GROWTH AND HABITUATION IN TISSUE CULTURES OF ENGLISH IVY,HEDERA HELIX

Tissue cultures from both juvenile and adult stems of English ivy, Hedera helix L., were established in White's medium supplemented by coconut water and auxin (usually naphthalene acetic acid). With repeated transfers, cultures were habituated in less than a year to grow well without coconut water by using an auxin and kinetin. Cultures from juvenile seedlings were less demanding in requirements for growth. In all types of cultures occasionally small areas of rapidly growing cells were noticed. These when isolated gave rise to rapidly growing cultures with many cells of unusual appearance. Abnormally long cells and chain-type cells were abundant. When 0.1 mg/ liter of kinetin was added to the medium, these cells grew well without auxin and coconut water.     

PLASTOCHRON INDICES FOR JUVENILE AND MATURE FORMS OF HEDERA HELIX L. (ARALIACEAE)

English ivy (Hedera helix) plants were assessed for the applicability of the plastochron index (PI). Juvenile ivy satisfied all requirements for the use of the PI and showed a plastochron of 4.23 days. Mature ivy grown under long day conditions flowered after 11–12 leaves. Two distinct groups of leaves were produced with different plastochrons (0.83 and 3.2 days, respectively) and leaf morphologies. Long-day-grown ivy did not satisfy the requirements for the use of the PI. Short-day-grown mature ivy continued production of leaves beyond the 12th leaf. Vegetative growth was perpetuated for at least 25 plastochrons. By 19 plastochrons (ca. 41 days after budbreak) a linear PI vs. time relationship was established with a plastochron of 3.16 days. This newly acquired ability to maintain vegetative growth in mature ivy plants may allow a direct comparison with the vegetative indeterminant juvenile in order to assess possible anatomical factors responsible for phase stability and phase change using the PI as a basis for comparison.     

Dihydroflavonol Reductase Activity in Relation to Differential Anthocyanin Accumulation in Juvenile and Mature Phase Hedera helix L

Juvenile phase English ivy (Hedera helix L.) plants accumulate anthocyanin pigment in the hypodermis of stems and petioles, whereas genetically identical plants of the mature phase do not. The objective of this work was to assess which enzyme(s) might limit anthocyanin accumulation in mature phase ivy. Leaf discs of both juvenile and mature phase ivy accumulated comparable levels of the flavonols kaempferol and quercetin, whereas only juvenile phase discs accumulated anthocyanin. The accumulation of quercetin, but lack of accumulation of leucocyanidin or anthocyanin in mature phase discs, suggested that mature discs lacked dihydroflavonol reductase activity. There was no detectable dihydroflavonol reductase activity in mature phase discs, whereas there was an induction of activity in juvenile phase discs in response to sucrose, or photosynthetically fixed carbon, and light as a photomorphogenic signal. Phenylalanine ammonia-lyase, an enzyme early in the anthocyanin biosynthetic pathway, was induced above its basal level by sucrose and light in discs of both phases of ivy, with greater activity in mature phase discs. Phenylpropanoids, a class of compounds that are precursors to flavonoids, accumulated in leaf discs of both phases, with greater levels in mature phase discs. These results indicate that the lack of dihydroflavonol reductase activity limits the accumulation of anthocyanin in mature phase tissue.     

Light acclimation in leaves of the juvenile and adult life phases of ivy (Hedera helix)

