Glandular Hairs and Secreted Material inSalvia blepharophyllaBrandegee ex Epling Grown in Italy

Morphological and histological investigations of cuticle andindumentum, as well as identification of the main componentsof the secreted material, were carried out forSalvia blepharophyllaBrandegeeex Epling. Besides non-glandular hairs, three types of glandulartrichomes (peltate and capitate) are described and comparedwith trichomes in other species. The histological findings andchemical analysis of the essential oil and leaf surface extractsrevealed a complex secretion product. GC-MS analysis of theessential oil showed that eugenol,cis-3-hexenyl benzoate,cis-jasmone,trans-nerolidol,benzyl alcohol and C₁₉-C₂₃n-alkanes were the main identifiablecomponents, whereas the flavonoids nuchensin and pedalitin,the neo-clerodane diterpenoid salvianduline D, and the triterpenoidsursolic acid and     

Glandular Hairs of Salvia officinalis: New Data on Morphology, Localization and Histochemistry in Relation to Function

The structure, site and histochemistry of glandular hairs onthe vegetative and reproductive parts ofSalvia officinalis wereinvestigated by UV and conventional light microscopy and byscanning electron microscopy. Five distinct types of glandularhair (one peltate and four capitate) with different sites, secretorymodes and secretions, were identified, and a functional rolepostulated for each type. All the hair types show mixed secretions,i.e., hydrophilic and lipophilic, except type I capitate hairs,which have hydrophilic secretions only. In peltate hairs andin type II capitate hairs hydrophilic secretion prevails; inthe remaining types, lipophilic secretion dominates. The manner,time and role of erection of peltate hairs on the reproductiveorgans and the role of non-glandular hairs are also considered.Copyright 1999 Annals of Botany Company Salvia officinalis, Labiatae, rising of peltate hairs, capitate hairs, secretion, plant/insect interaction.     

Mineral nutrient uptake from prey and glandular phosphatase activity as a dual test of carnivory in semi-desert plants with glandular leaves suspected of carnivory

Background and Aims

Ibicella lutea and Proboscidea parviflora are two American semi-desert species of glandular sticky plants that are suspected of carnivory as they can catch small insects. The same characteristics might also hold for two semi-desert plants with glandular sticky leaves from Israel, namely Cleome droserifolia and Hyoscyamus desertorum. The presence of proteases on foliar hairs, either secreted by the plant or commensals, detected using a simple test, has long been considered proof of carnivory. However, this test does not prove whether nutrients are really absorbed from insects by the plant. To determine the extent to which these four species are potentially carnivorous, hair secretion of phosphatases and uptake of N, P, K and Mg from fruit flies as model prey were studied in these species and in Roridula gorgonias and Drosophyllum lusitanicum for comparison. All species examined possess morphological and anatomical adaptations (hairs or emergences secreting sticky substances) to catch and kill small insects.

Methods

The presence of phosphatases on foliar hairs was tested using the enzyme-labelled fluorescence method. Dead fruit flies were applied to glandular sticky leaves of experimental plants and, after 10–15 d, mineral nutrient content in their spent carcasses was compared with initial values in intact flies after mineralization.

Key Results

Phosphatase activity was totally absent on Hyoscyamus foliar hairs, a certain level of activity was usually found in Ibicella, Proboscidea and Cleome, and a strong response was found in Drosophyllum. Roridula exhibited only epidermal activity. However, only Roridula and Drosophyllum took up nutrients (N, P, K and Mg) from applied fruit flies.

