RESUMEN
Plants reorient the growth of affected organs in response to the loss of gravity vector. In trees, this phenomenon has received special attention due to its importance for the forestry industry of conifer species. Sustainable management is a key factor in improving wood quality. It is of paramount importance to understand the molecular and genetic mechanisms underlying wood formation, together with the hormonal and environmental factors that affect wood formation and quality. Hormones are related to the modulation of vertical growth rectification. Many studies have resulted in a model that proposes differential growth in the stem due to unequal auxin and jasmonate allocation. Furthermore, many studies have suggested that in auxin distribution, flavonoids act as molecular controllers. It is well known that flavonoids affect auxin flux, and this is a new area of study to understand the intracellular concentrations and how these compounds can control the gravitropic response. In this review, we focused on different molecular aspects related to the hormonal role in flavonoid homeostasis and what has been done in conifer trees to identify molecular players that could take part during the gravitropic response and reduce low-quality wood formation.
Asunto(s)
Cycadopsida/crecimiento & desarrollo , Flavonoides/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Cycadopsida/metabolismo , Homeostasis , Lignina/biosíntesisRESUMEN
The identity of genes causally implicated in the development and evolutionary origin of reproductive characters in gymnosperms is largely unknown. Working within the framework of plant evolutionary developmental biology, here we have cloned, sequenced, performed phylogenetic analyses upon and tested the expression patterns of LEAFY/FLORICAULA and NEEDLY orthologs in reproductive structures from selected species of the conifer genera Picea, Podocarpus, and Taxus. Contrary to expectations based on previous assessments, expression of LFY/FLO and NLY in cones of these taxa was found to occur simultaneously in a single reproductive axis, initially overlapping but later in mutually exclusive primordia and/or groups of developing cells in both female and male structures. These observations directly affect the status of the "mostly male theory" for the origin of the angiosperm flower. On the other hand, comparative spatiotemporal patterns of the expression of these genes suggest a complex genetic regulatory network of cone development, as well as a scheme of functional divergence for LFY/FLO with respect to NLY homologs in gymnosperms, both with clear heterochronic aspects. Results presented in this study contribute to the understanding of the molecular-genetic basis of morphological evolution in conifer cones, and may aid in establishing a foundation for gymnosperm-specific, testable evo-devo hypotheses.
Asunto(s)
Evolución Biológica , Proteínas de Plantas/metabolismo , Tracheophyta/metabolismo , Factores de Transcripción/metabolismo , Cycadopsida/clasificación , Cycadopsida/crecimiento & desarrollo , Cycadopsida/metabolismo , Funciones de Verosimilitud , Filogenia , Picea/clasificación , Picea/crecimiento & desarrollo , Picea/metabolismo , Proteínas de Plantas/clasificación , Proteínas de Plantas/genética , ARN Mensajero/metabolismo , Taxus/clasificación , Taxus/crecimiento & desarrollo , Taxus/metabolismo , Tracheophyta/clasificación , Tracheophyta/crecimiento & desarrollo , Factores de Transcripción/clasificación , Factores de Transcripción/genéticaRESUMEN
This paper describes the purification and characterization of a new N-acetyl-d-glucosamine-specific lectin from Araucaria angustifolia (AaL) seeds (Araucariaceae) and its anti-inflammatory and antibacterial activities. AaL was purified using a combination of affinity chromatography on a chitin column and ion exchange chromatography on Sephacel-DEAE. The pure protein has 8.0kDa (SDS-PAGE) and specifically agglutinates rabbit erythrocytes, effect that was independent of the presence of divalent cations and was inhibited after incubation with glucose and N-acetyl-d-glucosamine. AaL showed antibacterial activity against Gram-negative and Gram-positive strains, shown by scanning electron microscopy. AaL, intravenously injected into rats, showed anti-inflammatory effect, via carbohydrate site interaction, in the models of paw edema and peritonitis. This lectin can be used as a tool for studying bacterial infections and inflammatory processes.
