Cadmium induced changes in Solidago chilensis Meyen (Asteraceae) grown on organically fertilized soil with reference to mycorrhizae, metabolism, anatomy and ultrastructure.

Solidago chilensis Meyen (Asteraceae) is a medicinal important plant with few studies on nutrition and metabolism and none information on cadmium phytotoxicity. The objective of this study was to investigate Cd induced responses on the growth and metabolism in S. chilensis and on arbuscular mycorrhiza (AM). The experiment was carried out in a greenhouse, consisting of a 5 × 4 factorial with five doses of manure (0, 3.5, 7, 14 and 21gdm-3) and four doses of cadmium (0, 25, 50 and 75mgdm-3) applied to a Dystrophic Ultisol. After 250 days of plant cultivation, biomass, nutrient content, photosynthetic rate, guaiacol peroxidase activity, mycorrhizal colonization, glomalin content, anatomical and ultrastucture were evaluated. Plants were significantly affected by interaction of manure and Cd doses with anatomical, ultrastructural, physiological and nutritional modifications. Manure applied into Cd contaminated soil significantly improved mycorrhizal colonization and glomalin production. The highest organic manure dose (21gdm-3) alleviated toxicity symptoms of Cd on S. chilensis.

Unraveling the secretion mechanism of the curious nectaries in Gentianaceae.

Unusual nectaries were anatomically described as being usual traits for Gentianaceae. They are small, avascularized, and formed by 3 to 5 rosette cells with labyrinthine walls around one central cell. Such as nectaries have been reported for stems, petals, and sepals of different species of the family, however, there is no information on the mechanisms involved with the synthesis and release of secretion. Thus, this work aimed to unravel the mechanism of secretion and exudation of nectar for these curious nectaries using Calolisianthus speciosus as a model. Samples were processed according to standard methods for light and electron microscopy. Leaf and sepal nectaries were described, as were those of the apex of petals where ants were observed patrolling a darkened region. The enzymatic method was used for the detection of sugars, proteins, and amino acids in leaf and sepal exudates. The nectaries of petals of C. speciosus are similar to those of its leaves, sepals, and stem, although their activities are asynchronous. Polysaccharides were detected on the labyrinthine walls of rosette cells and protein in the opposite region of the cytoplasm. Labyrinthine walls increase the contact surface between rosette cells and the central cell, allowing for the transfer of secretion. After accumulation, the secretion is released to the subcuticular space of the central cell through disruption of the cuticle. The secretion and exudation of nectar were elucidated and involve distinct organelles.

Anatomia e ultraestrutura foliar de Ocimum gratissimum sob diferentes níveis de radiação luminosa / Leaf anatomy and ultrastructure of Ocimum gratissimum under different light radiation levels

Espécies vegetais são capazes de ajustar suas características fisiológicas, anatômicas e ultraestruturais aos fatores ambientais, como, por exemplo, a disponibilidade de radiação luminosa incidente. O objetivo deste estudo foi avaliar a influência de diferentes níveis de radiação luminosa na anatomia e ultraestrutura foliar de Ocimum gratissimum L. (Lamiaceae). As plantas foram cultivadas por 93 dias em quatro níveis de radiação fotossinteticamente ativa (20, 11, 7 e 4mol m-2 d-1). O incremento da intensidade de luz proporcionou aumento no espessamento dos parênquimas paliçádico e esponjoso e do limbo foliar, entretanto, a espessura da epiderme não foi alterada. Em relação aos aspectos ultraestruturais, verificou-se aumento no tamanho dos cloroplastos e grãos de amido e um aumento do empilhamento dos tilacoides com a redução da intensidade de luz. As variações anatômicas e ultraestruturais verificadas confirmam a plasticidade fenotípica dessa espécie em função da intensidade de radiação luminosa.

Plant species are able to adjust their physiological, anatomical and ultrastructural characteristics to changes in environmental factors, such as the availability of incident light. The objective of this study was to evaluate the influence of different light radiation levels on leaf anatomy and ultrastructure in plants of Ocimum gratissimum L. (Lamiaceae). Plants were grown for 93 days in four levels photosynthetic active radiation (FAR): 20, 11, 7 and 4mol m-2 d-1. The increase of light intensity resulted in increase of palisade and spongy parenchyma thickness and leaf blade. However, epidermal thickness was not changed. Regarding the ultrastructural aspects, there was an increase in the size of the chloroplasts and starch granules. However, there was an increase of the stacking of the thylakoids with reducing light intensity. Anatomical and ultrastructural changes confirm the phenotypic plasticity of this species as a function of changes in light intensity.

Light intensity on growth, leaf micromorphology and essential oil production of Ocimum gratissimum

Light conditions can promote the growth and development of plants and contribute to increase the essential oil production of commercially cultivated medicinal and aromatic species. In view of the great importance of Ocimum gratissimum L., Lamiaceae, as an aromatic plant, the objective of this work was to determine the effect of light intensities (approximately 4, 7, 11 and 20 mol m-2 d-1) on growth, foliar micromorphology, essential oil content, yield and chemical composition of O. gratissimum. Biomass production of different organs, root:shoot ratio and leaf mass per area were found to linearly increase with increased light availability, whereas stem dry matter fraction, number of leaves, leaf area and plant height have increased up to 10 mol m-2 d-1 and decreased from this value. The tector trichomes density increased with increased light availability, but there was no effect of light treatments on the glandular trichomes density and essential oil content. Regardless of the light level, the major component of the essential oil was eugenol. The essential oil yield per plant increased linearly with light intensity as a direct effect of increased leaf biomass under similar conditions.