Hoflacher, H. and Bauer, H. 1982. Light acclimation in leaves of the juvenile and adult life phases of ivy (Hedera helix). – Physiol. Plant. 56: 177–182. Light acclimation was investigated during the juvenile and adult life phases of the whole-plant-development in Hedera helix L. For this purpose, cuttings of the juvenile and adult parts of one single parent plant were grown under low-light (PAR 30–50 μmol photons m^?2 s^?1) and high-light (PAR 300–500 μmol m^?2 s^?1) conditions: CO₂ exchange, chloroplast functions, and specific anatomy of fully developed leaves differentiated under these conditions were determined. In juvenile plants the leaves formed under low and high light had light-saturated rates of net photosynthesis of 6.5 and 11.1 mg CO₂ (dm leaf area)^?2 h^?1, respectively. In adult plants the rates were 9.4 and 22.2 mg dm^?2 h^?1, indicating a more pronounced capacity for acclimation to strong light in the adult life phase. Higher photosynthetic capacities were accompanied by higher conductances for the CO₂ transfer through the stomata, leading to almost the same CO₂ concentration in the intercellular spaces. Thus, stomatal conductances were not primarily responsible for the different photo-synthetic capacities. The higher rates in adult and high-light grown leaves were mainly the result of formation of thicker leaves with more chloroplasts per unit leaf area. Expressed per chloroplast, the photosynthetic capacity, the Hill reaction, and the activity of ribulose bisphosphate carboxylase were almost identical in plants grown in low-light and high-light. Measurements of photosynthetic capacity and thickness of leaves of Hedera sampled from field habitats with contrasting light regimes confirm the results of growth chamber studies. It is, therefore, concluded that both life phases of Hedera are capable of acclimating to strong light, but that during the juvenile phase this capacity is not fully developed.     

Photosynthesis in leaves of the juvenile and adult phase of ivy (Hedera helix)

Abstract Photosynthetic and anatomical parameters of leaves from the juvenile and adult part of an ivy plant (Hedera helix L.) have been determined and compared with each other. Light-saturated net photosynthesis (per unit leaf area) was about 1.5 times higher in adult leaves than in juvenile ones. The lower photosynthetic capacity of juvenile leaves was caused by a lower stomatal and especially a lower residual conductance to the CO₂-transfer. This corresponds with anatomical features of the leaves, i.e. lower stomatal frequency, fewer chloroplasts per cell, and – most important – thinner leaves, as well as with a less efficient photosynthetic apparatus measured as Hill reaction of isolated broken chloroplasts and activity of ribulose bisphosphate carboxylase. No differences in the respiration in light (relative to net photosynthesis) and in the CO₂-compensation concentration could be detected between the two leaf types. These observed anatomical and photosynthetic parameters of the juvenile and adult ivy leaves resemble those reported for shade and sun leaves, respectively, although the leaves investigated originated from the same light environment.     

FURTHER OBSERVATIONS ON JUVENILE AND ADULT HEDERA

Robbins , William J. (The New York Botanical Garden, New York, N. Y.) Further observations on juvenile and adult Hedera. Amer. Jour. Bot. 47(6) : 485–491. Illus. 1960.—Plants of arborescent Hedera helix sprayed with gibberellic acid produced juvenile shoots. Juvenile characters appeared in December to March from applications of gibberellic acid made from May to July. Gibberellic acid modified inflorescences toward a vegetative condition. Previous reports that seeds of arborescent Hedera helix produce juvenile plants were confirmed. Seedlings of a variant, Hedera helix ‘238th Street,‘ which has adult-shaped leaves on a vine type of growth produced vines with lobed leaves. Heavy pruning of arborescent Hedera helix caused the production of juvenile shoots.     

Ribosomal RNA Gene Redundancy in Juvenile and Mature Ivy (Hedera helix)

Two-fold variation was found in rRNA gene redundancy in differentpopulations of ivy (Hedera helix). No consistent differencein rRNA gene number was observed between the juvenile and matureforms of the plant. Small significant differences between therRNA gene content of mature and juvenile forms and also betweenundeveloped buds and expanded leaves were found but these werein different directions in different populations.     

Responses of ivy (Hedera helix L.) to combinations of gibberellic acid,paclobutrazol and abscisic acid

A reduction in concentration of gibberellins has been implicated in the phase change from juvenile to mature forms of ivy (Hedera helix L.). Attempts were made to increase the effective internal concentration of gibberellins by exogenous application of GA₃, and to decrease them by various applications of abscisic acid (ABA) and paclobutrazol (PP333), alone or in combination with GA₃. ABA and GA₃ were fed directly into the xylem of ivy plants by a wick system (a less drastic procedure than the defoliation or decapitation used by earlier workers) whereas PP333 was applied as a soil drench.Mature ivy responded to the application of GA₃ by reversion to the juvenile form, although this reversion was incomplete with respect to leaf lobing and red (anthocyanin) pigmentation and could occur spontaneously without the application of GA₃. Contrary to expectation, applications of ABA and PP333 caused the stimulation of growth in juvenile ivy. No adult characteristics were induced. As similar concentrations of ABA and PP333 produced severe retardation of growth (which could be alleviated by the application of GA₃) in other species, it is suggested that ivy may be an unsuitable model system for the investigation of phase change in woody plants.     

