The Ultrastructure of the Host-parasite Interface in the Needles of Pinus nigra Infected with Lophodermella sulcigena

The hyphae of Lophodermella sulcigena are usually surroundedby an electron-opaque matrix when growing in the needles ofCorsican pine (Pinus nigra var. maritima). The host-parasiteinterface is of a type which has been little studied; the intercellularhyphae kill the mesophyll cells of the host ahead of themselvesand their walls are separated from those of the host by a matrix.The first signs of injury to the host are disorganized membranesystems, particularly the thylakoid and bounding membranes ofthe chloroplasts break down. The dead host cells are filledwith resin or tannin in which only the starch grains are visible.     

The development of the grape berry cuticle in relation to susceptibility to bunch rot disease

Some physical and morphological factors of grape berry cuticlewere investigated at different developmental stages of threeclones ofVitis vinifera cv. Pinot noir. The surface morphologyof grape berries was examined by scanning electron microscopyand cuticle anatomy was examined by light and transmission electronmicroscopy. During the period from flowering to maturity, thecomposition of the cuticular waxes changed, corresponding withan increase of waxy deposits and significant modifications ofthe wax surface morphology. The content in cutin per unit surfacedecreased more than 2.5-fold between berry set (16 d after anthesis)and veraison of the grape berries, and might predispose thegrape berry to fungal infection. This result was correlatedwith the differentiation of the cuticle layers and particularlywith a decrease in the thickness of the primary cuticle at harvest. Key words: Botrytis cinerea, cuticle, cutin, epicuticular waxes, Vitis vinifera L     

Long-distance Transport of Reduced Sulphur in Spruce (Picea abies L.)

Individual needles of 4-year-old spruce trees (Picea abies L.)were exposed to ³⁵S-GSH via the cut surface of the needle tipfor 2–3 h at different times during the growing season.From the previous year's source needle, ³⁵S-GSH was exportedinto the twig and translocated predominantly towards the twigapex. Independent from the growing season, transport towardsthe stem did not exceed 20% of the radioactivity recovered fromthe tissue samples. In July, the new needles appeared to bemetabolic sinks for reduced sulphur as indicated by the higherpercentages of both soluble and insoluble ³⁵S in this twig section,as compared to the previous years' needles. In October, thenew needles were no longer found to be a preferential sink forreduced sulphur. Estimates of the rate of GSH export from thesource needle in the light (2.5–11.3 nmol GSH g     

马尾松毛虫对马尾松和湿地松的选择与适应研究

用马尾松老叶、新叶,湿地松老叶、新叶,当年生马尾松新叶、湿地松新叶和当年生以20％和40％β-蒎烯处理过的马尾松新叶作食料饲养马尾松毛虫。结果表明：马尾松毛虫幼虫在第1代发生期取食马尾松老叶、马尾松新叶、湿地松老叶和湿地松新叶等4种不同质量的食料后,因其食料中10种必需氨基酸含量和挥发性物质β-蒎烯含量的不同,导致幼虫的存活率差异显著。其中,取食马尾松老叶的幼虫成活率最高（44％）,依次为马尾松新叶（32.7％）、湿地松老叶（4％）,而取食湿地松新叶的幼虫全部死亡。通过马尾松针叶增加外援β-蒎烯喂养马尾松毛虫实验,表明增加了外源β-蒎烯的松针饲养的马尾松毛虫幼虫与用同样松针未增加外源β-蒎烯饲养的幼虫相比,死亡率明显提高;松树中β-蒎烯含量的增加与幼虫成活率呈显著负相关。由此,我们阐明了马尾松与湿地松对马尾松毛虫的抗虫机制。     

The uptake of and structural changes induced by trichloroacetic acid in the needles of Scots pine seedlings

