Sesbania virgata stimulates the occurrence of its microsymbiont in soils but does not inhibit microsymbionts of other species

Abstract

The legume species Sesbania virgata establishes a specific and efficient symbiosis with Azorhizobium doebereinerae. Previous studies have shown that A. doebereinerae occurrence correlates to the presence of S. virgata. This work aimed to evaluate the occurrence of A. doebereinerae and of other nitrogen-fixing Leguminosae-nodulating bacteria (NFLNB) in soil samples collected adjacent to and 10 m away from the stems of five S. virgata plants in pasture areas. Symbiotic characteristics of isolates from these NFLNB populations were also studied. S. virgata and the four promiscuous legume species Leucaena leucocephala, Macroptilium atropurpureum, Phaseolus vulgaris and Vigna unguiculata were inoculated with soil samples to trap A. doebereinerae and other NFLNB. NFLNB capable of inducing nodulation in at least one of these legumes were found in all samples. M. atropurpureum was the most promiscuous species, as it trapped the highest number of NFLNB cultural types from soil suspensions. The other species were less promiscuous in the following order: V. unguiculata, P. vulgaris, and L. leucocephala. Isolates of the promiscuous legumes were classified into seven cultural groups. One of these groups, isolated from all promiscuous species, showed fast-growth alkali-reaction in culture medium (like Azorhizobium); it was identified as Cupriavidus. This is the first report of symbiosis of Cupriavidus with Papilionoideae species. The symbiotic efficiency of promiscuous hosts with NFLNB varied, but it was always less than that of controls with mineral nitrogen or an inoculant strain. S. virgata was efficiently nodulated only by A. doebereinerae, which occurred mainly in samples collected close to the plant stem, corroborating a high stimulus by its host species. A high diversity of NFLNB occurs as saprophytes close to the S. virgata root system.

Diversity and Efficiency of Rhizobia Communities from Iron Mining Areas Using Cowpea as a Trap Plant

“…Five subsamples were collected from each point, five meters apart from each other, at the 0.00-0.20 m depth, resulting in a composite sample from each of the 40 georeferenced points. Samples were deposited in sterile plastic bags and polystyrene boxes and taken to the laboratory, where they were stored at 4 °C in a cold chamber until use Capture and efficiency of bacterial communities using cowpea as a trap plant Seeds were disinfested and planted in longneck bottles containing Hoagland and Arnon (1950) nutrient solution, following the method described by Florentino et al (2009). Seeds were pre-germinated on moist sterile filter paper that was folded, wrapped in aluminum foil, and stored in a growth chamber at 28 °C until radicle emission.…”

Bradyrhizobium spp. Strains in Symbiosis with Pigeon Pea cv. Fava-Larga under Greenhouse and Field Conditions

“…The strain UFLA 04-212 was also effective in establishing symbiosis and in fixing N 2 in siratro (Macroptilium atropurpureum) under greenhouse conditions, with flasks containing nutrient solution (Florentino et al, 2009). The strains UFLA 03-320 and UFLA 03-321 also proved to be effective in promoting growth in cowpea (Vigna unguiculata) under greenhouse conditions with Leonard jars (Rufini et al, 2014a).…”

Diversity and efficiency of bradyrhizobium strains isolated from soil samples collected from around sesbania virgata roots using cowpea as trap species

“…Eight Bradyrhizobium strains from the municipalities of Nepomuceno and Ribeirão Vermelho in southern Minas Gerais (Florentino, 2007;Florentino et al, 2009) were analyzed. The strains were isolated from cowpea (trap plant) nodules formed after inoculation with soil samples collected from around the root system of S. virgata at a distance of 0 -10 m from the plant stem.…”