Secretory Canals Research Articles

Allelopathic Effects of Soil Extracts from Rhus typhina Plantations on Common Turfgrass Species in Northern China

The allelopathic plant Rhus typhina (Rt) has a shallowly distributed root system with a high density of secretory canals, which may allow it to exhibit indirect allelopathic effects through the soil on an understory turf species in a plantation. However, how these effects occur is still not well understood. For this study, the soil from the root zone of Rt was extracted via distilled water, and extracts at different concentrations (25, 50, and 100 g L−1) were used to treat six commonly planted turfgrass species, including Medicago sativa (Ms), Lolium perenne (Lp), Trifolium repens (Tr), Medicago falcata (Mf), Festuca arundinacea (Fa) and Coronilla varia (Cv), during a continuous germination–seedling culture experiment via the sand culture method. The germination, physiological, and growth indicators of the turfgrass seedlings were analyzed. The allelopathic effects of the soil extract at different concentrations on the six receivers were evaluated to provide a scientific basis for managing plantations with multilayer structures. The results indicated that, in general, the extracts of the soil from the root zone of Rt inhibited the germination and seedling growth performance characteristics of the mentioned turfgrasses; the inhibitory effects on Ms, Lp, and Mf increased with increasing concentrations of the Rt soil extracts, whereas those on Fa tended to decrease. In addition, the inhibitory effect on Tr obviously weakened at 50 g·L−1 relative to that at 25 g·L−1, whereas it became more obvious at 100 g·L−1; however, it exhibited the opposite trend for Cv. Generally, Mf and Cv were more sensitive to Rt allelochemicals at relatively low concentrations, and these species should be avoided when planting in Rt plantations at low densities. In contrast, Lp and Tr were more sensitive than those at relatively high concentrations and should be avoided when planting in Rt plantations at high densities.

Involvement of Programmed Cell Death and Autophagyon Schizogenous Secretory Canal Formation in Angelica dahurica var. formosana Root.

Schizogenous secretory canal is an important functional structure of Angelica dahurica var. formosana, which is the main part of the accumulation of essential oil, coumarin and other components. The developmental process of secretory tissue and the accumulation of components are closely related. Meanwhile, programmed cell death (PCD) plays an important role in the development of plant secretory tissues, which is usually associated with autophagy. However, there are fewer studies involving PCD and autophagy with the development of schizogenous secretory canal. This study aims to provide new data on the development of schizogenous secretory canal in A. dahurica var. formosana. Light and transmission electron microscopy were used to reveal the cytological characteristics of secretory canal in A. dahurica var. formosana roots at different developmental stages. PCD and autophagy signals during the developmental process were detected using techniques such as terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) detection, propidium iodide (PI) staining, and immunofluorescent labeling. The results showed that the walls of secretory cells were intact during the development of schizogenous secretory canal in A. dahurica var. formosana roots. Mature secretory cells showed high vacuolization and accumulated a large number of essential oils. Meanwhile, we also observed significant ultrastructural features of PCD and autophagy during the developmental process. The signal detection results indicated that PCD and autophagy were jointly involved in the development of schizogenous secretory canal in A. dahurica var. formosana roots, and caspase-3-like protease may act as an upstream signal and participate in PCD.

Cell-type specific localization and biological activity of the volatiles from the endemic species Chaerophyllum coloratum L.

Main conclusionNew findings are presented for Chaerophyllum coloratum L. on the volatile composition of the essential oil, based on data of hydrosol and fresh plant material, light and electron microscopy of leaves, and cytotoxic and antiviral activity.The widespread Apiaceae family includes many well-known and economically important plants that are cultivated as food or spices. Many produce essential oils and are generally a source of secondary metabolites and compounds that have numerous applications in daily life. In this study, the chemical composition of volatile organic compounds (VOCs), ultrastructure and biological activity of the Mediterranean endemic species Cheaerophyllum coloratum L. are investigated, as literature data for this plant species are generally very scarce. The essential oil and hydrosol were extracted from the air-dried leaves by hydrodistillation and the chemical composition of both extracts was analysed by GC–MS in conjunction with headspace solid-phase microextraction (HS-SPME) of VOCs from the hydrosol and the fresh plant material. In the composition of the essential oil, the oxygenated sesquiterpenes spathulenol and caryophyllene oxide were the most abundant components. In the fresh plant material, non-oxygenated sesquiterpenes dominated, with β-caryophyllene and germacrene D being the main components. The hydrosol was dominated by monoterpenes, with the oxygenated monoterpene p-cymen-8-ol being the most abundant. Light and electron micrographs of the leaf of C. coloratum show secretory structures, and we hypothesize that glandular leaf trichomes, secretory epidermal cells and secretory canals are involved in the production of volatiles and their secretion on the leaf surface. Since the biological potential of C. coloratum is poorly investigated, we tested its cytotoxic activity on cancer and healthy cell lines and its antiviral activity on plants infected with tobacco mosiac virus (TMV). Our results dealing with the composition, ultrastructure and biological activity show that C. coloratum represent a hidden valuable plant species with a potential for future research.

