DEVELOPMENTAL ANATOMY OF EPIDERMAL AND MESOPHYLL CHLOROPLASTS IN OPUNTIA BASILARIS LEAVES

Developmental studies of Opuntia basilaris Engelm. & Bigel. leaves revealed the presence of three morphologically distinct types of plastids. All epidermal cells examined contained chloroplasts. After 13 days of growth in the dark the plastids of epidermal and mesophyll cells were characterized by the presence of a prolamellar body and fibril inclusions. Epidermal plastids which developed under light conditions contained large stromacentres and a limited grana-fret membrane system. Guard cell plastids developed under similar conditions had a much poorer developed grana system with fibril inclusions apparent only during the developmental stages. At maturity these plastids appeared swollen or dilated. Mesophyll plastids had fibril inclusions during all stages of development and at maturity contained a very extensive grana-fret membrane system. Microbodies were found in association with the mesophyll plastids. Starch accumulation was common in subsidiary cell and guard cell plastids.     

PLASTIDS IN LATICIFERS OF PAPAVER. I. DEVELOPMENT AND CYTOCHEMISTRY OF LATICIFER PLASTIDS IN P. SOMNIFERUM L. (PAPAVERACEAE)

Plastids were observed in all stages of laticifer differentiation in Papaver somniferum L. Plastids in laticifer initials were present as proplastids that later developed electron-dense inclusions, but never possessed the thylakoids or starch grains that characterize chloroplasts in other cells. Electron-dense inclusions in laticifer plastids were membrane-bound and appeared to arise from the accumulation of material within an invagination of the inner plastid membrane. Cytochemical studies of these plastid inclusions indicated that their matrix was not composed of crystalline protein, α-amylose, amylopectin or polysaccharide. The results suggest that the electron-dense, membrane-bound inclusions in laticifer plastids may be composed of lipoprotein.     

Physiological Stress and Crystallites in Leaf Plastids of Phaseolus vulgaris L.

Crystalline inclusions were found in leaf plastids of Phaseolusvulgaris L. cultivar Limburg when excised plant parts were used.Removal of the root system induced crystalloid production afteran incubation period of optimal length. In agreement with thefindings of other authors physiological stress seems to be theunderlying condition of crystal formation in plastids.     

Cytological Mechanism of Cytoplasmic Inheritance in Pinus tabulaeformis: II. Transmission of Male and Female Organelles During Fertilization and Proembryo Development

In an earlier report the ultrastructure and nucleoid organelles of male gamete in Pinus tabulaeformis Carr. have been described. Presently, the ultrastructure of the cytoplasm of the egg cell and pollen tube—immediately before fertilization and during cytoplasmic transmission of male gametophyte—has been described for the same species. The fate of parental plastids and mitochondria in the proembryo has also been followed. The mature egg cell contains a large amount of mitochondria, but seems to lack normal plastids. Most plastids have transformed into large inclusions. Apart from the large inclusions, there are abundant small inclusions and other organelles in the egg cell. During fertilization, pollen tube penetrates into the egg cell at the micropylar end and thereafter the contents are released. Plastid and mitochondrion of male origin are lacking near the fusing sperm-egg nuclei. The second sperm nucleus—not involved in karyogamy—remains at a site near the receptive vacuole. This nucleus is surrounded by large amount of male cytoplasm containing mixed organelles from the sperm cell, tube cell, and egg cell. At the free nuclear proembryo stage, organelles of male and female origin are visible in the perinucleus-cytoplasmic zone. Most of the mitochondria have the same morphological features as those in the egg cell. Some of the mitochondria appear to have originated from the sperm and tube cells. Plastids are most likely of male gametophyte origin because they have similar appearance as those of the sperm and tube cell. Large inclusions in the egg cell become vacuole-like. Paternal plastids have been incorporated into the neocytoplasm of the proembryo. In the cellular proembryo, maternal mitochondria are more abundant. Plastids resembling those of the sperm and tube cell are still present. These cytological results clearly show that in P. tabulaeformis , plastids are inherited paternally and mitochondria bipaternally. The cytological mechanism of plastid and mitochondrion inheritance in gymnosperm is discussed.     

