Midrib Cells Research Articles

The Complete Genome Sequence, Molecular Detection, and Anatomical Analysis of Hibiscus Chlorotic Ringspot Virus Infecting Hibiscus rosa-sinensis in Peninsular Malaysia

Hibiscus rosa-sinensis is the national flower of Malaysia and is widely cultivated as landscape planting across the nation. In 1995, Hibiscus chlorotic ringspot virus (HCRSV) was reported for the first time in Malaysia. Until today, there have been no follow-up studies on the viral infection in the plant, yet the virus symptom of chlorotic spots has been observed throughout the Hibiscus population. Therefore, this study aimed to report the complete genome sequence of the HCRSV, validate a molecular detection tool for its diagnosis, and measure the impact of the virus symptom and infection in H. rosa-sinensis. This study reported the complete genome of the HCRSV through RNA sequencing. The phylogenetic analysis of the HCRSV isolated from different geographical sources and several other related viruses was performed to confirm its identity and classification. Additionally, primers based on the genome sequence were designed and used for RT-PCR to detect the presence of the virus in symptomatic leaves, further confirming the HCRSV identity and presence. Meanwhile, the impact of the virus was measured by examining the anatomical and morphological changes in the leaf structure of symptomatic samples. Light microscopy and scanning electron microscopy were used to examine potential adaptations and comparisons between the leaf structures of healthy and infected samples, especially in the leaf lamina, petiole, and midrib cells. The results confirmed the complete genome sequence of the HCRSV, its molecular detection strategy, and the impact of the viral infection on Hibiscus leaves in Peninsular Malaysia. This study is beneficial for the management strategy of the virus and for protecting an important plant in the nation.

Leaf and stem anatomical traits of Muntingia calabura L. (Muntingiaceae) emphasizing the production sites of bioactive compounds

Muntingia calabura L. is a neotropical Muntingiaceae tree with medicinal properties and economic interest. Extracts from its leaves and stems are rich in carbohydrates, volatiles and phenolic compounds with proved anti-tumor, antinociceptive and thermogenic properties. However, little is known about the structural features of leaves and stem and where these compounds are produced. In addition to the glandular trichomes registered in the literature, we hypothesized that other morphotypes of secretory cells and tissues could be present in M. calabura. In this paper, we analysed the leaf and stem anatomical traits of M. calabura to assess the production sites of bioactive compounds. Leaf and stem samples were collected from plants living in an urban area in Botucatu city, southeastern Brazil, and submitted to standard methods for anatomical and histochemical assessments. The leafblade was hypoestomatic, heterobaric and exhibited dorsiventral mesophyll. The petiole had parenchyma cortex, central vascular system and parenchyma pith. The stem presented parenchyma cortex, peripheral vascular system and parenchyma pith. Druses of calcium occurred mainly in the inner cortex of stem, petiole and midrib. Abundant glandular and non-glandular trichomes characterized the epidermis of leaves and stem. Phenolic compounds and mucilage were detected in the glandular trichome head cells in all the analysed organs, in addition to the cortical cells of midrib, petiole and stem. Voluminous bi-compartmentalized cells containing phenolic compounds and mucilage characterized the epidermis in the adaxial surface of the leaf blade. These cells were a remarkable feature that deserve further investigation. Our results shed light to the poorly known secretory system of M. calabura and proved the occurrence of different morphotypes of secretory cells and tissues in its leaves and stem. The obtained data can guide more studies with ecological, structural and taxonomic approaches, and for researches on drug bioprospecting from this species.

Autecology and Economic Importance of Weed Flora of the Nile Delta: Capsella bursa – pastoris L.

