Secondary Vascular Bundles Research Articles

Gibberellins Regulate Expression of Cyclins to Control Leaf Width in Rice

Leaves are the nutritive organs of rice. Leaf shape influences rice photosynthesis, subsequently impacting yield. Gibberellins, GAs, are important hormones, but the way in which GAs regulate leaf width is largely unknown. This study focuses on the d18 mutant with broader leaves due to defective GA biosynthesis. Statistical analysis indicates broader leaves in the d18 mutant compared to the wild-type group. An examination of leaf cell morphology shows a higher count of secondary vascular bundles in d18 than in the wild-type group. RNA-seq analysis demonstrates significantly higher expression of CYCB (CYCLIN B) and H4 (HISTONE H4) in d18 compared to wild type. In summary, the leaf width of d18 may due to a higher activity of cell division at leaf margin.

Anatomy and nutritional value of Dracaena cameroonianaBaker - an African wild vegetable

BackgroundEven though some Dracaena species are used as medicine, their utilization as food is rather unusual. In northern Angola, however, leaves and underground tubers of Dracaena cameroonianaBaker are frequently consumed. In particular, the leaves are of increasing economic value in the region. But the anatomy and nutritional aspects of the plant have not been studied so far. Therefore, a detailed anatomic description of the plant was conducted. In a second step the nutritional value of the defined material was analysed, providing a basis for the discussion of a more intensive utilisation of this rainforest shrub. ResultsThe leaf anatomy of Dracaena camerooniana differs from the species of the genus that have been examined so far, in showing adaptations to wet climatic conditions. The stems produce a secondary thickening meristem with amphivasal secondary vascular bundles. During tuber formation, the parenchyma of the pith in the vascular cylinder of the root markedly increases. From a nutritional point of view, leaves do not noteworthy contribute to vitamin intake. The nutritional composition of the tubers is comparable to that of cassava (Manihot esculentaCrantz) and potatoes (Solanum tuberosum L.). However, a high fructose value indicates inulin as a storage carbohydrate. ConclusionInspite of its rather moderate nutritional values, Dracaena camerooniana is an indigenous addition to the diet of the Angolan population that could also be cultivated in the future due to the easy vegetative propagation.

Anatomical structures of alligator weed (Alternanthera philoxeroides) suggest it is well adapted to the aquatic–terrestrial transition zone

The successful invasion of alligator weed (Alternanthera philoxeroides) into both aquatic and dry terrestrial environments has been attributed to its phenotypic plasticity and high rates of growth and vegetative propagation. Here, we evaluated whether the anatomical structures of alligator weed make it well adapted to colonize the aquatic-terrestrial transition zone. Anatomical and histochemical analysis revealed an impermeable apoplastic barrier that consists of a cuticle and an endodermis of the adventitious root and stem in both aquatic and terrestrial environment; stem and root possess a periderm in the terrestrial environment; and the root has a lignified cortex and hypodermis in the aquatic environment. A supernumerary cambia produces secondary vascular bundles, parenchyma and adventitious buds. Dilated parenchyma cells exist in the aged terrestrial roots. Aerenchyma tissue and pith cavities in the roots and stems produce air spaces, and the aquatic roots possess large aerenchyma compared with intercellular aerenchyma of terrestrial roots. In summary, phenotypic plasticity of anatomical characters, such as impermeable apoplastic barriers, air spaces, and reproductive supernumerary cambia, may be evidence that alligator weed is well adapted to the aquatic–terrestrial transition zone.

Does leaf anatomy aid in species identification of Butia (Arecaceae)?