Origins and formation of intracellular inclusions associated with two leguminous virus diseases

Summary Two hitherto undescribed viruses were isolated from naturally-infected white clover plants.One induced both cytoplasmic and intranuclear inclusions, and the other caused cytoplasmic inclusions of a new type, which we have called Corner inclusion bodies.All three kinds of inclusion were found in the same cells.Vital observations showed that the two kinds of cytoplasmic inclusion bodies developed principally from the plastids.The intranuclear inclusions were shown to develop from the nucleoli.Cytochemical tests showed that the cytoplasmic inclusions contained protein and ribonucleic acid.On the basis of these findings, the possibility of virus synthesis in plastids and nucleoli is discussed.     

Diversité des formes d'accumulation de la phytoferritine dans les cellules constituant l'épithème des hydathodes de Taraxacum officinale Weber et Saxifraga aizoon Jacq.

Summary In Taraxacum officinale and Saxifraga aizoon particular aggregations found in plastids of epithem are considered to be phytoferritin. The diversity of plant ferritin arrangement within the plastids is studied. High magnification study of these inclusions indicates that they can be classified morphologically into three distinct groups: dense and amorphous aggregate (F₁), crystalline inclusion (F₂) and diffuse paracrystalline arrangement (F₃). The crystalline (F₂) and amorphous (F₁) structures are both present in the plastids of Saxifraga aizoon; similarly, paracrystalline (F₃) and amorphous inclusions (F₁) are both present in the plastids of Taraxacum officinale. Because of their location and the nature of their organization, we think that the phytoferritin complexes under discussion may be important in phytoferritin synthesis or phytoferritin utilization within the living plant.     

Structure and development of sieve cells in the primary phloem ofPinus resinosa

Summary The primary phloem consists mostly of sieve cells. Procambial cells and very young sieve cells contain all the components characteristic of young nucleate cells. Increase in wall thickness, which is relatively limited, constitutes the first indication of sieve-cell differentiation. During the period of wall thickening, the plastids develop starch grains and then fibrillar inclusions. Eventually the internal lamellae of the plastids collapse. The plastids do not form crystalline inclusions. As the sieve cell approaches maturity, an extensive network of smooth, tubular endoplasmic reticulum (ER) appears and then becomes mostly parietal in distribution. At maturity, large aggregates of this ER occur at the sieve areas. These aggregates are interconnected longitudinally by the parietal network of ER. In addition to the ER, the mature, plasmalemma-lined primary sieve cell contains a degenerate nucleus, with intact nuclear envelope, plastids, and mitochondria. Dictyosomes, ribosomes, and vacuoles are lacking. P-protein is not present at any stage of development.This work was supported by U.S. National Science Foundation grants GB 8330 and GB 31417 to R. F.Evert.     

Some observations on coleoptile cell ultrastructure in ungerminated grains of rice (Oryza sativa L)

Summary The ultrastructure of coleoptile cells of ungerminated rice grains has been examined following fixation in glutaraldehyde and osmium tetroxide. In many respects the cell structure resembles that reported for other dormant seed tissues: the cells contain protein bodies and lipid droplets, mitochondria and plastids show little internal structure but cytoplasm invaginates into many plastids; golgi cisternae cannot be discerned. Rough ER is present as cisternae surrounding protein bodies, as occasional regions of parallel layers, and in concentric whorls where it alternates with smooth paired membranes of an unknown nature. The ribosomes on the ER are at least partly arranged into regular rows. Various crystalline, presumably proteinaceous, inclusions lie in the groundplasm, plastids and nuclei.     

