Assuntos
Medicago , Oligossacarídeos , Fosfotransferases , Medicago/crescimento & desenvolvimento , Medicago/metabolismo , Fosforilação , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Transdução de Sinais , Oligossacarídeos/metabolismo , Fosfotransferases/metabolismoRESUMO
Arthrobacter agilis UMCV2 is a rhizosphere bacterium that promotes legume growth by solubilization of iron, which is supplied to the plant. A second growth promotion mechanism produces volatile compounds that stimulate iron uptake activities. Additionally, A. agilis UMCV2 is capable of inhibiting the growth of phytopathogens. A combination of quantitative polymerase chain reaction and fluorescence in situ hybridization techniques were used here to detect and quantify the presence of the bacterium in the internal tissues of the legume Medicago truncatula. Our results demonstrate that A. agilis UMCV2 behaves as an endophytic bacterium of M. truncatula, particularly in environments where iron is available.
Assuntos
Arthrobacter/fisiologia , Endófitos/fisiologia , Medicago/microbiologia , Inoculantes Agrícolas , Arthrobacter/genética , Arthrobacter/isolamento & purificação , Meios de Cultura , DNA Bacteriano/análise , Endófitos/genética , Endófitos/isolamento & purificação , Compostos Ferrosos/administração & dosagem , Ferro/metabolismo , Medicago/crescimento & desenvolvimento , Medicago/metabolismo , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , Rizosfera , SimbioseRESUMO
The purpose of this study was assessing Cu and Zn availabilities in soils amended with a biosolid through the determination of their sequentially extracted chemical forms and their relationship with the contents of these metals in ryegrass (Lolium perenne L.) and subterranean clover (Trifolium subterraneum L.) plant tissues cultivated in a greenhouse using four soils classified as Aquic Xerochrepts and Ultic Haploxeralfs representatives of potential areas for biosolids application in the central zone of Chile. The soils were treated with sewage sludge at a rate of 0 and 30 Mg ha(-1). The greenhouse experiment was carried out through a completely randomized block design in a 2 x 4 (biosolid ratexsoil) arrangement, considering three repetitions per treatment. The soils used in the greenhouse experiment before and after cultivation, were sequentially extracted with specific reagents and conditions in order to obtain the following fractions: exchangeable, sodium acetate-soluble, soluble in moderately reducing condition, K(4)P(2)O(7)-soluble, soluble in reducing condition, and soluble in strongly acid and oxidizing condition. It was established that Cu and Zn were predominantly found in soils in less available forms, associated to organic matter, oxides and clay minerals. Zinc concentration in ryegrass plants was higher than that found in subterranean clover plants in biosolid-amended soils. Zinc contents in ryegrass shoot and root correlated with the exchangeable, bound-to-carbonate, and bound-to-FeOx metal forms in control soil. Copper and Zn bioavailabilities were estimated through satisfactorily fitted multiple linear regression models, with determination coefficients from 0.77 to 0.99, which showed a positive contribution of the labile metal forms in soils, especially in relation to Zn in both plant species.
Assuntos
Cobre/metabolismo , Lolium/metabolismo , Medicago/metabolismo , Metais Pesados/metabolismo , Zinco/metabolismo , Chile , Monitoramento AmbientalRESUMO
The potential of clover (Trifolium repens) and ryegrass (Lolium perenne) mixtures as raw materials for ethanol production was investigated. Wet oxidation, at 175, 185 or 195 degrees C during 10min at two different oxygen pressures and with either addition or no addition of sodium carbonate, was evaluated as pretreatment method for clover-ryegrass mixtures. The enzymatic hydrolysis of cellulose was significantly improved after pretreatment. The highest conversion efficiency, 93.6%, was achieved for the sample pretreated at 195 degrees C, 10min, 1.2MPa and no addition of Na(2)CO(3). For that sample, the overall glucose yield after pretreatment and hydrolysis was 75.5%. No inhibition of cellulose enzymatic conversion by the filtrates was observed. The simultaneous saccharification and fermentation of the pretreated material yielded cellulose conversions of 87.5 and 86.6%, respectively, with Saccharomyces cerevisiae and the filamentous fungus Mucor indicus, and revealed that no addition of nutrients is needed for the fermentation of clover-ryegrass hydrolysates.
Assuntos
Celulase/metabolismo , Fermentação , Lolium/metabolismo , Medicago/metabolismo , Saccharomyces cerevisiae/metabolismo , Trichoderma/enzimologia , Água/metabolismo , Celulose/metabolismo , Etanol/metabolismo , Hidrólise , Lolium/química , Medicago/química , Nitrogênio/análise , Oxirredução , Xilanos/metabolismoRESUMO
Recurring reports of a highly allergenic 42-46-kDa protein in Hevea brasiliensis latex appeared to have been resolved with the discovery of a 43-kDa allergenic latex protein that was a homologue to patatin. However, the low to moderate prevalence of sensitization to the protein, designated Hev b 7, among latex-allergic patients could not adequately explain the frequent observations of the 42-46-kDa allergen. This led to the hypothesis that another, more allergenic protein of a similar molecular mass existed in Hevea latex. We report the isolation and purification of a 42.98-kDa latex glycoprotein showing homology to the early nodule-specific protein (ENSP) of the legumes Medicago sativa, Medicago truncatula, and Glycine max. The protein is allergenic, being recognized by immunoglobulin E (IgE) in sera from latex-allergic patients. The IgE epitope resides on the carbohydrate moiety of the protein, and the presence of a similar carbohydrate component on potato tuber patatin enables the latter to inhibit IgE binding to the ENSP homologue. The cDNA encoding the ENSP homologue was isolated by reverse transcription-PCR and cloned. The protein predicted from the cDNA sequence has 391 amino acids, the first 26 of which constitute a putative signal peptide. The deduced molecular mass of the mature protein is 40.40 kDa, while its isoelectric point is estimated at 5.0. The discrepancy between the predicted and observed molecular mass might be due to glycosylation, for which three N-sites on the protein are predicted. The purified protein showed lipase and esterase activities and may be involved in plant defense.