Conclusions

Digestion of prey and absorption of their nutrients are the major features of carnivory in plants. Accordingly, Roridula and Drosophyllum appeared to be fully carnivorous; by contrast, all other species examined are non-carnivorous as they did not meet the above criteria.Key words: Roridula gorgonias, Drosophyllum lusitanicum, Proboscidea parviflora, Ibicella lutea, Cleome droserifolia, Hyoscyamus desertorum, phosphatase, phosphomonoesters, fruit flies, N, P, K, Mg uptake from prey     

Some Observations on the Diversity of Stomata and Trichomes in Six Species of Dioscorea

Stomata and trichomes are described on the leaves of six speciesof Dioscorea. As many as six types were found in D. bulbiferaand D. oppositifolia, four types in D.hispida and D. wallichii,three types in D. belophylla, but only two types in D. alata.Although there is a diversity of stomata even on the same surface,the predominant type is anomocytic in all the species exceptD. bulbifera in which it is tricytic. Rarely a stoma is alsocyclocytic in D. bulbifera. An increase in the number of subsidiarycells in paracytic, tricytic, or diacytic stomata takes placeby the wall formation in them. Similarly a reduction in thenumber of subsidiary cells of a tetracytic stoma is the resultof lateral subsidiary cells assuming the form of epidermal cells.Abnormalities such as a stoma with one guard cell, degenerationof guard cells, and contiguous stomata are also met with. Theorganization of different types of stomata is studied in D.bulbifera and D. wallichii and shown to be perigenous. Capitateglandular hairs were seen on the leaves of D. belophylla, D.bulbifera, D. hispida, and D. wallichii but non-glandular, uniseriate,3-celled trichomes were observed only in D. hispida.     

Dynamics of Salt Secretion by Sporobolus spicatus(Vahl) Kunth from Sites of Differing Salinity

Secretion of salts by bicellular salt glands and the water relationsof the grass Sporobolus spicatus were investigated at four sitesalong the coast of the Red Sea in Egypt that differed in theextremity of salinity and drought. Salt eliminated by the leaveswas similar in its composition at all sites. Na⁺and Cl^-werethe dominant ions in the soil, and together comprised about93% of the dry weight of secreted salt. The molar ratio of K⁺:Na⁺inthe plant leaves was more than ten-fold that in the interstitialsoil solution and thirteen-times that in the secreted salts,reflecting the high selectivity of the secretion mechanism forNa⁺. The concentration of Na⁺in the solution transported tothe leaves between 0900 and 1500 h was less than 0.1% of thatin the soil solution. Accumulation of salts by the plant shoots,which increased with increasing soil salinity and drought, wasmaximal during the day when the extent of secretion greatlyreduced. The ionic osmotic potential (     

Role of aluminum-binding ligands in aluminum resistance of Eucalyptus camaldulensis and Melaleuca cajuputi

We investigated the roles of Al-binding ligands in Al exclusion from roots and in internal Al detoxification in roots as Al resistance mechanisms in two Al-resistant Myrtaceae trees, Eucalyptus camaldulensis Dehnh. and Melaleuca cajuputi Powell. The amounts of ligands secreted from roots and contained in root tips of these species were compared with those of an Al-sensitive species, Melaleuca bracteata F. Muell., after the roots were exposed to 0 or 1 mM AlCl₃ solution. Secretion of well-known ligands (citrate, oxalate, and malate) from roots under Al treatment was low in all species. However, in E. camaldulensis, the Al-binding capacity of root exudates under Al treatment was considerable and was higher than that in M. bracteata. Gel filtration chromatography revealed that a low-molecular-weight Al-binding ligand was secreted from roots in response to Al only in E. camaldulensis. On the other hand, the Al-binding capacity of cell sap in root tips under Al treatment was similar for the resistant and sensitive species. These results suggest that Al exclusion by secretion of the unknown low-molecular-weight Al-binding ligand from roots contributes to the Al resistance of E. camaldulensis, whereas M. cajuputi has developed Al-resistance mechanisms other than secretion of ligands from roots or concentration of internal ligands in root tips.     

