Characterization of rhizobia isolates obtained from nodules of wild genotypes of common bean

Abstract This study aimed to evaluate the tolerance to salinity and temperature, the genetic diversity and the symbiotic efficiency of rhizobia isolates obtained from wild genotypes of common bean cultivated in soil samples from the States of Goiás, Minas Gerais and Paraná. The isolates were subjected to different NaCl concentrations (0%, 1%, 2%, 4% and 6%) at different temperatures (28 °C, 33 °C, 38 °C, 43 °C and 48 °C). Genotypic characterization was performed based on BOX-PCR, REP-PCR markers and 16S rRNA sequencing. An evaluation of symbiotic efficiency was carried out under greenhouse conditions in autoclaved Leonard jars. Among 98 isolates about 45% of them and Rhizobium freirei PRF81 showed a high tolerance to temperature, while 24 isolates and Rhizobium tropici CIAT899 were able to use all of the carbon sources studied. Clustering analysis based on the ability to use carbon sources and on the tolerance to salinity and temperature grouped 49 isolates, R. tropici CIAT899 and R. tropici H12 with a similarity level of 76%. Based on genotypic characterization, 65% of the isolates showed an approximately 66% similarity with R. tropici CIAT899 and R. tropici H12. About 20% of the isolates showed symbiotic efficiency similar to or better than the best Rhizobium reference strain (R. tropici CIAT899). Phylogenetic analysis of the 16S rRNA revealed that two efficient isolates (ALSG5A1 and JPrG6A8) belong to the group of strains used as commercial inoculant for common bean in Brazil and must be assayed in field experiments.

Eficiência de óleos essenciais na qualidade sanitária e fisiológica em sementes de feijão-fava (Phaseolus lunatus L. ) / Efficiency of essential oils in the sanitary and physiological quality of lima bean seeds (Phaseolus lunatus L. )

RESUMO A espécie Phaseolus lunatus L., conhecida popularmente como feijão-fava constitui uma das alternativas de renda e alimentação para a população da região Nordeste do Brasil. Um dos problemas enfrentados são as doenças que provocam grandes perdas na produção de sementes. O presente trabalho objetivou avaliar a eficiência dos óleos essenciais de copaíba, cravo-da-índia e manjericão na redução da incidência de fungos associados às sementes de feijão-fava, e sua interferência na qualidade fisiológica. Os tratamentos foram constituídos por óleos essenciais de copaíba, cravo-da-índia e manjericão nas concentrações de 0; 1; 1,5 e 2 mL. L-1 e fungicida (Captan®). Foram utilizadas 200 sementes por tratamento. Para análise da qualidade sanitária das sementes foi adotado o método de incubação em placas de Petri contendo dupla camada de papel-filtro umedecida com ADE, sob temperatura de 20 ±2 ºC, por 7 dias. A qualidade fisiológica das sementes foi determinada com base nos testes de germinação, emergência e vigor das sementes. Para o teste germinação foi empregado método de rolo de papel germitest e na emergência osemeio foi realizado em bandejas plásticas contendo areia lavada esterilizada, em condição de casa de vegetação, e após 9 dias da instalação foi determinado o vigor com base nos resultados de índice de velocidade de germinação e emergência; comprimento da parte aérea, raiz primária e plântula; e teor de massa seca da partes aérea, raízes e plântulas de feijão-fava. O delineamento experimental foi interiamente casualizados, em esquama de fatorial simples (3x4)+1 (óleos essenciais x concentrações + fungicida), com quatro repetições de 50 sementes. Os óleos essenciais de copaíba e manjericão reduziram consideravelmente o percentual de incidência dos fungos associados as sementes de feijão-fava. O óleo essencial de cravo-da-índia na concetração de 2 mL. L-1, reduziu a qualidade fisiológica das sementes de feijão-fava.