Phase Change in Hedera helix L: II. THE POSSIBLE BOLE OF ROOTS AS A SOURCE OF SHOOT GIBBERELLIN-LIKE SUBSTANCES

When synthesis was estimated by the agar diffusion techniqueboth basal and lateral adventitious roots of Hedera helix L.in the juvenile growth phase were shown to synthesize gibberellin-likesubstances. Seedlings and cuttings from juvenile ivy could begrown in water culture for several weeks. When roots were excisedfrom these plants shoot growth was reduced in comparison withthat of intact plants. The stems, apices, and leaves of derootedseedlings and cuttings contained lower levels of extractablegibberellin-like substances than comparable organs of intactplants. The major zone of gibberellin-like activity in intactplants co-chromatographed with gibberellins A₁ and A₃. Whenthese gibberellins were applied to plants grown in culture theywere found to promote growth of intact but not derooted plants.These findings are discussed in relation to the role of rootfactors and particularly gibberellins in phase change.     

DEVELOPMENTAL ANATOMY OF JUVENILE AND ADULT SHOOTS OF MARCGRAVIA RECTIFOLIA L

Marcgravia rectifolia L. is a dimorphic vine having distinct juvenile and adult shoots. The juvenile shoot is a climber characterized by an orthotropic growth habit, a flattened stem, adventitious roots, and ovate leaves. The adult shoot, on the other hand, possesses a plagiotropic growth habit, has a cylindrical stem, few or no adventitious roots, and lanceolate leaves. Both phases have distichous phyllotaxy, however the plastochron is shorter for the adult phase than for the juvenile. Internode elongation occurs earlier for adult shoots than for juvenile shoots. Cytological analyses show the flattened stem of the juvenile results from differential production of cells, especially in the pith region. On the other hand, internodes of the adult phase are longer than juvenile internodes, a result of more cells produced rather than longer cells. In juvenile stems a perivascular band of elongated fibers develops, while in adult stems this band consists of brachyosclereids. Both phases undergo secondary growth and have non-storied cambia. Cambial activity begins in the 6th internode of each phase. As secondary growth proceeds, the adult stem produces much more xylem than juvenile stems of the same age. Adventitious roots produced in the juvenile stem are located in vertical rows at the “corners” of flattened stems and are attachment structures aiding the climbing habit of this vine. Phase changes occur regularly in this species. The juvenile phase usually transforms into the adult, however the adult phase can spontaneously revert back into the juvenile phase. The anatomical features and the phase changes are discussed and compared to Hedera helix, a vine whose phase changes have been studied in some detail. It is suggested that the anatomical features of Marcgravia rectifolia L. including its phase changes, may provide an alternative system to study physiological changes similar to those done with Hedera helix.     

Host preference and growth patterns of ivy (Hedera helix L.) in a temperate alluvial forest

Recent studies have highlighted the role of lianas in shaping stand dynamics both in tropical and temperate forests. However, English ivy (Hedera helix L.), one of the most widespread lianas in Europe, has received little attention. We conducted a study in the Siro Negri alluvial forest (NW Italy) to determine what factors most affected ivy distribution and investigate its interactions with the trees in the stand. We evaluated the influence of tree size, age, species, and neighborhood crowding on ivy occurrence. In addition, growth ring widths were used to explore the development pattern of climbing stems. Fifty-two percent of trees in our study plots carried ivy, a value comparable to liana incidence found in mature tropical forests. Tree characteristics and their spatial pattern significantly influenced ivy distribution. Preferred hosts were large, isolated trees, while the effect of tree age and species on ivy occurrence was marginal. Growth pattern analysis revealed that radial growth was positively related to the available space on the tree trunk for each ivy stem. We conclude that neighborhood crowding around trees and competition among climbing stems relying on the same trunk may reduce the colonization rate of ivy.     