The present study was conducted to investigate the morphology, anatomy, karyotype, palynology, biogeography and seed germination of Capsella bursa – pastoris. Also, the ecological characteristics and metabolic products were examined. C. bursa – pastoris (shepherd’s purse) is annual cruciferous herb shows considerably variety of habit form. It is a serious weed responsible for yield loss of many crops. The stem shows the typical dicot characters, with intervascular cambium gives few secondary tissues and has wide parenchymatous pith. The leaf has adaxial epidermal cells of midrib are large and projecting from the blade. The root shows normal secondary thickening and the ruptured epidermis covered by multilayered periderm. The chromosomes are 2n = 16. Pollen grains are spheroidal isopolar, tricolpate with sinuaperturate. The highest rate of seeds germination attained at 30 - 35o C, low salinity (0 – 0.2 M NaCl) and 25 – 30 mm rainfall. Capsella community comprised 25 species belonging to 15 families. Cynodon dactylon, Urtica urens, Rumex dentatus and Lamium amplexicaule were the common associates. The major life – forms were therophytes, hemicryptophytes and geophytes. The assemblage of this community belongs to six chorotypes with predominance of Mediterranean and Irano – Turanian. Capsella flourished in wet, loose, non – saline soil. The nutritive value was 69.29 cal./ 100g. The residues of the different extracts of leaves, stems and roots were 15.64, 11. 97 and 8.30 %, respectively. The polyphenols and flavonoids were detected in ethyl alcohol, chloroform and acetone extracts. These extracts exhihited antioxidant and antimicrobial spectrum only against. Bacillus cereus, Staphyloccus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa.

A New Species of the GenusMetzgeriaRaddi (Metzgeriaceae, Marchantiophyta) from India

A new species of Metzgeria Raddi, M. mizoramensis sp. nov. is described from Mizoram (Mamit district), India. The species is distinguished by its monoicous sexuality, 2–3 rows of epidermal cells of midrib in ventral view, hairs usually disposed singly along the margin and also scattered on ventral surface of thallus and presence of marginal gemmae.

Anatomical characters and chemical profile of leaves of three species in Lauraceae family

The Lauraceae family is widely distributed in tropical and subtropical climates, has more than 2500 species and in the taxonomic point of view, it is one of the most difficult families to identify species. The aim of this study was to analyze the leaf anatomy of three species of Lauraceae (Ocotea indecora (Schott) Mez, Nectandra barbellata Coe-Teix. and Endlicheria paniculata (Spreng.) J.F.Macbr.) and identify the chemical profile of essential oil extracted from the leaves by hydrodistillation method. The leaves of the three species were obtained in “Parque Estadual Intervales”, Atlantic Forest, São Paulo state, Brazil. Samples of leaves were fixed, dehydrated, embedded in synthetic resin and sectioned for mounting histological slides for anatomical description of leaf tissues. The essential oil extracted by hydrodistillation method from dried leaves was analyzed by gas chromatography to establish its chemical profile. The leaves are hypostomatic, the epidermis in E. paniculata and N. barbellata present regular cells walls and irregular cells walls in O. indecora in both sides of epidermis. The three species present a dorsiventral mesophyll. Histochemical analyses presented lipid substances in secretory cavity and cuticle; starch, phenolic compounds and mucilage were observed in parenchyma cells of midrib and mesophyll. Ultra structural analyses demonstrated that trichomes in the species E. paniculata and O. indecora are shown only on the abaxial leaf face and species N. barbellata presented trichomes on both sides of the epidermis (abaxial and adaxial). Ocotea indecora essential oil revealed as main compound the bicyclogermacrene and N. barbellata the δ-cadinene. The species showed different morphological characters and different compounds of the essential oil, being these data useful for the differentiation of the species.

Leaf structural traits of tropical woody species resistant to cement dust.