Anatomy of vegetative organs of Eleutherococcus senticosus (Rupr. & Maxim.) Maxim. (Araliaceae)

Eleutherococcus senticosus (Araliaceae) is widely used as adaptogen in herbal medicine. Since comprehensive anatomical analysis of its vegetative organs was not available, the present study aimed at providing the reference data on the structure of leaves and roots, under- and aboveground stems of 1–4 year-old plants by means of conventional light microscopy. In the primary structure, roots were di- or triarch, with secretory canals facing protoxylem. Concurrently with cambium initiation, additional pericyclic secretory canals differentiated close to the existing ones. In the root secondary structure, secretory canals were formed in the conductive secondary phloem and maintained in the nonconductive one. Stem primary structure encompassed uniseriate epidermis with scant prickles, primary cortex and stele. Primary cortex was composed of collenchyma, chlorenchyma, ground parenchyma with secretory canals and ca. triseriate starch sheath. In outer stele (pericycle) strands of sclerenchyma fibers (stereids) differentiated, alternated with parenchyma. In the ring of open collateral bundles, cambium became continuous concurrently with (sub)epidermal initiation of phellogen. In the wide pith, ground parenchyma occurred, with a few secretory canals close to protoxylem. Secondary structure stems retained the cortical tissues in the 4th year; new secretory canals appeared in the conductive secondary phloem. The epithelial cells/sheath cells complexes were maintained even in the oldest nonconductive phloem (and in the cortex) in stems of 4 year-old plants, while the successively formed sieve tube-companion cell complexes functioned till the end of the vegetation periods only. The bifacial leaves exhibited shade adaptation in chlorenchyma structure; secretory canals were formed mainly in veins’ phloem.

Comparative study of morphological and anatomical features of Bidens L. Species

Introduction. Determining closely related impure species when confirming the authenticity of medicinal plant raw materials (mprms) is a very difficult and controversial task, especially for crushed and powdered mprms. One of such objects is the three-part beggarticks, which is prone to polymorphism and occupies the same area with the nodding beggarticks, the Spanish needles and the devil's beggarticks. Objective: to conduct a comparative pharmacognostic analysis of species of the genus Bidens L., which can be collected together with the pharmacopoeial species – three-part beggarticks. Material and methods. The objects of study were dried herbs of three-part beggarticks (Bidens tripartita L.), nodding beggarticks (Bidens cernua L.), Spanish needles (Bidens bipinnata L.), and devil's beggarticks (Bidens frondosa L.), collected in the Moscow region in 2020–2021. In this work, we studied the anatomical and morphological structure of leaves, as the most preferred part from a diagnostic point of view. The study of anatomical and morphological characteristics was carried out in accordance with the General Pharmacopoeial Monograph of the Russian Federation State Pharmacopoeia XIV 1.5.1.0003.15 “Leaves”. Results. A comparative description of the anatomical-diagnostic external and microscopic characteristics of the Bidens leaves has been obtained. Bidens tripartita and Bidens frondosa are higher than others. In contrast to the impure species, the Bidens tripartita has the largest deeply trifid, irregular serrated leaves, more pronounced tortuosity of the epidermal cells of the upper side of the leaf, multicellular thin-walled caterpillar-like and simple thick-walled hairs are combined, and the secretory canals in the mesophyll located along the vein. Conclusion. Among the studied Bidens species, each has characteristic features of its morphological and anatomical structure. These specific features can be used to establish the authenticity of the mprms and distinguish it from impure Bidens species, which require further research.

