RESUMO
Ethylene acts as a major regulator of the nodulation process of leguminous plants. Several rhizobial strains possess the ability to modulate plant ethylene levels through the expression of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase; however, rhizobia present low enzymatic activities. One possible alternative to this problem resides on the use of free-living bacteria, such as Pseudomonas, presenting high levels of ACC deaminase activity that may be used as adjuvants in the nodulation process by decreasing inhibitory ethylene levels. Nevertheless, not much is understood about the specific role of ACC deaminase in the possible role of free-living bacteria as nodulation adjuvants. Therefore, this work aims to study the effect of ACC deaminase in the plant growth-promoting bacterium, Pseudomonas fluorescens YsS6, ability to facilitate alpha- and beta-rhizobia nodulation. The ACC deaminase-producing P. fluorescens YsS6 and its ACC deaminase mutant were used in co-inoculation assays to evaluate their impact in the nodulation process of alpha- (Rhizobium tropici CIAT899) and beta-rhizobia (Cupriavidus taiwanensis STM894) representatives, in Phaseolus vulgaris and Mimosa pudica plants, respectively. The results obtained indicate that the wild-type P. fluorescens YsS6, but not its mutant defective in ACC deaminase production, increase the nodulation abilities of both alpha- and beta-rhizobia, resulting in an increased leguminous plant growth. Moreover, this is the first report of the positive effect of free-living bacteria in the nodulation process of beta-rhizobia. The modulation of inhibitory ethylene levels by free-living ACC deaminase-producing bacteria plays an important role in facilitating the nodulation process of alpha- and beta-rhizobia.
Assuntos
Alphaproteobacteria/fisiologia , Proteínas de Bactérias/metabolismo , Carbono-Carbono Liases/metabolismo , Cupriavidus/fisiologia , Mimosa/microbiologia , Phaseolus/microbiologia , Pseudomonas fluorescens/enzimologia , Inoculantes Agrícolas/fisiologia , Proteínas de Bactérias/genética , Carbono-Carbono Liases/genética , Etilenos/metabolismo , Mimosa/fisiologia , Phaseolus/fisiologia , Nodulação , Pseudomonas fluorescens/genéticaRESUMO
Exotic species are used to trigger facilitation in restoration plantings, but this positive effect may not be permanent and these species may have negative effects later on. Since such species can provide a marketable product (firewood), their harvest may represent an advantageous strategy to achieve both ecological and economic benefits. In this study, we looked at the effect of removal of a non-native tree species (Mimosa caesalpiniifolia) on the understory of a semideciduous forest undergoing restoration. We assessed two 14-year-old plantation systems (modified "taungya" agroforestry system; and mixed plantation using commercial timber and firewood tree species) established at two sites with contrasting soil properties in São Paulo state, Brazil. The experimental design included randomized blocks with split plots. The natural regeneration of woody species (height ≥0.2 m) was compared between managed (all M. caesalpiniifolia trees removed) and unmanaged plots during the first year after the intervention. The removal of M. caesalpiniifolia increased species diversity but decreased stand basal area. Nevertheless, the basal area loss was recovered after 1 year. The management treatment affected tree species regeneration differently between species groups. The results of this study suggest that removal of M. caesalpiniifolia benefited the understory and possibly accelerated the succession process. Further monitoring studies are needed to evaluate the longer term effects on stand structure and composition. The lack of negative effects of tree removal on the natural regeneration indicates that such interventions can be recommended, especially considering the expectations of economic revenues from tree harvesting in restoration plantings.
Assuntos
Conservação dos Recursos Naturais , Agricultura Florestal/métodos , Florestas , Mimosa/fisiologia , Biodiversidade , Brasil , Espécies Introduzidas , Dinâmica Populacional , Especificidade da Espécie , Árvores/fisiologia , Clima TropicalRESUMO
The objective of this study was to evaluate the efficiency of pre-germination treatments on the germination of Mimosa flocculosa clear and dark seeds, collected in different years (Lots 1 and 2). The work was divided into two stages: the first, seeds were treated to break dormancy (immersion in cold water for 24 hours, soaking in hot water (98C) for 18 hours, immersion in concentrated sulfuric acid for one minute and three minutes and seeds intact (control). In the second stage, the seeds, of two lots, were visually separated into two color classes: clear and dark seeds, and submitted the best treatment for dormancy breaking of the first stage. In both stages, the seeds were sterilized with sodium hypochlorite at 2% for three minutes and placed in a germination chamber with constant light at 25C. Percentage and speed of germination were analyzed. The experimental design was completely randomized with four replications of 25 seeds for each treatment, and the treatment means were compared by Tukey test (p 0.05). Soaking the seeds in sulfuric acid for one minute resulted in higher germination percentage and speed for Lot 1 as Lot 2. For Lot 2, beyond this treatment, the highest percentage and IVG were obtained with immersion in sulfuric acid for three minutes. In the second stage, the dark seeds with immersion in sulfuric acid showed higher germination percentages, 36% and 59%, in Lots 1 and 2, respectively. By considering the results, it was observed that the immersion of seeds in sulfuric acid for one minute and dark seed selection methods are effective in promoting germination of Mimosa fl occulosa.