The uptake of trichloroacetic acid (TCA) and structural changesinduced in the needles of Scots pine (Pinus sylvestris L.) seedlingswere studied. Two exposure set-ups, a root route and an atmosphericroute through the surfaces simulating the wet deposition offog, were used. Both set-ups included two dose levels and correspondingcontrol treatments. The temperature and the relative humidityin the climate chambers were adjusted to represent the conditionsof June–July in a subarctic area in central Finland. Theseedlings were exposed three times a week for two months. Theresults showed that the uptake of TCA in needles occurred bothvia roots and via needle surface. However, most of the TCA viathe atmospheric route was absorbed on the surface of the needles.The structural responses in pine needles depended partly onthe treatment method: TCA applied via the atmospheric routedisintegrated the structures of the epicuticular waxes and thatof the stomatal cells, which was not seen in the exposures viaroots. A common feature was the decrease in size of the chloroplastsin concert with the increasing TCA concentrations inside theneedles. Key words: Pinus sylvestris L., climate chamber, effects, microscopic structure, secondary pollutant, TCA, trichloroacetic acid     

Needle browning and death in the flagged crown of Abies mariesii in the timberline ecotone of the alpine region in central Japan

In the flagged crown, which is asymmetric growth formed by severe stresses during winter in alpine regions, needles of evergreen conifers often became brown and died in early spring, but did not in a cushion-shaped crown. Needle browning and death is thought to occur by increasing transpiration due to a thinner cuticle or mechanical damage to the cuticle by wind-born snow and ice particles. To confirm whether the needle browning and death in the flagged crown of Abies mariesii Mast., in the alpine region of Japan conform with this concept, we assessed mechanical damage of the needle cuticle in a timberline ecotone and evaluated the effect of cuticle thickness on cuticular resistance. Mechanical damage on needle cuticles of A. mariesii was not observed. In the cushion-shaped crown, epicuticular wax covered the cuticle and plugged stomatal antechambers. In the flagged crown, epicuticular wax was mostly absent. Cuticular resistance in the flagged crown was lower than that in the cushion-shaped crown. However, the cuticle in the flagged crown was thicker than that in the cushion-shaped crown. The needle browning and death in the flagged crown of A. mariesii occurred even though needle cuticles were not mechanically damaged. The thicker cuticle of the flagged crown may play a role in other stresses. To estimate desiccation stress in relation to the cuticle, we need to elucidate not only cuticular resistance and cuticle thickness, but also cuticle quality and structure.     

Structure of the Needles in the Early Phases of Development in Pinus ponderosa P. et C. Lawson with Special Reference to Plastids

Before they emerged from the fascicular sheath, the tissuesof young needles of Pinus ponderosa P. et C. Lawson alreadyshowed some characteristics typical of mature needles. The organelles,particularly the plastids, had undergone different development.The plastids in different types of cell varied in their ultrastructureand in association with the endoplasmic reticulum (ER). A sheathof ER was observed around the amoeboid plastids in epidermalcells, epithelial cells of resin ducts and maturing transfusiontracheids whereas there was no ER sheath around the young mesophyllchloroplasts, the fusiform chloroplasts in some transfusiontracheids and the proplastids in xylem and phloem cells. Thecontent of chlorophyll (a+b) was 0·85 g kg^-1 dry matterand chlorophyll a/b ratio was 2·70. The needles may becomephotosynthetically active whilst still within the fascicularsheaths.Copyright 1993, 1999 Academic Press Pinus ponderosa, ponderosa pine, needle structure, needle ontogeny, plastids, endoplasmic reticulum     

Studies on Mature Seeds of Cuscuta pedicellata and C. campestris by Electron Microscopy

