Search

Rare earth elements induce ER membrane remodeling and increase ER–PM connectivity in a process that involves phosphoinositide-associated reorganization of synaptotagmin-tethering complexes., In plant cells, environmental stressors promote changes in connectivity between the cortical endoplasmic reticulum (ER) and the plasma membrane (PM). Although this process is tightly regulated in space and time, the molecular signals and structural components mediating these changes in interorganelle communication are only starting to be characterized. In this report, we confirm the presence of a putative tethering complex containing the synaptotagmins 1 and 5 (SYT1 and SYT5) and the Ca2+- and lipid-binding protein 1 (CLB1/SYT7). This complex is enriched at ER–PM contact sites (EPCSs), has slow responses to changes in extracellular Ca2+, and displays severe cytoskeleton-dependent rearrangements in response to the trivalent lanthanum (La3+) and gadolinium (Gd3+) rare earth elements (REEs). Although REEs are generally used as non-selective cation channel blockers at the PM, here we show that the slow internalization of REEs into the cytosol underlies the activation of the Ca2+/calmodulin intracellular signaling, the accumulation of phosphatidylinositol-4-phosphate (PI4P) at the PM, and the cytoskeleton-dependent rearrangement of the SYT1/SYT5 EPCS complexes. We propose that the observed EPCS rearrangements act as a slow adaptive response to sustained stress conditions, and that this process involves the accumulation of stress-specific phosphoinositide species at the PM.

In the present study, we investigated the sites of aluminum (Al) accumulation and its effects on the growth, morphology and nutritional status in root tips of soybean (Glycine max L.) genotype Conquista. The seedlings were exposed to nutrient Clark solution, pH 4.0, with 0 (control) and 100 µM of Al for 24, 48 and 72 h. Our results showed an Al accumulation in the superficial layers of the root tip, such as the root cap cells, epidermis and cortex cells, and internally in the cell walls of the meristematic cells. The Al accumulation in the outer cells prevented the entry of this metal in the inner tissues. However, scanning electron micrographs showed damage in the external micromorphology of the root tips. This damage resulted in cellular disorganization in the root cap and epidermis cells leading to a reduction in Ca and Mg uptake. Despite that, there was no change in root growth. Taken together, our findings suggest that genotype Conquista has a capacity to avoid Al toxicity, probably by Al immobilization in the cell walls and in the external tissues of the root tip.

The leaf anatomy of Ocotea paulensis Vatt., Ocotea odorifera (Vell.) J. G. Rohwer, Nectandra lanceolata Nees et Mart. ex Nees and Nectandra rigida (H.B.K) Nees was made, in order to identify anatomical characters that may assist in the identification of these species. The presence of trichomes, the type of stomata, the formation of the periderm in the petiole, the buttresses in the outer periclinal wall of the epidermal cells, the leaf edge conformation, the presence of hypodermis, the vascular system conformation in the median rib and venation pattern showed marked differences, allowing species separation based on these traits.

A major issue in modern agriculture is water loss through stomata during photosynthetic carbon assimilation. In water-limited ecosystems, annual plants have strategies to synchronize their growth and reproduction to the availability of water. Some species or ecotypes of flowers are early to ensure that their life cycles are completed before the onset of late season terminal drought ("drought escape"). This accelerated flowering correlates with low water-use efficiency (WUE). The molecular players and physiological mechanisms involved in this coordination are not fully understood. We analyzed WUE using gravimetry, gas exchange, and carbon isotope discrimination in florigen deficient (sft mutant), wild-type (Micro-Tom), and florigen over-expressing (SFT-ox) tomato lines. Increased florigen expression led to accelerated flowering time and reduced WUE. The low WUE of SFT-ox was driven by higher stomatal conductance and thinner leaf blades. This florigen-driven effect on WUE appears be independent of abscisic acid (ABA). Our results open a new avenue to increase WUE in crops in an ABA-independent manner. Manipulation of florigen levels could allow us to produce crops with a life cycle synchronized to water availability.

Secretory structures were little studied in Gentianaceae. Glandular areas on the calyx dorsal region are commonly reported for Helieae species, the main tribe of Gentianaceae. So, the elucidation of nature of glandular areas is particularly relevant. Trichomes secreting mucilage, interpreted as colleters, are reported only for the sepals of Gentianinae species. We aimed to anatomically characterize and identify the nature of the calycinal secretory structures in Calolisianthus pedunculatus. Samples from floral buds, flowers, and fruits were collected, fixed, and processed following usual procedures for light and scanning electron microscopies. Histochemical tests were performed to determine the nature of the secretion. Glucose, fructose, and sucrose were measured with an ELISA reader. Colleters occur on the sepal ventral region and are composed of a multicellular secretory head and a stalk. These structures secrete polysaccharides and proteins, and the secretion is probably released through cuticle microchannels. Nectaries, on the other hand, occur on the sepal dorsal region. They are formed by 3-5 cells arranged in rosettes circling a central cell or pore. These structures also secrete polysaccharides (mainly fructose), lipids, and proteins. The identification of the secretory structures in the sepals of Calolisianthus pedunculatus highlights the importance of anatomical studies in this family. The interpretation of the glandular areas on the calyx of the Helieae species as nectaries has been proven, as well as the confirmation of colleters as common structures in the sepals of Gentianaceae. Besides the taxonomic and phylogenetic importance of nectars and colleters, we highlight the importance of the secretion for the protection of floral buds against dehydration.

Background: Herbivores cause biochemical, physiological, and morphological changes on plants. The ultimate effects of the herbivore activities are damages on the plant's body that can lead from local tissues death to the plant death. The intensity of herbivore attack and the plant's capability to defend itself determine the outcomes of herbivory. When the plant under attack has economic importance, such damages can diminish the productivity of the plantation and compromise the economy of families and the local communities. Although the adverse effects of herbivory on plants and economy are entirely known, some biological mechanisms underlying these damages remain unclear, especially at the anatomical and hormonal levels. The psyllid Triozoida limbata (Hemiptera: Triozidae) is a critical guava (Psidium guajava) pest in the Neotropical region, causing productivity plantation losses up to 55%. Psyllids cause visible morphological changes on guava leaves; however, there is a lack of detailed studied of the cellular, anatomical, and hormonal aspects of the subject. Thus, this work aimed to determine the alterations caused in guava leaves by T. limbata through anatomical and hormonal analyzes. Results: We found that the psyllid's nymphs feeding causes cells hypertrophy and hyperplasia determining the formation of the leaf-roll galls. Although there was no anatomical differentiation of the mesophilic tissues, the cells accumulate starch. Along with the anatomical changes, we observed increasing in the jasmonic acid and reduction of zeatin concentrations in the leaves. Conclusions: The alteration of phytohormone contents and the anatomical changes indicates that the feeding of T. limbata activates plant defenses, but it is not active toward the insects off. The insect nymphs live inside the leaf-roll galls until adults' phase, feeding on the guava leaves xylem and phloem. In commercial guava orchard, the control of T. limbata nymphs have been difficult. Thus, the understanding of the composition of this protective layer can help to find the most effective and efficient control solution for this pest.

Cacti have a highly specialized stem that enables survival during extended dry periods. Despite the ornamental value of cacti and the fact that stems represent the main source of explants in tissue culture, there are no studies on their morpho-anatomical and cytological characteristics in Melocactus. The present study seeks to address the occurrence of cells with mixed ploidy level in cacti tissues. Specifically, we aim to understand how Melocactus stem tissue is organized, how mixoploidy is distributed when present, and whether detected patterns of ploidy change after long periods of in vitro culture. To analyze tissue organization, Melocactus glaucescens and Melocactus paucispinus plants that had been germinated and cultivated in vitro were analyzed for stem structure using toluidine blue, Xylidine Ponceau, Periodic Acid Schiff, ruthenium red, and acid floroglucin. To investigate patterns of ploidy, apical, medial, and basal zones of the stem, as well as, periphery, cortex, and stele (vascular tissue and pith) regions of the stem and root apexes from four- and ten-year old cultured in vitro were analyzed by flow cytometry. X-ray micro-computed tomography (XRµCT) was performed with fragments of stems from both species. The scarcity of support elements (i.e., sclereids and fibers) indicates that epidermis, hypodermis, and wide-band tracheids present in cortical vascular bundles and stele, as well as water stored in aquifer parenchyma cells along the cortex, provide mechanical support to the stem. Parenchyma cells increase in volume with a four-fold increase in ploidy. M. glaucescens and M. paucispinus exhibit the same pattern of cell ploidy irrespective of topophysical region or age, but there is a marked difference in ploidy between the stem periphery (epidermis and hypodermis), cortex, stele, and roots. Mixoploidy in Melocactus is not related to the age of the culture, but is a developmental trait, whereby endocycles promote cell differentiation to accumulate valuable water.

