Water-storage Cells Research Articles

Comparative leaf anatomy of New Zealand and Tasmanian Inuleae (Compositae)

Abstract Leaf anatomy is compared for 47 taxa of the tribe Inulcae (Compositae) from New Zealand and Tasmania. The taxa are tabulated according to their lamina structure. Noteworthy anatomical features are lamina type and grade of differentiation, stomatal position, epidermis and cuticle thickness, shape of palisade cells, number of bundle-sheath layers; presence or absence of sclerenchyma caps, water storage cells, secretory canals, abaxial collenchyma and protruding midrib. It is shown that leaf anatomy data provide characters which are taxonomically useful in classification of Inuleae.

Anatomical Changes in Prosopis cineraria (L.) Druce Seedlings Growing at Different Levels of NaCl Salinity

Seedlings of Prosopis cineraria were grown in artificial substrates with additions of 0, 50, 100. 200, 400 and 600 mM NaCl. At an NaCl concentration of 600 mM the germination was greatly hindered. At 400 mM the radicles scarcely emerged. An anatomical study of seedlings grown in the presence of 0-200 mM NaCl showed that salinity induced structural changes in the roots, hypocotyls, epicotyls and leaflets. The secondary xylem differentiated earlier in treated plants than in the controls especially in the root and epicotyl as salinity rose. This could be an adaptive strategy to facilitate water transport. The number of water storage cells in the epidermal and cortical layers of the hypocotyls increased with salt concentration. Leaflets of seedlings grown in increasing salinity tended to show a less dorsiventral and more isolateral organization, and a greater thickness of leaf mesophyll. A preliminary comparison with other species of the genus Prosopis is briefly discussed.

Anatomical Changes in Prosopis tamarugo Phil. Seedlings Growing at Different Levels of NaCl Salinity

Seedlings of Prosopis tamarugo were grown in artificial substrates with additions, of 200, 400 and 600 mm NaCl. and without salt treatment. Salinity induced anatomical changes in the roots, stems and leaflets. The diameters of the roots of seedlings grown in the increasing salt concentrations (up to 400 mm) were progressively smaller and differentiation of the stelar tissues was delayed. At an NaCl concentration of 600 mm, the root structure was strongly altered. On the contrary, stem diameter increased as salinity rose. In the stems of seedlings grown in a concentration of 200 mm NaCl, secondary xylem differentiation appeared earlier than in the controls. At a concentration of 400 mm NaCl, disorganization of the vascular cylinder of the stem was evident. Leaflets of seedlings grown in 200 mm NaCl showed a delay in structural differentiation: no water-storage cells or 'special cells' could be seen. The leaflets from plants grown in 400 mm NaCl, had larger numbers of intercellular air spaces; probably an indication of the beginning of tissue disorganization. A progressive decrease in cell size of leaflets as salinity rose was also demonstrated.

Structural Analysis of Water-Storage Tissue in Leaves of Sansevieria (Agavaceae)

Leaves in 49 species of Sansevieria contain water-storage (WS) tissue in their central mesophyll region consisting of two cell types: a three-dimensional network of living cells and interspersed dead WS cells. In 28 species, WS cells have secondary cell wall bands. In this study, 15 species were examined to determine variations in density, width, and amount and type of branching of wall bands. In cross section, wall bands in WS cells surrounding vascular and fiber bundles are oriented concentrically around the bundles. In thick flat leaves, wall bands are oriented mostly parallel to the surface of the leaf blade. Wall bands are aligned at corners but not across faces of adjacent WS cells and provide structural support during desiccation, either reducing the collapse of WS cells or restricting the direction in which the WS cells shrink. In cell wall replicas, wall bands appear as massive aggregations of microfibrils. Secondary wall material, as a very thin continuous layer between wall bands, is also deposited. Three species without WS cell wall bands were also examined. WS cells in these species also deposit a secondary wall but without localized thickenings.

Leaf Anatomy in Sansevieria (Agavaceae)

Forty-nine taxa of Sansevieria were examined to provide the first detailed description of leaf anatomy in the genus, as well as to determine the cellular organization of the water-storage tissue present in the central mesophyll of all leaves. Leaf form ranges from flat through cylindrical, with varying degrees of xeromorphic characteristics, including cuticle thickness, stomatal depth, fiber content, and fiber cell development. Mesophyll in all species is divided into an outer region of chlorenchyma and a central region of colorless water-storage tissue. The water-storage tissue comprises a highly branched 3-dimensional network of living cells, among which are many dead, thin-walled water-storage cells. Species with more extreme xeromorphic characteristics tend to have a greater percentage of their water-storage tissue composed of water-storage cells. In 28 taxa, water-storage cells have spiral or reticulate wall bands. These taxa tend to be more xeromorphic. The wall bands may serve an important structural role in drought tolerance.

LEAF ANATOMY IN SANSEVIERIA (AGAVACEAE).