The seeds of Cuscuta pedicellata have been investigated by transmissionand scanning electron microscopy. Additional observations havebeen made on seeds of C. campestris by SEM only. The seed coatconsists of an outer single epidermis, two different palisadelayers, and an inner multiparenchyma layer. The outer epidermalwall in C. pedicellata has a thick cuticle and zones rich inpectic substances. The thicker ‘U-shaped’ cell wallsin the outer palisade layer are strengthened by a wall layerof hemicellulose. The inner palisade layer has thick walledcells with a ‘light line’. The inner cell wall ofthe compressed multiparenchyma layer has a thin cuticle. A fairlythick cuticle is positioned directly on the endosperm surface.The aleurone cell walls are different from the remaining endospermwalls. The latter are thick and believed to be of galactomannans.There is a ‘clear’ zone between the plasmalemmaand the cell wall in the aleurone cells. The embryo cells arepacked with lipids and proteins. In Cuscuta campestris mostendosperm has been absorbed during the seed development. Theembryo apex has two minute leaf primordia. The features of theCuscuta seeds are discussed in relation to functional and environmentalconditions. Cuscuta pedicellata, Cuscuta campestris, seed, seed coat, cuticle, cell walls, endosperm, aleurone cells, galactomannan, embryo, TEM, SEM     

Movement of Nutrients in Radiata Pine Needles in Relation to the Growth of Shoots

The pattern of needle growth and the movement of mineral nutrients(nitrogen, phosphorus, potassium and calcium) in needles ofradiata pine (Pinus radiata D. Don) were studied from needleinitiation to 2 years of age. During this period, very prominentcyclic patterns of nutrient accumulation, retranslocation andreplenishment were observed for nitrogen, phosphorus and potassium,which highlighted the potential role of needles as a nutrientreserve for growth. Significant retranslocation occurred from very young needlesabout 3 months after initiation. The phases of retranslocationcoincided with new flushes of shoot growth, and the growth ofnew shoots on a branch resulted in nutrient withdrawal frompre-existing needles, regardless of needle age and season. Suchwithdrawal occurred even in fertilized and irrigated trees onhigh quality sites and under environmental conditions conducivefor nutrient uptake. At all times, except for the short periodafter initiation when needles were actively growing, the nutrientsin the needle were readily available for retranslocation. Contraryto the general view, retranslocation of nutrients was not necessarilyrelated to senescence and ageing of needles. Because new shoots are the primary ‘sinks’ for retranslocatednutrients, an ongoing competition between different parts ofa branch for internal nutrients can be envisaged, preferencebeing for the youngest shoot in the hierarchy. The relevanceof these results to our understanding of ‘optimum nutrition’of pine trees is discussed. Pinus radiata D. Don, radiata pine, mineral nutrition, retranslocation, phosphorus, nitrogen, shoot growth     

Variation with Tree Age of Needle Cuticle Topography and Stomatal Structure in Pinus radiate D. Don

Scanning electron microscopy reveals differences in the surfacetopography and stomatal structure of 1-year-old needles of Pinusradiata sampled from trees of different ages. The cuticularridges on young-tree needles show an even pitch, whereas theridges on mature-tree needles appear slightly puckered, withsmall discontinuities. The stomata on mature-tree needles havea smaller pore (10–15 µm) than young-tree needles(15–20 µm). In young trees a fine rodlet, or tubularwax covers the walls of the guard and subsidiary cells. Thestomatal antechamber predominating in mature-tree needles containsan amorphous wax, which frequently closes the pore between theoverarching stomatal lips. The yield of crude wax from chloroformextracts of needles of trees of all ages is approximately 0.2per cent, and there is more of the acidic component in the waxof mature-tree needles. It is suggested that wax occlusionswithin the stomatal antechamber of P. radiata may contributeto mature-tree resistance to the needle pathogen, Dothistromapini Hulbary.     

Accumulation of Phenolic Compounds in the Necrotic Areas of Austrian and Red Pine Needles Due to Salt Spray

Austrian pine (Pinus nigra) and red pine (P resinosa) were testedfor needle damage caused by salt spray. Morphology and histologyof newly grown needles were compared in 3- and 6-year-old plantsgrowing in the greenhouse under controlled conditions. Pottedplants covered with plastic bags were sprayed daily either withdistilled H₂O or saturated salt solution. Needle tips, mid-partsand bases were fixed after 1, 3 and 24 h, and 3, 7 and 30 din glutaraldehyde+0·1 % caffeine for precipitation ofphenolics. Histochemical reactions and electron microscope observationsshowed that the morphological damage is linked to increasedphenolic compound deposition in mesophyll cells, beginning directlyunder the stomata. Disorganization of membranes leads to deathof the mesophyll cells, even before morphological damage isrecognizable as brown spots on the needle surface. Thus thehistochemical reactions and observations of cell structure revealeddamage earlier than macroscopic observations. Salt injury, phenolic compounds, histological damage, ultrastructural damage, salt spray, Pinus nigra, Austrian pine, Pinus resinosa, red pine     

