Aerial Vegetative Organs Research Articles

Anatomical features of ecological importance and taxonomic value revealed by scanning electron microscopy and light microscopy in Camonea umbellata (L.) A.R. Simões & Staples (Convolvulaceae).

This article describes detailed and novel data on the anatomy and histochemistry of leaves, stems, and roots of Camonea umbellata (L.) A.R.Simões & Staples in different environments for the identification of characters with taxonomical value and of ecological importance, with provision of light and scanning electron microscopy images. To analyze the characters, we collected samples of the vegetative organs of three individuals in each of three populations, which were in a grazing area, an urban environment, and a biological reserve. The main diagnostic anatomical markers for the identification of C. umbellata include amphistomatic leaves, tetracytic and brachyparatetracytic stomata, peltate trichomes, long simple trichomes, epidermis with striated cuticle ornamentation, mesophyll with acute borders, presence of druses, secretory channels, angular collenchyma, fibrous pericycle in the stem, intraxylary phloem in the vegetative organs, oil bodies throughout the midrib, petiole, stem and root, and epicuticular waxes of the crust and coiled rodlet types. Since the characters above did not show variation in the environments evaluated, we consider these characters taxonomically useful for the identification of C. umbellata. RESEARCH HIGHLIGHTS: The anatomy of the aerial vegetative organs of Camonnea umbellata retains common Convolvulaceae characters. The sinuosity of the epidermal cell walls and the density of trichomes in the epidermis of the petiole were visually variable characters among the analyzed individuals. Amphistomatic leaves, tetracytic and brachyparatetracytic stomata, peltate trichomes, epidermis with striated cuticle ornamentation, dorsiventral mesophyll with border acute, presence of druses, secretory structures, angular collenchyma, fibrous pericycle in the stem, intraxillary phloem, presence of oil bodies in all organs, and epicuticular waxes of the crust type and coiled rods were considered important anatomical markers for the recognition and correct identification of Camonea umbellata.

Genome-wide identification and expression analysis of the ZF-HD gene family in pea (Pisum sativum L.).

Pea is a conventional grain-feed-grass crop in Tibet and the only high-protein legume in the region; therefore, it plays an important role in Tibetan food and grass security. Zinc finger-homeodomain (ZF-HD) belongs to a family of homozygous heterotypic cassette genes, which play an important role in plant growth, development, and response to adversity stress. Using a bioinformatics approach, 18 PsZF-HD family members were identified. These genes were distributed across seven chromosomes and two scaffold fragments, and evolutionary analysis classified them into two subgroups, MIF and ZHD. The MIF subgroup was subdivided into three subclasses (PsMIFⅠ-III), and the ZHD subgroup was subdivided into five subclasses (ZHDⅠ-V). The PsZF-HD members were named PsMIF1-PsMIF4 and PsZHD1-PsZHD14. Twelve conserved motifs and four conserved domains were identified from PsZF-HD family, of which MIF subgroup only contained one domain, while ZHD subgroup contained two types of domains. In addition, there were significant differences in the three-dimensional structures of the protein members of the two subgroups. Most PsZF-HD genes had no introns (13/18), and only five genes had one intron. Forty-five cis-acting elements were predicted and screened, involving four categories: light response, stress, hormone, and growth and development. Transcriptome analysis of different tissues during pea growth and development showed that PsZHD11, 8, 13, 14 and MIF4 were not expressed or were individually expressed in low amounts in the tissues, while the other 13 PsZF-HDs genes were differentially expressed and showed tissue preference, as seen in aboveground reproductive organs, where PsZHD6, 2, 10 and MIF1 (except immature seeds) were highly expressed. In the aerial vegetative organs, PsZHD6, 1, and 10 were significantly overexpressed, while in the underground root system, PsMIF3 was specifically overexpressed. The leaf transcriptome under a low-nitrogen environment showed that the expression levels of 17 PsZF-HDs members were upregulated in shoot organs. The leaf transcriptome analysis under a low-temperature environment showed stress-induced upregulation of PsZHD10 and one genes and down-regulation of PsZHD6 gene. These results laid the foundation for deeper exploration of the functions of the PsZF-HD genes and also improved the reference for molecular breeding for stress resistance in peas.