Forty-nine taxa of Sansevieria were examined to provide the first detailed description of leaf anatomy in the genus, as well as to determine the cellular organization of the water-storage tissue present in the central mesophyll of all leaves. Leaf form ranges from flat through cylindrical, with varying degrees of xeromorphic characteristics, including cuticle thickness, stomatal depth, fiber content, and fiber cell development. Mesophyll in all species is divided into an outer region of chlorenchyma and a central region of colorless water-storage tissue. The water-storage tissue comprises a highly branched 3-dimensional network of living cells, among which are many dead, thin-walled water-storage cells. Species with more extreme xeromorphic characteristics tend to have a greater percentage of their water-storage tissue composed of water-storage cells. In 28 taxa, water-storage cells have spiral or reticulate wall bands. These taxa tend to be more xeromorphic. The wall bands may serve an important structural role in drought tolerance.

Anatomy of three species ofBulbophyllum (Orchidaceae) with comments on their ecological adaptability and taxonomy

Vegetative anatomy ofBulbophyllum andersonii, Bulbophyllum dyerianum andBulbophyllum leopardianum has been studied. Stomata are hypostomatic and cyclocytic with 4–7 subsidiary cells. Twin stomata occur inBulbophyllum dyerianum. Hypodermis is present only inBulbophyllum andersonii. InBulbophyllum dyerianum mesophyll is differentiated into palisade and spongy parenchyma, whereas in.Bulbophyllum andersonii it is less differentiated. InBulbophyllum leopardianum mesophyll is homogeneous. InBulbophyllum andersonii andBulbophyllum dyerianum columnar or club-shaped water storage cells with multispiral cellulosic thickenings are present in mesophyll of leaf and cortex of pseudobulb. In roots ofBulbophyllum dyerianum andBulbophyllum leopardianum fibrous mats are present. In all these taxa vessels are absent but vessel-like tracheids are abundant.Bulbophyllum species developed many adaptive characters for conservation of water. On the basis of anatomical data it is concluded that the genusBulbophyllum is closely related toDendrobium.

Water Movement and Storage in a Desert Succulent: Anatomy and Rehydration Kinetics for Leaves of Agave deserti

Smith, J. A. C. and Nobel, P. S. 1986. Water movement and storage in a desert succulent: anatomy and rehydration kinetics for leaves of Agave deserti.—J. exp. Bot. 37: 1044-1053. Anatomic and kinetic aspects of water storage were investigated for the succulent leaves of the desert CAM plant, Agave deserti. An approximately linear relationship was found between the number of vascular bundles and leaf surface area, both for leaves of different sizes and also along the length of a single leaf. The bundles, which were distributed throughout the leaf cross-section, were separated from each other by about eight water-storage cells. Even though the cell walls of the water-storage ground tissue made up only 2-5% of the cell volume, they provided about 10% of the total cross-sectional area available for water transport radial to the xylem because cell-cell contact in such a direction averaged 25% of the cell surface area. The rehydration kinetics of partially dehydrated leaf segments were resolved into three phases: (1) a relatively rapid movement into the vascular tissue (half-time of 2 min); (2) water movement into storage in the ground tissue (half-time of 59 min); and (3) water movement into the intercellular air spaces (half-time of about 10 h). Using the observed kinetics for water movement into the storage tissue and standard diffusion theory, the bulk-averaged diffusivity of water in the relatively homogeneous ground tissue (flt) was 2 0 x 1U-10 m2 s_1. Using this D, and pathway analysis, most of the water moving from the xylem into storage in the massive leaves of A. deserti apparently occurred from cell to cell across the cell membranes rather than through the cell walls. Key words—Agave deserti, capacitance, diffusivity, leaf anatomy, succulence, water storage. Correspondence to: Department of Biology, University of California, Los Angeles, CA 90024, U.S.A.

