title: An invasive Mimosa in India does not adopt the symbionts of its native relatives.
abstract: OBJECTIVE
  The large monophyletic genus Mimosa comprises approx. 500 species, most of which are native to the New World, with Central Brazil being the main centre of radiation. All Brazilian Mimosa spp. so far examined are nodulated by rhizobia in the betaproteobacterial genus Burkholderia. Approximately 10 Mya, transoceanic dispersal resulted in the Indian subcontinent hosting up to six endemic Mimosa spp. The nodulation ability and rhizobial symbionts of two of these, M. hamata and M. himalayana, both from north-west India, are here examined, and compared with those of M. pudica, an invasive species.
  
  
  METHODS
  Nodules were collected from several locations, and examined by light and electron microscopy. Rhizobia isolated from them were characterized in terms of their abilities to nodulate the three Mimosa hosts. The molecular phylogenetic relationships of the rhizobia were determined by analysis of 16S rRNA, nifH and nodA gene sequences.
  
  
  RESULTS
  Both native Indian Mimosa spp. nodulated effectively in their respective rhizosphere soils. Based on 16S rRNA, nifH and nodA sequences, their symbionts were identified as belonging to the alphaproteobacterial genus Ensifer, and were closest to the 'Old World' Ensifer saheli, E. kostiensis and E. arboris. In contrast, the invasive M. pudica was predominantly nodulated by Betaproteobacteria in the genera Cupriavidus and Burkholderia. All rhizobial strains tested effectively nodulated their original hosts, but the symbionts of the native species could not nodulate M. pudica.
  
  
  CONCLUSIONS
  The native Mimosa spp. in India are not nodulated by the Burkholderia symbionts of their South American relatives, but by a unique group of alpha-rhizobial microsymbionts that are closely related to the 'local' Old World Ensifer symbionts of other mimosoid legumes in north-west India. They appear not to share symbionts with the invasive M. pudica, symbionts of which are mostly beta-rhizobial.
authors.affiliation: BNF and Stress Biology Lab., Department of Botany, J.N. Vyas University, Jodhpur-342001, India.
authors.forename: Hukam Singh
authors.initials: HS
authors.lastname: Gehlot
authors.forename: Nisha
authors.initials: N
authors.lastname: Tak
authors.forename: Muskan
authors.initials: M
authors.lastname: Kaushik
authors.forename: Shubhajit
authors.initials: S
authors.lastname: Mitra
authors.forename: Wen-Ming
authors.initials: WM
authors.lastname: Chen
authors.forename: Nicole
authors.initials: N
authors.lastname: Poweleit
authors.forename: Dheeren
authors.initials: D
authors.lastname: Panwar
authors.forename: Neetu
authors.initials: N
authors.lastname: Poonar
authors.forename: Rashmita
authors.initials: R
authors.lastname: Parihar
authors.forename: Alkesh
authors.initials: A
authors.lastname: Tak
authors.forename: Indu Singh
authors.initials: IS
authors.lastname: Sankhla
authors.forename: Archana
authors.initials: A
authors.lastname: Ojha
authors.forename: Satyawada Rama
authors.initials: SR
authors.lastname: Rao
authors.forename: Marcelo F
authors.initials: MF
authors.lastname: Simon
authors.forename: Fabio Bueno Dos
authors.initials: FB
authors.lastname: Reis Junior
authors.forename: Natalia
authors.initials: N
authors.lastname: Perigolo
authors.forename: Anil K
authors.initials: AK
authors.lastname: Tripathi
authors.forename: Janet I
authors.initials: JI
authors.lastname: Sprent
authors.forename: J Peter W
authors.initials: JP
authors.lastname: Young
authors.forename: Euan K
authors.initials: EK
authors.lastname: James
authors.forename: Prasad
authors.initials: P
authors.lastname: Gyaneshwar
mesh_terms: D059827:Agricultural Inoculants / Q000235:genetics; D020561:Alphaproteobacteria / Q000235:genetics / Q000302:isolation & purification; D044822:Biodiversity; D019117:Burkholderia / Q000235:genetics / Q000302:isolation & purification; D049921:Cupriavidus / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D007194:India; D058865:Introduced Species; D031298:Mimosa / Q000382:microbiology*; D010802:Phylogeny; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012231:Rhizobium / Q000502:physiology*; D013020:South America; D013559:Symbiosis
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: Betaproteobacteria; Burkholderia; Cupriavidus; Ensifer; Mimosa hamata; Mimosa himalayana; Mimosa pudica; Thar Desert; arid regions; bacterial symbionts; nitrogen fixation; nodulation; rhizobia