The Generic Position of Protorhus namaquensis Sprague (Anacardiaceae): Evidence from Fruit Structure

In Protorhus namaquensis the outer epidermis of the ovary formsthe exocarp. At maturity it is uniseriate and consists of palisade-likeparenchyma cells and modified stomata (MS). A cuticle, extensivecutinization of the outer cell walls and starch also characterizethe exocarp. The mesocarp develops from the ground tissue ofthe ovary wall and includes an outer zone of large-celled tanniniferousparenchyma, secretory ducts associated with some of the vascularbundles, prismatic crystals of calcium oxalate and brachysclereids.The inner epidermis of the ovary undergoes successive periclinaldivisions whose derivatives form the mature endocarp. It isstratified and tetraseriate, comprising successive layers (frommesocarp inwards) of crystalliferous cells, brachysclereids,osteosclereids and macrosclereids. The morphology of the femaleflower, and the fruit structure of P. namaquensis are comparedwith that of P. longifolia (lectotype of the genus and onlyother African species) and species of Ozoroa. We present abundantevidence that P. namaquensis should be associated with somemembers of the genus Ozoroa , rather than with P. longifolia.The new combination, Ozoroa namaquensis (Sprague) Von Teichman& Van Wyk, is proposed. Characters of the perianth and pericarp,inter alia the occlusion of the pores of most MS, are consideredadaptations of the species to its harsh semi-desert habitat.Copyright1994, 1999 Academic Press Anacardiaceae, Protorhus namaquensis, Ozoroa namaquensis, pericarp, fruit, flower, modified stomata, ontogeny, histochemistry, cutin     

Mechanisms Involved in Delayed Germination of Quercus nigra L. Seeds

Neither the pericarp nor the seed coat impose significant barriersto passage of water in Quercus nigra seeds. The pericarp eventuallybecomes limiting to continued swelling due to its mechanicalstrength. During stratification trapped gasses escape and continuedswelling of the cotyledons causes expansion of the pericarp.Vigorous acorns need around 105 days of combined stratificationand germination time to reach maximum germination. This additivityphenomenon is true for stratification times between 4 and 10weeks. Delayed germination is caused by at least three factors:(1) Mechanical strength of the pericarp, which was constantduring the observation period of 13 weeks; (2) Chemical inhibitionby the pericarp, which was alleviated by stratification forapproximately 4 weeks; (3) Slowly increasing capacity to imbibewater required for pericarp rupture. This component was apparentlynot dependent on temperature within the range of 5 to 30 °C,and operates during the entire stratification and germinationperiod. Quercus nigra L, water oak, seed germination, pericarp, stratification, dormancy     

Changes in nitrogen contents and in proteolytic activities in different parts of field-grown wheat ears (Triticum aestivum L.) during maturation

Aminopeptidase, carboxypeptidase and neutral endopeptidase activitieswere analyzed in glumes and in kernels of field-grown wheat(Triticum aestivum L.) during ear development. Kernels harvestedon two dates were subdivided into outer pericarp, cross cells,endosperm and embryo. In developing parts with a net nitrogeninflux (young glumes, embryo, endosperm) the aminopeptidaseactivity is high, but in nitrogen-mobilizing tissues (senescingglumes, Outer pericarp) this activity decreases. Carboxypeptidaseis most active in fully expanded tissues. Neutral endopeptidaseshows the highest activity in the nitrogen mobilizing partsand extremely low activity in the embryo and the endosperm. (Received July 15, 1978; )     

Dehiscence of Fruit in Oilseed Rape (Brassica napus L.): I. ANATOMY OF POD DEHISCENCE

The development sequence of anatomical changes taking placewithin the pericarp tissues of Brassica napus siliquae havebeen studied at a fine- and ultra-structural level. Tissue differentiationoccurred during the initial 20 d after anthesis (DAA) and allowedthe identification of dehiscence zone cells. This descrete tissuewas subsequently further delineated by extensive lignificationof adjacent valve edge and replar vascular cells. Concomitantwith the onset of pericarp lignification, cytoplasmic contentsof the thin-walled dehiscence zone cells exhibited progressivesenescence and degradation. Wall breakdown, initially evidentin pods by 60 DAA, exclusively affected cells within the dehiscencezone, and eventually extended throughout this tissue from theepidermal suture to the locule, thus precipitating valve detachment.Ultrastructural examination confirmed that this loss of cellularcohesion was primarily attributable to middle lamella degradationand, furthermore, the dissolution of wall material was apparentlydependent on rupture of the dehiscence zone protoplast. Thesignificance of dehiscence zone cell modifications in relationto autolytic cell wall breakdown, together with possible implicationsfor the regulation of pod shatter, are discussed. Key words: Oilseed rape, Brassica napus, pod shatter, dehiscence zone, cell wall breakdown     

Centaurea subsect. Phalolepis in Southern Italy: ongoing speciation or species overestimation? Genetic evidence based on SSRs analyses