Pityrogramma calomelanos is interestingly the single non-Pteris arsenic (As)-hyperaccumulating fern. It has been pointed as a potential species for phytoremediation and a model plant to study the As toxicity and its mechanisms of action. In order to investigate the morphoanatomical traits associated to As tolerance, P. calomelanos plants were exposed to different As concentrations in hydroponic solution. At low As dose (1 mM As), 90% of the As accumulated in plants was allocated in shoots, and no symptoms of As stress were observed in fronds and roots. Under higher As exposure (10 and 30 mM As), 81-74% of the total As in plants was present in shoots, and apical and marginal necroses on pinnae were observed. Anatomical observations showed that As induces damages mainly in the secondary veins and adjacent cells. High amounts of phenols were observed in pinna tissues of control and treated plants. In the roots, As promoted slight alterations as detachment of border-like cells and accumulation of granular substances in cortical cells. The high root-to-shoot As translocation and the constitutive presence of phenols and border-like cells protecting the root tips showed to be adaptive traits that allow P. calomelanos to survive in contaminated sites.

Plants growing on soils poor in phosphorus (P) develop P-acquisition strategies such as symbiotic associations with arbuscular mycorrhizal fungi (AMF). In very poor soils, cluster roots, a non-symbiotic alternative strategy enables plants to extract P uptake by developing modified roots. The latter strategy is characteristic (if not a derived trait) of the Southern Hemisphere Proteaceae, which are thus non-mycorrhizal. The Proteaceae have been studied mainly in Australia, where they are very diverse, especially on very P-poor soils. We investigated the presence of cluster roots and/or AMF in the Proteaceae Roupala montana Aubl. from three areas of the Brazilian Cerrado. This is, a seasonal neotropical savanna on highly weathered soils characterised by high aluminium content, low pH, and very low available P. We discovered that R. montana forms arbuscular mycorrhiza and no cluster roots were observed. All the plantlets collected were mycorrhizal. We also evaluated the fertility of the soil (especially the P availability). It was found that R. montana grows in soils containing more than 220 mg kg−1 total P. Thus, they are, more fertile than in most of Australian soils and likely have sufficient available P to support plant nutrition by way of mycorrhizae. Further research should investigate whether other Brazilian, and more generally non-Australian, Proteaceae species can establish associations with AMF, and the link with soil P availability. Our findings have implications for the phylogenetic patterns of loss of symbiosis with AMF within the Proteaceae.

Fluoride (F) is the most phytotoxic atmospheric pollutant. The use of plants for passive or active biomonitoring has been a common strategy to detect abnormal atmospheric F concentrations. Tree species are mostly used, although the high sensitivities of some, associated with costly processes of plant replacement, will increase cost outlays associated with F-biomonitoring processes. After a few days of exposure, F-sensitive species often die, and must be replaced in active biomonitoring stations. We therefore investigated the potential use of the grass Panicum maximum for atmospheric F biomonitoring. Although that grass shows fast accumulations of F in their leaves, no visual symptoms of intoxication were observed. Despite of their F-tolerance, plants showed reliable microscopic responses to F (epicuticular wax erosion, plasmolysis of bulliform cells, and damage associated with trichomes). Since microscopic evaluations are mandatory in F-biomonitoring projects, the use of grass species such as P. maximum that show F-tolerance, fast F-uptake and reliable microscopic responses, could represent an option for F biomonitoring that would decrease costs related to plant production and replacement in monitoring stations.

Glandular trichomes and laticifers occur in I. pes-caprae (L.) Stweet (Convolvulaceae) and I. imperati (Vahl) Griseb. However, the importance of their secretion for the species survival in “Restinga” environments had not yet been investigated. This study aimed to anatomically and histochemically characterize such secretory structures in the two species, indicating which type of laticifers they have and whether or not the trichomes secret saline solution. Moreover, knowing the composition of secretion can help to clarify the species strategies of survival under the stressful conditions in halophilous ecosystems. Leaf samples were used in light microscopy analyses. Both species have multicellular glandular trichomes on the leaf blade, and laticifers on the mesophyll and midrib. Trichome secretion is mucilaginous, but sodium was not detected, and therefore, such trichomes are not salt glands. Laticifers are typical and classified as articulated non-anastomosing, and are not covered by an epithelium, as reported in some studies. Mucilage secretion by the glandular trichomes can aid in the species survival in the “Restinga”. The species latex contains terpenoids and rubber, which may constitute important defenses against herbivores.

Rudgea viburnoides (Cham.) Benth. is an aluminum (Al) hyperaccumulator species native to the Brazilian Cerrado and can be found on soils with different fertilities and Al availabilities. We studied the relationship between the chemical composition of different soils and the Al and nutrient concentrations in the species. Histolocalization of Al and its probable complexation with phenols were investigated. Aluminum in R. viburnoides roots, stems and leaves was detected through histochemical tests, confocal microscopy, and X-ray microanalysis. Phenol localization and concentration were determined, as was the plant nutritional status. Despite the low soil fertilities, nutrient concentrations in vegetative organs were high. Even with the differences in Al availability in the soils, R. viburnoides accumulated more than 10 g Al kg−1 DW on leaves. Pectocellulosic cell walls were preferential sites for Al deposition, but the metal also accumulated in suberized cell walls and chloroplasts. Aluminum localization coincided with Si distribution in cell walls and phenol distribution in the cytosol. Rudgea viburnoides has a great ability to absorb nutrients from poor soils and the hyperaccumulation of Al is independent of the metal availability in the soil. Aluminum accumulation on the phellem and chloroplasts was described for the first time in this species.

Coastal areas present limiting environmental conditions, such as high soil salinity, intense winds, elevated temperature and coastal flooding, which may be related to adaptive anatomical characters. This study aims to evaluate the anatomy of the stems and roots of Restinga plants (eudicots: Blutaparon portulacoides, Canavalia rosea, Ipomoea pes-caprae and Scaevola plumieri; monocot: Remirea maritima) and their relationship to parameters of the microenvironment. These five species were selected because they are dominant and present great occurrence in Restinga vegetation nearest to the sea. Stems and roots of five species (n = 5) were fixed and submitted to standard techniques for analyzing under light microscope. Wind velocity, air temperature, air relative humidity and evaporation level were evaluated close to individuals and above them. The nutritional conditions from rhizosphere were also estimated. The winds were weak close to individuals, while the temperature was higher than compared to measurements above individuals. Minor differences of the soil were noted between areas close and far from the plants. Seven anatomical characters may be related to adaptability to the stressful conditions, as stem succulence, root aerenchyma, root starch reserves and epidermal cell of the stems with thick outer periclinal walls, however there was little convergence between species. Aerenchyma and water reserve tissue were the most frequent anatomical traits. In contrast, elevated cortex lignification in roots was the lowest occurrence trait, being a specific feature of the monocot.

Arsenic (As) hyperaccumulation trait has been described in a limited number of fern species. The physiological basis of hyperaccumulation remains unclear, especially in non-Pteris species such as Pityrogramma calomelanos. Aiming at a better understanding of As-induced responses, P. calomelanos plants were exposed to 1 mM As for 21 days and compared with control plants. Chemical analyses revealed that As accumulation was ten times higher in pinnae then in roots and stipes. In pinnae, As was present mainly as arsenite, whereas arsenate was the dominant form in stipes and roots. Arsenic promoted an increase in antioxidant enzyme activities in both fern parts and several alterations in mineral nutrition, especially with regard to P and K. A higher content of non-protein thiols was observed in pinnae of plants exposed to As, whereas As induced the increase in lipid peroxidation in roots. The results showed that Pityrogramma calomelanos shares with Pteris vittata several aspects of As metabolism. High root-shoot As translocation showed to be essential to avoid toxic effects in roots, since the root is more sensitive to the metalloid. The higher capacity of P. calomelanos to sequester arsenite in the pinna and its efficient antioxidant system maintain the reactive oxygen species at a low level, thus enhancing the continuous accumulation of As. Molecular investigations are needed to elucidate the evolution of As-tolerance mechanisms in Pteridaceae species, especially with regard to membrane transporters and ROS signaling.

