Cooper J E
Department of Applied Plant Science, Queen's University Belfast, Newforge Lane, Belfast, United Kingdom.
J Appl Microbiol. 2007 Nov;103(5):1355-65. doi: 10.1111/j.1365-2672.2007.03366.x.
The exchange of chemical signals between soil bacteria (rhizobia) and legumes has been termed a molecular dialogue. As initially conceived in the early 1990s, it involved two main groups of molecules: nod gene-inducing flavonoids from plants and the mitogenic lipochito-oligosaccharide Nod factors of rhizobia. This review considers how subsequent research revealed the existence of a more complex set of interactions, featuring expanded roles for the original participants and contributions from additional plant and bacterial metabolites. Rhizobia respond to chemoattractants and growth-enhancing compounds in root exudates, and several plant nonflavonoids possess nod gene-inducing properties. Expression of non-nod genes is induced by flavonoids; these include encoders of a type I secreted protein and the entire type III, and possibly also type IV, secretion systems. Many other genes and proteins in rhizobia are flavonoid-inducible but their functions are largely unknown. Rhizobia produce far more Nod factor variants than was previously envisaged and their structures can be influenced by the pH of the environment. Other symbiotically active compounds or systems of rhizobia, some of them universally present, are: the surface polysaccharides, quorum-sensing N-acyl homoserine lactones, plant growth-promoting lumichrome and two-component regulatory systems.
土壤细菌（根瘤菌）与豆科植物之间的化学信号交换被称为分子对话。正如20世纪90年代初最初设想的那样，它涉及两大类分子：植物产生的诱导结瘤基因的类黄酮和根瘤菌的促有丝分裂脂壳寡糖结瘤因子。本文综述了后续研究如何揭示了一组更为复杂的相互作用的存在，其特点是原始参与者的作用得到扩展，以及其他植物和细菌代谢产物的贡献。根瘤菌对根际分泌物中的化学引诱剂和生长促进化合物作出反应，几种植物非类黄酮具有诱导结瘤基因的特性。非结瘤基因的表达受类黄酮诱导；这些基因包括一种I型分泌蛋白的编码基因以及整个III型，可能还有IV型分泌系统的编码基因。根瘤菌中的许多其他基因和蛋白质也受类黄酮诱导，但其功能大多未知。根瘤菌产生的结瘤因子变体比以前设想的要多得多，其结构会受到环境pH值的影响。根瘤菌的其他共生活性化合物或系统，其中一些普遍存在，包括：表面多糖、群体感应N-酰基高丝氨酸内酯、促进植物生长的光色素和双组分调节系统。
