Secondary Xylem Vessels Research Articles

Alfalfa Responses to Intensive Soil Compaction: Effects on Plant and Root Growth, Phytohormones and Internal Gene Expression.

The perennial legume alfalfa (Medicago sativa L.) is of high value in providing cheap and high-nutritive forages. Due to a lack of tillage during the production period, the soil in which alfalfa grows prunes to become compacted through highly mechanized agriculture. Compaction deteriorates the soil's structure and fertility, leading to compromised alfalfa development and productivity. However, the way alfalfa responses to different levels of soil compaction and the underlying molecular mechanism are still unclear. In this study, we systematically evaluated the effects of gradient compacted soil on the growth of different cultivars of alfalfa, especially the root system architecture, phytohormones and internal gene expression profile alterations. The results showed that alfalfa growth was facilitated by moderate soil compaction, but drastically inhibited when compaction was intensified. The inhibition effect was universal across different cultivars, but with different severity. Transcriptomic and physiological studies revealed that the expression of a set of genes regulating the biosynthesis of lignin and flavonoids was significantly repressed in compaction treated alfalfa roots, and this might have resulted in a modified secondary cell wall and xylem vessel formation. Phytohormones, like ABA, are supposed to play pivotal roles in the regulation of the overall responses. These findings provide directions for the improvement of field soil management in alfalfa production and the molecular breeding of alfalfa germplasm with better soil compaction resilience.

Regulation of root development in nitrogen-susceptible and nitrogen-tolerant sweet potato cultivars under different nitrogen and soil moisture conditions

BackgroundDue to unreasonable nitrogen (N) application and water supply, sweet potato vines tend to grow excessively. Early development of storage roots is conducive to inhibiting vine overgrowth. Hence, we investigated how N and soil moisture affect early root growth and development.ResultsA pot experiment was conducted using the sweet potato cultivars Jishu26 (J26, N-susceptible) and Xushu32 (X32, N-tolerant). Two N application rates of 50 (N1) and 150 mg kg− 1 (N2) and two water regimes, drought stress (DS) (W1) and normal moisture (W2), were applied to each cultivar. For J26, the lowest expansion root weight was observed in the N2W2 treatment, while for X32, the N1W2 and N2W2 treatments resulted in higher root weights compared to other treatments. The interaction between N rates and water regimes significantly affected root surface area and volume in J26. Root cross-sections revealed that N2W2 increased the percentage of root area covered by xylem vessels and decreased the amount of secondary xylem vessels (SXV) in J26. However, in X32, it increased the number of SXV. A high N rate reduced the 13 C distribution ratio in J26 expansion roots, but had no significant effect on X32. In J26, N2W2 inhibited starch synthesis in roots by downregulating the expression of AGPa, AGPb, GBSS I, and SBE I.ConclusionThe observed effects were more pronounced in J26. For X32, relatively high N and moisture levels did not significantly impact storage root development. Therefore, special attention should be paid to N supply and soil moisture for N-susceptible cultivars during the early growth stage.

MiR395c Regulates Secondary Xylem Development Through Sulfate Metabolism in Poplar.

Secondary xylem development requires the coordination of multiple regulatory factors, including plant hormones, transcription factors, and microRNAs (miRNAs). MiR395 is an important regulator involved in sulfate metabolism, but its function in plant development is unclear. This study investigated the functions of miR395c in the secondary xylem development in Populus alba × P. glandulosa. MiR395c was highly expressed in the shoot apex and secondary xylem. The overexpression of miR395c resulted in an increase in both secondary xylem width and vessel dimension, as well as a decrease in the thickness of the secondary cell wall of the xylem fiber. Further analysis showed that miR395c inhibited biosynthesis of sulfate metabolic products by targeting ATPS genes, which led to the reduction of Abscisic acid (ABA) synthesis and down-regulation of MYB46 expression. Our results indicate that miR395c regulates the secondary xylem development process via sulfate metabolism in Populus.