Absorption and Distribution of Copper in Plants with Sufficient or Deficient Supplies

Wheat, red clover and ryegrass were grown in flowing solutionculture with sufficient (+ Cu) and deficient (–Cu) suppliesof copper. The rates of Cu absorption (µg g^–1 dryroot day^–1) did not differ greatly between species ineither treatment. Wheat plants, when transferred from the –Cu to the +Cu treatment, absorbed Cu at a much slower rate thanthose which had remained throughout in the + Cu treatment. Inall plants considerable proportions of the absorbed Cu wereretained in the roots, even when the plants were Cu-deficient,and the concentration in roots usually exceeded that in anypart of the shoots in both treatments. Transferring wheat plantsfrom the +Cu to the –Cu treatment decreased the concentrationin all plant parts except old leaves; similarly, transferringfrom the –Cu to +Cu treatment increased the concentrationin all parts of the shoots, execept old leaves, and in the roots. Lolium perenne, Trifolium pratense, Triticum aestivum, ryegrass, red clover, wheat, absorption, copper, flowing solution culture     

Relative Importance of Ion Exclusion, Secretion and Accumulation in Spartina alterniflora Loisel.

The extent to which Spartina alterniflora Loisel. excluded,secreted or accumulated the major seawater ions (Cl^-, SO^2-₄,Na⁺, K⁺, Mg²⁺, and Ca²⁺) was investigated under varying salinitytreatments. From a quantitative viewpoint, ion exclusion wasmost prominent and accounted for 91–97% of the theoreticalmaximum ion uptake as a result of transpiration and growth.Of those ions taken up, approximately half was secreted fromthe shoots. Relative to K⁺, a disproportionate amount of Na⁺was excluded at the roots and secreted by the shoots. The concentrationwithin the tissues of S. alterniflora did not change with salinitytreatment for the majority of the ions examined, but Na⁺ wasmore than twice as concentrated at 40 g dm^-3 than at lOgdm^-3.Calculations of the flux of ions from salt marsh sediments tothe flood water via shoot secretion or stem/leaf turnover indicatethat these processes may be important to the ecology of S. alternifloraas mechanisms that limit the accumulation of salt within theroot zone.     

Striga gesnerioidesParasitising Cowpea: Development of Infection Structures and Mechanisms of Penetration

Striga gesnerioides(Scrophulariaceae) is an obligate hemiparasiticangiosperm, that infects the roots of cowpea (Vigna unguiculata).The development ofStrigaseedlings was characterized after transferto the surface of cowpea roots using cryo-scanning electronmicroscopy. Contact with the surface of the root caused distinctmorphological changes in theStrigaradicles. Radicle elongationceased 8 h after contact with host roots and radicle hairs developed.These hairs adhered to the surface of the host root. Early stagesof root penetration, i.e. prior to connection to the host vascularsystem were examined by light microscopy and transmission electronmicroscopy to determine the mechanisms by whichStrigainvadesroot tissue. Cowpea roots were penetrated byS. gesnerioidesradiclesafter 48 h. Host cells immediately surrounding the invadingStrigawerecompressed, but other host cells were not affected. Immunocytochemistry,using monoclonal antibodies JIM 5 and JIM 7, showed thatStrigaadvancedintercellularly through the root tissues without extensive removalof pectins at the site of penetration.Copyright 1998 Annalsof Botany Company Striga gesnerioides,Vigna unguiculata, mechanisms of penetration, host-parasite interactions, electron microscopy, immunocytochemistry.     

Does Cytokinin Transport from Root-To-Shoot in the Xylem Sap Regulate Leaf Responses to Root Hypoxia?

We have examined the hypothesis that cytokinins transportedfrom roots to shoots affects leaf growth, stomatal conductance,and cytokinin concentration of leaves of Phaseolus and a hybridpoplar (Populus trichocarpa x Populus deltoides) with hypoxicroots. Because cytokinins may interact with other substances,potassium and calcium concentrations were determined in xylemsap of Populus plants with hypoxic and aerated roots while gibberellin(GA) concentrations were measured in shoot tissues. Root hypoxiadecreased leaf growth and closed stomata in both species. Inboth species, fluxes of cytokinins out of the roots were reduced,but no differences in bulk leaf concentrations were measuredbetween the hypoxic and aerated plants. Shoots with aeratedroots contained slightly higher concentrations of GA₁ and GA₃than shoots from hypoxic plants. There were no differences incalcium or potassium concentrations in xylem sap between aerationtreatments. Exogenously applied cytokinins did not alleviatethe growth or stomatal responses caused by root hypoxia. Informationon the site(s) and mechanism(s) of cytokinin action and theways in which cytokinins are compartmentalized within plantcells will be required to understand the physiological significanceof cytokinin transport in the transpirational stream. Key words: Cytokinins, hypoxia, Populus, Phaseolus     