Herb and Flowers of Achillea millefolium subsp. millefolium L.: Structure and Histochemistry of Secretory Tissues and Phytochemistry of Essential Oils.

Achillea millefolium L. herb and flowers have high biological activity; hence, they are used in medicine and cosmetics. The aim of this study was to perform morpho-anatomical analyses of the raw material, including secretory tissues, histochemical assays of the location of lipophilic compounds, and quantitative and qualitative analysis of essential oil (EO). Light and scanning electron microscopy techniques were used to analyse plant structures. The qualitative analyses of EO were carried out using gas chromatography-mass spectrometry (GC/MS). The results of this study showed the presence of exogenous secretory structures in the raw material, i.e., conical cells (papillae) on the adaxial surface of petal teeth and biseriate glandular trichomes on the surface flowers, bracts, stems, and leaves. Canal-shaped endogenous secretory tissue was observed in the stems and leaves. The histochemical assays revealed the presence of total, acidic, and neutral lipids as well as EO in the glandular trichome cells. Additionally, papillae located at the petal teeth contained neutral lipids. Sesquiterpenes were detected in the glandular trichomes and petal epidermis cells. The secretory canals in the stems were found to contain total and neutral lipids. The phytochemical assays demonstrated that the A. millefolium subsp. millefolium flowers contained over 2.5-fold higher amounts of EO (6.1 mL/kg) than the herb (2.4 mL/kg). The EO extracted from the flowers and herb had a similar dominant compounds: β-pinene, bornyl acetate, (E)-nerolidol, 1,8-cineole, borneol, sabinene, camphor, and α-pinene. Both EO samples had greater amounts of monoterpenes than sesquiterpenes. Higher amounts of oxygenated monoterpenes and oxygenated sesquiterpenoids were detected in the EO from the herb than from the flowers.

Türkiye'de Yetişen Beş Artemisia L. Türünün Gövde Ve Yaprak Anatomisinin İncelenmesia

In this study, it is aimed to make anatomical analysis of five different Artemisia L. species (A. absinthium L., A. annua L., A. abrotanum L., A. incana (L.) Druce, A. tournefortiana Rchb.) grown in Turkey and contribute to the definition of this genus, which has some taxonomic problems. The materials for anatomical study were preserved in 70% alcohol. Free hand cross sections were taken using sharp razor blades, stained and mounted in Sartur Reagent and Chloralhydrate (50%) solution. Anatomical structures of the stem and leaf of selected species were examined under the light microscope. Their detailed structures were illustrated with photographs. Results have shown that stem and leaf anatomical features of the Asteraceae family are mostly shared by all species. However, some characters could be considered species-specific. In cross- sections, the stems of all studied species have more or less irregular rounded shapes, but prominent ribs containing collenchyma tissue could be noticed only in A. annua stem. The leaves of A. absinthium and A. incana were covered by glandular and densely T-shaped non--glandular trichomes on both sides however, A. tournefortiana had no hair at all. There were highly apparent secretory canals located in both the stem (next to the endodermal cells) and the leaf (near to xylem) of A. tournefortiana. The anatomical structure of leaves and stems of A. tournefortiana and A. incana growing in Turkey was demonstrated for the first time. Our results revealed that the studied species are anatomically distinguishable from each other and also provided valuable features for better species identification and contribute to the anatomy of the genus Artemisia.

Micromorphology and anatomy of fruit in Iris pseudacorus L.