Distinctive wood anatomy of early-diverging Asteraceae: Barnadesioideae

Abstract Asteraceae subfamily Barnadesioideae (ten genera, c. 90 species), confined to South America, are sister to the remainder of the family. The relative antiquity of the barnadesioids might lead one to expect that they contain more wood features plesiomorphic for the family, but only one character clearly falls in that category. Pits on imperforate tracheary elements are bordered (except for annuals), whereas simple pits occur in two related families, Calyceraceae (part) and Stylidiaceae (all that have been examined); in Goodeniaceae bordered pits only occur. By attaining fully bordered pits in Chuquiraga, the imperforate tracheary elements qualify as an apomorphy, ‘neotracheids’, valuable for resisting embolism formation in dry and cold South American habitats. Neotracheids are found also in Loricaria (Asteraceae: Inuleae), also from these habitats. Neotracheids, like plesiomorphic tracheids, are conductive, unlike fibre tracheids and libriform fibres. Other barnadesioid wood characters adapted to cold and drought include grouping of vessels, high vessel density, shorter vessel elements and helical sculpture (including helical thickenings on lumen-facing walls) of secondary xylem vessels. In Chuquiraga and Dasyphyllum, these helical thickenings are bordered in some species (new report for angiosperms). Some of the barnadesioid adaptations to cold and drought can be found in North American Artemisia spp. (Asteraceae: Anthemideae), especially in montane and desert areas. Wood features of barnadesioids match their respective habits and habitats: a few trees; shrubs of humid, dry or desert areas; a distinctive rhizomatous succulent in the pampas (Schlechtendalia); a scree/gravel perennial (Huarpea) and two genera of annuals, one with succulent leaves (Duseniella) and one with rayless (at least at first) stems in arid and open soils (Doniophyton). Diversity is unusual considering the small size of the subfamily. Examples of endodermal crystals (Arnaldoa only), pith sclereids and primary xylem fibres are cited.

Tiba Induced Morphological and Root Anatomical Changes in Lentil

A field experiment was conducted to evaluate the effect of 2,3,5-triiodobenzoic acid (TIBA) at 0, 10, 20, 30 and 40 ppm on the morphological and root anatomical changes of lentil (Lens culinaris Medik. cv. BARI Mosur-7). Foliarly applied TIBA decreased plant height significantly with the increasing concentrations of TIBA. Significantly maximum number of branches and leaves per plant were recorded due to 10 ppm TIBA treatment. Leaves were darker green in plants receiving 10 ppm TIBA due to high chl-a, -b and low carotenoid contents compared to control. Ten ppm TIBA increased root length significantly and root diameter non-significantly than the control plants. Root diameter in plants treated with 10 ppm TIBA increased due to the increase in the width of the cortex, decrease in vessel diameter and enhancement of the formation of more secondary xylem vessels.
 Journal of Bangladesh Academy of Sciences, Vol. 43, No. 2, 107-112, 2019

Effects of Urtica cannabina to Leymus chinensis Ratios on Ruminal Microorganisms and Fiber Degradation In Vitro.

Simple SummaryUrtica cannabina is an unconventional forage crop that has a wide distribution in northern parts of China and is rich in nutritional values. It has a considerable practical significance in cases of shortage of quality forage, such as Leymus chinensis, which is used for the growth and production of ruminants. Our study found that proper addition ratios of U. cannabina and L. chinensis can increase the fiber digestibility by modulating the rumen microbial community in vitro. We also suggest that proper addition of U. cannabina and L. chinensis ratios may be one of the nutritional strategies that can improve the digestion and absorption performance of fiber feedstuff and potentially alleviate the shortage of quality forage for ruminants.The study was conducted in vitro to investigate the effects of different ratios of Urtica cannabina and Leymus chinensis on fiber microstructure and digestibility in ruminal fluid. The experiment was divided into five groups based on the U. cannabina/L. chinensis ratios: A (0:100), B (30:70), C (50:50), D (70:30), and E (100:0). The culture medium was collected at 0, 1, 3, 6, 12, and 24 h. The results showed that: (1) in vitro crude protein degradability (IVCPD) was higher in group A, whereas in vitro neutral detergent fiber degradability (IVNDFD) was higher in group C (p < 0.05); (2) protozoa count was increased from 1 h to 3 h and decreased afterwards, with significant differences observed in several genera (p < 0.05); (3) microbial crude protein (MCP) contents at 1, 3, 6, and 24 h were higher in groups A and C (p < 0.05); (4) the basic tissue of U. cannabina was gradually degraded. At 24h, the secondary xylem vessel structure was observed in groups B and C, but not in groups D and E. In summary, there was higher neutral detergent fiber (NDF) digestibility, higher rumen MCP contents, and lower protozoa count, showing the significance of the 50:50 ratio for microbial growth and fiber digestibility.