Phase Change in Hedera helix L: I. GIBBERELLIN-LIKE SUBSTANCES IN THE TWO GROWTH PHASES

Gibberellin-like substances were extracted from all parts ofthe juvenile and adult growth phases of Hedera helix. A numberof extraction techniques were employed and estimatos of theamount of gibberellin-like activity present were made usingthree bioassays. Gibberellin like substances were present inapproximately equal amounts in leaves at the two growth phasesand appeared to be localized, in the main, in chloroplasts.Apical ‘buds’ of the juvenile phase were shown tocontain higher levels of gibberellin-like substances than theiradult counterparts. Roots, which under normal circumstancesare associated only with the juvenile phase, contained highlevels of extractable gibberellin-like substances.     

Nanoparticle biofabrication using English ivy (Hedera helix)

Background

English ivy (Hedera helix) is well known for its adhesive properties and climbing ability. Essential to its ability to adhere to vertical surfaces is the secretion of a nanocomposite adhesive containing spherical nanoparticles, 60?C85 nm in diameter, produced exclusively by root hairs present on adventitious roots. These organic nanoparticles have shown promise in biomedical and cosmetic applications, and represent a safer alternative to metal oxide nanoparticles currently available.

Results

It was discovered that the maximum adventitious root production was achieved by a 4 h application of 1 mg/ml indole-3 butyric acid (IBA) to juvenile English ivy shoot segments cultured in custom vessels. After incubation of the shoots under continuous light at 83 ??mol/m² s at 20°C for 2 weeks, the adventitious roots were harvested from the culture system and it was possible to isolate 90 mg of dry weight nanoparticles per 12 g of roots. The nanoparticle morphology was characterized by atomic force microscopy, and found to be similar to previous studies.

Conclusions

An enhanced system for the production of English ivy adventitious roots and their nanoparticles by modifying GA7 Magenta boxes and identifying the optimal concentration of IBA for adventitious root growth was developed. This system is the first such platform for growing and harvesting organic nanoparticles from plants, and represents an important step in the development of plant-based nanomanufacturing. It is a significant improvement on the exploitation of plant systems for the formation of metallic nanoparticles, and represents a pathway for the generation of bulk ivy nanoparticles for translation into biomedical applications.     

Naturally occurring nanoparticles from English ivy: an alternative to metal-based nanoparticles for UV protection

Background  

Over the last decade safety concerns have arisen about the use of metal-based nanoparticles in the cosmetics field. Metal-based nanoparticles have been linked to both environmental and animal toxicity in a variety of studies. Perhaps the greatest concern involves the large amounts of TiO₂ nanoparticles that are used in commercial sunscreens. As an alternative to using these potentially hazardous metal-based nanoparticles, we have isolated organic nanoparticles from English ivy (Hedera helix). In this study, ivy nanoparticles were evaluated for their potential use in sunscreens based on four criteria: 1) ability to absorb and scatter ultraviolet light, 2) toxicity to mammalian cells, 3) biodegradability, and 4) potential for diffusion through skin.     

Mixed culture of micro-organisms in the rhizosphere of ivy (Hedera helix L.)

Summary The development ofAzotobacter chroococcum is promoted in the ivy (Hedera helix L.) rhizosphere when it is colonized by the pectinolytic moldMucor fragilis. The multiplication of Azotobacter cells in the mineral solution of ivy cultures induces a decrease of the amount of sugars excreted by the roots and a increase of the amount of nitrogen. Within the experimental period Azotobacter does not influence the growth of ivy roots although it seems to be promoted by Mucor. Filtrates of Mucor culture are, however, harmful to the plant.     