Indolamine accumulation and TDC/T5H expression profiles reveal the complex and dynamic regulation of serotonin biosynthesis in tomato (Solanum lycopersicum L.).

Tryptamine and serotonin are indolamines that fulfill diverse biological functions in all kingdoms of life. Plants convert l-tryptophan into tryptamine and then serotonin via consecutive decarboxylation and hydroxylation reactions catalyzed by the enzymes tryptophan decarboxylase (TDC) and tryptamine 5-hydroxylase (T5H). Tryptamine and serotonin accumulate to high levels in the edible fruits and seeds of many plant species, but their biological roles in reproductive organs remain unclear and the metabolic pathways have not been characterized in detail. We identified three TDC genes and a single T5H gene in tomato (Solanum lycopersicum L.) by homology-based screening and confirmed their activity by heterologous expression in Nicotiana benthamiana. The co-analysis of targeted metabolomics and gene expression data revealed complex spatiotemporal gene expression and metabolite accumulation patterns that suggest the involvement of the serotonin pathway in multiple biological processes. Our data support a model in which SlTDC1 allows tryptamine to accumulate in fruits, SlTDC2 causes serotonin to accumulate in aerial vegetative organs, and SlTDC3 works with SlT5H to convert tryptamine into serotonin in the roots and fruits.

MICROSTRUCTUAL FEATURES OF VEGETATIVE ORGANS OF ACONITUM NUSUTUM FISCH. EX REICHENB., AN ALKALOID-CONTAINING PLANT WIDESPREAD IN GEORGIA

Anatomical structure of the common in the forests and meadows of the Georgian subalpine zone plant - Aconitum nasutum Fisch. ex Reichenb - underground and aerial vegetative organs, rich in diterpene alkaloids, was studied. A set of diagnostic features has been established using the accepted microtechnical methods. The conductive system the axial organs of A. nasutum, root, twig and leaf stalk, has a separated collateral structure. Casparian strips are prominent in the root endoderma but no clearly expressed radial interaction with the conductive tissue is observed. The thickening of the inner membrane of the differentiated conductive vessels in the wood is circular-spiral and reticular. Basal cells of the epidermis of the twig are arranged in a stitched, linear, thistle-rhombic structure. The underlying curved-walled type cells of the upper and lower epidermis of the leaf are non-curved and stitched. Both in the epidermis of the twig and in the leaf-covering tissue, the buds are simple, anomocytic in appearance. The leaf of A. nasutum has a bifacial shape, dorso-ventral, hypostomatic structure, a conductive bundle has collateral structure, and conical shaped villi of the leaf are single-celled.

Morpho-anatomical features of the leaves and stems of Baccharis notosergila (Asteraceae) and their relationship with the environment and chemical control

Background and aims: Baccharis notosergila is an aggressive weed inhabiting the Salado river basin, Buenos Aires province, Argentina. The aims of this work were: to analyze the morpho-anatomy and histochemistry of aerial vegetative organs in order to understand the adaptation strategies that ensure its survival, as well as to expand knowledge on traits determining resistance to the control methods applied. M&M: The material collected was prepared and examined with conventional techniques of microscopy. Histochemical tests to identify starch, resins, polyphenols, and lipophilic substances were performed. Results: The major features found were small and deciduous leaves; uniseriate epidermis with massive and striate cuticle; stomata at level or slightly above the other epidermal cells and glandular trichomes secreting oily substances; stomata on both surfaces and isobilateral mesophyll. Tannins, starch and lipophilic substances were identified in leaves and stems; polyphenols, resins and lipids in ducts, and calcium oxalate crystals in leaves, stems and capitate trichomes. Conclusions: The aerial vegetative organs features of B. notosergila explain its tolerance to the unfavorable conditions of the Salado river basin area, as well as its high competitive ability over others species of the natural prairie. The reduced and deciduous leaves, the epidermal traits, and chemical substances found constitute a physical and chemical barrier reducing dehydration as well as the penetration of the herbicides applied for its control. Botanical knowledge of B. notosergila is the basis for the design and development of new and appropriate management methods for this species.