Based on the suggestion that flower and fruit are integrally evolving structures, we aimed to reveal the floral traits persisting in the fruit structure in Iris pseudacorus, a widely distributed riparian species in Ukraine. We intended to compare the results with the other Iris species studied previously and reveal the constancy of micromorphological features of fruit interior structure. We revealed exomorphological and micromorphological peculiarities of the fruiting ovary using the model of vertical zonality of the gynoecium, vascular anatomy, and general anatomy of the fruit wall. In the fruiting ovary of I. pseudacorus, we revealed the presence of three vertical zones: short synascidiate zone, long symplicate zone bearing uniseriate seeds, and hemisymplicate zone located in the fruit beak. The vascular system of the ovary is composed of dorsal, septal, and ventral veins. Each of three dorsal veins divides radially into the outer tepal trace, stamen trace, and dorsal carpellary bundle, while each septal vein divides tangentially into three bundles of the inner tepal trace. Paired ventral veins enter the ovary from its bottom and supply ovules and seeds. The exocarp is composed of polygonal cells with thickened cellulose walls. The endocarp is uniseriate, unlignified, and composed of live prosenchymal cells, which are elongated tangentially. In the parenchymatous mesocarp, a great number of secretory canals with tannin-like content occur. The dehiscence of fruit on three valves proceeded by both dorsal and ventral slits. Dorsal slits are formed along dorsal grooves and provided by small-celled tissue surrounding the dorsal veins. The presence of ventral sutures of carpels in the symplicate zone of the ovary provides ventral dehiscence of fruit. Hence, the structure of the fruiting ovary in I. pseudacorus is comparable to that of other Iris species. Our investigation confirmed that the vertical zonality, placentation, and vascular system of the gynoecium in Iris can be appropriately estimated in the fruiting stage because the structural components of the ovary, which developed at the pre-anthetic phase, persist in the fruit.

Structural, histochemical, and phytochemical characterization of Mikania cordifolia (L. f.) Willd. (Asteraceae) in a coastal dune environment

Coastal dune is a habitat that presents determining and often limiting factors for plant development. Species of Asteraceae, such as Mikania cordifolia, are commonly found in this environment, including occupying frontal dunes, where winds, salinity, and soil represent severe environmental conditions. Asteraceae is recognized for its different secretory structures and for containing species with potential for bioprospecting. Mikania cordifolia is a species with a voluble habit, wide geographic distribution, and records of medicinal use. However, no studies in the literature cover the anatomical, histochemical, and chemical investigation of all vegetative organs of the mentioned species. In this sense, this study evaluated the anatomical organization of the vegetative organs of M. cordifolia, including secretory structures, as well as the chemical composition of the extract of each organ. For this, diaphanization, microtomy, histochemistry, and phytochemistry techniques were used. Our results showed that the vegetative organs have several adaptations to the coastal dunes environmental conditions, among them the presence of four types of secretory structures – secretory canals and cavities, trichomes and hydathodes. Histochemical analyzes indicated sesquiterpene lactones, pectic and phenolic compounds, lipophilic substances, flavonoids, coumarins, starch and tannins. Nuclear magnetic resonance analyzes showed kaurane diterpenes, steroids, fatty acids, phenolic derivatives, and methoxylated substances. Our results contribute to the understanding of the structure and phytochemistry of the genus Mikania, the adaptations of the species to the coastal dune environment, and the occurrence and distribution of secretory structures in the genus, promoting knowledge and justifying the conservation of the coastal dunes flora.

Morphoanatomy, Histochemistry, and Phytochemistry of Stem and Leaves of Crateva tapia L.

Crateva tapia L. occurs only in Brazil and belongs to the family Capparaceae. This study aimed to characterize the morphoanatomy and histochemistry of stem and leaves, and phytochemical tests of the leaf of C. tapia. Macroscopic characterization was performed with the aid of a pachymeter and a stereomicroscope. Cross-sections of the stem, petiole, petiolule, and leaf blade, as well as paradermal sections of the leaf blade were mounted on microscope slides. Analyzes were carried out with optical microscopy. For histochemical analysis, different reagents were useda ccording to the targeted metabolite. Phytochemical tests of the methanolic extracts of the leaves were performed using thin layer chromatography. Crateva tapia has a stem with a circular cross-section and smooth bark. The leaves are alternate spirally, compound 3-foliolate. The leaf blade is elliptical and has a reticulate dictiodromous nerve. Through anatomical characterization, it was possible to identify a hypostomatic leaf blade with anisocytic, tetracytic, and anomocytic stomata and the presence of secretory canals. Through histochemistry and phytochemical tests, it was possible to observe the presence of different metabolites. Thus, the results obtained in this study contribute to the quality control of C. tapia, a species only found in Brazil, increasing the taxonomic knowledge of the family Capparaceae.