Studies on pollutant accumulation in plants are essential for the diagnosis of species with potential for revegetation and remediation of contaminated environments. Hydroponic systems are commonly used for this purpose, but little is known about the influence of the nutrient solution in the results. Borreria verticillata can be found in arsenic (As)-contaminated environments, and research using Hoagland’s nutrient solution has reported a differential tolerance to the metalloid in populations from contaminated (CS) and non-contaminated (NCS) sites. However, some authors suggest the use of Clark’s solution to study As tolerance in plants. We evaluated the growth and nutritional status of plants from these populations, cultivated in Hoagland’s and Clark’s solutions, and determined the most appropriate solution for comparative studies on tolerance to As. The selected solution was used in plant cultivation for As exposure. In Hoagland’s solution plants from the NCS exhibited higher root volume, fresh and dry weight and macronutrient accumulation than those from the CS. Clark’s solution promoted more similar responses and was used in plant exposure to 0, 33 and 66 µM As, for 4 days. The metalloid promoted reduction of total fresh weight in both populations. Alterations were more severe on plants from the NCS, with decreased values of root volume, gas exchanges, height and nutrient concentration in shoots. The severe damage caused by As in plants from the NCS demonstrates its sensitivity to this metalloid, while the responses of the CS population confirm the As-tolerance. These findings suggest that these populations are different ecotypes of B. verticillata.

Colleters are common secretory structures in Rubiaceae. In this study, we describe colleter morphoanatomy and histochemistry in 10 species belonging to Chiococceae, Coussareae, and Psychotrieae tribes of Rubiaceae. Colleter morphoanatomy was analyzed by light and scanning electron microscopy. Microscopy analysis revealed that colleters were present on the stipule adaxial surface in all species. In the case of Palicourea marcgravii A.St.-Hil. and Chiococca alba Hitchc., colleters were also found on leaf primordia and at the stipule apex, respectively. Colleters were classified into three types: standard, bifurcated standard, and reduced standard. Further analysis showed that colleter epidermal cells are thin-walled and possess a thin cuticle, conspicuous nuclei located at the equatorial or basal region, and abundant cytoplasm. Intercellular spaces were found among epidermal cells in Chiococca alba, Coussarea triflora Müll.Arg., Coussarea verticillata Müll.Arg., Psychotria conjungens Müll.Arg., and Psychotria sessilis Vell. Crystalliferous idioblasts containing raphides were observed in the colleter central parenchymatous axis of all species, while crystal sand was found only in Chiococca alba. Histochemical tests revealed that colleter secretion is composed of a mixture of mucilage and protein. We conclude that colleter position, typological variation, presence of vascularization, and type of calcium oxalate crystals represent promising characters for future taxonomic and phylogenetic studies in Rubiaceae. Les collétères sont des structures sécrétoires communes chez les Rubiaceae. Dans cette étude, les auteurs décrivent la morpho-anatomie et l’histochimie de collétères de 10 espèces appartenant aux tribus des Chiococceae, Coussareae et Psychotrieae des Rubiaceae. La morpho-anatomie de collétères a été analysée par microscopie optique et microscopie électronique à balayage. L’analyse en microscopie a révélé que les collétères étaient présentes sur la surface adaxiale des stipules de toutes les espèces. Dans le cas de Palicourea marcgravii A.St.-Hil. et Chiococca alba Hitchc., les collétères se trouvaient aussi sur les ébauches foliaires et à l’apex des stipules, respectivement. Les collétères ont été classifiées en trois types : standard, standard bifurqué et standard réduit. Des analyses supplémentaires ont montré que les cellules épidermiques des collétères possèdent une paroi et une cuticule minces, un noyau bien évident localisé dans la région équatoriale ou basale, et un cytoplasme abondant. Des espaces intercellulaires ont été trouvés entre les cellules épidermiques chez Chiococca alba, Coussarea triflora Müll.Arg., Coussarea verticillata Müll.Arg., Psychotria conjungens Müll.Arg. et Psychotria sessilis Vell. Des idioblastes cristallifères contenant des raphides ont été observés dans l’axe parenchymateux central des collétères de toutes les espèces, alors qu’un sable cristallin était trouvé seulement chez Chiococca alba. Des tests histochimiques ont révélé que la sécrétion des collétères est composée d’un mélange de mucilage et de protéines. Les auteurs concluent que la position des collétères, la variation typologique, la présence de vascularisation et le type de cristaux d’oxalate de calcium représentent des caractères prometteurs pour la réalisation d’études taxonomiques et phylogénétiques futures chez les Rubiaceae.

Chamaecrista (L.) Moench (Caesalpinioideae– Leguminosae) with 330 species is organized into six sections: Apoucouita, Absus, Grimaldia, Chamaecrista, Caliciopsis and Xerocalyx. Section Absus is the largest section of the Chamaecrista and is organized into four subsections, viz., subsect. Adenophyllum, subsect. Baseophyllum, subsect. Otophyllum and subsect. Absus. This section is not monophyletic and has a complex taxonomy. This study aims to anatomically characterize 60 taxa of Chamaecrista, identifying meaningful morphoanatomical characters that may shed light on the evaluations of the taxonomic and phylogenetic framework of Chamaecrista, especially C. sect. Absus. Standard light microscopy techniques were used to anatomically characterize the leaves. The anatomical data were subjected to a multivariate analysis (Jaccard index). Epidermal papillae on the abaxial side, the distribution and types of secretory and tector trichomes, variations in the arrangement of the vascular system of the midvein and the type of arrangement of the vascular system of the petiole are useful for separating species or groups of species. The presence and type of secretory structure, the type and position of stomata and the venation pattern are important in establishing the affinities between sections and subsections. The phenetic analysis demonstrates that the anatomical data contribute to the establishment of affinities between sections and subsections, supporting the elevation of the taxonomic status of the clade Baseophyllum to section and the insertion of C. absus (C. sect. Grimaldia) into C. sect. Absus, corroborating molecular studies.

The accumulation and spatial distribution of arsenic and phosphorus in the As-hyperaccumulator fern Pityrogramma calomelanos were investigated by micro-energy dispersive X-ray fluorescence spectrometry (μ-EDXRF). Ferns were grown in half-strength Hoagland nutrient solution without and with 1.0, 10 or 30 × 10−3 mol L−1 As during three weeks. Microchemical As and P maps in different areas of the pinna were obtained by μ-EDXRF, and the same elements were also determined in pelletized powdered samples from the pinna, stipe and root. The reference method for the determination of As and P in the fern samples was a validated method based on microwave-assisted acid digestion followed by ICP OES analysis. Correlations between X-ray characteristic emission intensities and the corresponding As and P mass fractions obtained from the analysis of pelletized test samples exhibited linear correlation coefficients higher than 0.98 (n = 42). Better root mean square errors of prediction (RMSEPs) were obtained when different calibration models were built with pinna, stipe and root test samples separately. Arsenic was accumulated mainly in the pinna midrib, secondary veins, and apical and marginal regions of the pinnule of P. calomelanos, causing alterations in the P distribution. The proposed μ-EDXRF method is an appropriate analytical tool for simultaneously mapping As and P in P. calomelanos. In addition, useful information for either environmental monitoring or phytoremediation studies regarding As contamination is properly obtained.

The waterlogging of commonly non-flooded soils acts as a filtering for plant communities. River impoundments can flood a large area never flooded before, changing the local conditions and affecting seeds and growing plants. Therefore, the recruitment process in the regenerating community on these new formed margins may be inhibited. Lists containing plant species indicated for restoration of periodically flooded habitats have been published but the germination and initial development behavior of these species are poorly known. We hypothesize that species indicated to restore flooded habitats (FH) are faster to germinate and their seedling also develop better than species from non-flooded habitats (NH) under waterlogging conditions. Seeds of species from flooded and non-flooded habitats were submitted to treatments of flooding (F) and non-flooding (N) for 90 days, and germination was daily registered. Seedlings of Psidium guajava and Handroanthus serratifolius were submitted to flooding and morphophysiological parameters were measured. Species from both groups had similar patterns of germination, and for most species flooding led to a faster germination. In general, the number of germinated seeds was smaller under flooding. P. guajava seedlings presented decreasing growth and photosynthesis under flooding and H. serratifolius seedlings presented chlorosis, foliar abscission, negative net photosynthetic rate, and root-rotting. Flooding was harmful for plants of both groups, but was worse for seeds and seedlings from NH species. The outcomes show that the use of plant species in restoration programs of dams and reservoir margins must take into account if it will be used seeds or seedlings, since the success and sustainability of this action will depend on the fast and well development of the plants.

