New Betaproteobacterial Rhizobium Strains Able To Efficiently Nodulate Parapiptadenia rigida (Benth.) Brenan

Abstract

c Among the leguminous trees native to Uruguay, Parapiptadenia rigida (Angico), a Mimosoideae legume, is one of the most promising species for agroforestry. Like many other legumes, it is able to establish symbiotic associations with rhizobia and belongs to the group known as nitrogen-fixing trees, which are major components of agroforestry systems. Information about rhizobial symbionts for this genus is scarce, and thus, the aim of this work was to identify and characterize rhizobia associated with P. rigida. A collection of Angico-nodulating isolates was obtained, and 47 isolates were selected for genetic studies. According to enterobacterial repetitive intergenic consensus PCR patterns and restriction fragment length polymorphism analysis of their nifH and 16S rRNA genes, the isolates could be grouped into seven genotypes, including the genera Burkholderia, Cupriavidus, and Rhizobium, among which the Burkholderia genotypes were the predominant group. Phylogenetic studies of nifH, nodA, and nodC sequences from the Burkholderia and the Cupriavidus isolates indicated a close relationship of these genes with those from betaproteobacterial rhizobia (beta-rhizobia) rather than from alphaproteobacterial rhizobia (alpha-rhizobia). In addition, nodulation assays with representative isolates showed that while the Cupriavidus isolates were able to effectively nodulate Mimosa pudica, the Burkholderia isolates produced white and ineffective nodules on this host. Parapiptadenia rigida (Benth.) Brenan, which is also known by its vernacular names Angico, Angico vermelho, and Gurucaia, belongs to the tribe Mimoseae within the Mimosoideae subfamily of the Fabaceae (Leguminosae) (5,26,27,38). It is native to southern South America (south Brazil, Argentina, Paraguay, and Uruguay), where it can be found as one of the tallest species in the canopy of riverside forests, where it can reach heights of approximately 30 m and breast height diameters of from 30 to 120 cm. The wild tree is currently exploited by the locals owing to its economic value, although commercial cultivation of P. rigida has never been developed in Uruguay. Its main economic value is based on the excellence of its timber, which is appreciated for its high density (0.74 to 0.98 g/cm 3 ) and natural durability (26). It is mostly used for high-quality furniture, house construction, carpentry, and fire wood, and the reddish brown parquet floors built with its timber are deeply valued. Other reported uses are as a source of gums, tannins, and essential oils as well as for medicinal purposes (14, 37). Indeed, it is much appreciated by people in Brazil for its medicinal qualities and is duly included in the Brazilian Pharmacopeia.This heliophyte species is part of the forest succession during the first steps of recovery of degraded areas, as it can grow under adverse and low-soil-fertility conditions. Its ability to establish a nitrogen-fixing association with rhizobia is well documented (18)(19)(20)32), but information about the rhizobia associated with this leguminous...

Genetic Variability and Symbiotic Efficiency of Erythrina velutina Willd. Root Nodule Bacteria from the Semi-Arid Region in Northeastern Brazil

“…Amplification of an intragenic nodA gene fragment using a NodAforB and NodArevB primer set can exhibit positive results, with sizes ranging from 245 to 800 bp (Klonowska et al, 2012;Taulé et al, 2012). So, the amplification of different molecular size amplicons found in the present study can be considered positive for both bacteria, indicating that ESA 71 exhibits a nodA gene copy with some similarity to that found in the Paraburkholderia.…”

Novel Cupriavidus Strains Isolated from Root Nodules of Native Uruguayan Mimosa Species

“…Reference strains were the highly resistant bacterium Cupriavidus metallidurans CH34 (49,50), the type strains C. taiwanensis LMG19424 T (15) and B. phymatum STM815 T , the P. rigida symbionts C. necator UYPR2.512 and Burkholderia sp. UY1.413 (30), and the metalsensitive strain Escherichia coli S17-1 (51).…”

“…All of the symbiotic Cupriavidus strains described so far, as well as the isolates from the present study fall within clade I, in which three distinct subclades were also observed. Clade Ia comprises sequences from isolates UYMM14A, UYMS13B, UYMAM01A, UYMAM01B, and UYMS01A from the present study, two nodulating C. necator strains isolated from trap plants nodulated in pasture soils from Minas Gerais state in central Brazil (UFLA02-71 and UFLA01-669) (56), and strains (UYP2.512, UYPR2.54, and UYPR2.56) isolated from P. rigida nodules in Uruguay (30). Clade Ib comprises sequences of type strains of both the symbiotic species C. taiwanensis (15), as well as various unclassified Cupriavidus symbionts isolated from diverse Mimosa spp.…”

“…This was the opposite pattern of nodulation response by most other South American (especially Brazilian) species (10,23) and hinted that Uruguayan mimosas might have different symbiont preferences to their more northerly cousins. Such a possibility was given additional credence by the isolation in Uruguay of M. pudica-nodulating Cupriavidus strains from nodules of Parapiptadenia rigida (30), a tree that is related to Mimosa, and is included within the Piptadenia group of mimosoid legumes (8).…”

The Structure and Evolution of Beta-Rhizobial Symbiotic Genes Deduced from Their Complete Genomes

“…Several studies have hypothesized the horizontal transfer of symbiotic genes between Alpha-and Beta-rhizobia, or between Burkholderia and Cupriavidus on the basis of phylogenies using sequences of their symbiosis-related genes, such as nodA, nodC and nifH [19,20,30,32,57] but both vertical and horizontal transfer occur in Burkholderia [13] their phylogenies displaying signs of the origin of Beta-rhizobia to some degree. Although it is widely reported [58], some reports have indicated that horizontal gene transfer (HGT) has not been common even within Alpharhizobia, as revealed by the nodA and nodC phylogenies of some Ensifer and Rhizobium symbionts [8,31].…”