Objetivou-se com este trabalho avaliar a eficiência de tratamentos pré-germinativos na germinação de sementes claras e escuras de Mimosa flocculosa colhidas em anos diferentes (Lotes 1 e 2). O trabalho foi separado em duas etapas: na primeira, as sementes dos dois lotes (sem separação por cor) foram submetidas a tratamentos para superação da dormência (imersão em água fria por 24 horas, imersão em água quente (98C) por 18 horas, imersão em ácido sulfúrico concentrado por um minuto e por três minutos e sementes intactas (testemunha). E na segunda etapa, as sementes dos dois lotes foram separadas visualmente em duas classes de coloração: sementes claras e sementes escuras, e submetidas ao melhor tratamento de superação de dormência da primeira etapa. Nas duas etapas, as sementes foram desinfestadas com hipoclorito de sódio a 2% por três minutos e semeadas em caixas tipo gerbox sobre papel e colocadas em câmaras de germinação com luz constante, a 25C. Foram avaliadas a porcentagem e a velocidade de germinação. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições de 25 sementes para cada tratamento, e as médias dos tratamentos foram comparadas pelo teste de Tukey (p 0,05). A imersão das sementes em ácido sulfúrico por um minuto proporcionou maiores porcentagens e velocidade de germinação para os Lotes 1 e 2. Já para o Lote 2, além desse tratamento, as maiores porcentagens e velocidade de germinação foram obtidas com a imersão em ácido sulfúrico por três minutos. Na segunda etapa, as sementes escuras com imersão em ácido sulfúrico apresentaram maiores porcentagens de germinação 36% e 59%, nos Lotes 1 e 2, respectivamente. Conclui-se que a imersão de sementes em ácido sulfúrico por um minuto e a seleção de sementes escuras são métodos eficientes na promoção da germinação de sementes de Mimosa fl occulosa.
Assuntos
Dormência de Plantas , Germinação/fisiologia , Mimosa/embriologia , Mimosa/fisiologia , Sementes/fisiologiaRESUMO
The objective of this study was to evaluate the efficiency of pre-germination treatments on the germination of Mimosa flocculosa clear and dark seeds, collected in different years (Lots 1 and 2). The work was divided into two stages: the first, seeds were treated to break dormancy (immersion in cold water for 24 hours, soaking in hot water (98C) for 18 hours, immersion in concentrated sulfuric acid for one minute and three minutes and seeds intact (control). In the second stage, the seeds, of two lots, were visually separated into two color classes: clear and dark seeds, and submitted the best treatment for dormancy breaking of the first stage. In both stages, the seeds were sterilized with sodium hypochlorite at 2% for three minutes and placed in a germination chamber with constant light at 25C. Percentage and speed of germination were analyzed. The experimental design was completely randomized with four replications of 25 seeds for each treatment, and the treatment means were compared by Tukey test (p 0.05). Soaking the seeds in sulfuric acid for one minute resulted in higher germination percentage and speed for Lot 1 as Lot 2. For Lot 2, beyond this treatment, the highest percentage and IVG were obtained with immersion in sulfuric acid for three minutes. In the second stage, the dark seeds with immersion in sulfuric acid showed higher germination percentages, 36% and 59%, in Lots 1 and 2, respectively. By considering the results, it was observed that the immersion of seeds in sulfuric acid for one minute and dark seed selection methods are effective in promoting germination of Mimosa fl occulosa.(AU)