We aimed to verify whether morphoanatomic alterations occur in response to excess iron, in roots of Setaria parviflora and Paspallum urvillei (Poaceae), and to localize the presence of the sites of iron accumulation. Plants were subjected to 0.009, 1, 2, 4, and 7 mM Fe-EDTA in nutrient solution. Both species presented iron contents in the roots above the critical toxicity level. The presence of iron plaque on roots of the two species was confirmed, and it may have reduced iron absorption by the plants. Roots from the two species showed typical visual symptoms of stress by excess iron: change in color and mucilaginous and flaccid appearance. Anatomical damage was observed in both species: aerenchyma disruption, alterations in endodermal cells, and irregular shape of both vessel and sieve tube elements. The metal was histolocalized in the cortex and in protoxylem and metaxylem cell walls in both species, which suggests a detoxification strategy for the excess iron. Phenolic compounds were not histolocalized in roots. Microscopic analyses were therefore effective in evaluating the real damage caused by excess iron.

We investigated biomarkers for early fluoride (F)-detection in the environment using the F-sensitive species Spondias dulcis. Plants were exposed to F (5 ml l−1) to determine the sequence of events preceding the visual appearance of the characteristic symptomatology of F toxicity. Decreases in photosynthetic rates in plants upon F exposure were related to decreasing stomatal conductance due to F-induced damage to guard-cells. Chlorophyll fluorescence was not a good indicator of F stress to plants, meanwhile the scanning electron microscopy and gas-analyzer evaluations were the best techniques to attest to atmospheric F concentrations using S. dulcis, since their results were predictive and preceded F-induced visual symptomatology in plant leaflets. Our results demonstrated that microscopic damage precedes physiological disturbances in sensitive plant species (such as S. dulcis) exposed to F.

UNLABELLED PREMISE OF THE STUDY Extrafloral nectaries (EFNs) are structures that secrete nectar and protect plants against herbivores and pathogens. In Gentianaceae, these structures have been described in species of Calolisianthus, Fagraea, and Anthocleista and are important morphological markers for taxonomic and phylogenetic studies. To establish a foundation for further studies, we investigated the occurrence, distribution patterns, and anatomy of EFNs on leaves of 27 species belonging to 13 genera and three tribes of neotropical Gentianaceae. • METHODS Leaf samples were diaphanized, stained with basic fuchsin, and mounted in glycerinated gelatin. Cross sections were obtained from material embedded in methacrylate or paraffin, stained, and mounted in Permount. Polysaccharides were histochemically stained with periodic acid-Schiff stain. Samples were also examined with scanning electron microscopy. • KEY RESULTS Unusual EFNs, visible only with light microscopy, were formed of modified epidermal cells. Each EFN consisted of 2-5 secretory cells encircling a central cell. The EFNs varied in size and in the shape and arrangement of the adjacent cells surrounding the secretory cells. EFNs occurred in all analyzed species as isolated units distributed throughout the leaf blade or as aggregates; aggregates were generally visible to the naked eye. Based on their occurrence as aggregates or isolated units and on their location on the leaf blade, six distribution patterns were identified. • CONCLUSIONS This is the first comprehensive study of EFNs on the leaves of neotropical Gentianaceae. The data suggested that NEFs evolved from isolated units for NEFs in aggregates. The results represent a new source of data for future ecological, systematic, and phylogenetic studies in Gentianaceae.

The morpho-anatomical leaf structure may be directly affected by variations in the environmental conditions to which plants are exposed during development. The “campos rupestres” vegetation (rocky fields) is subjected to several stress conditions and microclimatic variations that result in important adaptations that enable the survival in these environments. In this study, we analyzed the leaf morpho-anatomy of two bromeliads, Billbergia elegans Martius ex Schultes f. and Neoregelia mucugensis Leme, occurring in the rock fields of Itacolomi State Park, southeastern Brazil, and tested for morpho-anatomical variations in response to light conditions. The analysis followed usual techniques in plant anatomy. Both species exhibited variations in the shape of the rosette, leaf color, and size of leaf sheath and blade. Scale density was higher on both leaf surfaces of individuals exposed to high solar radiation. Thickness of the leaf blade, water-storage parenchyma, chlorenchyma, and stomatal density were higher in individuals exposed to low solar radiation, which disagrees with most previous studies and may be related to the environment where these species occur, where water availability is one of the main limiting factors. Our observations point out a need for studies on herb species from xeric environments, which may bring new information on adaptations to these environments.

This study aimed to seed germination and adventitious shoot regeneration from Psychotria ipecacuanha inverted hypocotyls. The results showed a percentage of 84.17% of seeds germinated with normal seedlings development. The germination started after the second day of cultivation and was observed up to 70 days. After 40 days seedlings were obtained with average 10 cm in length, responding satisfactorily to the process of acclimatization under laboratory conditions. In hypocotyls with inverted polarity adventitious shoots were formed directly from the explant tissue in the region of contact with the medium, and on the hypocotyl portion out of contact with the medium. The use of hypocotyls with inverted polarity has not been previously reported for the species. The organogenesis occurred directly in the explants and the BA at 1 mg L-1 enhanced the induction of greater number of adventitious shoots. Anatomical analysis confirmed the formation of adventitious shoots by direct pathway. Elongated adventitious shoots were rooted in the presence of IBA. The highest percentage of rooting shoots occurred in the presence of 1.5 mg L-1 of this growth regulator.

The goal of this study was to determine the symptoms and microscopic damage caused by fluoride on Spondias dulcis, a fluoride-sensitive species. The plants were exposed to simulated fog with fluoride (0, 5, 10, 15 and 20 mg L-1) for 20 min daily during four consecutive days. Samples from leaflets without any apparent fluoride injury were collected to microscopic analysis. The percentage of necrosed leaf area was measured, and the level of pollutant in the dry matter from the basal and apical portions of the plant was determined. The necroses began 24 h after the first simulation mainly from the base of the leaflets. A higher level of necrosis was observed at the apical portion of the plants, a region of higher fluoride accumulation. The damage on the surface of the leaflets was characterized as plasmolysis, erosion of the epicuticular waxes and epidermal rupture. Structurally, the noticeable accumulation of granules and droplets green stained by toluidine blue in the spongy parenchima and the boundaries of ending veinlets was observed. The limb thickness reduction occurred due to plasmolysis in the mesophyll, showing an apparent correlation with the damage observed on the surface. The parameters observed in the laboratory are promising for field biomonitoring studies.O objetivo deste estudo foi determinar os sintomas e danos microscópicos causadas pelo flúor em Spondias dulcis, espécie sensível a essa substância. As plantas foram expostas a nevoeiros simulados com flúor (0, 5, 10, 15 e 20 mg L-1) por 20 minutos diários, durante quatro dias consecutivos. Amostras de folíolos sem qualquer lesão aparente ao flúor foram coletadas para análise microscópica. Mensurou-se a percentagem de área foliar necrosada e o teor do poluente na matéria seca das porções basal e apical da planta. As necroses surgiram 24 horas após a primeira simulação e tiveram início, principalmente, a partir da base dos folíolos. As necroses foram mais severas na porção apical das plantas, região com maior acúmulo de flúor. O dano na superfície dos folíolos foi caracterizado como plasmólise, erosão das ceras epicuticulares e ruptura da epiderme. Estruturalmente, observou-se considerável acúmulo de grânulos e gotas coradas de verde pelo azul de toluidina no parênquima lacunoso e nas proximidades das terminações xilemáticas. Houve redução da espessura do limbo devido a plasmólise no mesofilo, havendo aparente correlação com os danos observados na superfície. Os parâmetros observados em laboratório são promissores para estudos de biomonitoramento em campo.

Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil ( Wawra and (Baker) Leme) and a forest fragment located within Bom Sucesso Farm, Viçosa, Minas Gerais, Brazil ( E. Morren and Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of and showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species and the terrestrial species have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species and the epiphytic species also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect microclimatic conditions under which these species occur or genetically fixed characteristics. Les Bromeliaceae, comprenant 3172 espèces, constituent une des familles les plus importantes de la forêt atlantique brésilienne par son fort degré d'endémisme et par sa présence dans différents habitats. La sous-famille des Bromelioideae, la plus représentative des Bromeliaceae, est la mieux représentée dans l'état de Minas Gerais, au Brésil, avec 120 espèces. L'objectif de l'étude consiste à comparer l'anatomie foliaire de quatre espèces trouvées dans deux régions de la forêt atlantique : parc de l'état « Serra do Brigadeiro », MG, Brésil ( Quesnelia strobilispica Wawra et Wittrockia gigantea (Baker) Leme), et un fragment forestier localisé sur la ferme « Bom Sucesso », Viçosa, MG, Brésil ( Billbergia euphemiae E. Morren et Bromelia antiacantha Bertol.), en reliant les caractéristiques environnementales avec l'habitat. Les auteurs ont étudié les feuilles à l'aide de la microscopie photonique et électronique par balayage, ainsi que des colorations au Sudan, phloroglucinol, et rouge de ruthénium. Les feuilles du B. euphemiae et du W. gigantea montrent plusieurs adaptations à l'habitat épiphyte, incluant des écailles sur les deux surfaces, des parois cellulaires épaissies, la présence de corps siliceux, un hypoderme avec des cellules sclérifiées, des tissus accumulateurs d'eau (hydranchymes) et des canaux aérifères formés par des cellules stellées, dans le chlorenchyme. L'espèce épiphyte, B. euphemiae, et l'espèce terrestre, Q. strobilispica, possèdent en général des structures similaires, incluant un parenchyme bien développé et des groupes de fibres extra-vasculaires. Les feuilles de l'espèce terrestre, B. antiacantha, et de l'espèce épiphyte, W. gigantea, montrent également des similarités de structures comme l'absence de fibres extra-vasculaires et un parenchyme moins développé. La similitude des caractères chez des espèces provenant de différents habitats peut refléter soit les conditions microclimatiques sous lesquelles ces espèces se développent, ou encore des caractéristiques génétiques fixées.

This work aims to characterise the morphology and anatomy of roots, stems and leaves of Calolisianthus species (Gentianaceae – Helieae) to assist in the taxonomy and understanding of some adaptive responses to high luminosity, prolonged water deficit and nutritional stress in their environment. Samples of Calolisianthus speciosus and C. pendulus were collected in campo rupestre (rocky land) and samples of C. amplissimus were collected in cerrado (savanna) areas in southeastern Brazil. The roots have a cortex with Arum-type arbuscular mycorrhizae. The three species have winged and square stems and in Calolisianthus amplissimus the stem is hollow. Calolisianthus pendulus and C. speciosus have a pair of conspicuous extrafloral nectaries at the leaf base, which are absent in C. amplissimus. Calolisianthus pendulus has a dorsiventral mesophyll and a round leaf margin with parenchymatic cells. Calolisianthus amplissimus has a homogeneous mesophyll and a leaf margin with collenchyma. Calolisianthus speciosus leaves have a homogeneous mesophyll and a margin with sclerenchyma and collenchyma. Our results demonstrate that some anatomical characters are useful for the identification of Calolisianthus species and might be used to elucidate evolutionary relationships among Calolisianthus and their adaptive responses.

Ocimum selloi Benth. (Lamiaceae) é uma espécie nativa da América do Sul e na medicina popular tem sido usada devido suas propriedades analgésica, anti-inflamatória e antiespasmódica. O objetivo do presente trabalho foi identificar os tipos de tricomas glandulares que ocorrem nos órgãos vegetativos e reprodutivos de O. selloi e determinar a ontogenia desses tricomas. Ramos laterais em início de formação, folhas totalmente expandidas, flores em diferentes estádios de diferenciação, amostras de caule e do eixo das inflorescências foram analisados em microscopias de luz e eletrônica de varredura. Tricomas glandulares do tipo peltado e capitado subséssil foram observados no caule, nas folhas, no eixo da inflorescência e na superfície adaxial das sépalas. Nas sépalas foi encontrado, além dos tricomas secretores peltados e capitados subsésseis, o tricoma glandular capitado pedunculado. A ontogenia inicia-se com a expansão de uma célula protodérmica que, de acordo com a seqüência de divisões periclinais e anticlinais (ora simétricas, ora assimétricas), dá origem aos tricomas. A diferenciação dos tricomas glandulares peltados e capitados não é sincrônica e ocorre muito cedo no desenvolvimento da folha, do caule e do eixo floral.

This work describes the leaf anatomy of 16 species belonging to three genera of the Malpighiaceae family found in the Cerrado (Minas Gerais State, Brazil). The scope of this study was to support the generic delimitation by contributing to the identification of the species and constructing a dichotomous identification key that includes anatomical characters. The taxonomic characters that were considered to be the most important and used in the identification key for the studied Malpighiaceae species were as follows: the presence and location of glands; presence of phloem in the medullary region of the midrib; mesophyll type; presence and type of trichomes; and presence, quantity, and disposition of accessory bundles in the petiole. It was also possible to indicate promising characters for future taxonomic and phylogenetic studies in the Malpighiaceae family, especially for the Banisteriopsis, Byrsonima, and Heteropterys genera.

O presente estudo objetivou caracterizar anatomicamente raízes de espécies de Orchidaceae ocorrentes em um campo de altitude no Parque Estadual da Serra do Brigadeiro, identificando caracteres de significado ecológico e valor taxonômico. Foram estudados apenas indivíduos terrestres, exceto Pleurothallis teres espécie exclusivamente rupícola. A comparação dos caracteres anatômicos das espécies estudadas mostrou dois grupos com estratégias distintas: Epidendrum secundum, E. xanthinum, Oncidium barbaceniae, O. blancheti, Pleurothallis prolifera, P. teres, Zygopetalum mackayi e Z. brachypetalum são espécies perenes e xeromórfitas, enquanto Cleistes gracilis, Habenaria hydrophila, H. janeirensis, H. macronectar e Prescottia montana são espécies que completam o ciclo de vida antes do período seco com redução das partes aéreas neste período, sendo consideradas plantas mesófitas. Observou-se maior similaridade entre os gêneros Epidendrum, Oncidium e Pleurothallis. No caso do gênero Habenaria observou-se maior similaridade entre as espécies Habenaria hydrophila e H. macronectar, devido às diferenças no cilindro vascular e na região cortical de Habenaria janeirensis. The present study characterized the root of some orchids occurring in an altitudinal field at the Parque Estadual da Serra do Brigadeiro, pointing out both ecological and taxonomical relevant characters. Only terrestrial individuals were studied, except for P. teres, a rupestrine species. Anatomical comparative analysis of the studied species reveled clear definitions of two groups: Epidendrum secundum, E. xanthinum, Oncidium barbaceniae, O. blancheti, Pleurothallis prolifera, P. teres, Zygopetalum mackayi, and Z. brachypetalum are perennial species and xerophytes, while Cleistes gracilis, Habenaria hydrophila, H. janeirensis, H. macronectar and Prescottia montana are species that present shoot reduction in order to complete life cycle before dry periods, being considered mesophyte plants. There where great similarities between genera, especially within Epidendrum, Oncidium and Pleurothallis. In the case of Habenaria, greater similarities were found between H. hydrophila and H. macronectar, due to the differences in vascular cylinder and cortex of H. janeirensis.

O objetivo do trabalho é caracterizar a morfo-anatomia do corpo vegetativo de Deianira erubescens, Deianira pallescens, Deianira nervosa, Deianira chiquitana e Schultesia gracilis, visando fornecer subsídios à taxonomia e compreender algumas estratégias adaptativas. Coletaram-se amostras de indivíduos de Deianira no cerrado e de Schultesia no campo rupestre, MG. O material foi processado para observações em microscopia de luz. D. erubescens e D. pallescens apresentam folhas em rosetas e opostas cruzadas, concrescidas na base, ao longo do caule; D. chiquitana apresenta folhas concrescidas na base apenas na região proximal do caule e folhas opostas cruzadas livres; D. nervosa e S. gracilis apresentam folhas opostas cruzadas livres. No gênero Deianira são observadas raízes com crescimento secundário, sendo não usual em D. erubescens e D. nervosa e micorrizas arbusculares (MAs) do tipo Arum, exceto em D. nervosa; caule fistuloso em D. pallecens; folhas anfiestomáticas e mesofilo homogêneo, exceto em D. nervosa na qual são observadas folhas hipoestomáticas e mesofilo dorsiventral. S. gracilis apresenta raízes com aerênquima e MAs do tipo Paris; caule prismático, alado, fistuloso e folhas hipoestomáticas com mesofilo homogêneo. Caracteres anatômicos podem ser utilizados para distinção das espécies e podem contribuir para compreender estratégias adaptativas ao cerrado e campo rupestre. We characterized the morphology and anatomy of the vegetative body of Deianira erubescens, Deianira pallescens, Deianira nervosa, Deianira chiquitana and Schultesia gracilis to aid in the taxonomy and understanding of adaptive strategies. Samples of Deianira and Schultesia were collected from Cerrado and campo rupestre, MG. The material was processed for observation by light microscopy. D. erubescens and D. pallescens have rosulate, decussate leaves, concrescent at the base along the stem; D. chiquitana has concrescent leaves at the base in the proximal region of the stem and decussate leaves not fused; D. nervosa and S. gracilis have decussate leaves not fused. In the genus Deianira, there are roots with secondary growth, these are not usual in D. erubescens and D. nervosa and Arum-type arbuscular mycorrhizae (AM), except in D. nervosa; stems fistular in D. pallecens; amphistomatic leaves and homogenous mesophyll, except in D. nervosa where there are hypostomatic leaves and dorsiventral mesophyll. S. gracilis has roots with aerenchyma and Paris-type AM, stem prismatic, winged and fistular and hypostomatic leaves with homogenous mesophyll. Anatomical characters may be used successfully in the distinction of species and may be used to understand the adaptation to environment.

