title: Biogeography of nodulated legumes and their nitrogen-fixing symbionts.
abstract: Contents 40 I. 40 II. 41 III. 44 IV. 48 V. 49 VI. 49 VII. 52 VIII. 53 53 References 53 SUMMARY: In the last decade, analyses of both molecular and morphological characters, including nodulation, have led to major changes in our understanding of legume taxonomy. In parallel there has been an explosion in the number of genera and species of rhizobia known to nodulate legumes. No attempt has been made to link these two sets of data or to consider them in a biogeographical context. This review aims to do this by relating the data to the evolution of the two partners: it highlights both longitudinal and latitudinal trends and considers these in relation to the location of major land masses over geological time. Australia is identified as being a special case and latitudes north of the equator as being pivotal in the evolution of highly specialized systems in which the differentiated rhizobia effectively become ammonia factories. However, there are still many gaps to be filled before legume nodulation is sufficiently understood to be managed for the benefit of a world in which climate change is rife.
authors.affiliation: Division of Plant Sciences, University of Dundee at JHI, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Janet I
authors.initials: JI
authors.lastname: Sprent
authors.affiliation: School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, 6150, Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: Ardley
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Euan K
authors.identifier: http://orcid.org/0000-0001-7969-6570
authors.initials: EK
authors.lastname: James
mesh_terms: D044822:Biodiversity; D005075:Biological Evolution; D007887:Fabaceae / Q000145:classification / Q000382:microbiology / Q000502:physiology*; D009586:Nitrogen Fixation; D058974:Phylogeography; D053204:Root Nodules, Plant / Q000378:metabolism / Q000382:microbiology; D013559:Symbiosis
keywords: ammonia factories; evolution of nodulation; legume flowers; legume taxonomy; nitrogen fixation; nodule morphology and structure; rhizobial diversity; terminally differentiated bacteroids