Cellular and Molecular Life Sciences

, Volume 68, Issue 8, pp 1327–1339

Rhizobial measures to evade host defense strategies and endogenous threats to persistent symbiotic nitrogen fixation: a focus on two legume-rhizobium model systems

Multi-author review

DOI: 10.1007/s00018-011-0650-5

Cite this article as:
Saeki, K. Cell. Mol. Life Sci. (2011) 68: 1327. doi:10.1007/s00018-011-0650-5

Abstract

The establishment and maintenance of rhizobium–legume symbioses require a sequence of highly regulated and coordinated events between the organisms. Although the interaction is mutually beneficial under nitrogen-limited conditions, it can resemble a pathogenic infection at some stages. Some host legumes mount defense reactions, including the production of reactive oxygen species (ROS) and defensin-like antimicrobial compounds. To subvert these host defenses, the infecting rhizobial cells can use measures to passively protect themselves and actively modulate host functions. This review first describes the establishment and maintenance of active nodules, as well as the external and endogenous attack and threat stages. Next, recent studies of ROS scavenging enzymes, the BacA protein originally found in Sinorhizobium meliloti, and the type III/IV secretion systems are discussed, with a focus on two legume–rhizobium model systems.

Keywords

Nitrogen-fixing mutualismHost defenseReactive oxygen speciesType III secretion systemType IV secretion systemBacA protein

Copyright information

© Springer Basel AG 2011

Authors and Affiliations

  1. 1.Department of Biological Sciences, Faculty of ScienceNara Women’s UniversityNaraJapan