In order to correlate sintomatology with anatomical alterations caused by acid rain in leaves of tropical species, seedlings and saplings of Spondias dulcis Forst. F., Mimosa artemisiana Heringer and Paula and Gallesia integrifolia (Spreng.) Harms were exposed to simulated low-pH acid rain (pH 3.0). Control plants were submitted only to rain with distilled water (pH 6.0). The plants were exposed daily to the acid rain for 20 min for 10 consecutive days. Necrotic spots on the leaf blade occurred and most of the injuries onset on the epidermis in all species studied. S. dulcis displayed epicuticular wax erosion and rupture of epidermis. The abaxial surface of M. artemisiana was colonized by a mass of fungi hyphae and stomatal outer ledge rupture occurred. Some epidermal cells of G. integrifolia showed appearance similar to plasmolysis. The plants accumulated phenolic compounds in necrotic areas. Afterwards, leaves presented injuries in the mesophyll and collapsed completely. Cells surrounding the injured areas accumulated starch grains in S. dulcis. M. artemisiana showed more drastic symptom intensity in response to acidic rain. S. dulcis displayed visual symptoms similar to G. integrifolia, however, anatomical alterations were more severe.

Eugenia uniflora and Clusia hilariana seedlings were submitted to simulated acid rain, pH 3, for 40 days. The degree of visible injury and the anatomical and micromorphological alterations were determined 24 hours after the last simulation. E. uniflora presented a higher degree of leaf necrosis. The adaxial epidermis and part of the palisade parenchyma of the entire leaf blade were affected and hypertrophy, hyperplasia and cicatrization tissue differentiation occurred. Erosion and morphological modification of the epicuticular wax and alterations in the epidermis were detected on the upper and lower leaf surfaces. Stomata with deformed ostioles and rupture of the stomatal ledge were observed. C. hilariana presented necrosis in leaf margin and in abaxial leaf surface, showing collapsed cells or with plasmolized aspect, cicatrization tissue, epicuticular wax alterations, occasional leaf perforations, irregular arrangement of adaxial epidermis cells and twisted subsidiary cells. The structural alterations indicated a greater susceptibility of E. uniflora to acid rain. he lower sensibility of C. hilariana can be related with the anatomical characteristics as: thick cuticle with evident cuticular flanges, three layers of hypodermis and mesophyll more thick and compact.

Com o objetivo de analisar a variação anatômica ao longo do caule de Terminalia ivorensis, estudaram-se amostras de madeira de três indivíduos, nos planos radial e axial. Para tal, corpos de prova foram obtidos a partir de discos de madeira, de 2 em 2cm, no sentido medula-câmbio. A metodologia usada para desenvolver o trabalho foi aquela tradicionalmente recomendada para estudos em anatomia vegetal. A descrição anatômica realizada seguiu as recomendações do IAWA Committee. No sentido radial do caule, alguns elementos anatômicos apresentaram tendências de variação definidas e significativas estatisticamente quando aplicado o teste Tukey para comparação de médias. São eles: freqüência, diâmetro e comprimento dos elementos de vaso, freqüência de raios/mm linear, comprimento dos raios em número de células, e comprimento e espessura da parede das fibras. Já no sentido axial, todas as variáveis analisadas não se mostraram estatisticamente significativas. Os resultados observados devemse, principalmente, à caracterização bem definida dos lenhos juvenil e adulto na madeira de Terminalia ivorensis.

A bactéria Pasteuria penetrans é um parasita obrigatório do nematóide das galhas (Meloidogyne spp.) e produz esporos que persistem por anos no solo. A sua produção por cultivo in vitro ainda é inviável e a produção de inoculo requer o seu cultivo in vivo em nematóides parasitando plantas em vasos. Neste trabalho, buscou-se, por meio do estudo histológico de raízes, averiguar diferenças no desenvolvimento de P. penetrans em Meloidogyne spp. parasitando raízes de tomateiro (Lycopersicon esculentum), maxixe (Cucumis anguria) e camapu (Physalis angulata), e possíveis razões para estas diferenças, como forma e tamanho de células gigantes e das fêmeas do nematóide. O maxixe foi o pior dentre os hospedeiros em teste para a produção de inóculo e apresentou células gigantes anormais. A estrutura das células gigantes assim como o desenvolvimento da bactéria foram semelhantes no camapu e no tomateiro, entretanto o ciclo de vida de P. penetrans foi ligeiramente mais curto no tomateiro. The bacterium Pasteuria penetrans is an obligate parasite of root-knot nematodes and produces spores that persist in soil for many years. At present, in vitro cultivation is not feasible, thereby requiring inoculum production in vivo cultivation, inside nematode parasitizing potted plants. In this work, the differences in the development of P. penetrans in Meloidogyne spp. parasitizing roots of tomato (Lycopersicon esculentum), gherkin (Cucumis anguria) and "camapu" (Physalis angulata) were evaluated by histopathology of infected roots. Possible reasons for the differences found were analyzed, such as change in the giant cells or nematode females. The gherkin was the worst host for inoculum production and presented abnormal giant cells. The anatomy of giant cells and the bacterium development were similar in tomato and "camapu" root systems, but the P. penetrans life cicle was slightly shorter in tomato than in camapu.

Arsenic (As) is a toxic element to most organisms. Studies investigating anatomic alterations due to As exposure in plants are scarce but of utmost importance to the establishment of environmental biomonitoring techniques. So, this study aimed to investigate the effects of As on the development and initial root growth in Cajanus cajan (Fabaceae), characterize and quantify the possible damages, evaluate genotoxic effects, and identify structural markers to be used in environmental bioindication. Plants were exposed hydroponically to 0.5, 1.0, 1.5, and 2.0 mg As L(-1), as sodium arsenate. Growth parameters were measured, and in the end of the exposure, root samples were analyzed for qualitative and quantitative anatomical alterations. Arsenic genotoxicity was evaluated through analysis of the mitotic index in the root apex. Compared to the control, As-treated seedlings showed an altered architecture, with significantly decreased root length (due to the lower mitotic index in the apical meristem and reduced elongation of parenchyma cells) with darkened color, and abnormal development of the root cap. A significant increase in vascular cylinder/root diameter ratio was also detected, due to the reduction of the cellular spaces in the cortex. The secondary xylem vessel elements were reduced in diameter and had sinuous walls. The severest damage was visible in the ramification zone, where uncommon division planes of phellogen and cambium cells and disintegration of the parenchyma cells adjacent to lateral roots were observed. The high sensibility of C. cajan to As was confirmed, since it caused severe damages in root growth and anatomy. The main structural markers for As toxicity were the altered root architecture, with the reduction of the elongation zone and increase of ramification zone length, and the root primordia retained within the cortex. Our results show a new approach about As toxicity and indicate that C. cajan is a promising species to be used for bioindication of environmental contamination by As.

Aiming to evaluate responses in terms of growth rates, physiological parameters, and degree of sensitivity to SO2 and SPMFe in Eugenia uniflora L. (Myrtaceae, a C3 species) and Clusia hilariana Schlecht (Clusiaceae, a CAM species); saplings were exposed to emissions from a pelletizing factory for 7 months. The species were distributed along a transect (200, 500, 800, 1400, and 1700 m away from the emission source), and analyses were performed after 71, 118, and 211 days of exposure to the pollutants. E. uniflora received higher superficial deposition of particulate iron. The highest total iron foliar contents were observed 200 m away from the emission source in both plant species, while the highest total sulfur foliar contents were observed 200 m away in C. hilariana and 800 m away in E. uniflora. E. uniflora presented decreased values of height growth rate, number of necrotic leaves, chlorophyll analysis (SPAD index) and transpiration, in relation to the distances from the emission source. C. hilariana showed decreased values of height growth rate, number of leaves, number of necrotic leaves, total ionic permeability, stomatal conductance, transpiration, net CO2 assimilation, and total dry matter, in relation to distances from the emission source. In relation to the days of exposure, both species presented increased number of necrotic leaves and foliar phytotoxicity index, and decreased values in the chlorophyll analysis. The two native plant species, both of which occur in the Brazilian Restinga, showed damage when exposed to emissions from an iron ore pelletizing factory. C. hilariana was considered the most sensitive species due to the decreased values in a higher number of variables after exposition.

