A Cytochemical Study of Cell Wall Hydrolysis in the Secondary Xylem of Poplar (Populus italica Moench)

Certain developmental features of cell wall hydrolysis werestudied in the secondary xylem of poplar (Populus italica Moench).At the intervascular pit membrane hydrolysis starts prematurelybefore differentiation of the secondary wall is complete andincreases progressively. Eventually the whole of the middlelamella is hydrolysed, and the primary wall undergoes lyticmodification. The modified polysaccharides are dispersed, presumablyby the transpiration stream. During differentiation the vessel-parenchymapit membrane remains unaltered and undergoes thickening. Thepresent investigation suggests that the plasalemma plays animportant role in the ordered hydrolysis of certain regionsof the primary walls. Populus italicaMoench, poplar, secondaryxylem, xylem, cell wall hydrolysis, plasmalemma, pit membram     

Structural Changes During Vitrification of Carnation Plantlets

The structure of plantlets of Dianthus caryophyllus cv. CeriseRoyalette was studied at various developmental stages. In vitrifiedplantlets there were the following main differences from normalstructure: (a) reduction in the period in which cells remainmeristematic in developing parts of the shoot, up to full maturationof the shoot apex itself; (b) hypertrophy of the cells, witha loss of a clear axis of elongation; (c) defective cell wallsin which disintegration occurs at certain regions to form cavities. Dianthus caryophyllus, vitrified plantlets, shoot apex, stomata     

'Vitrified' Dianthus--Teratomata in vitro due to Growth Factor Imbalance

Cultured shoot tips of Dianthus caryophyllus often develop asabnormal, ‘vitrified’ plants that have the characteristicsof teratomata: stable, unlimited development with fasciatedshoot apices, a bush habit, reduced stem elongation and succulentleaves. High concentrations of NAA in the culture medium increasedand benzylaminopurine decreased the proportion of shoot-tipsthat developed as abnormal plants. The requirements of abnormaland normal plants for continued development differed. Duringthe initial stages of development abnormal plants did not requireauxin and they were able to continue their growth in the absenceof roots. It is suggested that the abnormal plants are teratomata,similar to those induced by Crown Gall bacteria, and their inductionand abnormal traits could be due to imbalance of auxins andcytokinins. Dianthus caryophyllus L., carnation, abnormal plant growth, habituation, vitrification, teratoma (plant)     

The Effect of Cytokinins on Vitrification in Melon and Carnation

The influence of exogenous cytokinin on vitrification of melonand carnation buds grown in vitro was assessed. In melon, theanatomical traits of vitrification were found to be similarto those previously described for carnation grown on a highconcentration of auxin. In carnation, the plantlets treatedwith high cytokinin concentrations became bushy but the anatomicalstructure remained normal. The relation of cytokinin and vitrificationis discussed. Cucumis melo L., Dianthus caryophyllus L., vitrified plantlets, habituation, cytokinin     

Normal and Abnormal Developments of the Stem Apex in Carnation

Normal and abnormal development of the stem apex is describedfor the carnation Dianthus caryophyllus, cultivated varieties.Abnormalities described include adventitious buds within theflower, carpel-like structures in the stamen whorl, excessivedevelopment of ovules, and axile secondary flower formations.Some comments are made on their occurrence and they are discussedin the light of present hypotheses concerning flower initiationand development.     

Growth of Carnation Meristems in vitro: Anatomical Structure of Abnormal Plantlets and the Effect of Agar Concentration in the Medium on their Formation

Carnation meristems cultured in vitro grow into shoots of threetypes: normal, translucent and succulent. The apical meristemof succulent shoots was of the mantle-core type and it lackedpro-vascular tissue. The leaf had large vacuolated mesophyllcells, fewer stomata (often plugged), and no plate meristem.A higher agar concentration in the medium increased the percentageof normal shoots developing. This supports other indicationsthat the water potential of the medium affects morphogenesis. carnation, Dianthus caryophyllus L, meristem culture, abnormal plantlets, shoot meristem     

The Differentiation of Contact Cells and Isolation Cells in the Xylem Ray Parenchyma of Populus maximowiczii

A histochemical analysis was made of the differentiation ofcontact cells and isolation cells in the xylem ray parenchymaof Populus maximowiczii. The contact cells formed secondarywalls at approximately the same time as adjoining vessel elements.The lignification of the cell walls of contact cells and vesselelements began earlier than that of wood fibres and isolationcells. Thus, the formation of the secondary wall, includinglignification, of the contact cells might occur at the sametime as that of the vessel elements to which they are directlyconnected. By contrast, the isolation cells began to form secondarywalls later than the vessel elements and wood fibres in thevicinity of the isolation cells. After the deposition of thesecondary wall, a protective layer was formed in contact cellsbut no isotropic layer was observed in isolation cells. Theresults suggest the importance of vessel elements in the determinationof the differentiation of adjoining ray parenchyma cells.Copyright1999 Annals of Botany Company Contact cell, isolation cell, vessel element, xylem differentiation, Populus maximowiczii Henry.     