An AP2/ERF transcription factor ERF139 coordinates xylem cell expansion and secondary cell wall deposition.

Differentiation of xylem elements involves cell expansion, secondary cell wall (SCW) deposition and programmed cell death. Transitions between these phases require strict spatiotemporal control. The function of Populus ERF139 (Potri.013G101100) in xylem differentiation was characterized in transgenic overexpression and dominant repressor lines of ERF139 in hybrid aspen (Populus tremula × tremuloides). Xylem properties, SCW chemistry and downstream targets were analyzed in both types of transgenic trees using microscopy techniques, Fourier transform-infrared spectroscopy, pyrolysis-GC/MS, wet chemistry methods and RNA sequencing. Opposite phenotypes were observed in the secondary xylem vessel sizes and SCW chemistry in the two different types of transgenic trees, supporting the function of ERF139 in suppressing the radial expansion of vessel elements and stimulating accumulation of guaiacyl-type lignin and possibly also xylan. Comparative transcriptomics identified genes related to SCW biosynthesis (LAC5, LBD15, MYB86) and salt and drought stress-responsive genes (ANAC002, ABA1) as potential direct targets of ERF139. The phenotypes of the transgenic trees and the stem expression profiles of ERF139 potential target genes support the role of ERF139 as a transcriptional regulator of xylem cell expansion and SCW formation, possibly in response to osmotic changes of the cells.

酸枣根系结构可塑性对自然梯度干旱生境的适应机制

PDF HTML阅读 XML下载 导出引用 引用提醒 酸枣根系结构可塑性对自然梯度干旱生境的适应机制 DOI: 10.5846/stxb201708271544 作者: 作者单位: 扬州大学,扬州大学,扬州大学,扬州大学,扬州大学 作者简介: 通讯作者: 中图分类号: 基金项目: 江苏省高校自然科学基金项目（17KJB210008）；扬州大学高层次人才科研启动项目（137011178） Plasticity of root morphology of Ziziphus jujuba var. spinosa in response to natural drought gradient ecotopes Author: Affiliation: Yangzhou university,,Yangzhou university,Yangzhou university,Yangzhou university Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根系是植物吸收水分和养分的主要器官，是直接接触土壤最先感受土壤逆境胁迫的部位。在干旱环境中，植物根系的结构特征必定发生改变以维持正常的生物机能而生存。目前，关于根系解剖结构的研究大多集中于根系的某一特定结构对单一逆境因子的响应。以生长在烟台-石家庄-银川-吐鲁番不同地域气候条件形成的自然梯度干旱环境中的酸枣为试验材料，应用植物显微技术研究酸根系结构的可塑性对不同自然梯度干旱环境的适应机制，结果表明：酸枣根的初生结构包括表皮、皮层和维管柱，表皮位于幼根的最外层，由单层体积较小、紧密排列的表皮细胞组成。皮层占根初生结构的大部分比例，由体积较大的多层薄壁细胞组成，薄壁细胞近似圆球形，数目众多，呈环形分布。维管柱位于最内层，细胞小而密集，由中柱鞘、初生木质部、初生韧皮部及薄壁细胞组成。随生境干旱加剧，酸枣根初生结构表皮细胞的厚度和宽度逐渐增加，皮层薄壁细胞的厚度和宽度、皮层薄壁细胞层数和皮层厚度均以宁夏银川样地的最大。酸枣根的次生结构包括周皮（木栓层、木栓形成层、栓内层）和次生维管组织（次生韧皮部、维管形成层和次生木质部）。从烟台至新疆吐鲁番随生境干旱加剧，酸枣植株根系周皮逐渐加厚、致密度提高。次生木质部中，导管的数量增加，管径增大。干旱环境中，酸枣植株根系结构上的变化一方面提高了吸水能力和输水效率，另一方面增强了保水能力，减少水分散失，这可能是其适应干旱逆境的机制之一。 Abstract:Water and nutrition are mainly uptaken by the root system, and the root system is directly grown in the soil and is sensitive to stress. In arid environments, the structure of the root system could be changed to maintain normal biology function and adapt to stress conditions. To date, most of the studies have focused on the structure or morphology of root system responses to single stress factors. However, less attention has been concentrated on the adaptive mechanism of the entire root structure to different ecotopes. Therefore, this study explored the root morphological plasticity of Ziziphus jujuba var. spinosa in response to natural drought gradient ecotopes. Root samples were selected from Yantai-Shijiazhuang-Yinchuan-Turpan of China. The four ecotopes formed a natural drought gradient environment according to their soil moisture, annual precipitation, and humidity coefficients. The purpose of this study was to elucidate the mechanism of root plasticity response to different environments caused by climate change. The results showed that root primary structure of Ziziphus jujuba var. spinosa included the epidermis, cortex, and vascular cylinder. The epidermis is on the surface of the young root, which is constituted by a single layer of epidermis cells that are small and arranged closely. The cortex takes the greatest proportion of the primary structure, and it is constituted by a larger quantity of parenchymal cells. The vascular cylinder is located in the innermost layer, and the cells are small and crowded together. It is composed of pericycle, primary xylem, primary phloem, and parenchymal cells. When drought aggravated, the thickness and width of the epidermis cells were increased. In addition, the thickness, width, and number of plies of parenchymal cells, and the thickness of the cortex were all largest at the Yinchuan ecotope. The root secondary structure of Ziziphus jujuba var. spinosa was divided into periderm (phellem layer, phellogen, phelloderm) and secondary vascular tissue (secondary phloem, vascular cambium, secondary xylem). As the drought intensified from Yantai to Turpan, the thickness and density of periderm was gradually increased. In addition, the diameter and quantity of vessels in secondary xylem were increased. These results illustrated that one of the adaptive mechanisms of plant to drought stress is the changes in the plasticity of root structure that enhance water uptake capacity and water transport efficiency. On the other hand, it improves water retaining capacity and decreases water desorption. 参考文献 相似文献 引证文献