The taxonomy of neotropical Salicaceae, a family that now includes the majority of the former Flacourtiaceae, has been problematic, especially because they display very diverse morphology and have several characteristics in common with many other families. Recent phylogenetic studies have proposed substantial changes at both family and generic levels. Considering the importance of anatomy as an aid for taxonomy, the gathering of anatomical data for the family is fundamental to help clarify the taxonomic problems. Leaves belonging to Abatia americana (four samples), Banara brasiliensis (2), Casearia arborea (4), C. decandra (5), C. gossypiosperma (2), C. obliqua (1), C. sylvestris (3), C. ulmifolia (3), Prockia crucis (3), and Xylosma prockia (4) and the closely related Carpotroche brasiliensis (3) from Achariaceae, were studied by standard microscopy techniques. The leaves were anatomically described, emphasizing their differences and similarities. Similar characters for the neotropical Salicaceae (former Flacourtiaceae) and Salicaceae strictu sensu were recognized, such as the presence of salicoid leaf teeth, brachyparacytic stomata, secondary growth of the petiole, abundance of crystals, collateral and arch-shaped vascular system at the midrib, and sclerenchyma accompanying the bundles. These data demonstrate that leaf anatomy can provide evidence to assist with the taxonomy of Salicaceae, at family, generic, and specific levels.

Fluoride in simulated rain: symptomatology and effects on leaf structure and growth of wood plants). The objectives of this study was to characterize the effects of fluoride on seedlings and young plants of native woody species from Parque Estadual do Rio Doce (MG) and on the leaf blade structure of the most sensitive of the studied tree species. This work was carried out to gain information on diagnosing criteria for bioindication and to throw some light on the mechanisms of plant resistance and tolerance in order to assist in the revegetation programs of highly affected areas. The employed species were Gallesia gorazema Moq. (Phytolac- caceae), Genipa americana L. (Rubiaceae), Joannesia princeps Vell. (Euphorbiaceae), Peltophorum dubium (Spreng.) Taub. (Legu- minosae, Caesalpinioideae) and Spondias dulcis Forst. f. (Anarcadiaceae). Seedlings and young plants of those species were submitted to rain with dissolved fluoride (30 mg.L -1 ), during 20 min daily, for 10 consecutive days. Apical and marginal necrosis occurred in the leaf blades of all species just after the first simulated rain. Two days after treatment, S. dulcis, in the young plant stage, showed to be the most sensitive species by exhibiting large necrotic areas, while G. americana was the most resistant species. At the young plant stage, the species that accumulated more fluoride were also the most sensitive ones; such a relation was not observed in plants at the seedling stage. The pollutant at the level employed caused drastic alterations in the leaf blade of S. dulcis and also damaged all of its anatomical structure. The high susceptibility of S. dulcis to fluoride suggests that this species possess potential features to be employed as a bioindicator. However, for a better characterization of the responses of S. dulcis to fluoride and its usage in biomonitoring programs, more studies are required. RESUMO - (Fluor em chuva simulada: sintomatologia e efeitos sobre a estrutura foliar e o crescimento de plantas arboreas). Os objetivos deste trabalho foram: caracterizar os efeitos do fluor em especies arboreas nativas, nos estadios de plântula e muda; identificar injurias provocadas pelo fluor na estrutura da lâmina foliar da especie mais sensivel; fornecer subsidios para selecao de caracteristicas a serem utilizadas na bioindicacao; e contribuir com informacoes sobre a resistencia ou tolerância das plantas, visando ao reflorestamento de areas impactadas pela chuva com fluor. As especies analisadas foram Gallesia gorazema Moq. (Phytolaccaceae), Genipa americana L. (Rubiaceae), Joannesia princeps Vell. (Euphorbiaceae), Peltophorum dubium (Spreng.) Taub. (Leguminosae, Caesalpinioideae) e Spondias dulcis Forst. f. (Anacardiaceae). Plântulas e mudas dessas especies, provenientes do Parque Estadual do Rio Doce (MG), foram submetidas a 20 min diarios de chuva com fluor (30 mg.L -1 ), por 10 dias consecutivos. Necroses apicais e marginais foram observadas em todas as especies analisadas, logo apos a primeira chuva simulada. S. dulcis, no estadio de muda, foi a especie mais sensivel ao fluor, pois apresentou extensas necroses com apenas dois dias de tratamento, enquanto que G. americana foi a especie mais resistente. Nas mudas, as especies que acumularam mais fluor foram tambem as que apresentaram maior sensibilidade a esse poluente; essa relacao nao foi verificada nas plântulas. A concentracao de fluor utilizada promoveu alteracoes drasticas na lâmina foliar de S. dulcis com extensas areas necrosadas, danificando toda a sua estrutura anatomica. A sensibilidade ao fluor observada em S. dulcis indica que essa especie apresenta potencial para ser usada como bioindicadora. Entretanto, estudos detalhados serao necessarios para a melhor caracterizacao das respostas de S. dulcis ao fluor visando a sua utilizacao em programas de biomonitoramento ambiental.

Fluoride is among the most phytotoxic atmo- spheric pollutants, commonly linked to the appearance of lesions in susceptible plants around emitting sources. In order to assess the effects of fluoride on leaves of Spondias dulcisParkinson (Anacardiaceae), plants were examined 78 km (non-polluted area) and 0.78 km (pol- luted area) from an aluminium smelter. The level of fluoride increased with the exposure time of the plants in the polluted area. On the third day of exposure in the polluted area, necroses with typical colouration were observed. Micromorphological damage began at the abaxial epidermis, mainly associated with the stomata. Starch grain accumulation was more pronounced in the midrib. The cell membranes and chloroplasts were greatly affected by the pollutant. We observed accumu- lation of phenolic compounds and electron-dense mate- rial at the boundaries of the ending veinlets. The micro- scopic events described precede the appearance of symptoms and are therefore of prognostic value in predicting injury by fluoride and will be useful as biomarkers. The high sensitivity of S. dulcis to fluoride and the specificity of the symptoms confirm, for the first time, in an experiment of active biomonitoring, the potential of this species as a bioindicator.

Setaria parviflora (Poir.) Kerguélen and Paspalum urvillei Steudel are grasses that grow naturally in a soil with high iron contents. This study aimed to characterize morphoanatomically and histochemically the iron phytotoxicity on leaves and evaluate the phytoextraction potential of these grasses. Saplings were cultivated in hydroponic solution with and without excess Fe-EDTA. Regarding measurements taken on leaves, reduction was observed among treatments of Fe-EDTA on height values of abaxial epidermis and bundle sheath in both species. As for iron histolocalization, stronger reaction was observed in leaves of S. parviflora, in comparison with P. urvillei. Anatomical damage, such as protoplast retraction, irregular xylem, changes in cell volume, and cell collapse, and visual symptoms, like leaf bronzing, chlorosis, and necrosis, were similar in both species when exposed to excess iron; however, P. urvillei showed more severe damage. This species accumulated more iron in shoots than S. parviflora and therefore is more favorable for use in phytoextraction. The root system of both species accumulated higher iron concentrations in relation to shoots.

We have identified new arsenic-tolerant plant species Borreria verticillata (Rubiaceae) that has mine and non-mine populations at a highly contaminated site (CS) and an uncontaminated site (UCS), respectively, in Brazil. Plants of B. verticillata from both sites were cultivated at different As and P concentrations. At low P concentration, CS plants showed reduced As uptake, higher P translocation to shoots, higher constitutive levels of phenolic compounds in roots, and higher tolerance to this metalloid. At the lowest P and highest As concentration, CS plants showed higher biomass. In addition, CS plants showed higher P uptake in the absence of As, suggesting that more efficient P translocation could contribute more to tolerance than decreased As uptake. In contrast, at low P concentration, UCS plants showed higher As content in shoot and root, increase in phenol levels in roots, reduction in dry biomass, and decrease of the effective efficiency of photochemical reactions and the electron transport rate. Under higher P concentrations, the decrease in As uptake was similar in both populations. The differences between the two populations with respect to As and P uptake suggest that altered kinetic properties or expression of P transporters contribute to higher As tolerance in B. verticillata from CS. As a ruderal and As-tolerant plant, B. verticillata could be successfully used for the revegetation of contaminated soils.