Microscopy and Histochemistry of Leaves and Stems of Baccharis Subgenus Coridifoliae (Asteraceae) Through LM and SEM-EDS

This research reports for the first time the anatomical characteristics of all species belonging to Baccharis subgenus Coridifoliae (Asteraceae). The anatomy and micro-morphology of aerial vegetative organs of ten species: B. albilanosa, B. artemisioides, B. bicolor, B. coridifolia, B. erigeroides, B. napaea, B. ochracea, B. pluricapitulata, B. scabrifolia, and B. suberectifolia are investigated by light and scanning electron microscopy. The number of secretory ducts, crystal morphology, presence or absence of conical nonglandular trichomes, leaves cross-section shape, margin morphology, anticlinal epidermal cell walls shape, and cuticle structure were identified as characters with diagnostic value for species. Similarity cluster analysis allows the formation of three groups based on a percentage of similarity between 45 and 84%. Some species showed differential characteristics as the presence of up to four secretory ducts in the midrib in B. albilanosa; smooth cuticles onboth sides of the leaf epidermis in B. erigeroides; flat midrib shape on both sides of the leaves in B. napaea; and convex–flat midrib shape in B. suberectifolia. The remaining species can be differentiated by a set of anatomical features. Anatomical and histochemical characteristics of stems and leaves provided data to support species identification.

Ectopic expression of the atypical HLH FaPRE1 gene determines changes in cell size and morphology

PACLOBUTRAZOL RESISTANCE (PRE) genes code atypical HLH transcriptional regulators characterized by the absence of a DNA-binding domain but present an HLH dimerization domain. In vegetative tissues, the function of these HLH proteins has been related with cell elongation processes. In strawberry, three FaPRE genes are expressed, two of them (FaPRE2 and FaPRE3) in vegetative tissues while FaPRE1 is fruit receptacle-specific. Ubiquitous FaPRE1 accumulation produced elongated flower receptacles and plants due to the elongation of the main aerial vegetative organs, with the exception of leaves. Histological analysis clearly demonstrated that the observed phenotype was due to significant changes in the parenchymal cell’s morphology. In addition, transcriptomic studies of the transgenic elongated flower receptacles allowed to identify a small group of differentially expressed genes that encode cell wall-modifying enzymes. Together, the data seem to indicate that, in the strawberry plant vegetative organs, FaPRE proteins could modulate the expression of genes related with the determination of the size and shape of the parenchymal cells.

Diversity and Structure of the Endophytic Bacterial Communities Associated With Three Terrestrial Orchid Species as Revealed by 16S rRNA Gene Metabarcoding.

The endophytic microbiota can establish mutualistic or commensalistic interactions within the host plant tissues. We investigated the bacterial endophytic microbiota in three species of Mediterranean orchids (Neottia ovata, Serapias vomeracea, and Spiranthes spiralis) by metabarcoding of the 16S rRNA gene. We examined whether the different orchid species and organs, both underground and aboveground, influenced the endophytic bacterial communities. A total of 1,930 operational taxonomic units (OTUs) were obtained, mainly Proteobacteria and Actinobacteria, whose distribution model indicated that the plant organ was the main determinant of the bacterial community structure. The co-occurrence network was not modular, suggesting a relative homogeneity of the microbiota between both plant species and organs. Moreover, the decrease in species richness and diversity in the aerial vegetative organs may indicate a filtering effect by the host plant. We identified four hub OTUs, three of them already reported as plant-associated taxa (Pseudoxanthomonas, Rhizobium, and Mitsuaria), whereas Thermus was an unusual member of the plant microbiota. Core microbiota analysis revealed a selective and systemic ascent of bacterial communities from the vegetative to the reproductive organs. The core microbiota was also maintained in the S. spiralis seeds, suggesting a potential vertical transfer of the microbiota. Surprisingly, some S. spiralis seed samples displayed a very rich endophytic microbiota, with a large number of OTUs shared with the roots, a situation that may lead to a putative restoring process of the root-associated microbiota in the progeny. Our results indicate that the bacterial community has adapted to colonize the orchid organs selectively and systemically, suggesting an active involvement in the orchid holobiont.