Asunto(s)
Bacterias/citología , Bacterias/efectos de los fármacos , Cycadopsida/metabolismo , Inflamación/tratamiento farmacológico , Lectinas de Plantas/administración & dosificación , Semillas/química , Animales , Relación Dosis-Respuesta a Droga , Extractos Vegetales/administración & dosificación , Extractos Vegetales/aislamiento & purificación , Lectinas de Plantas/aislamiento & purificación , RatasRESUMEN
A general structural characterization and an investigation on the dynamics of formation of cell wall polysaccharides was performed, using plantlets stem samples from a typical gymnosperm from southern Brazil, Araucaria angustifolia, as experimental model. Microscopic examination and monosaccharide composition of plantlet segments at different heights were carried out to show the representative portions of stem cell wall development. The plantlets were divided in portions (tip, middle and base) which were submitted to sequential extractions. The extraction with water gave rise to large amounts of pectic material in the three portions and more highly substituted pectins occurred in the tip portion of the stems. Increase in alkali concentration extracted, respectively, higher amounts of xyloglucan structurally similar to those from dicotyledons. However, oligosaccharides containing galactose and fucose where found in higher amounts in base than tip portion. The changes in cell wall composition suggest that the development in gymnosperm cell walls follow the same key events as found in dicotyledon walls (type I).
Asunto(s)
Pared Celular/metabolismo , Cycadopsida/metabolismo , Carbohidratos/química , Cromatografía , Cromatografía por Intercambio Iónico , Germinación , Hidrólisis , Espectroscopía de Resonancia Magnética , Monosacáridos/química , Monosacáridos/metabolismo , Fenómenos Fisiológicos de las Plantas , Polisacáridos/química , Semillas/metabolismo , Espectrometría de Masa por Ionización de Electrospray , Ácidos Urónicos/químicaRESUMEN
Syagrus coronata is an economically important palm tree grown as an ornament, for the oil extracted from its seeds, and the wax from its leaves which has several applications in industry. Silicon biocomposites were analyzed in leaves of S. coronata. Silica bodies were found as extracellular silica masses between the hypodermal-layer cell walls and in granules present in the vacuoles of palisade cells. Scanning electron microscopy of the hypodermal layer of cells showed a collection of spherical bodies embedded in enveloping cavities that outlined the general structure of the bodies. Globular subunits with sharp edges formed the spherical bodies that ranged from 6 to 10 microm in diameter (average, 7.8 microm). X-ray microanalysis detected only silicon and oxygen homogeneously distributed throughout the bodies. Vacuoles of palisade cells contained a large number of granules ranging from 20 nm to 1.2 microm in size (average, 300 nm). Transmission electron microscopy associated with electron spectroscopic imaging and electron energy loss spectroscopy were used to determine the elemental composition of the granules. Vacuolar granules were amorphous and composed of silicon and oxygen, suggesting they consist of amorphous silica biominerals. No nitrogen, indicative of organic matter, was detected in the granules.
Asunto(s)
Pared Celular/metabolismo , Cycadopsida/metabolismo , Gránulos Citoplasmáticos/metabolismo , Estructuras de las Plantas/metabolismo , Compuestos de Silicona/metabolismo , Vacuolas/metabolismo , Pared Celular/ultraestructura , Cycadopsida/ultraestructura , Gránulos Citoplasmáticos/ultraestructura , Microscopía Electrónica , Microscopía Electrónica de Rastreo , Estructuras de las Plantas/ultraestructura , Análisis Espectral , Vacuolas/ultraestructuraRESUMEN
Protein kinases and phosphatases are responsible for several cellular events mediated by protein phosphorylation and dephosphorylation. Among these events are cell growth and differentiation and cellular metabolism. Casein kinase I (CKI) and casein kinase II (CKII) are involved in the phosphorylation of several substrates. Endogenous protein phosphorylation and casein kinase activity were investigated in the megagametophyte of the native Brazilian conifer Araucaria angustifolia, during seed development. It was observed that a number of different polypeptides are phosphorylated in vitro in the three megagametophyte stages of development tested (from globular, cotyledonary and mature embryos, respectively) and the phosphate was incorporated mainly in serine residues. The use of okadaic acid and vanadate in the phosphorylation reactions increased phosphate incorporation in several polypeptides suggesting the presence of serine/threonine as well as tyrosine phosphatases in the megagametophyte. Also, the results obtained in experiments with CKII inhibitor, GTP as phosphate donor, RNA hybridizations, and in-gel kinase assays indicate the presence of CKII in the A. angustifolia megagametophyte.