Beckers G J M, Spoel S H
Plant Biochemistry and Molecular Biology Unit, Department of Plant Physiology, RWTH - Aachen University, Worringerweg 1, 52074 Aachen, Germany.
Plant Biol (Stuttg). 2006 Jan;8(1):1-10. doi: 10.1055/s-2005-872705.
Plant defences against pathogens and herbivorous insects form a comprehensive network of interacting signal transduction pathways. The signalling molecules salicylic acid (SA) and jasmonic acid (JA) play important roles in this network. SA is involved in signalling processes providing systemic acquired resistance (SAR), protecting the plant from further infection after an initial pathogen attack. SAR is long-lasting and provides broad spectrum resistance to biotrophic pathogens that feed on a living host cell. The regulatory protein NPR1 is a central positive regulator of SAR. SA-activated NPR1 localizes to the nucleus where it interacts with TGA transcription factors to induce the expression of a large set of pathogenesis-related proteins that contribute to the enhanced state of resistance. In a distinct signalling process, JA protects the plant from insect infestation and necrotrophic pathogens that kill the host cell before feeding. JA activates the regulatory protein COI1 that is part of the E3 ubiquitin ligase-containing complex SCFCOI1, which is thought to derepress JA-responsive genes involved in plant defence. Both synergistic and antagonistic interactions have been observed between SA- and JA-dependent defences. NPR1 has emerged as a critical modulator of cross-talk between the SA and JA signal and is thought to aid in fine tuning defence responses specific to the encountered attacker. Here we review SA- and JA-dependent signal transduction and summarize our current understanding of the molecular mechanisms of cross-talk between these defences.
植物抵御病原体和食草昆虫的防御机制构成了一个由相互作用的信号转导途径组成的复杂网络。信号分子水杨酸（SA）和茉莉酸（JA）在这个网络中发挥着重要作用。SA参与了提供系统获得性抗性（SAR）的信号传导过程，在病原体初次攻击后保护植物免受进一步感染。SAR具有持久性，能为以活宿主细胞为食的生物营养型病原体提供广谱抗性。调节蛋白NPR1是SAR的核心正向调节因子。SA激活的NPR1定位于细胞核，在那里它与TGA转录因子相互作用，诱导大量病程相关蛋白的表达，这些蛋白有助于增强抗性状态。在一个不同的信号传导过程中，JA保护植物免受昆虫侵害和坏死营养型病原体的侵害，这些病原体在取食前会杀死宿主细胞。JA激活调节蛋白COI1，它是含有E3泛素连接酶的复合物SCFCOI1的一部分，该复合物被认为能解除对参与植物防御的JA反应基因的抑制。在SA依赖型防御和JA依赖型防御之间已观察到协同和拮抗相互作用。NPR1已成为SA和JA信号之间相互作用的关键调节因子，被认为有助于微调针对所遇到攻击者的特异性防御反应。在这里，我们综述了SA和JA依赖型信号转导，并总结了我们目前对这些防御之间相互作用分子机制的理解。
