REGULATION OF DEFENSE SIGNALING IN TOMATO

这项拟议研究的长期目标是了解 调控植物表达的分子信号途径 防御基因。研究这些途径的一个有用的模型系统是 系统诱导植物抗食草动物防御基因对 由植食性昆虫造成的伤口。在番茄植株中，信号 创伤与全身激活相结合的转导途径 的靶基因由一种由18个氨基酸组成的多肽 系统素。最近的研究结果表明，系统素在 通过上调脂肪酸来源的合成来实现基因活性 荷尔蒙茉莉酸(JA)，一种强大的应激诱导基因调节因子 在几乎所有被检查的植物物种中。这项提案的重点是 利用遗传策略来开发这种模型，并识别 参与系统素介导的信号转导的基因。建议数 实验计划依赖于我们最近在分离番茄方面的成功 不表达防御基因的无防御(Def)突变体 对系统致伤和引诱的反应。四个具体的 提出了目标。首先，现有的两个突变体(Def1和Def2) 将根据与 创伤的主动反应，包括JA的生物合成和伤口的诱导 反应基因。第二，def1和def2的染色体位置 地点将被绘制出来。第三，至少有一个DEF基因参与了系统蛋白- 介导的信号将被克隆。第四，基因筛查将是 进行以鉴定新类别的伤口反应突变体，包括 A)在没有伤口反应的情况下伤口反应是结构性的突变体 B)对信号不敏感的突变体 JA的行动。创伤反应的鉴定和表征 突变体将提供对遗传和生化复杂性的洞察 植物防御信号通路。分子克隆及其后续研究 对相关基因的分析应该有助于理解 在植物和动物中运行的基本生物过程， 包括多肽信号的生物合成和感知， 脂肪酸信号级联调控和细胞间通讯 在东道主防守期间。

The long-term goal of this proposed research is to understand the molecular signaling pathways that control the expression of plant defense genes. A useful model system for studying these pathways is the systemic induction of plant anti-herbivore defense genes in response to wounds inflicted by phytophagous insects. In tomato plants, the signal transduction pathway that couples wounding to the systemic activation of target genes is regulated by an 18-amino-acid peptide called systemin. Recent results indicate that systemin exerts its effects on gene activity by up-regulating the synthesis of the fatty acid-derived hormone jasmonic acid (JA), a potent regulator of stress-induced genes in virtually all plant species examined. The focus of this proposal is to exploit genetic strategies to develop this model and to identify genes involved in systemin-mediated signal transduction. The proposed experimental plan relies on our recent success in isolating tomato defenseless (def) mutants that fail to express defense genes in response to wounding and elicitation by systemin. Four specific objectives are proposed. First, two existing mutants (def1 and def2) will be characterized with regard to parameters associated with an active wound response including JA biosynthesis and induction of wound response genes. Second, the chromosomal position of the DEF1 and DEF2 loci will be mapped. Third, at least one DEF gene involved in systemin- mediated signaling will be cloned. And fourth, genetic screens will be performed to identify new classes of wound response mutants including a) mutants in which the wound response is constitutive in the absence of wound stimuli and b) mutants that are insensitive to the signaling action of JA. Identification and characterization of wound response mutants will provide insight into the genetic and biochemical complexity of plant defense signaling pathways. Molecular cloning and subsequent analysis of the genes involved should contribute to an understanding of basic biological processes that operate in both plants and animals, including the biosynthesis and perception of polypeptide signals, the regulation of fatty acid signaling cascades, and cell-cell communication during host defense.