Growth and Nutrient Retranslocation in Needles of Radiata Pine in Relation to Nitrogen Supply

The effects of N application on tree growth and the retranslocationof N, P, and K from young needles to new growth were examinedin young radiata pine (Pinus radiata D. Don) trees. Nitrogen fertilization increased the number and size of needles,rates of shoot production, stem volume growth and tree biomass.Foliar N and P contents (µg per needle) fluctuated ina cyclic fashion with prominent phases of accumulation, retranslocationand replenishment. The patterns of these fluctuations in controland N-fertilized trees were similar, although the fluxes ofN, P and K in and out of needles were increased by N fertilization.Greater translocation (g per tree) of N and K from needles ofN fertilized trees occurred because fertilization increasedthe needle weight and the proportion of N and K retranslocatedfrom individual needles. Nitrogen fertilization increased theretranslocation of P largely as a result of higher needle mass.Trees supplied with more than adequate amounts of P in the soilretranslocated up to 58 per cent of the initial pool of P fromyoung needles. The periods of high retranslocation coincidedwith periods of high concentrations of soil mineral N and withshoot production. Conversely, the periods of rapid replenishmentof N and P into the needles coincided with the time of slowshoot growth and low concentration of soil mineral N. The growthrate of trees, rather than the availability of nutrients inthe soil was the main factor controlling retranslocation. For radiata pine, retranslocation from needles is not a mechanismspecific for coping with low soil fertility. It seems to bea mechanism which enhances the nutrient supply to apical growingpoints, especially during periods of flushing. Pinus radiata, nitrogen supply, shoot growth, nutrient fluctuations and retranslocation, nutrient use and adaptation     

Surface areas,lengths and volumes of Picea abies (L.) Karst. needles: determination,biological variability and effect of environmental factors

Summary A method for the rapid determination of the lengths and surface areas of very large samples of needles of Picea abies (L.) Karst. using a computer-aided image analysis system was developed. Two independent methods for measuring non-destructively the volumes of individual needles and of all needles attached to a twig were devised. The surface areas and lengths of about 38000 needles sampled from the three youngest needle age-classes (1986, 1985, 1984) of 48 trees approximately 130 years old at four sites in the Fichtelgebirge mountains (N. E. Bavaria, FRG) were measured. The frequency distributions of lengths and areas for each site and age-class are given. Variability of needle size was fairly large. Even though the sites differed in climate, soil, and air pollution levels no consistent effect of these factors on needle size could be detected. Needle lengths and surface areas did not correlate with either the total chlorophyll content of the needles or the degree of crown thinning. The needle surface area (in mm²) of fully developed P. abies needles can be estimated by the empirical equation surface area = 4.440 x needle length -24.8 (r = 0.937), and the needle volume (in mm³) by needle volume = 0.208 x projected needle area ^1.353 (r = 0.969).     

Pollen-Stigma Interaction in the Leguminosae: Stigma Organization and the Breeding System in Vicia faba L.