Cement industries located nearby limestone outcrops in Brazil have contributed to the coating of cement dust over native plant species. However, little is known about the extent of the response of tropical woody plants to such environmental pollutant particularly during the first stages of plant development and establishment. This work focused on the investigation of possible alterations in leaf structural and ultrastructural traits of 5-month-old Guazuma ulmifolia Lam. (Malvaceae), 6-month-old Myracrodruon urundeuva Allemão (Anacardiaceae), and 9-month-old Trichilia hirta L. (Meliaceae) challenged superficially with cement dust during new leaf development. Leaf surface of plants, the soil or both (leaf plus soil), were treated (or not) for 60days, under controlled conditions, with cement dust at 2.5 or 5.0mgcm(-2). After exposure, no significant structural changes were observed in plant leaves. Also, no plant death was recorded by the end of the experiment. There was also some evidence of localized leaf necrosis in G. ulmifolia and T. hirta, leaf curling in M. urundeuva and T. hirta, and bulges formation on epidermal surface of T. hirta, after cement dust contact with plant shoots. All species studied exhibited stomata obliteration while T. hirta, in particular, presented early leaf abscission, changes in cellular relief, and organization and content of midrib cells. No significant ultrastructural alterations were detected under the experimental conditions studied. Indeed, mesophyll cells presented plastids with intact membrane systems. The high plant survival rates, together with mild morphoanatomic traits alterations in leaves, indicate that G. ulmifolia is more resistant to cement dust pollutant, followed by M. urundeuva and T. hirta. Thus, the three plant species are promising for being used to revegetate areas impacted by cement industries activities.

Light‐induced transpiration alters cell water relations in figleaf gourd (Cucurbita ficifolia) seedlings exposed to low root temperatures

Water relation parameters including elastic modulus (epsilon), half-times of water exchange (T(w)(1/2)), hydraulic conductivity and turgor pressure (P) were measured in individual root cortical and cotyledon midrib cells in intact figleaf gourd (Cucurbita ficifolia) seedlings, using a cell pressure probe. Transpiration rates (E) of cotyledons were also measured using a steady-state porometer. The seedlings were exposed to low ambient (approximately 10 micromol m(-2) s(-1)) or high supplemental irradiance (approximately 300 micromol m(-2) s(-1) PPF density) at low (8 degrees C) or warm (22 degrees C) root temperatures. When exposed to low irradiance, all the water relation parameters of cortical cells remained similar at both root temperatures. The exposure of cotyledons to supplemental light at warm root temperatures, however, resulted in a two- to three-fold increase in T(w)(1/2) values accompanied with the reduced hydraulic conductivity in both root cortical (Lp) and cotyledon midrib cells (Lp(c)). Low root temperature (LRT) further reduced Lp(c) and E, whether it was measured under low or high irradiance levels. The reductions of Lp as the result of respective light and LRT treatments were prevented by the application of 1 microM ABA. Midrib cells required higher concentrations of ABA (2 microM) in order to prevent the reduction in Lp(c). When the exposure of cotyledons to light was accompanied by LRT, however, ABA proved ineffective in reversing the inhibition of Lp. LRT combined with high irradiance triggered a drastic 10-fold reduction in water permeability of cortical and midrib cells and increased epsilon and T(w)(1/2) values. Measurement of E indicated that the increased water demand by the transpiring plants was fulfilled by an increase in the apoplastic pathway as principal water flow route. The importance of water transport regulation by transpiration affecting the hydraulic conductivity of the roots is discussed.

Chloroplast Movement as Response to Wounding in Elodea canadensis

Summary Chloroplast movement was studied in intact, detached or cut leaves of Elodea canadensis Michx. The influence of external factors (light, temperature, water supply) and of leaf age on activity and pattern of chloroplast movement was observed. Chloroplast movement does not occur in unsevered leaves; in leaves severed either by detachment or by a lateral incision, chloroplast movement occurs at room temperature in similar patterns. In midrib cells axial chloroplast movement starts within 10 min after setting the wound, almost independently from external conditions. In epidermis cells, lateral chloroplast movement is time-limited depending on the pretreatment of the plant (light, dark, cold). Lateral chloroplast movement is minimal in young leaves and maximal in mature leaves. In the morning hours chloroplast movement is restricted to midrib cells, but in the afternoon additional lateral movement occurs. Predarkening of plants reduced lateral chloroplast movement, but continuous illumination activated the movement. Cooling of plants to the temperature of melting ice (+5 °C) inhibited chloroplast movement in detached and incised leaves. However, after transfer to room temperature, axial chloroplast movement started within 20 min, and lateral chloroplast movement started within 40 min. The velocity of movement was highest after several warm-cold-warm changes following detachment or incision (maximum 36.8 µm s -1 ). The time course of chloroplast movement coincides with rapid changes of the membrane potential with low amplitudes (humming, 4 to 7 mV), which was recorded with microelectrodes impaled into the midrib of the attached leaf. Cutting a leaf of the third, last-formed generation initiated a sudden depolarization (from -200 mV to -140 mV) and a subsequent hyperpolarization to -240 mV, which slowly increased, but after 10 min suddenly changed to the humming period in the range of -200 mV ± 1.5 mV. It is concluded that chloroplast movement is initiated and enhanced by wound reactions transmitted from cell to cell via plasmodesmata.