PERBEDAAN STRUKTUR XILEM BATANG SENGON (Falcataria moluccana) DARI PROVENAN SOLOMON DAN WAMENA

Sengon (Falcataria moluccana) is fast growing species mostly planted by farmers due to its high productivity. Sengon originating from Solomon Island has been known with the high productivity eventhough susceptible to gall rust attack; on the other hand, sengon originating from Wamena is known to be more tolerant to gall rust attack. There is no previous study in terms of stem xylem structures comparing sengon from those seed origins. Therefore, this study was undertaken to identify the differences in anatomical structure of sengon stem; and to compare the xylem cell based on proportions and dimensions of the stems between the two provenances. Six stem samples of tolerant Wamena provenance and six samples of susceptible Solomon provenance were used in this study. Samples were collected from progeny trial of sengon in Lumajang, Jawa Timur. The observations include the anatomical structures and vessel element, parenchyma apotracheal cell, parenchyma paratracheal cell, xylem fiber, fiber length, and fiber diameter. The result showed that there was no difference in terms of anatomical structures between sengon Wamena (tolerant) and Solomon (susceptible) stem in cross section, tangential and radial section of periderm, phloem, secondary xylem (vessel cell, xylem fiber, and parenchyma xylem) and pith. However, in one of susceptible stem sample, a black reaction zone on the secondary xylem was found. Analysis of variance showed that parenchyma paratracheal cell, apotracheal cell, number of xylem fibers, xylem fiber diameter and length were not significantly different between stem of sengon Wamena (tolerant) and Solomon (susceptible).

Anatomical convergence and diversity in the taproots of 16 herbaceous perennial species from subhumid New South Wales, Australia

Herbaceous perennial plants are an important part of the biodiversity of the subhumid western slopes of New South Wales, Australia. However, these species are usually ‘out of sight, out of mind’ as while they are perennials, they are usually relatively small and they die back to an underground perennating structure during dry periods. These structures are critical for survival as they store non-structural carbohydrates and moisture that allow resprouting to occur. Their anatomical features have rarely been investigated. The taproots or similar of 16 frequently recorded dicotyledonous herbaceous perennials of the South West Slopes, NSW were anatomically examined. One species from each of 14 families and two species from the Asteraceae were sampled. All species had roots with a high proportion of parenchyma and relatively few secondary xylem vessels that generally had a narrow lumen diameter (average 26μm). The ratio of secondary cortex (tissues external to the vascular cambium excluding the phellem) to secondary xylem was highly variable between species (ranged from 0.24 to 75.13), with most species having a greater area of secondary cortex than xylem (median ratio 5.22). The species exhibited a wide array of anatomical variation, probably related to the wide taxonomic diversity. The high proportion of parenchyma facilitates storage of non-structural carbohydrates and water that are used for resprouting after adverse environmental periods. The relatively low density of vessels and small lumen diameters could be expected given that these plants generally have small leaves and short stems that are short lived. The high percentage of parenchyma and the small area of small diameter vessels show a form of functional convergence across the 15 families, while the wide variation in secondary cortex to xylem ratio and the wide variation in distribution and pattern of vessels and fibres reflects the wide taxonomic diversity of the studied species.

