Title : Different solubilizing phosphate bradyrhizobium spp. from symbiovar genistearum nodulate the endemic retama dasycarpa in the Maamora forest, Morocco.
Abstract:
The Maamora is the largest cork oak forest in the Southern Mediterranean area and serves important social, economic, and environmental purposes. However, it faces significant edaphoclimatic and anthropic pressures, leading to erosion, desertification, and regression. To counteract forest degradation, several types of plants are being replanted or newly introduced to overcome the lack of tree and vegetation cover. Some shrubby legumes represent an appropriate alternative to reduce forest degradation, and an ecologically sustainable strategy that respects the environment, protects against desertification, and improves soil quality and fertility. Retama species are generally used to fight desertification thanks to their aptitude to elicit symbiotic nitrogen-fixing associations with soil bacteria called rhizobia. Our work focuses on the ability of R. dasycarpa to form nitrogen-fixing symbioses with compatible rhizobia in the soils of Maamora forest, and the assessment of their biodiversity. Out of 73 isolates from root nodules of R. dasycarpa, 20 strains were selected for molecular and phenotypic analyses based on their REP-PCR fingerprinting. The analysis of the 16S rRNA and nodC gene sequences revealed that all isolated strains are members of the genus Bradyrhizobium symbiovars genistearum. Multilocus Sequence Analysis (MLSA) of five housekeeping genes (glnII, gyrB, recA, atpD and dnaK) showed that the strains are closely related to B. lupini, B. canariense, B. cytisi, and B. rifense. The strains metabolize a wide variety of carbohydrates and amino acids as sole sources of carbon and nitrogen. Additionally, they exhibited the plant growth-promoting activities of phosphate solubilization and auxin production.
This work shows that although endemic to the High Atlas Mountains, R. dasycapa could be nodulated by different species of Bradyrhizobium in the Region of Rabat.
