Nodulation of the endemic Retama dasycarpa by Bradyrhizobium spp. in the Maamora forest

Some shrubby legumes represent an appropriate alternative to reduce forest degradation and also an ecologically sustainable strategy that respects the environment, protects against desertification, and improves soil quality and fertility. Retama species are generally used to prevent desertification due to their aptitude to elicit symbiotic nitrogen-fixing associations with soil bacteria called rhizobia. In this work, we isolated and characterized some strains of rhizobia that nodulate Retama dasycarpa in the soils of the Maamora forest. Out of 73 bacteria isolated from R. dasycarpa root nodules, 20 strains were selected for molecular analyses based on their REP-PCR genomic fingerprints. The rrs and nodC gene sequence analyses showed that all the strains belong to Bradyrhizobium genus and members of the genistearum symbiovar. MLSA of the five housekeeping genes dnaK , atpD , gyrB , glnII , and recA revealed that the strains are related to B. lupini USDA 3051 T , B. cytisi CTAW11 T , B. canariense CTAW25 T , and a putative new genospecies. The strains metabolize a wide variety of carbohydrates and amino acids as sole carbon and nitrogen sources. Additionally, they solubilize phosphates, and produce siderophores. Our results show that Retama dasycarpa in the Maamora forest is nodulated by Bradyrhizobium spp. sv. genistearum, similar to the High-Atlas Mountains, and potentially new genospecies.