Nodulation of the neotropical genus Calliandra by alpha or betaproteobacterial symbionts depends on the biogeographical origins of the host species

• Published in: Brazilian journal of microbiology Vol. 52; no. 4; pp. 2153 - 2168
• Main Authors: Zilli, Jerri Édson, de Moraes Carvalho, Camila Pereira, de Matos Macedo, Aline Vieira, de Barros Soares, Luis Henrique, Gross, Eduardo, James, Euan Kevin, Simon, Marcelo Fragomeni, de Faria, Sergio Miana
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-12-2021; Springer Nature B.V
• Subjects: Acidic soils; Agroforestry; Biomedical and Life Sciences; Brazil; Burkholderiaceae; Dispersal; DNA, Bacterial - genetics; Endemic species; Environmental Microbiology - Research Paper; Fabaceae - microbiology; Food Microbiology; Host Microbial Interactions; Indigenous species; Life Sciences; Medical Microbiology; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Molecular structure; Mycology; Nodulation; Nodules; Paraburkholderia; Phylogeny; RecA protein; Rhizobium; Rhizobium - genetics; RNA, Ribosomal, 16S - genetics; Root Nodules, Plant - microbiology; rRNA 16S; Sequence Analysis, DNA; Soil Microbiology; Species diversity; Structural analysis; Symbionts; Symbiosis; Brazil; Central America; spp; Nodule anatomy; Nodulating-bacteria; Nodulation profile; Paraburkholderia; Rhizobium; Calliandra spp
• ISSN: 1517-8382; 1678-4405
• DOI: 10.1007/s42770-021-00570-8

The neotropical genus 
Calliandra 
is of great importance to ecology and agroforestry, but little is known about its nodulation or its rhizobia. The nodulation of several species from two restricted diversity centres with native/endemic species (Eastern Brazil and North-Central America) and species widespread in South America, as well as their nodule structure and the molecular characterization of their rhizobial symbionts based on phylogeny of the 16S rRNA,
recA
and
nodC
gene, is reported herein. Species representative of different regions were grown in Brazilian soil, their nodulation observed, and their symbionts characterized. 
Calliandra
 nodules have anatomy that is typical of mimosoid nodules regardless of the microsymbiont type. The rhizobial symbionts differed according to the geographical origin of the species, i.e. Alphaproteobacteria (
Rhizobium
) were the exclusive symbionts from North-Central America, Betaproteobacteria (
Paraburkholderia
) from Eastern Brazil, and a mixture of both nodulated the widespread species. The symbiont preferences of
Calliandra
 species are the result of the host co-evolving with the “local” symbiotic bacteria that thrive in the different edaphoclimatic conditions, e.g. the acidic soils of NE Brazil are rich in acid-tolerant 
Paraburkholderia
, whereas those of North-Central America are typically neutral-alkaline and harbour 
Rhizobium
. It is hypothesized that the flexibility of widespread species in symbiont choice has assisted in their wider dispersal across the neotropics.