REGULATION OF DEFENSE SIGNALING IN TOMATO

这项拟议研究的长期目标是了解 控制植物表达的分子信号通路 防御基因 研究这些途径的一个有用的模型系统是 系统诱导植物抗草食动物防御基因 由植食性昆虫造成的伤口。 在番茄植物中， 将损伤与系统激活偶联的转导途径 靶基因的表达受一种18个氨基酸的肽的调控， 系统素 最近的研究结果表明，系统素发挥其影响， 基因活性通过上调脂肪酸衍生的 茉莉酸（JA）激素，一种强有力的应激诱导基因调节剂 在几乎所有的植物物种检查。 这项建议的重点是 利用遗传策略来开发这个模型， 参与系统蛋白介导的信号转导的基因。拟议 实验计划依赖于我们最近成功地分离出番茄 无防御（def）突变体，不能表达防御基因， 对伤害和系统素诱导的反应。 四个具体 提出了目标。 首先，两个现有的突变体（def1和def2） 将根据与 主动伤口反应，包括JA生物合成和伤口诱导 反应基因第二，DEF 1和DEF 2的染色体位置 将绘制基因座。 第三，至少一个DEF基因参与系统素- 将克隆介导的信号传导。 第四，基因筛查将 用于鉴定新的创伤反应突变体类型，包括 a）突变体，其中创伤反应是组成性的， 和B）对信号传导不敏感的突变体 JA的行动。 伤口反应的识别和表征 突变体将提供深入了解遗传和生化复杂性 植物防御信号通路的一个重要组成部分 分子克隆及后续 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， 调节脂肪酸信号级联和细胞间通讯 在防御过程中。

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.