Ozone-induced ethylene release from leaf surfaces

Ozone-induced stress ethylene emissions from the adaxial and abaxial leaf surfaces of four plant species (Glycine max [L.] Merr. cv. Dare, Lycopersicon esculentum Mill cv. Roma VF, Eucalyptus globulus Labill. and Hedera helix L.) were studied to determine if the stress ethylene diffused through the stomata or cuticle. In plants not exposed to ozone, basal ethylene was detected above both the adaxial and abaxial leaf surfaces of all the plant species examined, indicating that some ethylene can diffuse across the leaf cuticle. Ozone induced stress ethylene production in all species examined. Significant ozone-induced ethylene concentrations were detected above both surfaces of amphistomatous soybean (Glycine) and tomato (Lycopersicon) leaves. In contrast, ozone-induced ethylene production was associated only with the leaf surface (abaxial) that contained stomata for hypostomatous blue gum eucalyptus and English ivy (Hedera) leaves; the leaf surface (adaxial) of the eucalyptus and ivy leaves which did not contain stomata did not release significant amounts of stress ethylene. These data indicate that ozone-induced stress ethylene primarily diffuses from the leaf via the stomata.     

Acute and chronic antiinflammatory profile of the ivy plant, Hedera helix, in rats.

Hedera helix is a plant well-known as ivy or English ivy, and a member of the Araliaceae family. In the present study, we tested the possible antiinflammatory effects of a crude saponin extract (CSE) and a saponin's purified extracts (SPE) of Hedera helix in carrageenan- and cotton-pellet-induced acute and chronic inflammation models in rats. Both the CSE and SPE of Hedera helix were found to have antiinflammatory effects. The most potent drug screened was indomethacin (89.2% acute antiinflammatory effect), while the most potent extract screened was the CSE of Hedera helix at 100 and 200 mg/kg body wt. doses with 77% acute antiinflammatory effects. For testing chronic antiinflammatory (antiproliferative) effects, the cotton-pellet-granuloma test was conducted. Indomethacin was found to be the most potent drug in the chronic phase of inflammation, with 66% effect. The SPE of Hedera helix was more potent than the CSE in its chronic antiinflammatory effect (60% and 49%, respectively).     

Phase Change in Hedera helix L.: III. THE EFFECTS OF GIBBERELLINS, ABSCISIC ACID AND GROWTH RETARDANTS ON JUVENILE AND ADULT IVY

Gibberellic acid, applied to delaminated petioles of rootedcuttings of juvenile and adult ivy initially induced internodeelongation and abnormal leaf development, and suppressed apicaldominance. Juvenile cuttings were affected only transientlyand soon reverted to normal growth. Adult cuttings, insteadof resuming normal growth after this initial response to GA₃,gradually developed many juvenile characteristics. Approximately16 weeks after treatment at 25 ?C nearly all shoots of adultcuttings had undergone complete rejuvenation. Lower temperaturereduced the speed of response to GA₃. A mixture of gibberellinsA₄ and A₇ had effects similar to those of GA₃ on the growthof juvenile and adult cuttings. Treatment of both phases ofivy with abscisic acid (ABA) induced no visible effects andwhen ABA was applied with GA₃ it did not reduce the responseof either phase to the gibberellin. CCC had a marked dwarfingeffect on juvenile ivy but did not induce pre-maturation. However,extraction of gibberellin-like substances from severely dwarfedplants suggested that CCC was not exerting its growth retardingeffect through an inhibition of gibberellin biosynthesis. AMO1618 did not retard growth of juvenile ivy cuttings.     

Aggressiveness of Hedera helix L. growing on monuments: Evaluation in Roman archaeological sites and guidelines for a general methodological approach

Ivy (Hedera helix L.) growing on monuments is a common issue in the study of nature’s relationship with artefacts in the Euro-Mediterranean area. This is due to its pervasiveness and its double role as protective and as deteriogen. We studied the effect of ivy colonization within the archaeological site of Villa of Massentius. We applied a quantitative method derived from monument mapping method by Fitzner, to evaluate deterioration due to ivy colonization on vertical surfaces. Instead, the capping ivy effects was investigated through a multi-parameter evaluation. We recognized three different damage categories: the superficial loss of surface (W), ivy residues on wall after the removal event (I), and the loss of compact stone fragments (P/O). Mean W corresponded to 58% and P/O to 14%. The total damage rate was positively correlated to the amount of ivy cover and to favourable shady conditions. For the capping ivy, we calculated an average loss of 4.34 cm³/m² and a high level of soil deposit, which led to a secondary ivy colonization process. This paper proposes a contribution to the identification and quantification of ivy deteriogen activity. The application of the proposed method also provides a useful tool for planning restoration activity.