In this paper, we investigated a set of narrow endemics of Centaurea subsect. Phalolepis from the mountains of South Italy (mainly Calabria and Salento), segregated from the widespread species Centaurea deusta, using microsatellite (SSR) markers. The goal was to analyse the genetic makeup (levels and structure) of C. deusta and the segregated species and verify whether genetic clusters were in agreement with current classification of the species. With C. deusta, we also carried out an ecological niche modelling (ENM) analysis to check its potential distribution under present climatic conditions and to project it to the Last Glacial Maximum (LGM). As also found in former studies with subsect. Phalolepis in Greece and Turkey using the same set of SSRs, genetic diversity for the segregated Italian species was higher than expected for narrow endemics with small populations. Genetic clusters, however, were not correlated with the described species and did not support the segregation of the purported narrow endemics from a widely defined C. deusta. The results of the ENM indicate that the Adriatic Sea was a migration corridor for C. deusta at the LGM.     

Morphology and Ultrastructure of Immature Cereal Grains in Relation to Transport

The surfaces of the pericarps of wheat and barley grains, 15–30days after anthesis, were examined. Stomata were found in thepericarp epidermis on the ventral side at the apical end inone variety of wheat and four varieties of barley. Layers whichstained red with Sudan IV were observed on the pericarp epidermisand on either side of the testa in immature barley grains. Theultrastructure of these layers was investigated. It was concludedthat the cuticular layer inside the testa is derived from thenucellus. The significance of these cuticular layers in relationto the supply of carbon dioxide to the photosynthesizing cellsof the pericarp is discussed. The movement of photosynthateand oxygen produced in the pericarp is also considered. Hordeum vulgare L, Triticum aestivum L, barley, wheat, cereal grain, cuticle, stomata, pericarp     

Light-Dependent CO2 Retrieval in Immature Barley Caryopses

Immature detached caryopses from barley (Hordeum vulgare L.var. distichum cv. Midas) were shown to be capable of light-dependentretrieval of internally-produced CO₂. In the first set of experiments,caryopses were radioactively labelled by supplying (U-14C)-sucroseto detached ears in liquid culture. Caryopses were then removedfrom the ear and given a 12 h chase of non-radioactive sucrosein either the light or dark. More ¹⁴C was recovered in the caryopsesafter the chase in the light than in the dark but the differenceswere not significant. In the second set of experiments, ¹⁴C-labelledcaryopses obtained by a 15 min light incubation in ¹⁴CO₂ weremaintained in either the light or dark for 3 h and any redistributionof label between the tissues recorded. The results show thatunder these conditions, photosynthesis in the Chl-containinggreen layer of the pericarp can prevent losses of internally-producedCO₂, since 3 times as much radiocarbon remained in the caryopsesincubated in the light as in the dark. These differences weresignificant at P=0.001. Experiments with the mutant barley Albinolemma, which has no Chi in the pericarp, showed that there waslittle difference between light and dark treatments. This confirmsthe suggestion that photosynthesis in the pericarp of the normalcultivar Midas may be concerned in the refixation of CO₂. Key words: Barley, pericarp, photosynthesis, carbon dioxide     

Development of Flat and Fan-Shaped Fruit in Actinidia chinensis var. chinensis and Actinidia deliciosa

We describe and quantify development of flat and fan-shapedfruit of Actinidia chinensis var. chinensis from inception tomaturity. Flat fruit arise from particularly large and flatfloral meristems. After bract initiation, the terminal flowerremains elliptic in cross section, produces elliptic whorlsof floral organs, and forms a flat-shaped ovary. The allometryof the ovary does not change from inception to maturity. Fan-shapedfruit develop from exceptionally flat floral meristems. Theyresult from postgenital fusion of the terminal flower with oneor two precocious lateral flowers. Timing of the fusion processvaries, resulting in a variable degree of integration of tissues.The fasciated flower has supernumerary floral organs, and isborne on a single pedicel. The histology of mature flat andfan-shaped fruit is described for commercially-grown Actinidiadeliciosa cv. Hayward. Mature flat fruit have a larger maximumdiameter, but are comparable to normal fruit in the minimumdiameter. Flat fruit have more locules and more pericarp tissuethan normal fruit, but these are not causally related to fruitshape. The flat shape can be attributed to differential planesof enlargement of cells in certain regions of the central core.Mature fan-shaped fruit are larger, and have more pericarp,core and locules than normal or flat fruit.Copyright 1994, 1999Academic Press Actinidia chinensis, Actinidia deliciosa, fruit shape, development, anatomy, fusion     

Purine Alkaloids of the Fruits of Camellia sinensis L. and Coffea arabica L. during Fruit Development

The amounts of two purine alkaloids, caffeine and theobromine,in the fruit of tea (Camellia sinensis L.) increased markedlyduring the growing season until the fruit was full-ripened anddried. In the dry fruit, the pericarp contained the most alkaloids,but there were also considerable amounts in the seed coat and,to a lesser extent, the fruit stalk and the seed. The shed seedsalso contained significant amounts of the alkaloids, especiallyin the seed coats. In contrast with the dry fruit of tea, seedsand pericarp of coffee (Coffea arabica L.) fruit contained aconsiderable amount of caffeine and a small amount of theobromide.A small amount of theophylline was also present in the pericarpof the ripened fruit. Relationships between growth and purinealkaloid content in tea and coffee fruits and their roles duringseed formation are discussed. Camellia sinensis L., tea, Coffea arabica L., coffee, purine alkaloids, fruit development, seed, seed coat, caffeine, theobromine, theophylline     