Morpho-anatomical and growth alterations induced by arsenic in Cajanus cajan (L.) DC (Fabaceae)

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

Anatomical Assessment of Root Formation and Tuberization in Cassava (Manihot esculenta Crantz)

Formation of storage root organs in cassava (Manihot esculenta) is poorly understood, but considered to occur when a subset of fibrous roots receive unknown signals to undergo secondary thickening. Large amounts of secondary xylem parenchyma are then produced in which starch is synthesized and stored. Anatomical studies were undertaken to examine rhizogenesis from greenhouse-grown cassava stem cuttings. Root formation was observed from the stem cut end (basal) and from close to the buried nodes (nodal) 5–10 days after planting. Transverse sectioning of the stem provided evidence that the basal roots were initiated from the cambium, while the nodal-derived roots developed from tissues deeper within the stem, at the boundary of the xylem and pith. Basal root anatomy remained constant with age, with minimal development of metaxylem. No tuberization was seen to occur from the basal roots. In contrast, nodal roots produced significant amounts of metaxylem and subsequently secondary xylem to form a large central stele. Further development established the storage organ in which secondary xylem parenchyma, tracheids and vessels were produced from the cambium. As a result, the nodal-derived roots were seen as precursors of the storage organs. It is proposed that nodal-derived and basal-derived fibrous roots are fundamentally different organs, that they originate through different rhizogenic processes and are committed to their respective developmental fates from the earliest stages of their initiation. These anatomical investigations offer new insight into root tuberization in cassava and should guide better focused studies into the underlying molecular and developmental control mechanisms.

Starch accumulation in cassava roots: Spatial and temporal distribution

The relationship between starch and morpho-physiology aspects of cassava plant has not been identified. Considering this aspects, the present study showed the temporal and spatial distribution of starch grains in storage roots of cassava, variety IAC 576-70 with 90 and 120 days after planting. From these evaluations, a concentration of starch around the secondary xylem vessels of the cassava tuberous roots was observed, which may be related to the movement of organic solutes in the xylem vessels, water flow and the occurrence of the symptoms of the physiological deterioration in these roots. Key words: Manihot esculenta Crantz., anatomy, histochemical test.

Comparison of root anatomy and xylem vessel structure in rain-fed and supplementary irrigated ‘Yaghooti-Syah Shiraz’ grapevine (Vitis vinifera L.)

Changes in environmental conditions may lead to modifications in structural development of plant root. Effects of supplementary irrigation and soil depths (0–90 cm) on anatomical changes in xylem were investigated in rain-fed Vitis vinifera L. cv. Yaghooti-Syah Shiraz. Irrigated and control roots were prepared according to routine histological procedure. Light microscopic observations revealed the structural features of drought tolerant control roots and their changes after the treatment. Irrigated roots were characterized by the absence of starch grains in parenchyma cells, uniformity of parenchymatous pith cells, and a decrease in periderm thickness. Morphometric investigation of xylem showed that irrigated and deep roots had larger mean and maximum vessel diameter and fewer vessel number than rain-fed and shallow roots, at every soil depth of every treatment. Secondary xylem vessel diameter and number were more affected by irrigation and soil depths than metaxylem. Grape roots responded to supplementary irrigation and increasing soil depth by reducing protective and supporting tissues and increasing vessel diameter.

Contrasting xylem vessel constraints on hydraulic conductivity between native and non-native woody understory species.