Reversible cytoplasmic rearrangements precede wall apposition, hypersensitive cell death and defense-related gene activation in potato/Phytophthora infestans interactions

We used video microscopy techniques as a tool for live examination of the dynamic aspects of plant/fungus interactions. Early, dynamic responses of epidermal midrib cells of leaves from a potato cultivar (Solanum tuberosum L. cv. Datura) carrying resistance gene R1 to Phytophthora infestans (race 1: compatible interaction, race 4: incompatible interaction) were monitored. Similar responses were observed in both types of interaction, ranging from no visible reaction of invaded plant cells to hypersensitive cell death. The overall defense response of each individual cell exhibited a highly dynamic behavior that appeared to be tightly coordinated with the growth of the fungus. Initial localized reactions, including major rearrangements within the cytoplasm, occurred directly at the fungal penetration site, where rapid apposition of autofluorescent material and callose took place. If fungal invasion stopped at this stage, the host cell restored its normal cytoplasmic activity and survived. Hypersensitive cell death occurred only when fungal growth had proceeded to the formation of a clearly identifiable haustorium. In such cases, cytoplasm and nucleus conglomerated around the intracellular fungal structure, followed by a sudden collapse of the whole conglomerate and an instantaneous collapse of the fungal haustorium. Only small quantitative differences between the compatible and incompatible interactions of the two fungal races were observed for these early responses of epidermal cells. In the incompatible interaction, a slightly larger number of epidermal cells responded to fungal attack. More pronounced quantitative differences between compatible and incompatible interactions occurred upon fungal invasion of the mesophyll. These differences in the number of responding cells were not reflected at the level of gene expression: the spatial and temporal activation patterns of two defense-related genes, encoding phenylalanine ammonia-lyase and pathogenesis-related protein 1, were similar in both types of interaction.

Transport of 14 C-indoleacetic Acid in the Hepatic Marchantia polymorpha

Tracer experiments using exogenous 14C-indoleacetic acid showed that its transport is localized in the midrib cells of Marchantia polymorpha vege- tative thalli. Transport occurs both acropetally and basipetally at approximately the same velocity, but basipetal transport is significantly greater in intensity. In- terference with energy-yielding metabolism due to anaerobic conditions, iodoacetic acid or sodium fluoride reduced basipetal transport by 40-50%. Disruption of cel- lular integrity via centrifugation or cytochalasin B reduced basipetal transport by 30-40%. IAA transport in M. polymorpha gametophytes is essentially the same as in vegetative axes of flowering plants with respect to all parameters compared. The presence of naturally occurring auxin in gametophytic tissue of Marchantia poly- morpha has been demonstrated by both chemical methods and bioassays. As early as 1956, an endogenous compound was isolated from thalli that gave positive results with the Avena curvature test (La Rue & Narayanaswami 1957). Schneider et al. (1967) isolated an Erlich and Salkowski-positive ethanol-soluble compound with an Rf corresponding to indoleacetic acid (IAA). La Rue and Narayanaswami (1957) also present evidence for the localized synthesis of auxin in the apical region of the thallus, and Maravolo (1976) dem- onstrated that IAA was the major transport form in Marchantia. Endogenous growth regulators exert correlative action over developmental processes in bryophytes analogous to their action in tracheophytes. Their correlative activity is dependent upon absolute concentrations, gradients, differential rates of synthesis, inacti- vation and the direction and intensity of transport. The polar distribution of auxin in Marchantia polymorpha assumes an important regulatory role in apical dominance, gem- mae-cup formation and rhizoid initiation through its influence on the balance between cell division and elongation (Maravolo & Voth 1966; Binns & Maravolo 1972; Davidonis & Munroe 1972; Rota & Maravolo 1975). Hebant (1970) and Scheirer (1977) demonstrated that some bryophytes possess spe- cialized cells within the midrib tissue with morphological characteristics of phloem sieve tube cells. Translocation of auxin in Marchantia is conducted in a similar transport system. This transport is strictly basipetal, and was adversely affected by triiodobenzoic acid, cinnamic acid and ethylene, all inhibitors of polar transport in tracheophytes (Maravolo 1976). The present investigation derives from the latter and investigates the nature of several aspects of the auxin transport mechanism in Marchantia.