Butia is a neotropical genus whose identification is based mostly on characters from external morphology, which are sometimes variable or inadequate for species differentiation. We aimed to verify if leaf anatomy of 18 Butia species brings new characters suitable for species identification and if it corroborates the phylogenetic relationship within the genus. Moreover, we propose an anatomical key to assist in species identification. Pinnae were collected and subjected to the usual techniques for light and scanning electron microscopies. The anatomical key was created with the aid of Xper2 software, based on the importance of characters to distinguish species according to the Jaccard index. All species have isobilateral mirrored mesophyll, amphistomatic leaves and secondary vascular bundles with sclerenchymatic sheath reinforcement connected to the hypodermis. Among the species studied, B. marmorii and B. matogrossensis showed exclusive characters. For the other species, up to five characters are sufficient for delimitation. Our anatomical key presents relevant characters that allow the identification of the recognized species of Butia. Reliable anatomical characters of easy observation, especially the raphides, are valuable in species distinction. Leaf anatomy, already used to support new taxa in related genera like Allagoptera and Syagrus, can also be useful to validate questionable Butia species and differentiate between similar species but do not reflect the proposed relationship between Butia species.

Cover Caption: Special issue: Plant vascular biology (2)

The cover shows secondary vascular bundles, produced by a unique monocot cambium, in which the phloem is centrally‐located, surrounded by a xylem ring (Zinkgraf et al., 436–449). In this issue, first insights into the genetic regulation and evolution of this fascinating meristem are presented in support of the hypothesis that genes regulating this vascular cambia were coopted in the evolution of this novel meristem that is found within some species of the Asparagales.

Transcript profiling of a novel plant meristem, the monocot cambium.

While monocots lack the ability to produce a vascular cambium or woody growth, some monocot lineages evolved a novel lateral meristem, the monocot cambium, which supports secondary radial growth of stems. In contrast to the vascular cambium found in woody angiosperm and gymnosperm species, the monocot cambium produces secondary vascular bundles, which have an amphivasal organization of tracheids encircling a central strand of phloem. Currently there is no information concerning the molecular genetic basis of the development or evolution of the monocot cambium. Here we report high-quality transcriptomes for monocot cambium and early derivative tissues in two monocot genera, Yucca and Cordyline. Monocot cambium transcript profiles were compared to those of vascular cambia and secondary xylem tissues of two forest tree species, Populus trichocarpa and Eucalyptus grandis. Monocot cambium transcript levels showed that there are extensive overlaps between the regulation of monocot cambia and vascular cambia. Candidate regulatory genes that vary between the monocot and vascular cambia were also identified, and included members of the KANADI and CLE families involved in polarity and cell-cell signaling, respectively. We suggest that the monocot cambium may have evolved in part through reactivation of genetic mechanisms involved in vascular cambium regulation.

Cover Caption: Special issue: Plant vascular biology (1)

The cover shows secondary vascular bundles, produced by a unique monocot cambium, in which the phloem is centrally‐located, surrounded by a xylem ring. In this issue, first insights into the genetic regulation and evolution of this fascinating meristem are presented in support of the hypothesis that genes regulating this vascular cambia were coopted in the evolution of this novel meristem that is found within some species of the Asparagales.

Leaf anatomy of Acrocomia (Arecaceae): an additional contribution to the taxonomic resolution of a genus with great economic potential

Acrocomia is one of the most complex genera to understand in the Neotropical Arecaceae, and there is no consensus on the number of species in the genus. A comparative study of leaf anatomy was conducted on seven species of Acrocomia: one with a wide distribution in the Americas (A. aculeata), five endemic to different regions of Brazil, Bolivia and Paraguay (A. emensis, A. glaucescens, A. hassleri, A. intumescens and A. totai) and one endemic to Cuba (A. crispa). Characters that unify the species of Acrocomia include the following: epidermis covered with cuticle, hypodermis on both sides of the leaflets, non-vascular fiber bundles, and primary and secondary vascular bundles. The shape of the leaflet margin, the distribution of the primary vascular bundles and fiber bundles, the number of idioblasts with raphides and the size of the vascular bundles, along with other characteristics, were used to distinguish these species in Acrocomia.