Insight into the structure and chemistry of glandular trichomes of Labiatae, with emphasis on subfamily Lamioideae

Glandular trichomes of Labiatae are among the most investigated secretory structures. Most species studied belong to subfamily Nepetoidae, including plants with aromatic properties, while so far a few species of subfamily Lamioideae were examined. In this work, we studied the micromorphology, ultrastructure, type and release of secretion of the glandular trichomes present on leaves and flowers of several species belonging to subfamily Lamioideae, (Stachys alopecuros (L.) Bentham subsp. alopecuros, S. officinalis (L.) Trevisan subsp. officinalis, S. germanica L. subsp. germanica, S. germanica L. subsp. salviifolia (Ten.) Gams, S. sylvatica L., S. heraclea All., S. plumosa Griseb., S. annua L., Prasium majus L., Sideritis romana L.) and one to the sister group Scutellarioideae (Scutellaria galericulata L.). Besides the well-known peltate and small capitate trichomes, widely described in the literature, other types of glandular trichomes were encountered; stalked peltate hairs and large capitate hairs. In particular, a new type of capitate trichome, exclusive of calices and corollas, which presents a mode and release of secretion never described before, is reported.     

Cryo-Preservation of Roots for Scanning Electron Microscopy

Fully hydrated roots can be examined in the scanning electronmicroscope after cryo-preservation. Shrinkage associated withdehydration by freeze-drying or critical point drying, to whichroot hairs and secreted mucigel are particularly vulnerable,is avoided. Roots, Lepidium sativum, scanning electron microscopy, cryo-preservation, fully hydrated     

Sodium Absorption and Distribution in Forage Grasses of Different Potassium Status

The absorption and distribution of sodium were examined in threegrasses grown in flowing solution culture with different suppliesof potassium. There were marked differences between the speciesin the rate of absorption by their roots, timothy absorbingat a much slower rate than either ryegrass or cocksfoot. Inall species, the rate of Na absorption was greatest when therewas a maintained supply of K and/or when the K contents of theplants were high. Transport of Na from roots to shoots of timothywas restricted; it was less restricted in the other speciesand large proportions of the Na moved from roots to shoots whenK was not supplied to the plants. Sodium transported from theroots accumulated in old leaves and not in the younger leaves.When K was no longer supplied, the growth of ryegrass was maintainedin the plants previously grown with Na plus K; Na supplied insteadof K, however, did not maintain growth. Cocksfoot grown withNa grew less well than when grown without Na when plants wereno longer supplied with K; the growth of timothy was unaffectedby Na. Dactylis glomerata L., Lolium perenne L., Phleum pratense L., cocksfoot, ryegrass, timothy, absorption of ions, distribution of ions, potassium, sodium     

Effects of Copper Toxicity on Leaves of Oregano (Origanum vulgare subsp. hirtum)

The effects of increasing concentrations of soil copper on anumber of leaf structural parameters in oregano plants werestudied to determine the effect of copper toxicity. Copper-stressedleaves were small and chlorotic and underwent a thickening oftheir lamina, due principally to an increase in the number andvolume of mesophyll cells. The number of stomata and glandularand non-glandular hairs increased significantly. Chloroplastsof mesophyll cells declined dramatically in number and volume.Grana and stroma thylakoids of chloroplasts did not undergoany noticeable alterations, but starch grains disappeared, plastoglobulibecame larger and the double membrane limiting the chloroplastbecame dilated. Leaf chlorosis was determined by total chlorophyllanalysis and measurement of the leaf Cu, Fe and Mg content.The effects of copper toxicity on oregano leaves comprised significantstructural alterations which reflect reduced metabolic activity.Copyright 2001 Annals of Botany Company Origanum vulgare subsp, hirtum, oregano, copper toxicity, leaf, structure and ultrastructure, morphometry, inorganic elements, tissue relative volumes     