ABSTRACT The Phaseolus lunatus L. species, popularly known as lima bean, is one of the alternative sources of income and food for the population of Northeast Brazil. One of the problems is the diseases that cause great losses in seed production. This study evaluated the effectiveness of essential oils of copaiba, clove, and basil in reducing the incidence of fungi associated with lima bean seeds, as well as the effect on their physiological quality. The treatments consisted of essential oils of copaiba, clove, and basil at concentrations of 0; 1; 1.5; and 2 mL. L-1 and fungicide (Captan®). A total of 200 seeds were used per treatment. To analyze the sanitary quality of the seeds, the method used was incubation in petri dishes containing a double layer of filter paper moistened with distilled sterilized water at a temperature of 20 ± 2°C, for seven days. The physiological quality of the seeds was determined by testing their germination, emergence, and vigor. For the germination test, the method used was a roll of Germitest paper. For the emergence, the seeds were sown in plastic trays containing washed sterilized sand in greenhouse conditions. After nine days, the vigor was determined based on the results of germination and emergence speed rates; length of the aerial part, primary root, and seedling; and dry matter content of the aerial part, roots, and seedlings of the lima beans. The experimental design was completely randomized in a simple factorial arrangement (3x4)+1 (essential oils x concentrations + fungicide) with four replications of 50 seeds. The essential oils of copaiba and basil considerably reduced the percentage of incidence of the fungi associated with lima bean seeds. The essential clove oil at 2 mL. L-1 reduced the physiological quality of the lima bean seeds.

Efecto del consumo de dietas con avena y caraotas negras sobre el perfil lipídico en un modelo experimental en rata / Effect of consumption of diets with oats and black beans on the lipid profile of an experimental model in rat

El consumo de alimentos ricos en fibra dietética (FD) soluble e insoluble, afecta favorablemente el perfil de lípidos séricos al reducir las concentraciones de colesterol total, colesterol- LDL y triglicéridos (TG). El objetivo de este trabajo, fue comparar el efecto del consumo de dietas con avena (Avena sa tiva) y con caraotas negras (Phaseolus vulgaris ) sobre el perfil lipídico de ratas. Quince ratas machos, cepa Sprague Dawley, fueron alimentadas ad libitum por 18 días, con tres tipos de dietas: un con trol, una conteniendo caraotas negras (15% p/p) y otra con avena (15% p/p). La concentración del colesterol total sérico disminuyo 50,56% en el grupo alimentado con avena y 40,52% en el alimentado con caraotas. Así mismo, se observó una disminución de colesterol-LDL de 49,21% en el grupo alimentado con avena y un 42,93% en el grupo alimentado con caraotas. Hubo una reducción de 52,47% del colesterol-HDL en el grupo alimentado con avena y 31,29% para el grupo alimentado con caraotas; esta reducción no es beneficiosa. La concentración de TG séricos fue significativamente menor, un 50,20% para el grupo alimentado con avena y de 51,8% para el grupo alimentado con caraota. La disminución de los lípidos séricos debido a la dieta, con avena o con caraotas, mostró diferencias significativas respecto al control, pero, no entre ellas. La consideración de estos resultados en el caso de la salud humana es bien importante, particularmente en la disminución de la prevalencia de enfermedades cardiovasculares. El efecto de FD sobre los niveles de colesterol-HDL, son hasta los momentos, contradictorios.

The consumption of foods rich in soluble and insoluble dietary fiber (DF) favorably affects the serum lipid profile by lowering total cholesterol, LDL-cholesterol and triglycerides (TG). The objective of this work was to compare the effect of consumption of diets with oats (Avena sativa) and black beans (Pha seo lus vulgaris) on the lipid profile of rats. Fifteen male rats, Spra gue Dawley strain were fed ad libitum for 18 days, with three different diets: a control, one containing black beans (15% w / w) and another with oats (15% w / w). The serum total cholesterol concentration decreased 50.56% in the group fed with oats and 40.52% in the group fed with beans. Also a de crease of LDL-cholesterol 49.21% in the group fed with oats and 42.93% in the group fed with beans was observed. There was 52.47% reduction of HDLcho lesterol in the group fed with oats and 31.29% for the group fed with beans, this is not a be neficial reduction. The serum TG concentration was significantly lower, 50.20% for the group fed with oats and 51.8% for the group fed with beans. The decrease of these lipids due to diet containing oats or beans, was significantly different from control but not between them. Consideration of these results for human health is very important, particularly in reducing the prevalence of cardiovascular disease. The FD effect on HDL-cholesterol levels, are until now contradictory.