Observations on the Growth of Carnation (Dianthus caryophyllus L.) in Natural and Long Days

Observations were made on the growth and development of carnationsgrown in containers under natural or 24 h days. The number ofleaf pairs produced before flower initiation and the final lengthof each flowering stem were affected by the date at which theshoot appeared and its position on the plant. Dusk-to-dawn lighting reduced the number of axillary shootsin each generation but increased their rate of development.This resulted in similar numbers of flowers being produced inboth treatments. Dianthus caryophyllus L., Carnation, growth, flowering, day length     

Shoot Regeneration from Fragmented Flower Buds of Carnation (Dianthus caryophyllus)

Adventitious shoots were regenerated from fragmented flowerbuds, individual petals and receptacles in a number of differentcarnation cultivars. The major site of shoot formation was thesubepidermal cells at the proximal end of the petals. The yieldof shoots from a single flower bud was high, ranging between70 and 275, for the 11 cultivars tested. The regeneration mediumcontained Murashige and Skoog basal medium supplemented with4–8 µm -naphthaleneacetic acid and 4–8 µmbenzyladenine. The preferred regeneration protocol appears highlysuited to the development of gene transfer systems. Adventitious shoots, Dianthus caryophyllus L., tissue culture, explant, auxin, cytokinin, cut flowers, floriculture, organogenesis     

On Vessel Member Differentiation in the Bean (Phaseolus vulgaris L.)

Certain ultrastructural features of vessel member differentiationwere examined in the primary xylem of petiole of bean (Phaseolusvulgaris L.). The cells used had helical secondary wall thickeningsand simple perforation plates. The primary cell wall increasesin thickness before the helices of secondary wall develop. Ina common wall between two vessel members of different ages,theprimary thickening occurs first in the older cell so thatfor a time the middle lamella is located closer to the youngercell rather than medianly. Apparently the helix is depositedafter the primary wall of a given cell reaches maximum thickness.The perforation of the end wall is preceded by primary thickeningof the part of the wall that is later removed. The marginalregion remains relatively thin and becomes covered with a rimof secondary wall. Vesicles with fibrous content appear nearthe surface within the end wall shortly before the perforationoccurs. A highly vacuolated protoplast with a much enlargednucleus and numerous organdIes is present during cell wall differentiation.After that process is completed, the protoplast disintegratesand the primary wall bearing the helix is hydrolysed where itis exposed to the cell lumen and, under certain conditions,also under the secondary wall.     

Adventitious Shoot Regeneration in Carnation (Dianthus caryophyllus) from Axillary Bud Explants

Adventitious shoots were regenerated from axillary bud explantsof 15 carnation cultivars. The use of leaf and stem explantswas not successful, largely due to explant senescence in thepresence of benzyladenine, kinetin and, to a lesser extent,zeatin. For axillary bud explants, a suitable optimum adventitiousregeneration medium contained Murashige and Skoog basal mediumsolidified with Gelrite and supplemented with 15 µm benzyladenineand 0.5 µM a-napthaleneacetic acid. Adventitious primordiaarose from the cut basal end of bud explants erupting as individualshoots after 2–3 weeks incubation. The axillary bud sizeand the time between subcultures of source material influencedthe production of adventitious shoots. Transfer of regeneratedshoots onto a medium solidified with agar minimized visiblesigns of vitrification. Regenerated shoots could be easily rooted,transferred to glasshouse conditions and grown to flowering. Vitrification, tissue culture, cut flowers, Dianthus caryophyllus L., carnation, cytokinins, explant     

Vulnerability of xylem to embolism in relation to leaf water potential and stomatal conductance in Fagus sylvatica f. purpurea and Populus balsamifera

The vulnerability of xylem vessels to water stress-induced cavitationwas studied by measuring hydraulic conductivity and ultrasoundacoustic emissions (AEs) in Fagus sylvatica L. f. purpurea (Ait.)Schneid. and Populus balsamifera L. The occurrence of xylemembolism in summer was investigated in relation to leaf waterpotential and stomatal conductance. Populus was extremely vulnerableto cavitation, losing functional vessels due to embolism atwater potentials lower than –0.7 MPa. Fagus experiencedembolism when water potential fell below –1.9 MPa. Middaywater potentials often approached these threshold values. Whenevaporative demand increased rapidly on sunny days, water lossbecame limited by low stomatal conductance. Thus water potentialsfell only slightly below the threshold values inducing cavitation.Despite the differences in vulnerability, both species tolerateda similar embolism rate of about 10% in the summer. There wasno embolism reversal during prolonged periods of rain. AEs werepredictive of loss in hydraulic conductivity, indicating thatAEs were mainly confined to vessels. Finally, vessel lengthdistribution, vessel diameter (tangential axis), vessel density,and vessel wall thickness had been determined for both speciesinvestigated. Populus had longer and wider vessels than Fagus,whereas vessel wall thickness was similar in both species. Key words: Acoustic emissions, Fagus, Populus, stomatal closure, xylem embolism     

