RESUMO
This study compares oil and mucilage idioblasts occurring together in the vegetative organs of Ocotea pulchella, a Lauraceae species. Our focus is specifically on the ontogeny and developmental cytology of these secretory cells. Both types of idioblasts originate from solitary cells located in the fundamental meristem, underlying the protodermis. The growth of both types of idioblasts is asynchronous, with the oil idioblasts developing first, but their initiation is restricted to the early stages of organ development. Mucilaginous idioblasts occur exclusively in the palisade parenchyma, while oil idioblasts are scattered throughout the mesophyll, midrib, and petiole of the leaves. The lamellar secretion of mucilage idioblasts is mostly made up of polysaccharides, while the secretion of oil idioblasts is made up of terpenes and lipids. Cupule occurred only in the oil idioblasts, while suberized layers occurred in both types of cells. We found that immature oil idioblasts that are close to each other fuse; mature mucilage idioblasts have labyrinthine walls arranged in a reticulate pattern; the cells close to the oil idioblasts have a pectin protective layer; and the oil idioblasts have a sheath of phenolic cells. In contrast to previous reports, the two types of secretory idioblasts were recognized during the early stages of their development. The results emphasize the importance of combining optical and electron microscopy methods to observe the ontogenetic, histochemical and ultrastructural changes that occur during the development of the secretory idioblasts. This can help us understand how secreting cells store their secretions and how their walls become specialized.
Assuntos
Lauraceae , Lauraceae/metabolismo , Mucilagem Vegetal/metabolismo , Óleos de Plantas/metabolismo , Folhas de Planta/ultraestrutura , Folhas de Planta/metabolismoRESUMO
A geographically isolated maize landrace cultivated on nitrogen-depleted fields without synthetic fertilizer in the Sierra Mixe region of Oaxaca, Mexico utilizes nitrogen derived from the atmosphere and develops an extensive network of mucilage-secreting aerial roots that harbors a diazotrophic (N2-fixing) microbiota. Targeting these diazotrophs, we selected nearly 600 microbes of a collection obtained from mucilage and confirmed their ability to incorporate heavy nitrogen (15N2) metabolites in vitro. Sequencing their genomes and conducting comparative bioinformatic analyses showed that these genomes had substantial phylogenetic diversity. We examined each diazotroph genome for the presence of nif genes essential to nitrogen fixation (nifHDKENB) and carbohydrate utilization genes relevant to the mucilage polysaccharide digestion. These analyses identified diazotrophs that possessed the canonical nif gene operons, as well as many other operon configurations with concomitant fixation and release of >700 different 15N labeled metabolites. We further demonstrated that many diazotrophs possessed alternative nif gene operons and confirmed their genomic potential to derive chemical energy from mucilage polysaccharide to fuel nitrogen fixation. These results confirm that some diazotrophic bacteria associated with Sierra Mixe maize were capable of incorporating atmospheric nitrogen into their small molecule extracellular metabolites through multiple nif gene configurations while others were able to fix nitrogen without the canonical (nifHDKENB) genes.
Assuntos
Microbiota/genética , Fixação de Nitrogênio , Mucilagem Vegetal/metabolismo , Raízes de Plantas/microbiologia , Zea mays/microbiologia , Bactérias/genética , Bactérias/metabolismo , Genoma Bacteriano , México , Nitrogênio/metabolismo , Óperon , Filogenia , Raízes de Plantas/metabolismo , Sequenciamento Completo do GenomaRESUMO
BACKGROUND: Among Cactaceae, the genus Opuntia is widely known for the use of its biomass as cattle fodder and in human nutrition (e.g. species such as Opuntia ficus indica and Opuntia streptacantha). In particular, O. streptacantha (OS) produces abundant mucilage and, hence, the characterization of its properties and nutritional value is important. Accordingly, determination of the dietary fiber content of the OS mucilage and the fermentability of its hydrolysis products (oligosaccharides, OLI) is important for developing new uses of the crop as a functional food. RESULTS: The values for insoluble dietary fiber and soluble dietary fiber in the mucilage were 204.6 and 371.6 g kg-1 , respectively. After hydrolysis of OS mucilage with α-amylase, three purified fractions of OLI were evaluated (OLI-A, OLI-B and OLI-C). OLI (1% w/v) stimulated the growth of the commercial probiotic strains (Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium animalis subsp. lactis) in vitro, showing behaviors similar to those of commercial inulin. The production of short chain fatty acids (SCFAs) in the fermentation broth was also determined. The final pH of the fermentation broth as well as the identification and concentrations of SCFA depended on the type of OLI and probiotic used. CONCLUSION: The OS mucilage is an unconventional fiber source and can be used to produce non-digestible OLI as functional compounds. This knowledge will be useful for proposing new sustainable ways of processing cacti crops for food and industrial purposes. © 2018 Society of Chemical Industry.