We examined the hydraulic properties of 82 native and non-native woody species common to forests of Eastern North America, including several congeneric groups, representing a range of anatomical wood types. We observed smaller conduit diameters with greater frequency in non-native species, corresponding to lower calculated potential vulnerability to cavitation index. Non-native species exhibited higher vessel-grouping in metaxylem compared with native species, however, solitary vessels were more prevalent in secondary xylem. Higher frequency of solitary vessels in secondary xylem was related to a lower potential vulnerability index. We found no relationship between anatomical characteristics of xylem, origin of species and hydraulic conductivity, indicating that non-native species did not exhibit advantageous hydraulic efficiency over native species. Our results confer anatomical advantages for non-native species under the potential for cavitation due to freezing, perhaps permitting extended growing seasons.

Histo-morphological, fluorescent and powder microscopic characterization of Cissampelos pareira Linn.

Introduction:Cissampelos pareira Linn. is a dioecious, perennial, twinning and climbing medicinal shrub belongs to the family Menispermaceae. It is being used as a traditional remedy by native peoples of South America for centuries, to treat women's ailments, such as for menstrual cramps, prevents threatened miscarriage, ease childbirth, to stop uterine hemorrhages after childbirth, postpartum pain and fibroid tumors. Drug is frequently prescribed for treating cough, abdominal pain and fever according to Ayurvedic Pharmacopeia of India. The genus is highly specialized for the richness of a diverse array of biologically active bisbenzylisoquinoline alkaloids. Objectives: The present study was performed with the objectives to elaborate the macroscopic and histo-morpho diagnostic profile of Cissampelos pareira and to analyze the quantitative, fluorescent and powder microscopic peculiarities to support its pharmacobotanical characterization. Materials and Methods: microscopic evaluation, quantitative, fluorescence standards of the drug and powder microscopy were carried out using the stem, root and leaves of Cissampelos pareira Linn. Results: Distribution of long uniseriate, bicellular clothing trichomes in the epidermal tissues of the aerial parts, presence of actinodromous venation with small, pentagonal shaped areoles, adaxial irregular and wavy epidermal cells, hypostomatic epidermis, abaxial anomocytic stomata, distinctive contour of the midrib, dorsiventral mesophyll with prominent spongy parenchyma zone having lobed and interconnected spongy cells, small palisade ratio, small stomatal index, and the vascular system having a ring of seven free collateral bundles in petiole were features characteristics of the species. Extraxylary fibres, distension and arching over to the vascular strands of the stem. Deposition of simple and compound starch grains, calcium oxalate crystals in the epidermal tissues of the lamina, ground tissues of petiole, stem, secondary xylem vessels of the root. Wagon wheel with spokes like appearance of the cross sectional view of the root, wood with more axial and radial parenchyma and less xylem fiber. Apotracheal diffuse axial parenchyma and wide non-lignified rays are also diagnostic features of the taxon. Conclusion: The present macroscopic and histo-anatomical observations of stem, root and leaves of Cissampelos pareira thus provides useful information for quality control parameters for the crude drugs. Powder, quantitative and fluorescence standards put forth could label valuable information as identifying parameters to substantiate and authenticate the phytomedicine.

Botanical pharmacognosy of Andrographis paniculata (Burm. F.) Wall. Ex. Nees

Introduction:Andrographis paniculata Nees is an important medicinal plant belongs to the family Acanthaceae. It is being used in traditional medicine, as a remedy for the cold, fever and detoxification of the body since time immemorial. Kalmegh has successfully halted the spread of 1919 Indian Flue (Influenza) pandemic. Drug has immense therapeutic potentials such as immunomodulatory, antibacterial and anti-inflammatory, laxative, depurative, prophylactic, hepatoprotective and cardiovascular effects. Most of the biological actions of Andrographis paniculata have been ascribed to its principal chemical constituent, Andrographolide. Objectives: The present work has been designed to delineate the Pharmacognostic profile of the leaves, stem, and root of Andrographis paniculata Nees. Materials and Methods: Macroscopic, microscopic evaluation, powder analysis, fluorescence standards of the drug and quantitative microscopy were carried out using the stem, root and leaves of Andrographis paniculata Nees Results: The presence of eucamptodromous pinnate venation with small, polygonal shaped areoles, upper epidermis lacking stomata, abaxial diacytic stomata, small palisade ratio, small stomatal index and fairly large Cystoliths in both upper and lower epidermis were features characteristics of the species. Quadrangular stem with dense collenchyma strands at the angles, uniseriate medullary rays with greater quantities of lignified fibers in the wood, abundant deposition of calcium oxalate in characteristic sites of the epidermal tissues of the lamina, ground tissues of petiole, stem, secondary xylem vessels of the root are also diagnostic characters of the taxon. Conclusion: The present study on botanical pharmacognosy of stem, root and leaves of Andrographis paniculata Nees thus provides useful information for quality control parameters for the crude drugs. Macro, microscopic, powder, quantitative and fluorescence standards discussed here can be considered as identifying parameters to substantiate and authenticate the drug. It could also fill the lacuna of our understanding about botanical pharmacognosy of Andrographis paniculata Nees.

