title: Never too many? How legumes control nodule numbers.
abstract: Restricted availability of nitrogen compounds in soils is often a major limiting factor for plant growth and productivity. Legumes circumvent this problem by establishing a symbiosis with soil-borne bacteria, called rhizobia that fix nitrogen for the plant. Nitrogen fixation and nutrient exchange take place in specialized root organs, the nodules, which are formed by a coordinated and controlled process that combines bacterial infection and organ formation. Because nodule formation and nitrogen fixation are energy-consuming processes, legumes develop the minimal number of nodules required to ensure optimal growth. To this end, several mechanisms have evolved that adapt nodule formation and nitrogen fixation to the plant's needs and environmental conditions, such as nitrate availability in the soil. In this review, we give an updated view on the mechanisms that control nodulation.
authors.affiliation: Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium.
authors.forename: Virginie
authors.initials: V
authors.lastname: Mortier
authors.forename: Marcelle
authors.initials: M
authors.lastname: Holsters
authors.forename: Sofie
authors.initials: S
authors.lastname: Goormachtig
mesh_terms: D007887:Fabaceae / Q000382:microbiology / Q000502:physiology*; D006706:Homeostasis; D009566:Nitrates / Q000378:metabolism; D009586:Nitrogen Fixation / Q000502:physiology*; D055170:Plant Root Nodulation / Q000502:physiology*; D012231:Rhizobium / Q000502:physiology*; D053204:Root Nodules, Plant / Q000382:microbiology*; D015398:Signal Transduction; D013559:Symbiosis
chemical_list: D009566:Nitrates