Fine Structure of Healthy and TMV-Infected Tobacco Cells Grown in Tissue Culture

Three types of tobacco (Nicotiana tabacum cv. Havana 38) callus: 1) healthy stem callus, 2) TMV-infected stem callus, 3) TMV-infected leaf callus; and leaves differentiated from healthy stem callus, and from TMV-infected leaf callus were compared for fine structure. In addition, the fine structure was observed of plastids in cells of leaves differentiated from callus isolated from stem sections of TMV-infected hybrid tobacco plants (N. tabacum cv. Havana 38 ×N. glutinosa) grown under high temperature. The cytoplasmic organelles in tissue cultured cells were similar to those in cells of greenhouse-grown tobacco plants. Except for plastids, TMV infection did not noticeably affect morphologically other cellular organelles in tissue culture cells. In TMV-infected leaf callus, numerous small bodies were seen in plastid-like bodies, while vesicle-like structures were observed in the stroma of plastids in leaves differentiated from callus of hybrid tobacco inoculated with TMV. Morphological variations of mitochondria, such as swelling and vacuolization of the inner matrix, occurred frequently in TMV-infected leaf callus. Needle-like crystalline inclusions or looped inclusions composed of many fine, long filaments were considered TMV particles orientated parallel to each other. The TMV particles were detected in the cytoplasm of tissue culture cells.     

Solitary bodies (S-bodies) in the parasitic red algaHarveyella mirabilis (Choreocolaceae,Cryptonemiales)

Summary Unusual spherical cytoplasmic inclusions identical to S-bodies described previously in three angiosperms were found in all cells of the parasitic red algaHarveyella mirabilis collected from several locations in the northeast Pacific. The inclusions are ca. 60–80 nm and consist of an outer double membrane bounding a granular mantle and a DNase sensitive central core. S-bodies are dispersed throughout the cytoplasm and are associated occasionally with nuclei, plastids, mitochondria, ER, and vacuoles. They have not been observed in any other alga except in host algal cells, connected to parasite cells by cellular pit connections. The possible function of these inclusions is considered with respect to the parasitic nature ofHarveyella mirabilis.     

Ultrastructure of crystalline inclusions in the thylakoids of dodder<Emphasis Type="Italic">(cuscuta japonica)</Emphasis> plastids

The plastids from seedlings of the parasitic angiospermCuscuta japonica were ultrastructurally investigated. In shoot subapical cells from 3-d-old seedlings grown in the dark, the etioplasts contained prolamellar bodies and amorphous and dense inclusions. In the shoot subapical cells obtained from 6-d-old seedlings grown under light conditions for the last 3 d, the underdeveloped chloroplasts contained phytoferritin within the stroma as well as amorphous and dense inclusions that were limited by the thylakoid membranes. In the developing chloroplasts, electron-dense materials were detected within the transversely sectioned thylakoid lumens. This dense material presented two different images, depending upon the sectional plane. When transversely prepared, the materials appeared as somewhat thick, linear structures, whereas longitudinally sectioned thylakoids revealed very large crystalline inclusions. In the developed chloroplasts, the amounts of electron-dense material or crystalline inclusions were remarkably reduced in the thylakoid lumens, which were electron-translucent. Far fewer crystalline inclusions were observed in the developed chloroplasts of seedlings than in the developing chloroplasts. These results suggest that the crystalline inclusions may be temporarily reserved within the thylakoid lumens of chloroplasts in the Gjaponica seedlings.     

Glandular scale development and essential oil secretion in Origanum dictamnus L.

Glandular scales of Origanum dictamnus L. originate from a single protodermal cell. They are composed of a 12-celled head and an unicellular stalk and foot. During the early stages of gland differentiation, the head cells possess a small number of plastids which contain globular inclusions. Similar inclusions are also observed in the plastids of the stalk and the foot cell. The lateral walls of the stalk cell progressively undergo cutinization which does not extend to the upper and lower periclinal walls. At the onset of secretion the electron density of the plasmalemma region lining the apical walls of the head cells remarkably increases. These walls are impregnated with an osmiophilic substance identical in appearance to the content of the subcuticular space. In a following stage of the secretory process osmiophilic droplets of various size arise in the cytoplasm of the secretory cells which undergoes simultaneously a reduction of its initial density. After secretion has been concluded the protoplast of the head cells becomes gradually degenerated. The chlorenchyma cells of the mesophyll possess numerous microbodies closely associated with various organelles. In the cytoplasm of these cells crystalloids occasionally occur.     