Morpho-Physiological and Ecological Characteristics of Melilotus officinalis (Fabaceae, Magnoliopsida) in the Conditions of the Republic of Tatarstan

The morphological variability of the aerial vegetative and generative organs of Melilotus officinalis in the ecotone communities of the forest-steppe zone, the forest zone of the Republic of Tatarstan including desecrated parts of the forest zone was studied. The ascorbic acid content in various parts of the plants growing in these habitats was also analyzed. It was revealed that the realization of the morpho-physiological potential of plants was determined by the conditions of botanical-geographical zones. The sweet clover, growing on black soils under the conditions of ecotone communities of the forest-steppe zone, was found to have higher indicators of “total biomass”, “biomass of leaves”, “biomass of inflorescences”, etc., as compared to the plants from similar communities growing on gray soils of the forest zone. Under the conditions of the ecotone communities of the forest-steppe zone, the content of ascorbic acid in all parts of the plant was also higher. Melilotus officinalis, growing in the conditions of a desecrated soil layer, was characterized by the maximum realization of its biomorphological potential with a low value of the coefficient of variation (CV), which reflected a stronger homogeneity of the samples. In the plants growing under extreme conditions, a sharp increase in the concentration of ascorbic acid in all parts was observed, which could be considered as an important mechanism for the adaptation of the species to survival under conditions of a sharp temperature difference of the substrate. Along with an increase in the generative period, an important component of the species adaptation was the low correlation between the indicator “biomass of inflorescences” and the concentration of ascorbic acid in inflorescences, “biomass of inflorescences” and the concentration of ascorbic acid in the leaves, which reflected the stable process of formation of the generative system of sweet clover. All coenopopulations were characterized by an incomplete ontogenetic spectrum with an absolute maximum on the plants with the middle-age ontogenetic status (95%).

Anatomía e histoquímica foliar y caulinar de Moringa oleifera (Moringaceae)

Introducción y objetivos: Moringa oleifera, es un árbol cultivado en regiones tropicales y subtropicales. Valorado por sus múltiples usos ornamentales, alimenticios, forrajeros, medicinales e industriales, ha sido recientemente incluido en el Código Alimentario Argentino. El objetivo fue estudiar la anatomía e histoquímica foliar y caulinar de ejemplares de M. oleifera, cultivados en Tucumán, Argentina y señalar caracteres de valor diagnóstico para su identificación. M&M: Las muestras fueron procesadas mediante técnicas estándares para microscopía óptica y electrónica. Resultados: M. oleifera presenta hojas compuestas, pinnadas con folíolos de venación pinnada, camptódroma-broquidódroma. Lámina foliar con ceras epicuticulares, tricomas eglandulares, estomas actinocíticos y anomocíticos, mesofilo dorsiventral con proteínas y lípidos, y haces colaterales. Campos glandulares formados por nectarios extraflorales estipitados, tricomas glandulares y eglandulares. Peciólulo, raquis y pecíolo presentan contorno circular a sub-circular, con un haz o un anillo de haces colaterales, delimitados por esclerénquima. Médula del pecíolo con 1-2 conductos secretores, conteniendo proteínas, alcaloides, mucílagos y lípidos. Tallo con médula parenquimática con 1-2 conductos secretores e idioblastos cristalíferos (cristales solitarios de oxalato de calcio). Idioblastos con fenoles, taninos, saponinas, triterpenos, polisacáridos y proteínas, en foliólulo, peciólulo, raquis, pecíolo y tallo. Se describe por primera vez para M. oleifera, su arquitectura foliolar, la presencia de campos glandulares e histología del nectario y del pecíolo; así como, la histoquímica de sus órganos vegetativos aéreos. Los caracteres de valor diagnóstico para M. oleifera son: tricomas, presencia de campos glandulares, nectarios extraflorales, idioblastos y conductos secretores.

