<b>Symbiosis of rhizobia with <i>Gliricidia sepium </i> and <i>Clitoria fairchildiana</i> in an Oxisol in the pre-Amazon region of Maranhão State

Abstract

ABSTRACT. Gliricidia (Gliricidia sepium) and sombreiro (Clitoria fairchildiana) have been recommended for agroforestry systems and reforestation of degraded areas due to their fast growth and symbiosis with rhizobia. However, little is known about native populations that nodulate these species. The objective of this study was to evaluate the phenotypic and genetic diversity of nitrogen-fixing bacteria isolated from nodules of gliricidia and sombreiro in alley cropping systems located in the pre-Amazon region of Maranhão State and to confirm their nodulation ability. Nodules were field collected from 20 plants of each species. The isolated strains were characterized morphologically, their 16S rRNA gene was partially sequenced, and their symbiotic ability was authenticated in siratro (Macroptilium atropurpureum). Despite being in the same climate and soil conditions, gliricidia and sombreiro are nodulated by different rhizobia genera, with Rhizobium predominant in gliricidia and Bradyrhizobium in sombreiro. Endophytic strains also colonized nodules in the field. Approximately 60% of Rhizobium strains did not nodulate siratro, whereas all Bradyrhizobium strains did. Native strains isolated from gliricidia nodules had low efficiency, and only four strains isolated from sombreiro nodules were efficient in siratro. These results highlight the importance of symbiotic relationships in the regulation of biological nitrogen fixation.Keywords: Bradyrhizobium; Rhizobium; Papilionoideae; tree legumes; acid soil. Simbioses de rizóbios comGliricidia sepium e Clitoria fairchildiana em um Oxisol na região da Pré-Amazônia do Estado do Maranhão RESUMO. Gliricídia (Gliricidia sepium) e sombreiro (Clitoria fairchildiana) têm sido recomendadas para uso em sistemas agroflorestais e reflorestamento de áreas degradadas devido ao seu rápido crescimento e simbiose com rizóbios. No entanto, pouco é conhecido em relação às populações nativas que nodulam estas espécies. O objetivo deste estudo foi avaliar a diversidade genética e fenotípica das bactérias fixadoras de nitrogênio isoladas de nódulos de gliricídia e sombreiro em sistemas alley cropping localizados na região pré-Amazônica do Estado do Maranhão, e autenticar sua capacidade de nodulação. Foram realizados: coleta dos nódulos em campo, isolamento, caracterização cultural, sequenciamento parcial do gene 16S rRNA e autenticação da capacidade simbiótica das estirpes em siratro (Macroptilium atropurpureum). Apesar de estarem sob as mesmas condições edafoclimáticas, gliricídia e sombreiro são colonizados por distintos gêneros de rizóbios, com predominância de Rhizobium em gliricídia, e Bradyrhizobium em sombreiro. Estirpes endofíticas também foram encontradas colonizando os nódulos. Cerca de 60% das estirpes de Rhizobium não nodularam siratro e todas de Bradyrhizobium nodularam esta espécie. Todas as estirpes nativas isoladas de nódulos de gliricídia apresentaram baixa eficiência, e somente quatro de sombreiro foram eficientes em siratro. Estes resultados ressaltam a importância das rela...

Silvopastoral systems drive the nitrogen-cycling bacterial community in soil

“…We anticipated that the introduction of Gliricidia and sabia in the pasture could modify the structure of diazotrophic bacterial communities in relation to planting with Brachiaria alone because these legumes are able to associate with symbiotic diazotrophic bacteria (Coelho et al, 2018;Martins et al, 2015). Instead, we observed a great dispersion of the samples in the intercropping treatments in relation to the nifH gene, which could be associated with the free-living and associative diazotrophic diversity in the silvopastoral system (Gupta et al, 2014).…”

INITIAL GROWTH OF Clitoria fairchildiana UNDER ORGANIC SUBSTRATES

“…Seedlings cultivated with organic compost from tree pruning in treatment 100:0 (soil:organic compost) showed the highest mean value for IQD ( Figure 3B). Literature reports C. fairchildiana as a nodulating legume, which shows abundant natural nodulation, efficiency in N 2 fixation and compatibility with populations of native rhizobia in the soil (Souza et al, 2007;Coelho et al, 2018). C. fairchildiana is preferentially nodulated by strains of the Bradyrhizobium genus (Coelho et al, 2018).…”

“…Besides being used as an ornamental plant, mainly due to its low and dense canopy, it is also used in landscape composition for urban and rural forestation. C. fairchildiana is also used in the reconstitution of vegetation in degraded areas (Lorenzi, 2008;Coelho et al, 2018). This species has the ability to establish symbioses with diazotrophic bacteria (Coelho et al, 2018).…”

“…C. fairchildiana is also used in the reconstitution of vegetation in degraded areas (Lorenzi, 2008;Coelho et al, 2018). This species has the ability to establish symbioses with diazotrophic bacteria (Coelho et al, 2018). Research performed by Souza et al (2007), verified nodulation of this species in soils from degraded areas, evidencing its compatibility with soil native rhizobia and showing abundant natural nodulation and efficient nitrogen fixation.…”

Characterization of rotenoid stemonal by semiempirical methods and molecular docking

“…Regarding the potential of phytochemical compounds, an Amazonian plant commonly known as sombreiro (Clitoria fairchildiana) is very popular in Brazil [4,7,9,18,28], once this kind of plant is common in large and open places, such as gardens, roads and national parks. Many papers show the activity of the phytochemical compounds extracted from sombreiro, such as stemonal that has cytotoxic [9], antioxidant [18], anti-inflammatory [28] applications towards many biological targets [29].…”