Activation of phospholipase D by calmodulin antagonists and mastoparan in carnation petals

An in vivo assay for phospholipase D (PLD; EC 3,1,4,4) activity,based on its transphosphatidylation property, is described indetail and was used to study putative post-translational regulationmechanisms of PLD activity in carnation (Dianthus caryophyllusL.) petals. A variety of agents was applied to petal discs.The calmodulin (CaM) antagonists propranolol, N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide(W7) and N-(6-aminohexyl)-1-naphthalenesulphonamide (W5), stimulatedPLD activity in a dose-dependent manner. EGTA partially inhibitedthe stimulation by the CaM antagonists. Erythrosin B, an inhibitorof CaM-dependent P-type Ca^z+-ATPases, slightly stimulated PLDactivity. The results suggest that part of the stimulation ofPLD activity by CaM antagonists is due to an increased intracellularCa²⁺-concentration, PLD activity was stimulated by mastoparanin a dose- and time-dependent manner. The signal-like activationkinetics suggests that mastoparan activates PLD (in)directlyvia a G protein. Key words: Phospholipase D, CaM antagonists, mastoparan, Dianthus, calcium     

Establishment of Isolated Root Cultures of Brassica Species and Regeneration from Cultured-root Segments of Brassica oleracea var. italica

Isolated root cultures which could be maintained over severalmonths by serial subculture were established from Brassica oleraceavar. italica cv. Green Comet F₁. A modified White's medium wasfound to be the best of several salt compositions tested. Theeffects on isolated root growth of the following were also examined;nutritional components, culture vessel type and closure, pHof the medium and auxin type and concentration. Using a mediumdevised for Green Comet, root cultures were established fromsix other B. oleracea, B. napus and B. campestris cultivars. It was possible to regenerate shoots from segments of culturedroots by incubation on agar-solidified media containing cytokininand auxin. The effects on regeneration of various auxins andcytokinins were investigated; the combination of Picloram withKN gave the highest frequency of shoot formation. It was demonstratedthat isolated roots retained their regenerative ability overa period of 5 months in culture. Brassica oleracea var. italica, Brassica napus, Brassica campestris, isolated root culture, shoot regeneration, organ culture     

Water Flow Through Vessel Perforation Plates--The Effects of Plate Angle and Thickness for Liriodendron tulipifera

The effects of scalariform perforation plate thickness and anglewithin vessel elements of Liriodendron tulipifera were studiedwith a computational fluid dynamical model. The pressure gradientand hence resistance to flow through the plate increased asthe perforation plate increased in thickness. Increasing theangle of the plate relative to the axis of the vessel (samenumber of pores) also increased the pressure gradient alongthe modelled cell. For the model matching the actual vesselelement, the plate contributed 8% to the flow resistance ofthe vessel element. This contribution increased only to 11%for doubled plate thickness, and to 14% for a plate at an angleof 60° to the vessel axis. The perforation plate alteredthe velocity profile across the vessel element, but to a differentextent depending on the angle of the plate. A plate at an acuteangle to the vessel axis has little effect on the paraboloidprofile as found upstream from the plate, while obtuse angleplates change the flow profile such that fluid through poresnear the wall is accelerated to a greater velocity than foundin the centre of the cell. Key words: Conductance, perforation plate, vessel, water flow     

A suberized perimedullary reaction zone in Populus balsamifera novel for compartmentalization in trees

 Following artificial inoculation of nonhost Populus balsamifera with Ophiostoma ulmi, structural defensive tissues were formed in the xylem. Among these tissues there was a perimedullary sheath of cells, located adjacent to the invaded xylem, that originated from the dedifferentiation of perimedullary and xylem parenchyma cells. Histochemical tests revealed that this sheath was intensively suberized. A band of lignified cells was frequently detected on both sides of this suberized tissue. The formation of such a tissue at the pith margin represents a new type of anatomical barrier in relation to compartmentalization processes described for trees. Ultrastructural examination showed that the wall of cells forming this zone was generally composed of a compound middle lamella, a suberized secondary wall and a tertiary wall layer. Using colloidal gold conjugated to monoclonal antibodies against pectin and to an exoglucanase for cellulose, only limited labelling was obtained for pectin whereas labelling for cellulose was abundant in the compound middle lamella and the tertiary wall layer. In a few fibres close to this suberized zone, the latter probe also made it possible to distinguish the occasional presence of several alternating wall layers mainly composed of either suberin or cellulose. In Salix sp., another tree species belonging to the Salicaceae, this type of suberized reaction zone was also observed. The new reaction zone is similar in structure and location to a suberized barrier formed in nonwoody carnation (Dianthus caryophyllus) plants in the defense against vascular fungi. Received: 30 July 1996 / Accepted: 7 January 1997     