First record of phytomelanin in aerial vegetative organs and its evolutionary implications in Lychnophorinae (Vernonieae: Asteraceae)

Background and aimsPhytomelanin is a hard and resistant, brown to black substance found mainly in the reproductive organs of Asparagales and Asteraceae, and may serve to protect organs against external agents. In this study, we report for the first time the occurrence of phytomelanin in the stems and leaves of Asteraceae (Lychnophorinae, Vernonieae) and try to answer the following questions: How is phytomelanin distributed in aerial vegetative organs? What are the patterns of phytomelanin deposition in these organs? How did the evolution of phytomelanin occur in aerial vegetative organs of subtribe Lychnophorinae?. MethodsSamples of leaves and stems of 77 species were analyzed using standard techniques in plant anatomy. Ancestral character state reconstructions were performed using maximum likelihood (ML) assumptions, combining anatomical information with the phylogenetic history of Lychnophorinae. Key ResultsThe deposition of phytomelanin in Lychnophorinae is frequently associated with sclereids and occurs in intercellular spaces. Phytomelanin is mostly found in the secondary phloem of the thickened stem but may occur in all young and thickened stem tissues and in all leaf parts. The species can present different patterns of phytomelanin deposition, related to distinct processes of the formation of sclereids. Ancestral character state reconstructions suggest that the most recent ancestor of Lychnophorinae probably had phytomelanin in the secondary phloem and pith of the thickened stem. ConclusionsNew findings on occurrence, deposition, and evolution of phytomelanin in aerial vegetative organs are important advances in the knowledge of this subject, particularly for Asteraceae. The results indicate that the occurrence of phytomelanin, mainly in vegetative organs, is underestimated and understanding the distribution of this pigment may bring light to new evolutionary perspectives related to this complex plant family. In addition to this evidence, melanins are considered highly protective substances in cells of living organisms, with remarkable functions. Therefore, considering that studies of the chemical nature of this pigment show a basic structure common among melanized organisms, future melanin research in plants may reveal unexpected ecologicaland evolutionary implications.

تأثیر نانو اکسید روی و شوری خاک بر میزان مشارکت ذخایر ساقه در عملکرد دانه، سرعت ظهور برگ و برخی شاخص های رشدی جو (Hordeum vulgaris L.)