Leaf anatomy of Qualea parviflora (Vochysiaceae) in three phytophysiognomies of the Mato Grosso State, Brazil

ABSTRACT Leaves have a variety of morphological and anatomical characters mainly influenced by climatic, edaphic and biotic factors. The aim of this study was to describe the anatomical leaf traits of Qualea parviflora from three phytophysiognomies. The studied phytophysiognomies were Amazon Savannah on rocky outcrops (ASR), Transition Rupestrian Cerrado (TRC), and Cerradão (CDA). Freehand sections of the leaf blade were made and stained with 0.5% astra blue and with basic fuchsin. From the adaxial and abaxial leaf surface, freehand paradermal sections were made for epidermis analysis. The Jeffrey´s method, with modifications, was used in the epidermis dissociation process. The samples from the TRC phytophysiognomy had relatively smaller ordinary epidermal cells, higher abundance of trichomes, and mesophyll with few intercellular spaces, in comparison to the other phytophysiognomies. The leaves from the ASR phytophysiognomy had higher stomatal index (SI = 21.02), and five to six layers of sclerenchyma surrounding the midrib vascular bundle. The secondary vascular bundles had thicker cell walls and the bundle sheath extended up to the epidermal tissue of both leaf sides. Leaves from the CDA phytophysiognomy had mesomorphic environmental traits, such as a thinner cuticle. It is concluded that trees from ASR and TRC phytophysiognomies have xeromorphic traits following the environmental conditions where they occur.

Use of Leaf Anatomy for Identification of Quercus L. Species Native to Kurdistan-Iraq

Anatomical features of the leaves of Quercus L. species are presented in this study for the first time. Leaves are bifacial and the palisade parenchyma of Q. aegilops and Q. libani is stratified into two layers, of nearly equal width, while that of Q. infectoria and Q.macranthera composed of only one layer. The cortex of both midrib and petiole is well developed with collenchyma starting just beneath the epidermis. The collenchyma of Q. aegilops is extremly thick compared with that of other species. Vascular bundles of the midrib and petiole are completely enclosed by the two pericycle layers of fibers and sclerenchyma. While the number of vascular bundles and sclerenchyma groups cupping them is 3 and 2 for midribs of Q. aegilops and Q. libani respectively, the number turns into 2 vascular elements of different appearance in their petioles. Petiole secondary vascular bundles are well developed and their sclerenchyma groups more lignified in Q. infectoria but less developed and reduced in Q. macranthera. From the results, it is concluded that the leaf blade and petiole anatomical features can provide diagnostic characters for distinguishing Quercus species of Iraq. Results also strongly support placing Q. aegilops and Q. libani in the section Cerris but Q. infectoria is more reliable in the section Mesobalanus.

The parenchymo-vascular cambium and its derivative tissues in stems and roots of Bougainvillaea glabra Choisy (Nyctaginaceae)

In the shoots and roots of <i>Bougainmllaea</i>, the parenchymo-vascular cambium produces thinwalled secondary parenchyma to one side and the secondary vascular bundles embedded in the "conjunctive tissue" to the other. Periclinal division of a single cambial cell in one radial row brings about periclinal divisions of the adjacent cells of the neighbouring rows. Anticlinal division of a single cambial cell at one level, on the other hand, causes anticlinal. divisions of the adjacent cells of the overlying and underlying tiers.

Preliminary pharmacognostic screening of Achyranthes coynei stem.

Achyranthes coynei is a rare, endemic perennial shrub reported from Karnataka and Maharashtra states of India. The plant is used to treat various disorders by folk healers and was proven to have antimicrobial and antioxidant properties. The present study was undertaken to evaluate microscopic and macroscopic characters of A. coynei stem, along with its physicochemical parameters. ProgRes® CapturePro and Microsoft Excel were used for statistical analysis. Perennial, shrubby nature and woody stem were the distinguishing morphological characters observed. Transverse section (TS) illustrated quadrangular outline of the stem and showed the presence of two types of trichomes on the thick-walled epidermis. TS also showed number of rosette calcium oxalates crystals; prismatic and microsphenoid crystals; conjoint, collateral open secondary vascular bundles; and two amphixylic medullary bundles in the pith. Ash and extractive values, micro and macro elements and nutritive factors were estimated in the present study. The presence of alkaloids, saponins and triterpenoids were observed in preliminary phytochemical screening. High-performance thin layer chromatographic analysis yielded different bands and also indicated the presence of oleanolic acid. The studied parameters for A. coynei stem will be useful for identification and authentication of the plant material.

