Abstract
Identification and selection of nitrogen-fixing bacterial strains for inoculation into native leguminous tree species can assist in the recovery of degraded areas. Additionally, native strains from these areas are genetic resources adapted to these conditions and are thus suitable for selection. The aim of this study was to symbiotically and genetically characterize 18 bacterial strains from the Rhizobium and Bradyrhizobium genera isolated from Machaerium nyctitans, Platypodium elegans, and Ormosia arborea grown in a nursery in an iron mining area. Three experiments were conducted under axenic conditions in a greenhouse. The nodulation capacity of the strains was evaluated by the number (NN) and dry matter (NDM) of nodules. Symbiotic efficiency was evaluated based on the following parameters: SPAD index (SPAD), shoot dry matter (SDM), root dry matter (RDM), and total dry matter (TDM) of the plants, relative efficiency (RE), shoot nitrogen content (SNC), and total nitrogen content in the plant (TNC). The atpD and gyrB housekeeping genes and the nifH gene were sequenced for phylogenetic analysis, and the nodC and nodD symbiotic genes of the strains were amplified. Out of the 18 strains, 16 were authenticated by nodulation capacity in the species of origin. The SPAD variable allowed for the detection of differences between treatments before the SDM. Additionally, the SPAD index showed correlation with TNC, and the strain Bradyrhizobium sp., UFLA01-839, which may represent a new species, was outstanding in Machaerium nyctitans. The nifH, nodD, and nodC genes were detected in UFLA01-839.
Highlights
Native leguminous tree species can be allies in the recovery of degraded areas since they do not pose the same ecological risk as non-native species, and they have desirable characteristics, such as biological nitrogen fixation as a result of their symbiosis with rhizobia strains (Sattler et al, 2018)
The aim of this study was to symbiotically and genetically characterize 18 bacterial strains from the Rhizobium and Bradyrhizobium genera isolated from Machaerium nyctitans, Platypodium elegans, and Ormosia arborea grown in a nursery in an iron mining area
In the experiment with M. nyctitans, of the seven strains tested, all nodulated in the species of origin, six of Bradyrhizobium and one of Rhizobium (Table 2)
Summary
Native leguminous tree species can be allies in the recovery of degraded areas since they do not pose the same ecological risk as non-native species, and they have desirable characteristics, such as biological nitrogen fixation as a result of their symbiosis with rhizobia strains (Sattler et al, 2018). Efficient strains compatible with target legume species must be selected. It is necessary to select strains that are efficient for each one of these forest species of interest due to the possible specificity between symbionts. It is necessary to isolate these microorganisms from the soil or root nodules of leguminous plants of interest, characterize them phenotypically and genotypically, authenticate them under axenic conditions in the species of origin, and confirm their symbiotic efficiency (Moreira, 2008)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call