Buckminsterfullerene (C-60 Carbon Allotrope) Inhibits Ethylene Evolution from 1-Aminocyclopropane-1-carboxylic acid (ACC)-treated Shoots of Pea (Pisum sativum), Broadbean (Vicia faba) and Flowers of Carnation (Dianthus caryophyllus)

When applied either in the form of a colloidal solution or inliposomes, buckyballs (C-60—buckminsterfullerene) markedlyreduced ethylene evolution from cut carnation (Dianthus caryophyllus)flowers, as well as pea (Pisum sativum) and broadbean (Viciafaba) foliage treated with ethylene precursor l-aminocyclopropane-l-carboxylicacid (ACC). The liposome preparation was approximately twiceas effective as colloidal solutions. Moreover, upon being incubatedin a closed atmosphere with ethylene, buckyballs induced a significantdepletion of ambient ethylene which was temperature and C-60—concentrationdependent. This mode of C-60 action is attributed to ethyleneadsorption stemming from the vast C-60 surface area, calculatedto be 1317 m² g_-1, and the affinity of its carbon atoms forthe component in the ethylene double bond.Copyright 1993, 1999Academic Press Dainthus caryophyllus, Pisum sativum, Vicia faba, adsorption, ethylene, fullerene     

The Carnation Succulent Plantlet -- A Stable Teratological Growth

Axillary buds of carnation (cv. Cerise Royalette) cultured invitro, frequently became ‘succulent’ plantlets,which proved to be a teratalogical stable type of growth. Agarconcentration (0.8–1.2 per cent) in the medium influencedthe type of development, and 0.05, 1 or 2 mg l^–1 of NAAin the medium did not change the results. The succulent plantletsdid not revert to normal growth when transferred to medium containingmore agar, which favoured normal plantlet development. Succulentexcised meristems developed mainly into succulent plantlets. A hypothesis is made that a rearrangement of the meristem occursin the first days of growth, the consequence of which is thesucculent plantlet, which is no longer influenced by agar concentrationin the medium. Carnation, Dianthus caryophyllus L. cv. Cerise Royalette, vegetative shoot meristem, agar effect, meristem organization     

Surface Changes on Fresh Carnation Shoot Apices During Scanning Electron Microscopy

The general morphology of fresh intact shoot apices of carnation,Dianthus caryophyllus L. cv. Improved White Sim was studiedwith a scanning microscope. The changes in the surface withtime under the electron beam were: (1) individual cells beingvisible, (2) a smooth apex and (3) wrinkling until the specimenbecame unsatisfactory for study. As indicated by time coursestudies, the initial individual cell observations representthe true features of the intact apex. The observation of a smoothapex was related to a ballooning of the surface layer resultingfrom water vaporization. Incisions in the apex to prevent pressurebuild-up under the surface layer revealed the smooth characteristicof the apex surface was due to lifting of the cuticle from underlyingcells. Areas adjacent to a micropuncture in the apical domedid not exhibit ballooning.     

Differentiation Between Tissues from Carnation (Dianthus caryophyllus) Stems by Pyrolysis-Mass Spectrometry

Small pieces of different tissues from stems of young and oldcarnation plants were analyzed for lignification (lignin/celluloseratios) and lignin composition by means of pyrolysis-(gas chromatography)-massspectrometry. The epidermis and phloem of young and old stemswere essentially non-lignified. Pith parenchyma was only lignifiedin mature and senescing tissues. The type of lignin in sclerenchymadiffered from that in xylem and pith. Lignification in the xylemof very young tissues was a mainly guaiacyl-type lignin, whichgradually changed into a mixed guaiacyl-syringyl lignin in oldertissues. In mature tissues, the sclerenchyma was more highlylignified than the xylem. All tissues yielded comparatively large amounts of dihydroferulicacid, a compound which may be specific for carnation. Carnation, Dianthus caryophyllus, epidermis, cortex, sclerenchyma, phloem, xylem, pith, lignification, aging, dihydroferulic acid, pyrolysis-(gas chromatography)-mass spectrometry