Photosynthetic Characteristics of Portulaca grandiflora, a Succulent C4 Dicot

The succulent, cylindrical leaves of the C(4) dicot Portulaca grandiflora possess three distinct green cell types: bundle sheath cells (BSC) in radial arrangement around the vascular bundles; mesophyll cells (MC) in an outer layer adjacent to the BSC; and water storage cells (WSC) in the leaf center. Unlike typical Kranz leaf anatomy, the MC do not surround the bundle sheath tissue but occur only in the area between the bundle sheath and the epidermis. Intercellular localization of photosynthetic enzymes was characterized using protoplasts isolated enzymatically from all three green cell types.Like other C(4) plants, P. grandiflora has ribulose 1,5-bisphosphate carboxylase and the decarboxylating enzyme, NADP(+)-malic enzyme, in the BSC. Unlike other C(4) plants, however, phosphoenolpyruvate carboxylase, pyruvate, Pi dikinase, and NADP(+)-malate dehydrogenase of the C(4) pathway were present in all three green cell types, indicating that all are capable of fixing CO(2) via phosphoenolpyruvate carboxylase and regenerating phosphoenolpyruvate. Other enzymes were about equally distributed between MC and BSC similar to other C(4) plants. The enzyme profile of the WSC was similar to that of the MC but with reduced activity in most enzymes, except mitochondrion-associated enzymes.Intracellular localization of enzymes was studied in organelles partitioned by differential centrifugation using mechanically ruptured mesophyll and bundle sheath protoplasts. Phosphoenolpyruvate carboxylase was a cytosolic enzyme in both cells; whereas, ribulose 1,5-bisphosphate carboxylase and NADP(+)-malic enzyme were exclusively compartmentalized in the bundle sheath chloroplasts. NADP(+)-malate dehydrogenase, pyruvate, Pi dikinase, aspartate aminotransferase, 3-phosphoglycerate kinase, and NADP(+)-triose-P dehydrogenase were predominantly localized in the chloroplasts while alanine aminotransferase and NAD(+)-malate dehydrogenase were mainly present in the cytosol of both cell types. Based on enzyme localization, a scheme of C(4) photosynthesis in P. grandiflora is proposed.Well-watered plants of P. grandiflora exhibit a diurnal fluctuation of total titratable acidity, with an amplitude of 61 and 54 microequivalent per gram fresh weight for the leaves and stems, respectively. These changes were in parallel with changes in malic acid concentration in these tissues. Under severe drought conditions, diurnal changes in both titratable acidity and malic acid concentration in both leaves and stems were much reduced. However, another C(4) dicot Amaranthus graecizans (nonsucculent) did not show any diurnal acid fluctuation under the same conditions. These results confirm the suggestion made by Koch and Kennedy (Plant Physiol. 65: 193-197, 1980) that succulent C(4) dicots can exhibit an acid metabolism similar to Crassulacean acid metabolism plants in certain environments.

Xeromorphic features of three stem assimilants in relation to their ecology

The anatomy of the assimilating stems of three brooms (Fabaceae) all show distinct xeromorphic features in their tissues, but these are developed to different degrees. The epidermis consists of very thick, cutinized outer walls, deeply sunken stomata, and a dense layer of trichomes, at least in younger steins. In older sterns some of the stomata are blocked by cell-plugs. The chlorenchyma is multilayered. The main supporting tissue consists of peripheral gelatinous fibre strands. It is argued that these may function in water storage. Parenchymatous water storage cells are present in the pith of two species. The structure and function of the xeromorphic features are discussed in relation to the ecology of the plants.

SOME FEATURES OF THE ANATOMY OF FOUQUIERIA SPLENDENS

Fouquieria splendens, ocotillo or candle bush, with its switch-like thorny branches, two to five meters in height, its recurrent short-lived foliage and flaming inflorescence, is a familiar and striking form of the south-western desert areas. From the 1norphological and taxonomic standpoints, it has been fully described (I, 2, 3), and certain aspects of its physiology have also been discussed (4, 5); but with regard to the detailed anatomy of the genus, I have been unable to find anything but a few scattered references (6). In the present paper, the structure of the plant as a whole is briefly reviewed, and certain characteristic features, such as the development of the corky layers and the distribution and structure of the peculiar water storage cells present in the cortex, are described in greater detail. The striking appearance of the stem of the ocotillo (text fig. i) is due to the reticulate pattern formed by the corky layers. The smooth hard spines which originate from the petioles (2, 3) are spirally arranged, and pass

RING DENSITY OF SUGAR BEETS AS A CHARACTER FOR SELECTION

The early investigations of Raspail, Decaisne, and Wiesner with the later investigations of Kraus, Peklo, Nikolskij, and many others have established the fact that the maximum percentage of sugar of the sugar beet is translocated and stored in the vascular-ring tissues. Proskowetz and Schindler placed the average number of rings in the Vilmorin Blanche Amelior6e, Vilmorin Rose, and Klein Wanzleben sugar beets of I890 as 9-IO, 7-9, and 9-IO, respectively. Briem in 1903 noted that the vascular rings in the sugar beet are of greater number and decrease much more slowly towards the exterior than the vascular rings of the feed beet. About this time Kraus made similar observations and counted the vascular rings and measured the diameters of sugar and feed beets. In 1920 Vivien stated that the richest beets are those with the largest number of rings and the most narrow parenchymatous zones. One year earlier Fruwirth recorded the fact that greater ring density in beets means higher sugar content. Seeliger (5) in 1920 defined ring density as the quotient obtained by dividing the number of vascular rings by the radius of a beet measured in centimeters. He gave the ring density for beets of different ages and sizes and also noted that the ring density did not change after the beet reaches a radius of 2.8 cm. Seeliger realized the irregularity of beets as to their ring density and suggested that this trait be used as a method of selection to supplement the polariscope with the idea of increasing the absolute mean and the uniformity of ring density. He concluded that the storage tissues of the feed beet are at a disadvantage because of its poorly developed conductive tissues. Along with this point it should be kept in mind that Roemer stated that a one-sided development of the ring density might harm the beet because of decreasing too greatly the water-storage cells of the parenchyma. As a result of furfher investigation of this problem the writer here presents the following data.