Anatomical root variations in response to water deficit: wild and domesticated common bean (Phaseolus vulgaris L)

Root anatomical responses to water deficit are diverse and regulation of water uptake strongly depends on plant anatomy. The ancestors of common bean (Phaseolus vulgaris L.) cultivars are the wild common beans. Because wild beans adapt and survive well in theon atural environment, it is hypothesized that wild common bean roots are less affected than those of domesticated beans at low substrate water potential (ψW). A wild common bean accession from Chihuahua Mexico and cv. Bayomex were studied. Seedlings with a mean root length between 3 and 4 cm were maintained for 24 h in vermiculite at ψW of -0.03 (well hydrated), -0.65, -1.48 and -2.35 MPa (partially dry). Ten anatomical characteristics of differentiation and cell division in root regions were evaluated. Thickness of epidermis and protoderm diminished similarly in wild and domesticated beans growing at low substrate ψW (between -0.65 and -2.35 MPa). At the same time, parenchymatic cell area diminished by 71 percent in the domesticated variety, but by only 32 percent in the wild bean at -2.35 MPa. Theon umber of cells in the cortex and the thickness of the xylem wall increased in both wild and domesticated beans at low substrate ψW;on evertheless, the effect was significantly lower in the wild bean. Theon umber of xylem vessels increased in the cultivar (up to 40 percent) while in the wild bean it decreased (up to 33 percent). The diameter of xylem vessels and transverse root area diminished (15 and 57 percent, respectively) in the cultivar, but in the wild common bean wereon ot affected. Anatomical root characteristics and their modifications in both differentiation and cell division in root regions demonstrated that the wild bean reacted quite differently to substrate ψW than the domesticated common bean.

Infectivity analysis of two variable DNA B components of Mungbean yellow mosaic virus-Vigna in Vigna mungo and Vigna radiata.

Mungbean yellow mosaic virus-Vigna (MYMV-Vig), a Begomovirus that causes yellow mosaic disease, was cloned from field-infected blackgram (Vigna mungo). One DNA A clone (KA30) and five different DNA B clones (KA21, KA22, KA27, KA28 and KA34) were obtained. The sequence identity in the 150-nt common region (CR) between DNA A and DNA B was highest (95%) for KA22 DNA B and lowest (85.6%) for KA27 DNA B. The Rep-binding domain had three complete 11-nt (5'-TGTATCGGTGT-3') iterons in KA22 DNA B (and KA21, KA28 and KA34), while the first iteron in KA27 DNA B (5'-ATCGGTGT-3') had a 3-nt deletion. KA27 DNA B, which exhibited 93.9% CR sequence identity to the mungbean-infecting MYMV, also shared the 3-nt deletion in the first iteron besides having an 18-nt insertion between the third iteron and the conserved nonanucleotide. MYMV was found to be closely related to KA27 DNA B in amino acid sequence identity of BV1 (94.1%) and BC1 (97.6%) proteins and in the organization of nuclear localization signal (NLS), nuclear export signal (NES) and phosphorylation sites. Agroinoculation of blackgram (V. mungo) and mungbean (V. radiata) with partial dimers of KA27 and KA22 DNA Bs along with DNA A caused distinctly different symptoms. KA22 DNA B caused more intense yellow mosaic symptoms with high viral DNA titre in blackgram. In contrast, KA27 DNA B caused more intense yellow mosaic symptoms with high viral DNA titre in mungbean. Thus, DNA B of MYMVVig is an important determinant of host-range between V. mungo and V. radiata.