Assuntos
Oligossacarídeos/química , Opuntia/química , Mucilagem Vegetal/química , alfa-Amilases/química , Bifidobacterium animalis/metabolismo , Biocatálise , Fibras na Dieta/análise , Fibras na Dieta/metabolismo , Ácidos Graxos Voláteis/metabolismo , Hidrólise , Lactobacillus acidophilus/metabolismo , Modelos Biológicos , Valor Nutritivo , Oligossacarídeos/metabolismo , Opuntia/metabolismo , Mucilagem Vegetal/metabolismo , Polissacarídeos/química , Polissacarídeos/metabolismo , alfa-Amilases/metabolismoRESUMO
Plants are associated with a complex microbiota that contributes to nutrient acquisition, plant growth, and plant defense. Nitrogen-fixing microbial associations are efficient and well characterized in legumes but are limited in cereals, including maize. We studied an indigenous landrace of maize grown in nitrogen-depleted soils in the Sierra Mixe region of Oaxaca, Mexico. This landrace is characterized by the extensive development of aerial roots that secrete a carbohydrate-rich mucilage. Analysis of the mucilage microbiota indicated that it was enriched in taxa for which many known species are diazotrophic, was enriched for homologs of genes encoding nitrogenase subunits, and harbored active nitrogenase activity as assessed by acetylene reduction and 15N2 incorporation assays. Field experiments in Sierra Mixe using 15N natural abundance or 15N-enrichment assessments over 5 years indicated that atmospheric nitrogen fixation contributed 29%-82% of the nitrogen nutrition of Sierra Mixe maize.
Assuntos
Microbiota/genética , Fixação de Nitrogênio/fisiologia , Nitrogênio/metabolismo , Zea mays/metabolismo , México , Microbiota/fisiologia , Filogenia , Desenvolvimento Vegetal , Mucilagem Vegetal/metabolismo , Raízes de Plantas/metabolismo , Polissacarídeos/metabolismo , Solo , Microbiologia do SoloRESUMO
Histochemical analysis is essential for the study of plant secretory structures whose classification is based, at least partially, on the composition of their secretion. As each gland may produce one or more types of substances, a correct analysis of its secretion should be done using various histochemical tests to detect metabolites of different chemical classes. Here I describe some of the most used methods to detect carbohydrates, proteins, lipids, phenolic compounds, and alkaloids in the secretory structures.
Assuntos
Histocitoquímica/métodos , Células Vegetais/metabolismo , Estruturas Vegetais/citologia , Plantas/metabolismo , Metabolismo dos Carboidratos , Carboidratos/química , Mucilagem Vegetal/química , Mucilagem Vegetal/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Metabolismo Secundário , Amido/química , Amido/metabolismoRESUMO
A comparative study of mucilage (locular tissue) and pulp polysaccharides from ripe tamarillo fruits (Solanum betaceum Cav.) was carried out. After aqueous and alkaline extractions and various purification steps (freeze-thaw and α-amylase - EC 3.2.1.1 treatments, Fehling precipitation and ultrafiltration through 50 kDa cut-off membrane), the obtained fractions from mucilage were analyzed by sugar composition, HPSEC, and NMR spectroscopy analyses. The results showed that the mucilage of tamarillo contains a highly methoxylated homogalacturonans mixed with type I arabinogalactans, a linear (1 â 5)-linked α-L-arabinan, and a linear (1 â 4)-ß-D-xylan. A comparison with polysaccharides extracted from the pulp revealed that differences were observed in the yield and in the ratio of extracted polysaccharides. Moreover, structural differences between pulp and mucilage polysaccharides were also observed, such as in the length of side chains of the pectins, and in the degree of branching of the xylans.