As in other papilionoid Leguminosae, the receptive surface ofthe stigma of Vicia faba L. is invested by a detached cuticle.This cuticle, the so-called ‘stigma membrane’ ofplant breeding literature, is lifted away from the epidermisduring development by the accumulation of a lipid-rich secretionreleased into the intercellular spaces of the stigma head bythe epidermal cells and the underlying three to four cell layers.The cuticle is thickened over the prominences left by the epidermalpapillae, thinning out between. Pollen, whether self or cross,cannot hydrate and germinate in contact with the intact stigmasurface, but must await the disruption of the cuticle and therelease of the retained secretion. In most genotypes this takesplace only when the flower is tripped by visiting pollinatorsor in consequence of severe agitation by wind. A comparison of lines differing in their degree of autofertilityin field conditions has revealed various differences in stigmastructure. A highly autofertile line had low papillae at thereceptive tip, with a relatively thin intervening cuticle, whilean autosterile line had longer papillae and a thicker cuticle.A line with partial autofertility was intermediate in thesecharacteristics. These properties of the stigma surface, togetherwith other differences in flower structure, are probably adequateto account for the variation in the degree of autosterility,since no evidence was obtained suggesting the presence of aneffective physiological self-incompatibility system in any ofthe lines studied. Since the rupturing of the stigma cuticle is affected by theturgor pressure of the cells of the stigma and style, some degreeof environmental interaction is to be expected: autofertilityshould be at the highest in conditions of adequate water supply,and lowest where there is water deprivation. Pollen-stigma interaction, Vicia faba L., Leguminosae, breeding system, self-incompatibility     

Within-crown Foliar Plasticity of Western Hemlock, Tsuga heterophylla, in Relation to Stand Age

Anatomy and morphology of needles from six different positionswithin the crowns of western hemlock,Tsuga heterophylla (Raf.)Sarg., were studied to investigate the plastic response of leafstructure to crown position, in relation to stand age. Treeswere sampled from three stands, all of which originated followingcatastrophic fires, representing a chronosequence (15, 55 and145 years old) of stand development. Needles from the highestand outermost crown positions showed morphological and anatomicalresponses normally associated with ‘sun leaves’.As a measure of expressed plasticity, we calculated a relativetrait range (RTR) index to quantify differences in expressedtraits between needles from the upper outer crown (UO needles)and those from the lower inner crown (LI needles). RTR was positivefor most morphological and anatomical traits, indicating largertrait measurements on UO needles relative to LI needles (e.g.UO needles were thicker and had more vascular tissue than LIneedles). However, the degree to which sun and shade leaf traitswere expressed varied between stands. In the youngest stand,UO needles had higher maximal rates of photosynthesis than LIneedles (positive RTR_Ps), but this trend was reversed in theoldest stand (negative RTR_Ps). Mean RTR across all morphologicaland anatomical traits was higher in the 145-year-old stand thanin either the 55-year-old stand (P = 0·03) or the 15-year-oldstand (P < 0·01). While this probably relates mainlyto differences in light conditions between the three stands,it may also indicate a connection between ontogeny and phenotypicplasticity. Copyright 2001 Annals of Botany Company Foliar plasticity, needle anatomy and morphology, ontogeny, photosynthesis, stand development, sun–shade, Tsuga heterophylla(Raf.) Sarg., western hemlock     

祁连圆柏针叶解剖结构对高原寒旱环境的适应性分析北大核心CSCD

祁连圆柏(Juniperus przewalskii)是青海省森林生态系统的重要组成部分,为揭示祁连圆柏对高原寒旱环境的适应特性,该研究以青海省祁连圆柏当年生针叶为研究对象,采用石蜡切片法制片,测定其叶宽、叶厚、下角质层厚、下表皮细胞厚、叶维管束木质部及韧皮部厚,并利用回归分析及偏相关分析探讨了针叶解剖结构对经纬度、海拔、坡向的响应特征。结果表明:(1)祁连圆柏针叶解剖结构在经纬度上无显著变化,其解剖结构与经纬度均无显著相关性。(2)祁连圆柏针叶解剖结构与海拔关系存在阶段性和结构间的差异性,在环境压力较小的低海拔段(<3 200 m)无显著变化;在海拔3 200 m以上,祁连圆柏叶宽、叶厚、下角质层厚、下表皮细胞厚随海拔升高而不同程度地增厚;当海拔高于3 680 m时各针叶解剖结构增长趋势变缓,尤其是叶宽、叶厚增速下降比例更大;下角质层厚和下表皮细胞厚与海拔相关性最强,其次是叶厚、叶宽,但叶维管束木质部厚以及韧皮部厚与海拔始终均未表现出显著相关性。(3)6个地区阴坡祁连圆柏针叶下角质层厚均高于阳坡,且下角质层厚与坡向显著相关。研究认为,祁连圆柏对高原寒旱环境适应性强,经纬度变化、低海拔段和阳坡的环境压力不足以使其产生相应结构变化;在阴坡其通过增厚针叶下角质层厚来提高耐寒性,在高海拔段其通过增厚下角质层、下表皮细胞层以及叶宽、叶厚来适应极寒极旱等复杂的环境压力。     