Systematics of Trigonochloa (Poaceae, Chloridoideae, Chlorideae)

A systematic treatment including descriptions and a key for identification is provided for the two species of Trigonochloa, a genus recently segregated from the polyphyletic Leptochloa s.l. Trigonochloa ranges from southern Africa east to India and Sri Lanka, reflecting the widely ranging Trigonochloa uniflora. Trigonochloa rupestris has a more limited distribution from East Africa to Yemen. Trigonochloa is diagnosable from other chloridoid grasses based on its unusually flaccid and membranous leaves that have uniquely enlarged lateral cells in the parenchyma sheath surrounding the vascular bundles in Trigonochloa uniflora (unconfirmed for Trigonochloa rupestris given limited material), primary and secondary vascular bundles that do not project above or below in fresh material, XyMS+ leaf anatomy, narrow spicate primary inflorescence branches, spikelets with one (or rarely two) florets, thinly membranous to hyaline lemmas, and a trigonous caryopses that bear a narrow but deep sulcus on the hilar side. Lectotypes are designated for Agrostis montana and Cynodon gracilis. The synonym Leptochloa laurentii De Wild. is confirmed for Trigonochloa uniflora.

Pharmacognostical Evaluation and Establishment of Quality Parameters of Medicinal Plants of North-East India used by Folklore Healers for Treatment of Hypertension

North-East india is in two biodiversity hotspots (Indo-Burma & Himalayan) in world map and the indigenous medicinal plants grown in the North - East India are useful folk medicines used by the people of this region. Prunus persica (L) Batsch and Clerodendrum colebrookianum Walp widely distributed in North-East India are popular folk medicine for the treatment of hypertension. The present investigation deals with the qualitative and quantitative microscopic evaluation of the leaf material and establishmentof itsquality parameters, including physicochemical and phytochemical evaluation. Chief characters of transverse section include primary and secondary vascular bundles surrounded by single layer endidermal cells in both the plants. In microscopic characters it is found that the anisocytic stomata surrounded by three subsidiary cells of which one markedly smaller than other in lower epidermal, but no stomata was found in upper epidermal of Prunus persica and the anomocytic stomata surrounded by varying number of cells in both upper and lower epidermis. The diagnostic characters of powders viz. sclerencnymatous fibres, sptocrophide or calcium oxalate crystals, starch grains, xylem vessels were found in Prunus persica and trichome, xylem vessel, phloem fiber, lignified fiber, epidermal cell in Clerodendrum colebrookianum. Various physicochemical parameters were also established. Phytochemical screening revealed the presence of many therapeutically important classes of phytoconstituents such as reducing sugar, proteins, steroid, cardiac-glycoside, flavonoids, tannins and saponins. The present investigation was also aimed at justifying the antioxidant potential of the leaves extracts of the plant that may contribute antihypertensive activity of plant.

A Comparative study of five species of Curcuma with special reference to Pseudostem and Rhizome characters

Identification of different species of Curcuma based on morphological and anatomical characters is difficult. Under commercial cultivation, the crop is usually harvested before flowering. Variation in number and arrangement of primary and secondary vascular bundles, orientation of endodermal layer, number and shape of curcumin cells and starch grains provide some tools for identification at this level but these are not completely dependable. The present study made it possible to easily identify five important species Curcuma longa L., C. amada Roxb., C. zanthorrhiza Roxb., C. aromatica Salisb. and C. aeruginosa Roxb. based on pseudostem and rhizome characters in the vegetative phase. A simple and easy method for identification of the five species of Curcuma by observing the rhizome pigmentation is reported.