Assuntos
Frutas/metabolismo , Mucilagem Vegetal/metabolismo , Polissacarídeos/metabolismo , Solanum/metabolismo , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Fracionamento Químico , Cromatografia em Gel , Monossacarídeos/análise , Pectinas/isolamento & purificação , Polissacarídeos/isolamento & purificação , Solubilidade , Água/químicaRESUMO
UNLABELLED: Coffee is among the most preferred nonalcoholic drinks, and its consumption is distributed globally. During the coffee fruiting process, however, a large amount of waste is generated in the form of pulp, mucilage, husks, and water waste. The pulp and mucilage have the chemical composition to support the growth of micro-organisms and the production of value-added product. The aim was testify pulp coffee can be considered as carbon and inductor source for ß-glucosidase by Bacillus subtilis CCMA 0087. The response surface methodology (RSM) based on a central composite rotatable design (CCRD) was employed for this optimization. The methodology used in the optimization process was validated by testing the best conditions obtained and comparing them with the values predicted by the model. The highest ß-glucosidase production (22·59 UI ml(-1) ) was reached in 24 h of culturing at coffee pulp concentration of 36·8 g l(-1) , temperature of 36·6°C, and pH of 3·64. SIGNIFICANCE AND IMPACT OF THE STUDY: Countries whose economy is based on agricultural activities generate a great deal of liquid and solid waste. Thus, it is important to develop new alternatives for using this waste rather than disposing it in the environment. The production of enzymes, and particularly cellulase, is one such alternative. In this study, we proposed to produce ß-glucosidase production from pulp coffee extract using a Bacillus subtilis strain.
Assuntos
Bacillus subtilis/metabolismo , Reatores Biológicos/microbiologia , Café/metabolismo , Mucilagem Vegetal/metabolismo , beta-Glucosidase/biossíntese , Carbono , Celulase/biossíntese , Fermentação , Concentração de Íons de Hidrogênio , Temperatura , ResíduosRESUMO
PREMISE OF THE STUDY: The term colleter is applied to trichomes or emergences positioned close to developing vegetative and floral meristems that secrete a sticky, mucilaginous, and/or lipophilic exudate. Several ecological functions are attributed to these glands, but none are exclusive to colleters. Patterns of morphology and distribution of colleters may be valuable for systematics and phylogeny, especially concerning problematic and large groups such as the subtribe Pleurothallidinae, and are also essential to understand the evolution of these glands in Orchidaceae as a whole. METHODS: We used scanning electron and light microscopy to examine the structure and occurrence of trichomes on bracts and sepals and in the invaginations of the external ovary wall (IEOW) in flowers in several developmental stages from species in seven genera. KEY RESULTS: The exudate was composed of polysaccharides, lipophilic, and phenolic compounds. Colleters were secretory only during the development of floral organs, except for the glands in the IEOW that were also active in flowers at anthesis. After the secretory phase, fungal hyphae were found penetrating senescent trichomes. CONCLUSIONS: Trichome-like colleters seem to be a widespread character in Epidendroideae, and digitiform colleters are possibly the common type in this subfamily. Mucilage from IEOW colleters may aid in the establishment of symbiotic fungi necessary for seed germination. The presence of colleters in the IEOW may be a case of homeoheterotopy, in which extrafloral nectaries that produce simple sugar-based secretions (as in other orchid species) have changed to glands that produce secretions with complex polysaccharides, as in Pleurothallidinae.
Assuntos
Flores/anatomia & histologia , Flores/fisiologia , Orchidaceae/anatomia & histologia , Orchidaceae/fisiologia , Flores/crescimento & desenvolvimento , Flores/ultraestrutura , Meristema/anatomia & histologia , Meristema/crescimento & desenvolvimento , Meristema/fisiologia , Meristema/ultraestrutura , Microscopia Eletrônica de Varredura , Orchidaceae/crescimento & desenvolvimento , Orchidaceae/ultraestrutura , Mucilagem Vegetal/metabolismoRESUMO
The colleter secretion can be useful to protect plants of Cerrado (Brazilian savanna) biome during the long and pronounced dry season. This study describes the presence of colleters in Tontelea micrantha and represents the first record of these structures in Celastraceae. To investigate colleter structure and their secretory processes, young leaves were collected, fixed, and processed according to conventional techniques for light, and electron microscopy. Colleters were observed at the marginal teeth on the leaf. They produce mucilaginous secretions that spread over the leaf surface. After secretory phase, colleters abscise. The secretory epithelium is uniseriate and composed of elongated cells whose dense cytoplasm is rich in organelles. The ultrastructure of the secretory cells is compatible with the pectin-rich secretion. Observations of the young leaves surface revealed the presence of superficial hydrophilic secretion films that appeared to have the function of maintaining the water status of those organs.