Entstehung von Regeneraten an den Blättern von Mnium undulatum L. in Abhängigkeit von deren Insertion und vom Blattbezirk

In isolated leaves of Mnium undulatum start of regeneration and number of regenerants (protonemata) depend on the position of leaves at the stem. In well developed plants possessing more than 25 leaflets a maximum of regeneration ability is situated near the shoot apex as well as near the base; between the two peaks there is a middle zone of minor regeneration power. The upper peak is caused by a gradient of progressive differentiation degree directed from the apex to the middle part combined with decreasing ability of cell de-differentiation, i.e. return into the embryonal state. The lower peak is produced by the diminution of correlative inhibition in consequence of the long distance from apex, and, combined herewith, of partial physiological cell isolation in basal leaves already before their excision. Shorter shoots having less than 25 leaflets show commonly a single maximum of regeneration power corresponding to the upper peak of longer plants. The leaf of Mnium possesses a distal-proximal gradient of increasing regeneration ability, but in many cases it is suppressed by other influences. In the well developed leaves from the middle part of shoots it can easily be demonstrated by cuffing crossways. In the young leaves next to the apex nearly alone the rather firm cells of mid-rib in the distal leaf section are able to regenerate probably by reason of nutrient supply. In basal leaves the promoted regeneration power of distal part may be caused by the much advanced physiological cell isolation by reason of 1J, geing and strong diminution of correlative inhibition starting from the apex. Owing to influences of culture medium and season start and lapse of regeneration can be varied, but, not the fundamental character of regenerative process.

Pharmacognostic Study of Root, Leaf and Seed of Asteracantha Longifolia Nees

AbstractAsteracantha longifolia Nees. applied in jaundice, dropsy, rheumatism, anasarca etc., show the pharmacognostic characters - spines, having perennial root stocks; bluish-purple 2-lipped flower; leaves - sessile, multichambered thick-walled sclerotic cell, among the epidermal cells of midrib, large flat bunch-shaped calcium carbonate crystals and needle-shaped calcium oxalate crystals in the epidermal cells of lamina and in the cortical cells of midrib respectively; stomata-caryophyllaceous; stomatal index on upper surface: 23.46 (± .47); lower surface: 27.44 (± 52); palisade ratio: 10.23 (± .19) and vein islet number: 25.8 (± .69).

遊離葉緑体のデンプン形成 III

1. Using midrib cells of a detached Elodea leaf, the cytoplasm was separated, by means of plasmolysis, into two or more cytoplasmic fragments with or without nucleus, whereby several types of chloroplast aggregates were observed in a single cell.2. In the absence of nucleus, either aggregated chloroplasts or chloroplasts in the cytoplasmic fragment remained green and accumulated starch grains, whereas the chloroplasts in the mother cytoplasm containing a nucleus showed the symptom of degeneration in size, color and structure, as well as the depletion of starch grains.3. When the chloroplasts accumulating starch grains were brought into the nucleated mother cytoplasm by centrifugation or deplasmolysis, the starch grains in chloroplasts disappeared in a few days even in the light, while the chloroplasts outside the mother cytoplasm continue to produce starch grains.4. With Elodea leaves it was demonstrated that the nucleus plays an important role in the digestion of starch grains in the chloroplasts.

