title: The Role of Plant Innate Immunity in the Legume-Rhizobium Symbiosis.
abstract: A classic view of the evolution of mutualism is that it derives from a pathogenic relationship that attenuated over time to a situation in which both partners can benefit. If this is the case for rhizobia, then one might uncover features of the symbiosis that reflect this earlier pathogenic state. For example, as with plant pathogens, it is now generally assumed that rhizobia actively suppress the host immune response to allow infection and symbiosis establishment. Likewise, the host has retained mechanisms to control the nutrient supply to the symbionts and the number of nodules so that they do not become too burdensome. The open question is whether such events are strictly ancillary to the central symbiotic nodulation factor signaling pathway or are essential for rhizobial host infection. Subsequent to these early infection events, plant immune responses can also be induced inside nodules and likely play a role in, for example, nodule senescence. Thus, a balanced regulation of innate immunity is likely required throughout rhizobial infection, symbiotic establishment, and maintenance. In this review, we discuss the significance of plant immune responses in the regulation of symbiotic associations with rhizobia, as well as rhizobial evasion of the host immune system.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Yangrong
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Division of Plant Sciences, C.S. Bond Life Sciences Center, and Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211.
authors.forename: Morgan K
authors.initials: MK
authors.lastname: Halane
authors.affiliation: Division of Plant Sciences, C.S. Bond Life Sciences Center, and Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211.
authors.forename: Walter
authors.initials: W
authors.lastname: Gassmann
authors.affiliation: Division of Plant Sciences, C.S. Bond Life Sciences Center, and Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211.|Division of Biochemistry, University of Missouri, Columbia, Missouri 65211; email: staceyg@missouri.edu.
authors.forename: Gary
authors.initials: G
authors.lastname: Stacey
mesh_terms: D005075:Biological Evolution; D007887:Fabaceae / Q000276:immunology / Q000382:microbiology*; D007113:Immunity, Innate; D008070:Lipopolysaccharides / Q000378:metabolism / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012231:Rhizobium / Q000502:physiology*; D015398:Signal Transduction; D013559:Symbiosis / Q000276:immunology / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species
keywords: legumes; plant innate immunity; rhizobia; symbiosis