Histochemistry of Corsican Pine Needles Infected by Lophodermella sulcigena (Rostr.) v.Hohn.

A histochemical survey was made on lesion development in Pinusnigra (Aiton) Melville infected by Lophodermella sulcigena (Rostr.)v. Höhn. The fungus colonized the intercellular spacesof the mesophyll and then invaded the endodermis, hypodermisand epidermis. All tissues within the lesion were killed. Lesionexpansion ceased in autumn when a stationary interface was establishedbetween infected mesophyll and healthy host cells at the needlebase. The stationary interface was marked by a zone of fungalfree,dead mesophyll cells and the appearance of an intercellularmatrix. Extensive hypertrophy and hyperplasia occurred in parenchymatissues at the interface. Protein, starch and DNA persistedin tanned cytoplasm for many months.     

Ultrastructure and Radiolabelling of Leaf Cuticles from Ivy (Hedera helixL.) Plantsin vitroand duringex vitroAcclimatization

Cuticle ultrastructure and radiolabelling of isolated cuticlesafter incorporation of [¹⁴C] acetate in foliar discs were investigatedwith ivy plants grownin vitrothenex vitro. Results show an increasein thickness, mass and wax content, between young and expandedleaves, for bothin vitroandex vitrocuticles. The cuticle ofinvitrounexpanded leaves was very thin and only constituted alamellate zone. The ultrastructure ofin vitroyoung and expandedleaf cuticles showed characteristics similar toin situcuticles.The thickness of the lamellate zone remained fairly constantand represented 33% of the cuticle thickness in young leaves,but only 11.4% in expanded leaves. The number of lamellar unitsdecreased from 14 to nine between these two growth stages. Themain difference between young leaves developedin vitroorex vitrowasa thinner lamellate zone forex vitrocuticles. However, theselatter cuticles had an intermediary zone between the lamellateand reticulate zones. The cuticle thickness of expanded leaveswas greater forin vitrocuticles suggesting a temporary decreasein cuticle biosynthesis after transfer of the plant fromin vitrotoexvitro.Results from cuticle radiolabelling show higher radioactivityincorporation in cuticles isolated from leaves developedex vitrocomparedtoin vitro. This radiolabelling was particularly marked forexvitroyoung leaf cuticles and depended on the duration of theexvitrogrowth period revealing a progressive activation of cuticlebiosynthesis in response to new environmental conditions. Hedera helix; ivy leaf cuticle; in vitroplants; electron microscopy; radiolabelling; isolated cuticles     

The presence of structural surface waxes on coniferousneedles affects the pattern of dry deposition of fine particles

Monodisperse particles (particle diameter 0.5 µm) wereproduced by a particle generator and tagged witha fluorescentdye. The particles were injected into asmall wind tunnel, intowhich single needles or small branches of Picea abies, Pinussylvestris, and Abies alba had been introduced. The needleswere examined after treatment, using fluorescence microscopy,and the spatial patterns of particle deposition determined. The particles deposited preferentially in the stomatal regionsof the needles. In these areas the incidence of micro-roughnessdue to epicuticular waxes is highest, reducing the laminar boundarylayer of the needle. Atmospheric particles of less than 1 /mdiameter are mostly hygroscopic and the potential effect ofsubstantial deposition of these particles to stomatal surroundingsand their influence on plant water relations is discussed. Key words: Conifers, air pollution, stomata, dry deposition, aerosols