Introduction Salinity is one of the major abiotic environmental stresses, which affect almost every aspect of plant life and significantly reduces crop yield. Thus it is a serious threat to agricultural productivity especially in arid and semi-arid regions. The response of plants to salinity depends on several factors such as developmental stage, severity, duration of stress, and cultivar genetics. Several strategies have been developed in order to decrease the toxic effects caused by high salinity on plant growth. Among them use of microelements such as zinc plays a very important role in yield improvement. Zinc is an essential micronutrient for humans, animals and plants, which act as the metal component of enzymes or as a functional structural. A number of researchers have reported the essentiality role of zinc for plant growth and yield. Zinc is required for chlorophyll production, pollen function, fertilization and germination plays an important role. So, recent researches have shown that a small amount of nutrients, particularly Zn applied by foliar spraying can affect the susceptibility of plants to stress. Zinc (Zn) is known as an important micronutrient and its deficiency is recognized as a critical problem in plants, especially grown on saline conditions with high pH values. Materials and methods In order to study of effects of foliar application with Nano zinc oxide on contribution of stem reserves in grain yield, leaf appearance rate and some growth indices of barley (Hordeum vulgaris L.) in various levels of soil salinity, a factorial experiment based on randomized complete block design with three replications was conducted at research greenhouse of faculty of Agriculture, University of Mohaghegh Ardabili in 2012. Experimental factors were included soil salinity in four levels (no salinity, salinity of 25, 50 and 75 Mm) with NaCl and foliar application of Nano-Zinc oxide at four levels (0 as control,0.25, 0.5, 0.75 and 1 g/lit). Results The results showed that increasing of soil salinity decreased yield, leaf appearance rate and growth indices of barley. It was vise versa in foliar application of Nano-Zinc oxide. Maximum of dry matter remobilization from stem and aerial vegetative organs was obtained in salinity of 75 Mm× no foliar application of Nano-Zinc. Means comparison showed that maximum of yield (1.22 g per plant), leaf appearance rate (0.466 leaf/ day) and growth indices were obtained in 0.75 g/lit of Nano-Zinc oxide× without of salinity application and minimum of they were obtained in no foliar application× soil salinity of 75 Mm. It seems that in order to increasing of yield and some growth indices such as total dry matter, crop growth rate and relative growth rate under salinity condition, can be suggested that be applied 0.75 g/lit of Nano-Zinc oxide.

Leaf and stem anatomy and essential oil composition of four Brazilian Aldama species (Asteraceae) and their taxonomic significance

Aldama La Llave is one of several Asteraceae genera that pose phylogenetic problems. The close similarity between species, as well as the inconsistencies found in the most recent phylogenetic analysis, shows that new data are needed to help delimit group species. Aldama anchusifolia (DC) E.E.Schill. & Panero, Aldama megapotamica (Malme) Magenta & Pirani, Aldama nudibasilaris (S.F.Blake) E.E.Schill. & Panero and Aldama pilosa (Baker) E.E.Schill. & Panero are difficult to identify because they are very closely related. Therefore, the aim of this study was to detect anatomical and phytochemical characteristics to help elucidate phylogenetic issues raised by Aldama. Aerial vegetative organs were prepared using the standard histological techniques. Essential oils were obtained by hydrodistillation, and their components identified using a gas chromatograph coupled to a mass spectrometer and flame ionization detector. Each species presented a set of unique leaf and stem anatomical features. The front view of the epidermal cell walls in the leaves, the presence of secretory ducts in the phloem and medulla sclerification in the stems proved useful in delimiting these species. The essential oils were characterized by the predominance of sesquiterpenes such as t-caryophyllene, germacrene D and bicyclogermacrene. Some unique constituents in each species were also identified as potential chemical markers.

Pharmacobotanical study of Hypericum thymopsis

Hypericum thymopsis Boiss., Hypericaceae, is an endemic herb which generally grows at the calcareous steppe regions of Central Turkey. In flowering stage, the aerial parts of this species are used for wound-healing and sedation, and its infusions are used against stomach diseases and throat infections by local people. The aim of this study, to examine and to reveal of the morphology, anatomy and histology of the aerial vegetative and reproductive organs of the H. thymopsis, which are used in popular medicine and thus contributing to the pharmacognostic evaluation of the species. In comparison with previous published morphological description of the species, some different findings about plant height and leaf length were found. In addition, some morphological characteristics such as dimensions of sepals and ovaries, length of filaments, anthers, pistils and pedicels were examined here for the first time. The anatomical characteristics of stem, leaf, sepal, filament and pistil were studied using light microscopy and additionally for stem and leaf using scanning electron microscopy. The stem has the secondary growth, and circular shape. The leaves are amphistomatic and the mesophyll is dorsiventral. Stomata are anisocytic and sunken. The glandiferous emergences are present on stem and translucent glands exist in leaf mesophyll. Type A secretory canals are present in stem, leaf, sepal and petal cross section. While type B secretory canals are observed in sepal and petal, type C secretory canals are observed solely in ovary cross section. All the structural features herein found can assist the diagnosis of H. thymopsis.