Plastids of sieve tube members in the stamen vascular bundle ofSorghum bicolor (Gramineae)

Summary The plastids in sieve tube members of the stamen vascular bundles ofSorghum bicolor, fixed in glutaraldehyde with postfixation in osmium tetroxide, are of the P-type containing cuneate crystalloids of a proteinaceous nature surrounded by a double envelope. Secondary inclusions are present in these P-type plastids. P-type plastids inSorghum often remain intact in the mature sieve tube members.This work was supported by a grant from the Iowa Agricultural and Home Economics Experiment Station, Ames, U.S.A. Project No. 1740 toHarry T.Horner, Jr., andNels R.Lersten and Project No. 1914 toHarry T.Horner, Jr. of the Department of Botany and Plant Pathology, Iowa State University, Ames, U.S.A. This work was completed by the author as part of the Ph. D. dissertation research.     

Changes in Ultrastructure of Phaseolus Vulgaris L. Cotyledons Associated with their Modulated Life Span

French bean (Phaseolus vulgaris L.) cotyledons lost most of their reserve substances during several early days of germination and turned green. In cotyledon mesophyll cells of one-week-old seedlings, plastids were represented predominantly by amyloplasts (starch grains) and chloroamyloplasts, and the cells appeared to be metabolically highly active. Cell heterogeneity associated with distance of the cells from cotyledon vascular bundles was evident. Only mesophyll cells near to the bundles were rich in plastids. In two-weeks-old intact bean plants, the cotyledons were yellow and shrunken, and their cells were nearly "empty". The plastids in them were represented by senescent plastids (gerontoplasts) only. In the gerontoplasts as well as freely in cytosol, fluorescent lipoid inclusions were accumulated. This cotyledon development was more or less independent of irradiance. In "decapitated" bean plants, senescence of mesophyll cells and plastids was slowed down considerably, and the life span of the cotyledons was prolonged.     

Further studies on phytoferritin

Summary Crystalline and paracrystalline inclusions found in plastids of willow cambium, grown under dim-light conditions, are considered to be phytoferritin. Phytoferritin is completely unaffected following treatment of cambial cells with deoxyribonuclease or ribonuclease, although other components are, at least in part, denatured. This is considered to exclude the possibility that the inclusions are viral particles. While not normally arranged in crystalline form, phytoferritin from embryonic axes of pea appears identical in structure with the complex found in cambial plastids. It, also, is not affected by treatment with nucleases for periods of up to 18 hours. Phytoferritin has been found only rarely in willow grown under conditions of high illumination.Four, five, or six electron-opaque subunits are most often found in the individual particles of phytoferritin. The most satisfactory explanation of the arrangements seen seems to be that the micellar configuration is in the form of an octahedron with a subunit at each of the six vertices.     

A light and electron microscopy study of the epidermis of Paphiopedilum spp. with emphasis on stomatal ultrastructure

Abstract Light and fluorescence microscopy studies indicated that chlorophyll was absent from the guard cells of the lady slipper orchids, Paphiopedilum insigne (Wall.) Pfitz, P. insigne (hybrid), P. venustum (Wall.) Pfitz and P. harrisseanum Hort. In the guard cells of P. aureum hyeanum Hort., however, very slight red fluorescence suggested that chlorophyll and hence chloroplasts were present. Ultrastructural studies of the lower epidermis of P. insigne (hybrid) confirmed the absence of chloroplasts in guard and epidermal cells although plastids of an unusual structure were found in these cells. In fully developed epidermal cells the plastids contained large amounts of a fibrous, possibly proteinaceous substance, spherical, lightly staining vesicles and an electron-dense material located in reticulate and non-reticulate regions. Additionally, latticed crystalline inclusions and plasto-globuli were occasionally observed in the epidermal cell plastids. In plastids of fully developed guard cells the fibrous material, starch and plastoglobuli were present. From the earliest stages of development of the epidermal tissue starch was present in both epidermal cell and guard cell plastids. At maturity, however, starch had accumulated to greater levels in the guard cell plastids and had entirely disappeared in the epidermal cell plastids. In differentiating epidermal tissue, plasmodesmata were found between neighbouring epidermal cells and between guard and epidermal cells. At maturity, plasmodesmata between guard and epidermal cells were not observed. Mitochondria were particularly abundant in guard cells. Large oil drops developed in guard and epidermal cells, being especially abundant in the former at maturity. Our results confirm the observations of Nelson & Mayo (1975) that certain lady slipper orchids possess functional stomata the guard cells of which do not contain chloroplasts.     