Organographic and anatomical evidence that the edible storage organs of Plectranthus esculentus N.E.Br. (Lamiaceae) are stem tubers

Plectranthus esculentus N.E.Br. is a member of the family Lamiaceae, to which many aromatic plants such as the mints and sages belong. It differs from most members of the family in that it produces tuberous subterranean organs at the base of the stem, which can weigh as much as 1.8 kg per tuber. These organs are often used by local people as a food source. Storage organs in plants can be modified roots (carrot and sweet potato), stems (potato), or composed of leave bases (onion). In the case of P. esculentus, there is a difference of opinion as to the exact ontogenetic origin of these organs, and whether they are roots, rhizomes, underground stems or root tubers. According to our observations, these tuberous, positively geotropic organs develop from axillary buds at the base of the stem, and even axillary buds along aerial parts of the stem. Their branching pattern follows the decussate phyllotaxis of the species, and flowering of some tubers has been observed. Anatomical studies show the presence of both primary and secondary vascular bundles arranged in a ring of vascular tissue. Therefore, these organs are true stem tubers.

Morphology, ontogeny and functional anatomy of the seeds of Colophospermum mopane

Only one seed is carried inside the indehiscent fruit of Colophospermum mopane . Both the seed and fruit constitute the dispersal unit and the seed germinates while still inside the fruit. The mature seed of C. mopane has a thin seed coat that shows little differentiation, similar to the seed coats of typical Leguminous overgrown seeds. The malpighian cells that usually form a mechanical layer of protection are absent and this may be attributed to the seed being enclosed in an indehiscent fruit where the pericarp forms the protective layer. The thin, undifferentiated seed coat may also be an adaptation to low rainfall as it allows for the rapid uptake of water where rainfall occurs in small quantities or is of short duration. The seed originates from a bitegmic ovule. The inner layer of the inner integument persists throughout most of seed development and differentiates into an endothelium. The remainder of the inner integument degenerates completely at the time of fertilisation but the entire outer integument persists and differentiates into the seed coat. The integumentary cells display high mitotic activity in both the anticlinal and periclinal planes throughout seed ontogeny another feature reminiscent of overgrown or neotenous seeds. Up to the 5mm stage of the young seed, the older cell layers towards the outside of the integument are obliterated and resorbed as they are continually being replaced by new cell layers that originate from the inner layers. After the 5mm stage, the cells of the subepidermal layer begin to divide periclinally and anticlinally to keep pace with the inner layers. The senescent cells of the middle layer are then obliterated between the dividing cells of the inner integumentary layers and the subepidermal layers. The number of cell layers remains more or less constant throughout seed ontogeny because the obliteration of the older layers prevents the seed coat from becoming thick and multiplicative. The anticlinal divisions bring about the lateral extension of the seed coat to give rise to an aril that circumvents the seed. Another feature reminiscent of overgrown seeds is the convoluted appearance of the cotyledons which suggests that extensive seed growth is limited by the size of the fruit locule. As a consequence of the convoluted cotyledons the seeds may be regarded as ruminate. Rumination is, however, not only an outcome of seed growth inside the limited space of the fruit locule but also of uneven anticlinal divisions in the endothelium during early stages of embryogenesis. The entire vascular supply of the seed is limited to the aril and no secondary ramifications of vascular traces occur in the remainder of the seed coat. Due to extensive anticlinal divisions of the seed coat the primary vascular bundle is stretched in a lateral plane, causing the xylem strands to separate from the surrounding parenchyma cells, as well as from one another. This causes an air canal to develop in the primary vascular bundle that originates from the funiculus. The lateral extension of the aril also causes the position of cambiai-like meristematic areas that initially surround the primary vascular bundle to shift so that the area occupied by these cells becomes V-shaped or U-shaped. The cambial-like meristematic areas give rise to secondary vascular bundles. The micropyle is small and occluded with a dark staining substance that makes it impermeable to water. The integuments as well as the mature seed coat contain high concentrations of tanniniferous substances. The large seed size of the xerophytic C. mopane may be explained by its common origin from the ancestors of Guibourtia and Copaifera that occurred in high rainfall zones.