Solving taxonomic problems within the Aldama genus based on anatomical characters

Anatomical characteristics have proved to be an invaluable asset for supporting taxonomic studies on different plant families, such as Asteraceae. Anatomical features can also help clarify taxonomical problems in the Aldama La Llave genus, especially among Brazilian representatives. The present study focussed on Aldama bakeriana, A. discolor, A. grandiflora and A. squalida. These species were chosen because they are difficult to identify taxonomically if the specimens have no flowers, they have biological and pharmacological potential and they are representative species from key morphological groups in the Aldama genus and could help in future taxonomical investigations. Aerial and underground vegetative organs from the four species were described herein for the first time and a comparative analysis was performed to highlight the unique features of each species and determine whether these species can be differentiated in terms of anatomy. All four species analysed were anatomically very similar. However, they could be differentiated on the basis of the set of anatomical features described for each species. On the basis of our findings, we concluded that anatomy is able to provide data to assist with the taxonomic problems within the four species analysed herein. The results also corroborated other studies on the Aldama genus.

Aerial stem and leaf morphoanatomy of some species of Smilax

This study aimed to describe the morphoanatomy of the aerial vegetative organs of seven Smilax species, used in Brazilian folk medicine. Samples of leaves and stems were fixed with FAA 50, embedded in historesin, sectioned on a rotary microtome, stained and mounted in synthetic resin. Cuticle ornamentation was analyzed with standard scanning electron microscopy. In the frontal view, the walls of the adaxial epidermis are straight in S. brasiliensis, S. cissoides, S. goyazana and sinuous in the other species. The walls of the epidermis on the abaxial surface are straight in S. brasiliensis, S. goyazana, S. rufescens, sinuous in S. campestris, S. fluminensis, S. oblongifolia, and wavy in S. cissoides. The stomata are paracytic in S. brasiliensis, S. goyazana, S. oblongifolia, and S. rufescens, anomocytic in S. cissoides, S. campestris; anisocytic and paracytic in S. fluminensis. The midrib has three vascular bundles that are individually wrapped by lignified cells in S. brasiliensis, S. cissoides, and S. fluminensis. In the other, the three vascular bundles are surrounded by a single lignified sheath. In the stems the vascular cylinder is surrounded by a sclerenchymatous ring with the exception of Smilax fluminensis, which has a starch sheath and internal layers of thin-walled cells.

Glandular trichomes on aerial and underground organs in Chrysolaena species (Vernonieae – Asteraceae): Structure, ultrastructure and chemical composition

Although the occurrence of glandular trichomes is frequently reported for aerial vegetative organs, many questions still remain opened about the presence of such trichomes in underground systems. Here, we present, for the first time, a comparative study concerning the structure, ultrastructure and chemical aspects of both, the aerial and underground glandular trichomes of two different Chrysolaena species, C. obovata and C. platensis. Glandular trichomes (GTs) were examined using LM, SEM, and TEM and also analyzed by GC–MS and HPLC coupled to UV/DAD and HR-ESI-MS (HPLC–UV–MS). In both aerial (leaf and bud) and underground (rhizophore) organs, the GTs are multicellular, biseriate and formed by five pairs of cells: a pair of support cells, a pair of basal cells, and three pairs of secreting cells. These secreting cells have, at the beginning of secretory process, abundance of smooth ER. The same classes of secondary metabolites are biosynthesized and stored in both aerial and underground GTs of C. platensis and C. obovata. These GTs from aerial and underground organs have similar cellular and sub-cellular anatomy, however the belowground trichomes show a higher diversity of compounds when compared to those from the leaves. We also demonstrate by means of HPLC–UV–DAD that the sesquiterpene lactones are located inside the trichomes and that hirsutinolides are not artifacts.