Effect of Root Temperature on the Infection Processes and Nodulation in Lotus and Stylosanthes

Infection threads were observed abundantly in the root hairsof Lotus corniculatus L., but very rarely in L. hispidus, Desf.,in response to infection by Rhizobium strains 3001 and 3002.Numbers of infections differed between species and strains andwere also affected by temperature. In L. corniculatus all thenodules originated from infection threads, but in L. hispidusmost nodules appeared to originate by direct bacterial penetrationthrough the epidermis, and infected root hairs were very rarelyseen. Both species of Lotus were tolerant to cold temperatures,the minimum temperature for nodulation being 10 ?C. The optimumtemperature for nodulation of L. corniculatus was 20 ?C with3001 and between 27 and 30 ?C with 3002, a few nodules beingformed with both strains at 35 ?C. L. hispidus formed more nodulesthan L. corniculatus and the optimum temperature for both thestrains was between 25 and 27 ?C. No infection threads were seen in root hairs or nodules of Stylosanthesguyanensis (Aubl.) S. W. and S. humilis H.B.K. infected withRhizobium strain CB1552, and all the nodules were formed inthe axils of lateral roots. Optimum temperature for nodulationin S. guyanensis and S. humilis was around 27 ?C; nodulationwas completely inhibited at 15 ?C and very few nodules wereformed at 35 ?C. Both in Lotus and Stylosanthes the transfer of plants from suboptimalto optimal and supraoptimal temperatures increased nodulation.Delayed inoculation and excision of root tips increased nodulation.     

Factors Influencing Adventitious Root Production in Cuttings of Griselinia littoralis and Griselinia lucida

Griselinia littoralis roots quickly and vigorously from cuttingsof seedlings and mature plants and also forms roots on detachedleaves. Cuttings root in the dark but leaves must be present.In contrast G. lucida roots vigorously only from cuttings takenfrom seedlings. Light is essential for root formation on oldermaterial. Detached leaves will not root. Although callus formationat the cut base commonly occurs in both species it is not directlyassociated with root formation. Griselinia littoralis Raoul Choix, Griselinia lucida Forst. f. Prodr., adventitious roots, stem cuttings, leaf cuttings, woody plants     

Ionic Relations of Garden Orache, A triplex hortensis L.: Growth and Ion Distribution at Moderate Salinity and the Function of Bladder Hairs

The growth of garden orache, A triplex hortensis was studiedunder conditions of mild NaCl or Na₂SO₄ salinity. Growth, drymatter production and leaf size were substantially stimulatedat 10 mM and 50 mM Na⁺ salts. Increased growth, however, appearedto be due to a K⁺-sparing effect of Na⁺ rather than to salinityper se. The distribution of K⁺ and Na⁺ in the plant revealeda remarkable preference for K+ in the roots and the hypocotyl.In the shoot the K/Na ratio decreased strongly with leaf age.However, the inverse changes in K⁺ and Na⁺ content with leafage were dependent on the presence of bladder hairs, which removedalmost all of the Na⁺ from the young leaf lamina. Measurementsof net fluxes of K⁺ and Na⁺ into roots and shoots of growingAtriplex plants showed a higher K/Na selectivity of the netion flux to the root compared to the shoot. With increasingsalinity the selectivity ratio S_{K, Na}^* of net ion fluxes tothe roots and to the shoots was increased. The data suggestthat recirculation of K⁺ from leaves to roots is an importantlink in establishing the K/Na selectivity in A. hortensis plants.The importance of K⁺ recirculation and phloem transport forsalt tolerance is discussed. Key words: Atriplex hortensis, Salinity, Potassium, Sodium, K⁺ retranslocation, Bladder hairs, Growth stimulation