Morphological differences of vessels in the secondary xylem of columnar and standard apple trees

La longitud, dimension y tipo de los vasos en el xilema secundario de arboles de manzana estandar y columnar se estudia - ron por el metodo de aislamiento y microfotografia. Los resultados mostraron que las celulas de los vasos del xilema del tallo fueron reticuladas y agujereadas en las manzanas estandar y columnar. La mayoria de las paredes del fondo fueron simples platos perforados. Comparado con los arboles de manzana columnar, los arboles de manzana estandar mostraron mas celulas anormales en las celulas de los vasos del xilema. El diametro promedio de las celulas de los vasos del xilema de tallos fue significativamente mas amplio en la manzana columnar (43.27 μ m) que en la manzana estandar (32.64 μ m). La longitud de las celulas de los vasos del xilema de tallos no tuvo un modelo consistente en las manzanas estandar y columnar. Los resul - tados de este estudio contribuirian a explicar porque los arboles de manzana columnar tienen mayores tasas fotosinteticas y relaciones de utilizacion de energia luminica que los arboles de manzana es - tandar. Estas caracteristicas deben haber contribuido a una floracion y fructificacion mas temprana en los arboles de manzana columnar

Histological pathogenesis of Pseudomonas savastanoi on Nerium oleander.

The development of the bacterial knot of oleander, caused by the Pseudomonas savastanoi, was studied at different intervals after inoculation to examine anatomical changes in inoculated twig tissues, the movement of bacteria within host tissues, and the formation of defense reactions of the host plant. Pseudomonas savastanoi invades stem tissues of oleander by moving from the inoculation wound into intercellular spaces of parenchyma tissues and systemically further away through the laticifers. Bacterial invasion of oleander tissues causes degradation of primary cell walls of parenchyma cells and laticifers and formation of bacterial cavities followed by hypertrophic and hyperplasic activities. Hyperplasic activities lead to the formation of meristematic cell masses, with differentiation of vascular bundles, which contributes to the development of the knot. The host develops observable microscopic anatomical defense reactions at the different stages of host invasion. Lignin deposits form on the primary cell walls of parenchyma cells and laticifers around bacterial cavities to limit the movement of the pathogen. Tyloses form in the secondary xylem vessels, blocking them and preventing further movement of the bacteria within the vessels. Finally, the formation of impermeable periderm around bacterial cavities, neoformed tissues, xylem elements, and at the surface of the knot, leads to its final decline.

Ultrastructural analysis of the differentiation process of secondary xylem vessel element in Populus deltoides

Using electronic microscopy, ultrastructural changes were observed during differentiation in a secondary xylem vessel element (VE) in Populus deltoides. Results showed that morphological development of VE differentiation was successively divided into three stages. First was primary cell wall outspread (the initial stage), where the VE was highly vacuolated and the protoplasma distributed along the cell wall. Second was secondary cell wall construction (the pivotal stage), where substances accumulated before the tonoplast broke, and the VE organelle was distinct. Golgi bodies and vesicles, which were associated closely with synthesis and transportation of secondary cell wall substances, were also abundant. After the tonoplast broke, these substances accumulated faster. Simultaneously, the protoplasm was disaggregated and the agglomerated chromatin was distributed over the margin of the nucleus, showing the typical characteristics of programmed cell death (PCD). During secondary cell wall formation, no cell wall substances accumulated between the terminal cell walls of neighboring VEs. In addition, terminal cell wall substances were disaggregated in the post secondary cell wall formation. Later, when the remnant terminal cell wall was broken in the third stage, perforation occurred. Thus, for these successive stages of VE differentiation, the critical stage, when differentiation was not reversible, was at the start of secondary cell wall formation with succeeding VE differentiation similar to a typical PCD process.