Sieve-element plastids ofTriticum andAegilops (Poaceae)

Fourteen taxa of the Triticum-Aegilops group have been investigated for their sieve-element plastids. At maturity they contain dense and thin crystalloid inclusions and are classified into the PIIc' plastid type; onlyAe. comosa var.biaristata lacked the thin crystalloids and thus conforms to the PII c type. The proteinaceous nature of the crystalloids was demonstrated by application of proteolytic enzymes. Ultrastructural evidence suggests that both kinds of crystalloid inclusions are involved in the sealing of sieve-plate pores of injured sieve tubes. Measurements and calculations of the spacings and angles carried out on crystalloid prints permitted the construction of a two- and three-dimensional pattern forT. aestivum thin crystalloids.     

Membrane-bound Plastid Inclusions and Chloroplast Thylakoid Formation in Sunflower (Helianthus annuus L.)

The ultrastructure, distribution and frequency of membrane-boundplastid inclusions present in the epidermal cells of leavesof intact sunflower plants (Helianthus annuus L.) and in theepidermal and mesophyll cells of sunflower leaf discs culturedin darkness have been studied. These inclusions appear to bedilated thylakoids containing a granular material which, undernormal conditions, is probably involved in chloroplast membraneformation. It is suggested that this material accumulates, andinclusions form, in the chloroplasts of sunflower leaves intwo specific situations. Firstly, in the completely differentiatedcells of the epidermis where the chloroplasts, although at arelatively immature stage, have nevertheless reached a terminalstage of development. Secondly, in the mesophyll cells of youngleaves when chloroplast development has been arrested at animmature stage by a 5-day dark period. In the latter situationthe material can be remobilized if plastid development is restimulated.The plastids of sunflower leaf discs cultured in darkness containboth membrane-bound inclusions and prolamellar bodies, indicatingthat they are separate and distinct structures possibly containingdifferent membrane components. Helianthus annuus L., sunflower, chloroplast, ultrastructure, plastid inclusions, thylakoid formation     

DEVELOPMENT AND CYTOCHEMISTRY OF THE THYLAKOIDAL BODY IN TOBACCO CHLOROPLASTS

Developing plastids in young tobacco leaves contain thylakoidal bodies, inclusions bound by a single membrane continuous with stroma lamellae. Both the thylakoidal body and its attached lamellae contain an enzyme that catalyzes an oxidation reaction with 3,3'-diaminobenzidine (DAB). DAB staining of the thylakoidal body and lamellae is not the result of photo-oxidation and is inhibited by potassium cyanide. The thylakoidal body disappears as plastids develop into chloroplasts and, further, the lamellar systems of the mature chloroplasts do not stain with DAB. In developing chloroplasts, it is suggested that the thylakoidal body forms by accumulation of protein which stains with DAB within primary lamellae derived from the inner plastid membrane. The ultrastructural and cytochemical evidence suggests that the thylakoidal body stores protein used later in lamellar formation.     

OBSERVATIONS ON PLASTID FINE-STRUCTURE IN THE HOLOPARASITIC ANGIOSPERM EPIFAGUS VIRGINIANA

The ultrastructure of plastids in cortex and phloem parenchyma cells of Epifagus virginiana (L.) Bart. is described. Based upon morphology and content, several distinct plastid types appear to exist. “Tubular” complexes, lipid globules and electron dense inclusions in different arrangements appear to account for the degree of plastid variability. When results obtained with Epifagus are compared with those obtained by others for a closely related genus, a striking parallel is shown to exist.