Cell physiological studies on the resistance of potato plant to Phytophthora infestans

1. Using living midrib cells of plants, the writer made microscopical observations on the protoplasmic changes induced by the infection of Phytophthora infestans.2. In the highly resistant variety, acceleration of the appearance of protoplasmic strands, the migration of the nucleus towards the infected part, and the rhythmic movement of the nucleus around the infected part were observed in the early stage of penetration of P. infestans. These activated visible movements in the infected cell may possibly be due to the enhanced motive force of the protoplasmic streaming in that cell. This acceleration of protoplasmic movement in the infected cell was more remarkable in the resistant variety than in the susceptible one.3. The number of protoplasmic strands in which the particles flow towards infected part is remarkably greater than that of the strands in which the particles flow in the opposite direction. So it seems that the motive force of the protoplasmic streaming is stronger in the direction towards the site of infection than in the contrary direction. The migration of the nucleus towards the site of infection may be resulted from this polarity of the motive force in the infected cell.4. It is presumed that the enhanced motive force in the infected cell of the resistant variety may be concerned with the increased energy metabolism in the infected tissues.

Cytological studies on resistance of potato plants to Phytophthora infestans

In the present study a series of experiments were carried out to measure the time required for young midrib cell of resistant and susceptible potato varieties to become brown when infected with Phytophthora infestans. The varieties used in the experiments are 41089-8 (Solanum demissum×S. tuberosum) as the resistant one, and Hokkai No. 9 (S. tuberosum) as the susceptible one. As has been shown in the former reports9, 10) when microscopical observation is successively made on the same living section, the degeneration process seems to be retarded by the injury caused in the act of handling.Accordingly in the present study microscopical observations were made always on fresh and living sections stripped by razor at a definite interval of time 10-20min. (in the case of 41089-8) or 1-several hours (in the case of Hokkai No. 9) after inoculation. The observations were finished in short time. Inoculation experiments were repeated 14 times in the case of 41089-8, and 7 times in the case of Hokkai No. 9.Seven phases were distinguished in the process of infection of the host cells by P. infestans. The number of cells belonging to each phase was divided by total number of cells observed and expressed in percentage in figs. 1 and 2. By plotting the values thus obtained as ordinates against time as abscissas, the curves shown in figs. 1 and 2 were obtained. From these curves, the time required for completion of each phase of the degeneration process of cells infected by P. infestans may be deduced (Table 1).About 12/3∼2 hrs. after inoculation, penetration was observed on midrib epidermis of the resistant variety, showing no difference from that in the susceptible variety. After the fungus penetrated into the cell and formed the primary intra-cellular mycelium, remarkable differences in the degeneration process of cells began to be observed between the two varieties.In the midrib cells of the highly resistant variety“41089-8”, within 10min. to 1 hour after completion of penetration, the first sign of injury appeared; the granules in Brownian motion appeared around the infected loci. About 10 minutes to 1 hour after the appearance of such granules, the contents in the infected cell began to discolor. Within about 10 minutes to 30 minutes after the beginning of discoloration, the granules stop their movement, and the cell content seems to gelatinize. In midrib cells of the susceptible variety, on the contrary, the granules in Brownian motion do not appear in the infected cell until 2 to 8 hours after the completion of penetration. Within about 7 to 10 hours after the appearance of such granules, discoloration of the content in infected cell does not take place. The granules stopped their movement 1 to 11/2 hours after discoloration of cell contents.In such process of reaction of the resistant and susceptible varieties, the most quick degeneration was observed in the basal tissue of midrib of unfording leaflets. The time required for degeneration seems to be greater in the tissues of comparatively older leaflets than in younger ones.Within about 10 hours after gelatinization of cell contents in infected cells, the brown color of that cell becomes deeper and finally blackish brown. Thereafter, however, it seems that further deepening in color in infected cells does not take place. Such deepening in color suggests that the deposition of polyphenol and other compounds in the browned infected cell continues for a comparatively longer period after the collapse of that cell.