The delimitation of species and even support of the genera Curtia and Hockinia, monotypic genus, are still controversial. To define anatomical characteristics that help resolve taxonomic problems, the stem and leaf anatomy of seven species of Curtia and Hockinia montana are described. Some characteristics are found in both genera: leaves with uniseriate epidermis, dorsiventral mesophyll, cells of the palisade parenchyma with invaginations, basal acrodromous venation with an incomplete marginal ultimate venation, presence of colleters and nectaries, stem with small wings and internal phloem. The types of stomata, the midrib vascular bundle, and the type and distribution of nectaries were used to separate the genera. The presence/absence of crystals, the sinuosity of the anticlinal walls of the epidermal cells, the type and distribution of stomata, and the distribution of nectaries distinguish species of Curtia. Our results suggest that these anatomical characteristics are potentially useful for clarifying the taxonomy of Gentianaceae, and that they represent an additional tool for distinguishing genera and identifying species of Curtia, particularly pointing out the need to revise the synonymy between C. patula and C. tenuifolia. We also highlight the first report of leaf nectaries and colleters in the Saccifolieae and the first record of stem nectaries in the Gentianaceae.

This study aimed to assess the influence of excess iron on the capacity of accumulation of this heavy metal, mineral composition, and growth of Setaria parviflora and Paspalum urvillei. Seedlings were submitted to 0.009; 1; 2; 4; and 7 mM of Fe-EDTA. In both species there was an increase in the concentration of Fe, Zn, P, and Ca and a decrease in Mn, K, and Mg in the iron plaque. Both species accumulated more iron in roots. In the shoots, S. parviflora showed higher iron content, except at 7 mM. Iron altered the contents of Fe, Cu, K, and Mg in roots, and of Fe, Mn, Zn, N, P, K, Ca, and Mg in shoots. The two species tolerated high iron concentrations and accumulated high content of this element in both shoots and roots. The iron did not reduce their growth. Both species are indicated for studies aiming restoration of iron-contaminated areas.

The underground systems of plants show the most varied structures adapted to survival in unfavorable environmental conditions. For instance, long-term droughts may induce the development of either water and reserve substances or vegetative propagation structures. Since Mandevilla atroviolacea is a species found at high altitudes on rocky outcrops, this study aimed to provide information on the morpho-anatomy of the underground system of this species that may assist in understanding the adaptive strategies at play. Samples from the underground system of three young and two mature plants collected in the field were sectioned and processed according to standard plant anatomical techniques. The upper area of the underground system corresponds to a xylopodium, while the lower is a tuberous stem organ. Tuberous roots account for the majority of the underground system. The increase in tuberous root diameter results from the action of a typical cambium. The high shoot-forming potential and storage of water and reserve substances observed in the underground system of this species are important strategies for it to survive in this habitat.

Arsenic (As) is toxic to most living things. However, plants growing in environments contaminated by this pollutant may exhibit tolerance strategies such as restrictions to its absorption and intracellular detoxification. In the present study we compared morphophysiological responses between Borreria verticillata (L.) G.F.W. Mayer (Rubiaceae) populations from an As-contaminated site (CS) and a non-contaminated site (NCS) in order to clarify their mechanisms of As detoxification and their differential tolerance to the metalloid. Plants were grown in nutrient solution without As addition (control) and with 66 µM As for 4 days. Arsenic accumulated in plant roots, and neither bioaccumulation nor translocation factors differed between the populations. Exposure to the metalloid promoted damage to the morphology and anatomy of both roots and shoots, particularly in plants from the NCS. These plants showed more severe phytotoxic symptoms, as well as greater reduction in shoot growth and fresh biomass accumulation. Plants from the CS showed fewer toxicity symptoms due to mechanisms that favoured As detoxification and scavenging of reactive oxygen species in roots (e.g. increases in Ca and S root concentrations, higher number of phenolic and crystalliferous idioblasts and increased antioxidant enzyme activity) and the prevention of oxidative stress in leaves (through increased superoxide dismutase activity). Thus, we verified that besides the differences in P metabolism that have been reported in the literature, plants from the CS are more As-tolerant due to their higher efficiency for As detoxification, and are therefore more well suited for the revegetation of As-contaminated areas.

The purpose of this paper was to carry out an anatomical and histochemical analysis of the vegetative organs of Cissus verticillata (L.) Nicolson & C.E. Jarvis, Vitaceae, to contribute for the attest the taxonomic identity of the medicinal plant. Samples from root, stem, leaf and tendril were cleared, dissociated and processed according to the usual methodology for observation under light and scanning electron microscopes. Histochemical tests were performed in order to identify polysaccharides, phenolic and lipid compounds. The C. verticillata root is typically protostelic, and the stem is eustelic with collateral bundles. The tendril presents structural organization similar to the stem, suggesting a common origin for both. The petiole has an epidermis with ornamented cuticle; the cortex is composed of collenchyma and parenchyma, and the vascular tissues are arranged in collateral bundles. The leaf blade is amphistomatic with non-glandular and glandular trichomes, and the mesophyll is dorsiventral. The identification of the idioblasts as secretion site of the phenolic compounds, mucilage and terpenoids as being responsible for the potential activity of the plant is of fundamental importance for future bioprospecting research on this species.

In this paper the ontogenesis and histochemistry of the petiolar glands found on the petiole/rachis of the eight Chamaecrista species of the section Absus, subsection Baseophyllum (Leguminosae, Caesalpinioideae) are studied by using light microscopy techniques, aiming to characterise these structures and to provide taxonomic characters which may be useful in phylogenetic approaches. Strips for glucose identification reacted positively with the exudates of the glands, confirming the presence of nectar in the secretion, characterising these glands as extrafloral nectaries (EFN). Histochemical tests also detected the presence of neutral and acid muco-polysaccharides, pectins, mucilages, total proteins, and phenolic compounds in the EFNs. The EFNs arise from a group of meristem cells (protodermis, ground meristem and procambium) in the petiole/rachis. All EFNs of the investigated taxa share some morpho-anatomical characters, so that their peculiarities are too weak to be used alone in the identification of particular species. Rather their similarities may be used to include these species into a single group, supporting the hypothesis of monophyly of the subsection Baseophyllum.

The restingas, a sandy coastal plain ecosystem of Brazil, have received an additional amount of iron due to the activity of mining industries. The present study aims to characterize morphoanatomically and histochemically the iron plaque formation on roots of Ipomoea pes-caprae L. and Canavalia rosea DC, cultivated in hydroponic solution with and without excess iron. The iron plaque formation as well as changes in the external morphology of the lateral roots of both species were observed after the subjection to excess iron. Changes in the nutrient uptake, and in the organization and form of the pericycle and cortex cells were observed for both species. Scanning electron microscopy showed evident iron plaques on the whole surface of the root. The iron was histolocalized in all root tissues of both species. The species of restinga studied here formed iron plaque in their roots when exposed to excess of this element, which may compromise their development in environments polluted by particulated iron.

Nectaries in leaves of Gentianaceae have been poorly studied. The present study aims to describe the distribution, anatomy, and ecological aspects of extrafloral nectaries (EFNs) of three Calolisianthus species and in particular the ultrastructure of EFNs in Calolisianthus speciosus during leaf development, discussing its unusual structure. Leaves of Calolisianthus species were fixed and processed by the usual methods for studies using light, scanning microscopy and transmission electron microscopy (TEM). Ion chromatography was used to analyze the nectar exudates of C. speciosus. The distribution patterns of nectar secretion units were analysed by ANOVA and t-tests. Two EFNs that can be seen macroscopically were observed at the bases of C. speciosus and C. pendulus leaves. Such large nectaries are absent there in C. amplissimus. Another similarly large EFN is observed at the apex of each leaf in all species. The EFNs at the base of the young leaves in C. speciosus are visited by ants during the rainy season. EFNs are formed by several nectar secretory units (nectarioles) that are present throughout the leaves. Each nectariole is formed by rosette cells with a central channel from which the nectar is released. Channels of old C. speciosus and C. pendulus EFNs were obstructed by fungi. TEM of EFNs in young leaves showed cytoplasms with secretion, small vacuoles, mitochondria, cell wall ingrowth, and plasmodesmata. TEM of EFNs in old leaves demonstrated dictyosomes, plastids, mitochondria, segments of endoplasmatic reticulum, and lipid droplets. The nectar contains sucrose, glucose and fructose.