植物免疫と細胞壁(<特集>情報処理システムとしての植物細胞壁)

抄録

Plants evolved a multilayered immune system against pathogenic microbes and insect herbivores. Plant cell wall and apoplast consist an essential component of this immune system as the first line of defense, where plant cells contact with these invaders. Plant immune responses can be triggered by the recognition of conserved microbial signature called MAMP (Microbe-associated molecular pattern) at the apoplastic region. In the plant immune system, plant cell wall can function as a barrier against invasion and also a sensor for pathogen attack. Alteration of cell wall integrity and the generation of cell wall-derived fragments are both considered to induce plant immune responses. These MAMPs and damage signals (including DAMPs, Damage-associated molecular patterns) trigger the generation of anti-microbial compounds in the apoplastic region and the reinforcement of the cell wall. On the other hand, pathogenic microbes evolved effector systems to inhibit/escape from the host defense machinery and surveillance system. These battles at the molecular level between plants and microbes often take place in the apoplast. It has also been becoming clear that the plant cell walls are involved in the detection of and defense responses against insect herbivores. Thus plant cell wall and apoplast are not only important as the battle field where host plants and invading organisms compete for the detection and defense responses but also important as a sensor and barrier for these invaders.