Objetivou-se com este trabalho avaliar a eficiência de tratamentos pré-germinativos na germinação de sementes claras e escuras de Mimosa flocculosa colhidas em anos diferentes (Lotes 1 e 2). O trabalho foi separado em duas etapas: na primeira, as sementes dos dois lotes (sem separação por cor) foram submetidas a tratamentos para superação da dormência (imersão em água fria por 24 horas, imersão em água quente (98C) por 18 horas, imersão em ácido sulfúrico concentrado por um minuto e por três minutos e sementes intactas (testemunha). E na segunda etapa, as sementes dos dois lotes foram separadas visualmente em duas classes de coloração: sementes claras e sementes escuras, e submetidas ao melhor tratamento de superação de dormência da primeira etapa. Nas duas etapas, as sementes foram desinfestadas com hipoclorito de sódio a 2% por três minutos e semeadas em caixas tipo gerbox sobre papel e colocadas em câmaras de germinação com luz constante, a 25C. Foram avaliadas a porcentagem e a velocidade de germinação. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições de 25 sementes para cada tratamento, e as médias dos tratamentos foram comparadas pelo teste de Tukey (p 0,05). A imersão das sementes em ácido sulfúrico por um minuto proporcionou maiores porcentagens e velocidade de germinação para os Lotes 1 e 2. Já para o Lote 2, além desse tratamento, as maiores porcentagens e velocidade de germinação foram obtidas com a imersão em ácido sulfúrico por três minutos. Na segunda etapa, as sementes escuras com imersão em ácido sulfúrico apresentaram maiores porcentagens de germinação 36% e 59%, nos Lotes 1 e 2, respectivamente. Conclui-se que a imersão de sementes em ácido sulfúrico por um minuto e a seleção de sementes escuras são métodos eficientes na promoção da germinação de sementes de Mimosa fl occulosa.(AU)
Assuntos
Mimosa/embriologia , Mimosa/fisiologia , Sementes/fisiologia , Dormência de Plantas , Germinação/fisiologiaRESUMO
While the occurrence of Betaproteobacteria occupying the nodules of tropical legumes has been shown, little is known about subtropical areas. Araucaria Forest is a subtropical endangered ecosystem, and a better understanding of the legume-rhizobial symbionts may allow their use in land reclamation. The 16S rRNA gene of bacteria isolated from nine leguminous species was sequenced and their nodulation tested in Mimosa scabrella and Phaseolus vulgaris. 196 isolates were identified as eight genotypes: Pantoea, Pseudomonas, Bradyrhizobium sp1-2, Rhizobium, and Burkholderia sp1-3. The majority of the isolates from native plants (87 %) were taxonomically related to ß-rhizobia, namely Burkholderia, however the legumes Galactia crassifolia and Collea speciosa were nodulated by both α and ß-rhizobia, and Acacia dealbata, an exotic plant, only by α-rhizobia. The nifH genes of some isolates were sequenced and N-fixing potential shown by the acetylene reduction test. Most of the isolates nodulated the test plants, some were effective in M. scabrella, but all presented low efficiency in the exotic promiscuous legume P. vulgaris. Pantoea and Pseudomonas did not nodulate and probably are endophytic bacteria. The presented data shows diversity of α, ß and γ-Proteobacteria in nodules of subtropical legumes, and suggests host specificity with ß-rhizobia. Potential isolates were found for M. scabrella, indicating that a high N-fixing strain may be further inoculated in plants for use in reforestation.
Assuntos
Fabaceae/microbiologia , Proteobactérias/genética , Proteobactérias/fisiologia , Rhizobium/genética , Rhizobium/fisiologia , Árvores/microbiologia , Brasil , Ecossistema , Fabaceae/genética , Fabaceae/metabolismo , Genótipo , Mimosa/fisiologia , Fixação de Nitrogênio , Phaseolus/genética , Phaseolus/metabolismo , Phaseolus/microbiologia , Filogenia , Nodulação , Proteobactérias/classificação , Proteobactérias/isolamento & purificação , RNA Ribossômico 16S/genética , Rhizobium/isolamento & purificação , Alinhamento de Sequência , Análise de Sequência de DNA , SimbioseRESUMO
The genus Burkholderia represents a challenge to the fields of taxonomy and phylogeny and, especially, to the understanding of the contrasting roles as either opportunistic pathogens or bacteria with biotechnological potential. Few genomes of nonpathogenic strains, especially of diazotrophic symbiotic bacteria, have been sequenced to improve understanding of the genus. Here, we contribute with the complete genome sequence of Burkholderia phenoliruptrix strain BR3459a (CLA1), an effective diazotrophic symbiont of the leguminous tree Mimosa flocculosa Burkart, which is endemic to South America.