A new gymnospermous stem from the Moscovian (Carboniferous) of North China, and its palaeoecological significance for the Cathaysian Flora at the early evolutionary stage

A new permineralized gymnospermous fossil stem, Parnaiboxylon wangi sp. nov., is described from the Moscovian Benxi Formation of Yangquan City, Shanxi Province, North China. It is composed of pith, primary and secondary xylems. The pith is solid, heterogeneous, with numerous secretory canals, ducts, and parenchymatous cells at the periphery. The primary xylem is endarch to mesarch. The secondary xylem is pycnoxylic, characterized by the presence of uni- to quariseriate araucarian radial tracheidal pitting, cupressoid to araucarioid cross-field pitting, and axial parenchyma. The fossil stem represents the fourth species of gymnosperms with anatomical features preserved from the Pennsylvanian of the Cathaysia. Anatomical characters, including solenoid pith and growth interruptions, and sedimentological evidence suggest a coastal environment with intermittent droughts or occasional incursions of seawater when the tree was alive. The presence of fungal hyphae, coprolites, and decayed tunnels in the secondary xylem of P. wangi sp. nov. indicate well-developed fungi–plant and animal–plant interactions when the Cathaysian flora at its early evolutionary stage.

(2929–2931) Proposals to conserve the names Dipterocarpoxylon with a conserved type against Hippocrateoxylon, Dryobalanoxylon against Naucleoxylon, and Shoreoxylon against Bredaea and Grewioxylon (fossil Dipterocarpaceae, Magnoliophyta)

(2929–2931) Proposals to conserve the names <i>Dipterocarpoxylon</i> with a conserved type against <i>Hippocrateoxylon</i>, <i>Dryobalanoxylon</i> against <i>Naucleoxylon</i>, and <i>Shoreoxylon</i> against <i>Bredaea</i> and <i>Grewioxylon</i> (fossil <i>Dipterocarpaceae</i>, <i>Magnoliophyta</i>)

Intraspecific variation in ultrastructure and secretion of the resin canals in Anacardium humile (Anacardiaceae).

The study combines a range of light and electron microscopy methods to access variation in secretion and ultrastructure in the secretory canals in the above- and belowground stems of Anacardium humile, which here serves as a model system. The aboveground stem canals show epithelial cells with ultrastructural characteristics typical of cells active in secretion, while in the belowground stems, the subcellular characteristics are typical of cells with low rates of metabolism. The secretory canals of the belowground stems show uniformity in size and shape, a large central vacuole, a cytoplasm reduced to a thin layer at the cell periphery, and a reduced population of organelles. The aboveground stem canals had voluminous nuclei with evident nucleoli, a very dense cytoplasm with free ribosomes, polyribosomes, mitochondria with developed cristae, and ellipsoid plastids with electron-opaque droplets surrounded by a periplastid reticulum. The vacuoles were of different sizes and often had membranous contents and the dictyosomes were very developed with dilated ends to the cisternae, rough endoplasmic reticulum, and numerous vesicles. The results show that particularities in above- and belowground environment have significant implications for ultrastructural morphology and functioning of secretory canals in the stems of A. humile.

The application of the full factorial design and Response Surface Methodology in optimization conditions for essential oils extraction from Lavandula stoechas, Carum carvi and Eucalyptus camaldulensis: Effect of plants particle size on the extraction of essential oils

The study applies experimental design to optimize hydrodistillation (HD) parameters in essential oils (EOs) extraction from the aerial parts of three different plants: Lavandula stoechas, Eucalyptus camaldulensis and Carum carvi. Three parameters have been examined: the particle size (Ps) the distillate flow (Q) and the volume of EOs vapor in the Clevenger (Vvap).The ratio of plant mass to the water volume has been kept constant as well as the extraction time. The full factorial design (FFD) gives a first-order model with an R2 > 0.99 for both plants Lavandula stoechas and Carum carvi. According to the Box–Behnken design (BBD) , the EOs yield of Eucalyptus camaldulensis seems to depend on the Vapor volume of the EOs, distillate flow and the particle size and, on the interaction between the Vapor volume and the distillate flow. A second order model obtained by the BBD application on the Eucalyptus camaldulensis plant. The analysis of variance (ANOVA) reveals that the model was significant, as evidenced from R2 of 0.991 and the model F-value of 196, 42. Finally, it seems that for plants whose secretory sites are superficial glandular trichomes, such as Lavandula stoechas leaves (Lamiaceae), or secretory canals, such as Carum carvi seeds (Apiaceae), the particle size has no effect on the extraction yield. On the contrary, the particle size is a limiting parameter in the case of endogenous secretory pockets of Eucalyptus camaldulensis (Myrtaceae).