THE RELATIONSHIP BETWEEN THE PRIMARY THICKENING MERISTEM AND THE SECONDARY THICKENING MERISTEM IN YUCCA WHIPPLEI TORR. I. HISTOLOGY OF THE MATURE VEGETATIVE STEM

Anatomical observations were made on 1‐, 2‐, and 3‐yr‐old plants of Yucca whipplei Torr, ssp. percursa Haines grown from seed collected from a single parent in Refugio Canyon, Santa Barbara, California. The primary body of the vegetative stem consists of cortex and central cylinder with a central pith. Parenchyma cells in the ground tissue are arranged in anticlinal cell files continuous from beneath the leaf bases, through the cortex and central cylinder to the pith. Individual vascular bundles in the primary body have a collateral arrangement of xylem and phloem. The parenchyma cells of the ground tissue of the secondary body are also arranged in files continuous with those of the primary parenchyma. Secondary vascular bundles have an amphivasal arrangement and an undulating path with frequent anastomoses. Primary and secondary vascular bundles are longitudinally continuous. The primary thickening meristem (PTM) is longitudinally continuous with the secondary thickening meristem (STM). Axillary buds initiated during primary growth were observed in the leaf axils. The STM becomes more active prior to and during root initiation. Layers of secondary vascular bundles are associated with root formation.

THE RELATIONSHIP BETWEEN THE PRIMARY THICKENING MERISTEM AND THE SECONDARY THICKENING MERISTEM IN YUCCA WHIPPLEI TORR. II. ONTOGENETIC RELATIONSHIP WITHIN THE VEGETATIVE STEM

Histological and anatomical observations were made on plants ranging from embryos to 1‐yr‐old plants of Yucca whipplei Torr. ssp. percursa Haines. Our objective was to determine the time and position of origin, ontogenetic relationship, and function of the primary thickening meristem (PTM) and the secondary thickening meristem (STM) during development of the vegetative axis. The PTM arises in the stem periphery during germination. It is longitudinally continuous from beneath the youngest leaf primordia to the primary root, and functions in the production of primary vascular bundles and ground tissue. The STM arises ontogenetically from the PTM in the base of 2‐ to 3‐month seedlings and produces secondary vascular bundles and ground tissue. The PTM and STM, primary and secondary vascular bundles, and files of primary and secondary ground tissue are continuous at all developmental stages studied. Development of the primary body is histologically and quantitatively similar to development in monocotyledons which possess only a PTM; and secondary growth is interpreted as a developmental continuation of the process of primary thickening.

The Relationship Between the Primary Thickening Meristem and the Secondary Thickening Meristem in Yucca whipplei Torr. II. Ontogenetic Relationship within the Vegetative Stem

Histological and anatomical observations were made on plants ranging from embryos to 1-yr-old plants of Yucca whipplei Torr. ssp. percursa Haines. Our objective was to determine the time and position of origin, ontogenetic relationship, and function of the primary thickening meristem (PTM) and the secondary thickening meristem (STM) during development of the vegetative axis. The PTM arises in the stem periphery during germination. It is longitudinally continuous from beneath the youngest leaf primordia to the primary root, and functions in the production of primary vascular bundles and ground tissue. The STM arises ontogenetically from the PTM in the base of 2- to 3-month seedlings and produces secondary vascular bundles and ground tissue. The PTM and STM, primary and secondary vascular bundles, and files of primary and secondary ground tissue are continuous at all developmental stages studied. Development of the primary body is histologically and quantitatively similar to development in monocotyledons which possess only a PTM; and secondary growth is interpreted as a developmental continuation of the process of primary thickening.