Structure, function and secretory products of the peltate glands of Centrolobium tomentosum (Fabaceae, Faboideae)

The glandular structures of Centrolobium tomentosum Guill. ex Benth. have been little studied despite the economic importance of this species. We describe here the distribution, development, structure and ultrastructure of the secretory cells of the peltate glands found on the vegetative organs of this species. Stem apices and leaves in various stages of development were collected and prepared for examination by light, scanning and transmission electron microscopy. Chemical analyses and conventional histochemical tests to determine the chemical nature of the secretory products were also carried out. Peltate glands occur on aerial vegetative organs during their primary growth stage. These trichomes are structurally stable, persisting throughout the development of the organ. During the initial stages of the gland development, cell separation creates a central space that expands as secretions accumulate. Maximum secretion rates occur during this phase and the secreting cells characteristically have well developed smooth and rough endoplasmic reticulum, and high numbers of plastids and mitochondria. During the later stages of the secretory phase, the central cells show symptoms of cell death and are incorporated in to the secretions. At trichome maturity, the central space is delimited by a uniseriate epithelium. In addition to the resin, which is the main secretory product, an extensive three-dimensional carbohydrate matrix was observed that extended throughout the central space, apparently giving support to the resin droplets. The terpenic nature of the secretion was confirmed by thin-layer chromatography. Given the terpenic nature of the secretion and the permanence of trichomes throughout all phases of leaf development, it is postulated that the resin-secreting trichomes act to protect the plant against herbivores.

Polymorphisme biochimique chez quelques halophytes autochtones du Nord Tunisien

Chemical polymorphism of some North Tunisian autochthonous halophytes. The study aims to explore and analyse osmoticums synthesized by four perennial halophytic Chenopodiaceae : Salicornia arabica, Atriplex portulacoides, Atriplex halimus and Suaeda fruticosa from Menzel Jemil, Soliman and Gammarth regions which belong to sub-humid and semi-arid bioclimatic zones. A sampling of aerial vegetative organs of these four halophytes has been made. Analyses focused on reducing sugars, starch, total proteins, soluble proteins and total lipids. Atriplex portulacoides harvested from Menzel Jemil station accumulates large amounts of starch, indicating a high photosynthetic activity. This could suggest that this species avoids drought and high salinity by an acceleration of its growth cycle and reproductive systems. Suaeda fruticosa is characterized by the highest levels in soluble sugars. This would mean that it is capable of synthesizing carbohydrate osmoticums for its osmotic adjustment. Atriplex sp. and Suaeda fruticosa have the highest levels of soluble protein indicating the possible intervention of amino acids in the regulation of intracellular osmotic pressure. This behavior was essentially observed at Soliman sampling site characterized by an upper semi-arid bioclimate and saline soils.

Potassium uptake and storage in oil palm organs: the role of chlorine and the influence of soil characteristics in the Magdalena valley, Colombia

Potassium is the main nutrient in oil palm nutrition. On oil palm estates, potassium fertilization is usually adjusted based on leaflet K content. However, in the Magdalena river valley in Colombia where the soils are deficient in Cl, KCl has always caused a drop in leaflet K content, sometimes to deficiency levels, yet yields remain high. To elucidate this paradox, we conducted a multi-annual trial on 11-year-old oil palms by comparing unfertilized plots and plots receiving KCl or NaCl. We analysed the physico-chemical characteristics of the soils and the K, Ca, Mg, Na, and Cl contents of different organs: leaflets, rachises, petioles, stems, roots, and fresh fruit bunches. Our results showed that Cl stimulated the uptake of K, Ca, and Mg cations in aerial parts and that K was primarily stored in the stem (72% of the K in aerial vegetative organs). Our results also showed that the soils were rich in K easily accessible to the crop, a fact that conventional extraction of exchangeable cations did not reveal, and that the richness was probably of volcanic origin. Lastly, analysis of rachis K content was seen to be a good potential indicator of K taken up by the plant, and could thus replace leaflets for monitoring potassium fertilization in oil palm plantations.