Age-dependent modulation of oleoresin production in the stem of Sindora glabra.

Plants produce specialized metabolites in various organs which serve important functions in defense and development. However, the molecular regulatory mechanisms of oleoresin production in stems from broadleaved tree species are not fully understood. To determine whether endogenous developmental cues play a role in the regulation of oleoresin biosynthesis in tree stems, anatomy, multi-omics and molecular experiments were utilized to investigate the change of secretory structures, chemical profiles and gene expression in different ontogenetic stages of Sindora glabra tree, which accumulates copious amount of sesquiterpene-rich oleoresin in stems. The size of secretory canals and the concentration of five sesquiterpenes in Sindora stems exhibited obvious increase with plant age, from 0.5- to 20-year-old plants. Moreover, α-copaene and β-copaene were found to be stem-specific sesquiterpenes. Metabolomic analysis revealed that salicylic acid highly accumulated in mature stems, but the content of triterpenes was greatly decreased. The expression of three repressors AUX/IAA, DELLA and JAZ involved in hormone signaling transduction pathways was significantly downregulated in stems of 10- and 20-year-old plants. Two key genes SgTPS3 and SgTPS5 were identified, whose expression was highly correlated with the accumulation patterns of specific sesquiterpenes and their enzymatic products were consistent with the chemical profiles in the stem. The promoters of three SgTPSs exhibiting high activity were isolated. Furthermore, we demonstrated that SgSPL15 directly interacts with SgTPS3 and SgTPS5 promoters and activates SgTPS5 expression but SgSPL15 inhibits SgTPS3 expression. In addition, SgSPL15 enhanced sesquiterpene levels by upregulating AtTPSs expression in Arabidopsis. These results suggested that sesquiterpene biosynthesis in S. glabra stem was dependent on the regulation of endogenous hormones as well as plant age, and SgSPL15 might act as a buffering factor to regulate sesquiterpene biosynthesis by targeting SgTPS genes.

Comparative anatomy of flowering and sterile shoot leaf of Hedera helix L. (Araliaceae)

Hedera helix L. is a medicinal plant and belongs to the Araliaceae family. Flowering shoots of the plant have elliptic-cordate and sterile shoots have palmately lobed leaves. Plant material was collected from Hacıkadın valley (Ankara-Turkey). The anatomical features of leaf and petiole were examined comparatively in this study. The results showed that both leaf types were dorsiventral. Single layer epidermis is covered by thick cuticle. The palisade parenchyma cell is oval-shaped in the flowering shoot mesophyll, also is elongated in the sterile shoots. In both leaf types, stomata are located in the lower epidermis. Flowering shoot leaf is covered with tufted hairs, sterile shoot leaf stellate hairs. The midrib of the leaves have a similar structure. Collenchyma tissue is located underside the upper and lower epidermal layers in the midrib. The vascular bundles are arc-form and tends to a ring-form. The sclerenchymatous tissue surrounds the vascular bundles and secretory canals are located in the adaxial side of the bundles. The leaves contain abundant druse crystals and starch grains. Petiole anatomy is similar in both leaf types. Unlike leaves, petioles are covered with stellate hairs, do not contain tufted-type. The collenchymatous tissue is located bottom the epidermal layer. The vascular bundles are embedded in the parenchymatous tissue and secretory canals are located on the adaxial side of petiole. Both petioles contain numerous druse crystals and starch grains.

Tovomita manauara (Clusiaceae): a new species revealed by fruit morphology and leaf anatomy

Herein, we present Tovomita manauara A. Nobre &amp; L. Marinho, a new species of Clusiaceae that is presumably endemic to the Amazonas state, in Brazil. The new species was initially identified as T. caloneura A.C. Sm., which is a morphologically similar and sympatric species. Although the species was based only on vegetative and fruit morphological characteristics, Tovomita manauara can be recognized by the large number of secondary veins (25–36 pairs vs. up to 26 pairs in T. caloneura) and 4-septate, turbinate to napiform fruits (vs. 5-septate and fusiform in T. caloneura). In addition to macromorphology, anatomical characters, such as the secretory canals larger, presence of collenchyma in the petiole, and the absence of druses in the midvein are also helpful for the identification of T. manauara.