Assuntos
Burkholderia/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Análise de Sequência de DNA , Burkholderia/isolamento & purificação , Burkholderia/metabolismo , Burkholderia/fisiologia , Temperatura Alta , Mimosa/microbiologia , Mimosa/fisiologia , Dados de Sequência Molecular , Fixação de Nitrogênio , América do Sul , Estresse Fisiológico , SimbioseRESUMO
Some studies showed that anesthetics reduce the response of physical stimuli in Mimosa pudica and in Venus Flytrap (Dionaea muscipula), peculiar plants that have the ability to respond to touch stimuli. In this research we tested the effects of ketamine, lidocaine, diethyl ether, and amlodipine on the movements of Mimosa pudica and Venus Flytrap. With a literature review, we tried to bring elements to theorize about the interaction of these substances with these plants. The angular displacement in Mimosa´s petiole and in Dionaea leaves is what was measured to compare the drugs group with control groups.
Assuntos
Anestésicos/farmacologia , Droseraceae/efeitos dos fármacos , Mimosa/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Anlodipino/farmacologia , Droseraceae/fisiologia , Éter/farmacologia , Humanos , Ketamina/farmacologia , Lidocaína/farmacologia , Mimosa/fisiologia , Movimento , Folhas de Planta/fisiologia , TatoRESUMO
Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu) P. laevigata, Site 2 (González) M. biuncifera, and Site 3 (Rincón) with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3) had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2). Soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), phosphorus-Olsen (P) and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI) created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystems.
Assuntos
Biodiversidade , Mimosa/fisiologia , Prosopis/fisiologia , Microbiologia do Solo , Solo/química , Clima Desértico , Ecossistema , Fungos/classificação , Fungos/isolamento & purificação , México , Mimosa/classificação , Prosopis/classificação , Estações do AnoRESUMO
Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu) P. laevigata, Site 2 (González) M. biuncifera, and Site 3 (Rincón) with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3) had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2). Soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), phosphorus-Olsen (P) and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI) created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystems.
Prosopis laevigata y Mimosa biuncifera coexisten en los matorrales semiáridos; sin embargo, se desconoce su influencia sobre la diversidad de la comunidad vegetal y el suelo. Este estudio evaluó el efecto de P. laevigata y M. biuncifera sobre la estructura, diversidad vegetal y nutrimentos del suelo, en tres matorrales del Valle del Mezquital, México. Los sitios difieren en la especie dominante: Sitio 1, P. laevigata; Sitio 2, M. biuncifera y Sitio 3, ambas leguminosas. En cada sitio se recolectó suelo, tanto abajo y fuera del dosel de las leguminosas, además, se realizaron transectos para medir e identificar las plantas arbóreas y arbustivas, se calculó el índice de valor de importancia y la diversidad del matorral. Asimismo, se registró mayor riqueza y diversidad en el Sitio 3 (ICE 29 spp. y H’ 2.7), en comparación con el Sitio 1 (24 spp. y 2.4) y Sitio 2 (26 spp. y 2.1). La materia orgánica y el carbono orgánico del suelo, así como el N total, el P-Olsen y la mineralización de C fueron mayores en el suelo bajo dosel de ambas leguminosas. La abundancia de esporas de hongos micorrizógenos arbusculares fue favorecida por M. biunficera. La influencia de P. laevigata para crear islas más ricas en recursos fue mayor que en M. biunficera, lo anterior sugiere que cada leguminosa modifica de una forma diferente el microambiente, sin embargo, juntas aumentan la disponibilidad de nichos para el establecimiento de otras especies, lo queayuda a comprender el papel de P. laevigata y M. biuncifera sobre la colonización vegetal en ecosistemas semiáridos.
Assuntos
Biodiversidade , Mimosa/fisiologia , Prosopis/fisiologia , Microbiologia do Solo , Solo/química , Clima Desértico , Ecossistema , Fungos/classificação , Fungos/isolamento & purificação , México , Mimosa/classificação , Prosopis/classificação , Estações do AnoRESUMO
Seismonastic or thigmonastic movements of Mimosa pudica L. is mostly because of the fast loss of water from swollen motor cells, resulting in temporary collapse of cells and quick curvature in the parts where these cells are located. Because of this, the plant has been much studied since the 18th century, leading us to think about the classical binomial stimulus-response (action-reaction) when compared to animals. Mechanic and electrical stimuli were used to investigate the analogy of mimosa branch with an artificial neuron model and to observe the action potential propagation through the mimosa branch. Boolean function applied to the mimosa branch in analogy with an artificial neuron model is one of the peculiarities of our hypothesis.