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Calolisianthus speciosus, an endemic species of cerrado and campos rupestres in Brazil, bears colleters in both the leaf base and sepal. These colleters (leaf and sepal) were anatomically compared to identify differences in their structure and secretion mechanism. Samples of sepals and leaves in different development stages were collected and processed according to standard methodologies for anatomical and ultrastructural studies. Sepal and leaf colleters were anatomically similar, being non-vascularized, sessile or short-stalked and composed of a multicellular secretory head with large intercellular spaces where secretion, with a predominance of protein and polysaccharides, is accumulated. The secretory cells have thin walls, dense cytoplasm with granular endoplasmic reticulum, numerous dictyosomes and mitochondria. The ultrastructural characters are in agreement with the production of mucilaginous/protein secretion. The large secretion-filled vacuole merges with the plasma membrane releasing its contents to the periplasmic space where it remains until release outside of the cell wall, where it is accumulated in intercellular spaces formed by schizogeny. This accumulation generates pressure that promotes the passage of secretion through the external wall and the cuticle of superficial secretory cells of the head of the colleter.

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.

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.

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.

In plant cells, environmental stressors induce changes in the cytosolic concentration of calcium ([Ca2+]cyt) that are transduced by Ca2+-sensing proteins. To confer specificity to the stress signaling response, [Ca2+]cytsensing must be tightly regulated in space and time; the molecular mechanisms that restrict the localization and dynamics of Ca2+sensors in plants, however, are largely unknown. In this report, we identify a putative Ca2+-sensitive complex containing the synaptotagmins 1 and 5 (SYT1 and SYT5) and the Ca2+-dependent lipid binding protein (CLB1), which is enriched at ER-PM contact sites (EPCS) and relocalizes in response to Rare Earth Elements (REEs)-induced endocytosis. Our results show that endocytosed REEs influence cytosolic Ca2+signaling, as indicated by the activation of the Ca2+/Calmodulin-based ratiometric sensor GCaMP3, and promote the cytoskeleton-dependent accumulation of ER-PM contact sites at the cell cortex. Based on these results, we propose that the EPCS-localized SYT1/SYT5/CLB1 complex is part of an evolutionarily conserved and spatially regulated Ca2+-responsive mechanism that control cER-PM communication during stress episodes.

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.

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.

Fluoride is the atmospheric pollutant with the highest phytotoxicity arising from aluminum smelting fertilizers, glass and, ceramic industry. The most affected plant organ is the leaf, in which the fluoride penetrates through two main ways: absorption by epidermis cuticle or absorption by stomata. Species susceptible to fluoride are potential tools in bioindicator studies because they provide a means for detecting the presence of the pollutant in the environment at a low cost. The aim of this study is to evaluate the sensibility of Spondias purpurea L. (Anacardiaceae) to fluoride through the simulated fog. Simulation was performed by applying 500 ml of solution containing 15 mg L−1 of potassium fluoride per plant for 20 min daily and for 10 consecutive days. The data of leaflet abscission, visual damage, and climate conditions were recorded daily. At the end of the experiment, data from the cell death analysis, electrolyte leakage determination, and accumulation of the fluoride in the dried matter were collected. Moreover, samples for phenolic compound accumulation, anatomical, and micromorphological analyses were collected. After 24 h, the appearance of visible damage was observed in the leaves with fluoride treatment. This damage consisted, mostly, of necrosis, chlorosis, and leaf apical shriveling. The necroses manifested in gray and brown discoloration. Leaf abscission was intense in the young leaves. Microscopic damage consisted of protoplast retraction, phenolic compound accumulation, collapse, hyperplasia, and cell rupture. Turgidity loss, epicuticular wax erosion, and damage of stomata and trichomes beyond the presence of fungal hyphae were noted in the epidermis. Evans Blue detected dead cell groups in the transition region between the necrosis and the apparent healthy area. Fluoride affected the selective permeability of the membrane, which was observed in this study according to the high rate of electrolyte leakage. Plants exposed to fluoride accumulated 14.48 times more fluoride in their leaves than plants in the control group. It follows that S. purpurea is susceptible to fluoride and responds quickly to the presence of this pollutant. Marginal and apical necrosis, presence of phenolic compounds, fluoride accumulation, anatomical alterations, and leaflet abscission in the young leaves are biomarkers of fluoride effects in this species. Therefore, S. purpurea is potentially useful in biomonitoring programs.

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.

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 objectives of this work were to evaluate if the pollution emitted by the pelletizing factory causes visual symptoms and/or anatomical changes in exposed Eugenia uniflora and Clusia hilariana, in active biomonitoring, at different distances from a pelletizing factory. We characterize the symptomatology, anatomical, and histochemistry alterations induced in the two species. There was no difference in the symptomatology in relation to the different distances of the emitting source. The foliar symptoms found in C. hilariana were chlorosis, necrosis, and foliar abscission and, in E. uniflora, were observed necrosis punctuais, purple spots in the leaves, and increase in the emission of new leaves completely purplish. The two species presented formation of a cicatrization tissue. E. uniflora presented reduction in the thickness of leaf. In C. hilariana, it was visualized hyperplasia of the cells and the adaxial epidermis did not appear collapsed due to thick cuticle and cuticular flanges. Leaves of C. hilariana showed positive staining for iron, protein, starch, and phenolic compounds. E. uniflora showed positive staining for total phenolic compounds and starch. Micromorphologically, there was accumulation of particulate matter on the leaf surface, obstruction of the stomata, and scaling of the epicuticular wax in both species. It was concluded that the visual and anatomical symptoms were efficient in the diagnosis of the stress factor. C. hilariana and E. uniflora showed to be good bioindicators of the atmospheric pollutants emitted by the pelletizing factory.

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.

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.