Characterization of indigenous rhizobia from Caatinga

Abstract

The aim of this study was to characterize rhizobial isolates from Cratylia mollis Mart. ex Benth, Calliandra depauperata Benth. and Mimosa tenuiflora (Willd.) Poir. by means of rhizobial colonies morphology and restriction analysis of the 16S ribosomal gene (16S rDNA-ARDRA). Nodules were collected in the field and from plants cultivated in a greenhouse experiment using Caatinga soil samples. Sixty seven isolates were described by morphological analysis. Forty seven representative isolates were used for ARDRA analysis using seven restriction enzymes. We observed high diversity of both slow and fast-growing rhizobia that formed three morpho-physiological clusters. A few fast-growing isolates formed a group of strains of the Bradyrhizobium type; however, most of them diverged from the B. japonicum and B. elkanii species. Cratylia mollis nodule isolates were the most diverse, while all Mimosa tenuiflora isolates displayed fast growth with no pH change and were clustered into groups bearing 100% similarity, according to ARDRA results.

Diversity of new root nodule bacteria from Erythrina velutina Willd., a native legume from the Caatinga dry forest (Northeastern Brazil)

“…The large genetic variability of the rhizobial isolates from tree legumes from the Brazilian Semiarid was already showed to other species, such as the Mimosa spp. (Teixeira et al, 2010;Freitas et al, 2014) and the data of the present study corroborate the reports already published.…”

“…There are still few results evaluating the diversity and efficiency of rhizobia native to the Northeastern region of Brazil. Recent studies have shown that the legumes from Brazilian Semi-arid can associate themselves to a large variety of rhizobia (Teixeira et al, 2010;Freitas et al, 2014), which show increased symbiotic efficiency (Freitas et al, 2010).…”

Phenotypic, Stress Tolerance and Plant Growth Promoting Characteristics of Rhizobial Isolates from Selected Wild Legumes of Semiarid Region, Tirupati, India

“…Intermediate values obtained with few fast and slow growing strains in the present study. The same was also reported [38] from studies on indigenous rhizobia in Caatinga. Variation in the production of EPS by the isolates was also reported by Rathore et al [27].…”

“…Polysaccharides also protect rhizobia in the soil against deleterious biotic and abiotic stress factors [38] and also restrict the oxygen diffusion through the nodular cells to protect the oxygen sensitive nitrogenase in the nodules. The amount of EPS produced by the isolates in the culture varied from 23 -91 µg/ml which is a fourfold variation ( Table 5).…”

Phenotypic diversity and amylolytic activity of fast growing rhizobia from pigeonpea [Cajanus cajan (L.) Millsp.]

“…The isolates were inoculated at Petri dishes containing YMA (Yeast Extract-Manitol-Agar) (27) medium and incubated at 28°C for 2-3 days. The isolates were characterized according to the following features: pH alteration of culture medium, colony color, colony size, gum production and uniformity (7,26,28). As reference strains, it was also culturally characterized two strains belonging to the Rhizobium tropici (BR 322) end Ensifer saheli (BR 526) species.…”