Two new petrified gymnosperms with solenoid piths from the Pedra de Fogo Formation, Permian of Maranhão, Brazil

Solenoid piths are formed by systems of secretory ducts or canals, and they are relatively common in petrified gymnosperms from the Permian of Gondwana. We described herein two new taxa, Polycanaloxylon merlottii gen. et sp. nov. and Europoxylon garapensis sp. nov., from the Pedra de Fogo Formation (Cisuralian), northeastern Brazil. In both species the pith is non-septate and solenoid, primary xylem bundles have endarch maturation, rays are short and uniseriate, pits on the radial walls of tracheids are commonly uni to biseriate, cross-field pitting is cupressoid and wood is pycnoxylic. Whereas P. merlottii has a solenoid pith with a parenchyma sheath and sclerenchyma cells, E. garapensis is distinguished by a pith that only has secretory canals and parenchyma cells. In addition to expanding the distribution area of a typical Euramerican taxon into Parnaíba Basin, the report of Europoxylon reinforces a connection between these areas in the Late Pennsylvanian, thus enabling the dispersion of floristic elements. Solenoid forms are especially common in Kungurian sedimentary deposits of southern Brazil, and possibly India. However, since the occurrence of them seems to be linked to specific habitats, it should be proven that such environments are indeed contemporaneous in order to use these stems as a tool for relative dating in Gondwanan localities.

Fruit Anatomy of the Canarieae (Burseraceae).

Fruits historically have been the key character for delimitation of tribes in the Burseraceae. However, fruit structure is incompletely known within the family, thus the importance of this character is unclear. This study of fruit anatomy in the traditional tribe Canarieae examines the distribution of the tissues that correspond to the exo-, meso-, and endocarp. The detailed arrangement and measurement of the tissues are reported here for the first time in all eight genera in the tribe. The evidence suggests that in all cases except Pseudodacryodes, the endocarp has at least one layer of parenchyma cells within which a sclereid layer is evident and, in some cases, an inner epidermis. All Canarieae fruits exhibit secretory canals, and some taxa have epidermal glands with resin-like contents. Evidence of carpellar sutures was found for all Canarieae, and in Dacryodes, Haplolobus, Rosselia, and Santiria, an articulated plate is present that corresponds to an abortive locule. The anatomical and morphological characters presented here are useful in delimiting genera within Canarieae.

Cell wall thickenings and tylosoid: developmental morphology reveals novelties for secretory canals in Protium ovatum (Burseraceae).

We investigated the structure, histochemistry, and ultrastructure of the secretory canals in the vegetative axis of Protium ovatum from a developmental perspective. Samples of roots, stems, and leaves were analyzed using light and transmission electron microscopy. Secretory canals composed of a uniseriate epithelium and a wide lumen occurred in the phloem of all analyzed organs. Schizogenesis and lysigenesis were merging processes involved in the origin, growth, ramification, and fusion of the secretory canals, forming an anastomosed secretory net. Essential oils, polysaccharides, and proteins were detected in the epithelial cells, as well as plastids with poorly developed thylakoids, dictyosomes, rough endoplasmic reticulum, polysomes, and oil drops, showing the mixed nature of the secretion. Epithelial cells exhibited pectin-cellulosic thickenings in the anticlinal and radial walls. These thickenings may act in directing the secretion flux toward the lumen, protecting the neighboring tissues from the toxicity of secreted metabolites. Structural irregularities observed in the mitochondria cristae in epithelial cells may be associated with processes induced by toxic substances. Epithelial cells protruded into the lumen and became lignified in the outer portion of the secondary phloem, obliterating the non-functional secretory canals. We propose that this phenomenon presents a physiological significance similar to that of tylose, preserving the secretion flow inside the active portions of the secretory system. To our knowledge, epithelial cells with wall thickenings, mitochondria with structural abnormalities, and obliteration of non-functional canals are features reported for the first time for Burseraceae. These features have important functional significance for Burseraceae secretory system and contribute to a deeper knowledge of P. ovatum, a medically and economically important plant.