂氧合酶在受到无害病原体攻击后迅速诱导，是抵抗疾病所必需的，并在茉莉酸的合成中起作用，茉莉酸可以调节宿主的防御反应。将在过量产生脂氧合酶cDNA的转基因植物或脂氧合酶活性降低的反义植物中测试病原体的防御反应。这些实验将提供证据，证明在病原体攻击时快速诱导脂氧合酶是有效的宿主防御反应的重要组成部分。通过原位杂交、免疫细胞化学和脂氧合酶启动子/GUS融合分析，分别确定了脂氧合酶mRNA、蛋白质积累和基因表达的空间格局，以响应病原体的攻击。最后，脂氧合酶诱导和茉莉酸产生的动力学响应病原体的攻击将被测量，以确定这两个物种在信号传导中的关系。这些实验的完成将导致对脂肪加氧酶在病原体防御中的作用的重要见解。

Lipoxygenases are of biological interest because the primary products of the reaction, fatty acid hydroperoxidase, are typically metabolized into molecules of known or suspected regulatory activity which may function in the response to stress. The goal of the proposed research is to understand the function of lipoxygenase in the Arabidopsis defense response to pathogenic Pseudomonads. The proposed experiments test the working hypothesis that lipoxygenase, rapidly induced upon attack by an avirulent pathogen, is required for disease resistance, and functions in the synthesis of jasmonic acid which serves to regulate the host defense response. The pathogen defense response will be tested intransgenic plants which either over-produce the lipoxygenase cDNA or in antisense plants with reduced levels of lipoxygenase activity. These experiments will provide evidence that the rapid induction of lipoxygenase upon pathogen attack is an important component of an effective host defense response. The spatial patterns of lipoxygenase mRNA, protein accumulation and gene expression will be determined in response to pathogen attack by in situ hybridization, immunocytochemistry and analysis of lipoxygenase promoter/GUS fusions, respectively. Finally, the kinetics of both lipoxygenase induction and jasmonate production inresponse to pathogen attack will be measured to determine the relationship of these two species in signalling. Completion of these experiments will lead to important insights into the role of lipoxygenase in pathogen defense.