Harrison Maria J
Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA.
Annu Rev Microbiol. 2005;59:19-42. doi: 10.1146/annurev.micro.58.030603.123749.
Many microorganisms form symbioses with plants that range, on a continuous scale, from parasitic to mutualistic. Among these, the most widespread mutualistic symbiosis is the arbuscular mycorrhiza, formed between arbuscular mycorrhizal (AM) fungi and vascular flowering plants. These associations occur in terrestrial ecosystems throughout the world and have a global impact on plant phosphorus nutrition. The arbuscular mycorrhiza is an endosymbiosis in which the fungus inhabits the root cortical cells and obtains carbon provided by the plant while it transfers mineral nutrients from the soil to the cortical cells. Development of the symbiosis involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells. The aim of this review is to explore the current understanding of the signals and signaling pathways used by the symbionts for the development of the AM symbiosis. Although the signal molecules used for initial communication are not yet known, recent studies point to their existence. Within the plant, there is evidence of arbuscular mycorrhiza-specific signals and of systemic signaling that influences phosphate-starvation responses and root development. The landmark cloning of three plant signaling proteins required for the development of the symbiosis has provided the first insights into a signaling pathway that is used by AM fungi and by rhizobia for their symbiotic associations with legumes.
许多微生物与植物形成共生关系，其范围在从寄生到互利共生的连续尺度上变化。其中，最广泛存在的互利共生关系是丛枝菌根，它由丛枝菌根（AM）真菌与维管开花植物形成。这些共生关系存在于世界各地的陆地生态系统中，对植物磷营养具有全球影响。丛枝菌根是一种内共生关系，真菌栖息在根皮层细胞中，获取植物提供的碳，同时将矿物质养分从土壤转移到皮层细胞。共生关系的发展涉及共生双方的分化，以在根细胞内形成新的共生界面。本综述的目的是探讨目前对共生体用于丛枝菌根共生关系发展的信号和信号通路的理解。尽管用于初始交流的信号分子尚不清楚，但最近的研究表明它们的存在。在植物体内，有证据表明存在丛枝菌根特异性信号以及影响磷饥饿反应和根系发育的系统性信号。共生关系发展所需的三种植物信号蛋白的标志性克隆，首次为AM真菌和根瘤菌与豆科植物共生关系所使用的信号通路提供了见解。