Monomeric and Dimeric Forms and the Mechanism-Based Inactivation of 1-Aminocyclopropane-1-Carboxylate Synthase

The molecular mass of 1-aminocyclopropane-1-carboxylate (ACC)synthase from a variety of sources was examined by both high-performancegel-filtration chromatography and polyacryl-amide gel electrophoresisin the presence of sodium dodecylsulfate. Enzymes used wereprepared from wounded or non-wounded pericarp of ripe tomatofruits and wounded mesocarp of winter squash fruits, as wellas from cells of E. coli that had been transformed with cDNAsfor the wound-induced or ripening-induced ACC synthases of tomatoand the wound-induced or auxininduced enzymes from winter squash.The enzymes from tomato fruit tissues were isolated in a monomericform, whereas the enzymes synthesized in E. coli from cDNAsfor tomato ACC synthase were isolated in a dimeric form. ACCsynthases of winter squash obtained either from fruit tissuesor from transformed E. coli cells were isolated in dimeric forms.ACC synthase in the monomeric form was less sensitive to theinactivation that is associated with the catalytic reaction(the mechanism-based inactivation) than the enzyme in the dimericform. A plausible mechanism relating the difference in molecularform to sensitivity to the mechanism-based inactivation of tomatoACC synthase is discussed. (Received February 1, 1993; Accepted May 17, 1993)     

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     

Inclusion bodies in several species of Ceratium Schrank (Dinophyceae) from the Caribbean Sea examined with DNA-specific staining

Several dinoflagellate species in the genus Ceraiium Schrankwere examined, with the help of a DNA-specific dye, for thepresence of a nucleus, chloroplasts and inclusion bodies. Theabundance of Ceratium in the Caribbean Sea in April 1990 wasbetween 1.3 and 4.9 x 10⁵ cells m^–3 Most Ceratium teresKofoid contained 5–10 small chloroplasts and among 529C.teres cells. 8% possessed an inclusion body. The shape andsize of inclusion bodies varied, and 7% of the inclusions hada DNA-containing particle inside. Similar inclusion bodies werealso observed in Ceratium declinatum f. normale Jörgensen,Ceratium furca (Ehrenberg) Claparede and Lachmann, and Ceratiumfusus (Ehrenberg) Dujardin. Our observations indicated thatinclusion bodies are common in oceanic Ceratium. ¹Present address: Institute of Marine Biology, National TaiwanOcean University, Keelung 20224, Taiwan, ROC     

Polygalacturonase Activity in Ripening Tomato Fruit Determined using Pericarp Discs

Discs prepared from the outer pericarp of tomato (Lycopersiconesculentum Mill. cv. Sunny) and placed in buffer exhibit anenzymic release of pectin fragments. Over a 2.5 h period at34 °C, discs from mature-green, 4 d and 10 d postbreakerfruit released approximately 90, 440 and 675 µg galacturonicacid equivalents (g^–1 disc fr. wt.), respectively. Bio-GelP-2 chromatography of the products revealed the presence ofpolymeric, oligomeric and monomeric uronic acids. The similarityof these products to those released from isolated, enzymatically-activecell walls and from enzymatically-inactive walls treated withpurified PG 2 provides evidence for the participation of polygalacturonase(PG, E. C. 3.2.1.15 [EC] ) in the release of pectin from disc tissue. The magnitude of pectin release from external pericarp discswas found to parallel ripening and increase progressively indiscs from the blossom, equatorial and shoulder regions, respectively.The use of discs and other systems to estimate in vivo PG activitywill be discussed. Key words: Cell wall, polyuronides     

Fine Structural Details of Tannin Accumulations in Non-Dividing Cambial Cells

The fine structure of autumn cambial cells of Aesculus hippocastanumand Populus x euramericana reveals the presence of electron-densebodies, other than lipids, in both the cytoplasm and vacuoles.These deposits are identified as tannins following a cytochemicaltest with ferrous sulphate. Small tannin bodies associated withthe strands of ER and inside small vesicles are often evidentin the cytoplasm. The cytoplasmic tannins are deposited intovacuoles by fusion of the tannin-containing vesicles with thetonoplast. The positive reaction of tannin inclusions with periodicacid-thiocarbohydrazide-silver proteinate suggests their polysaccharidicnature. The observations support the role of ER in tannin synthesisand deposition into the central vacuole. Aesculus hippocastanum, Populus x euramericana, cambial cells, tannin, vacuoles     

Solute Accumulation by Grape Pericarp Cells: V. RELATIONSHIP TO BERRY SIZE AND THE EFFECTS OF DEFOLIATION

We have studied the accumulation of water, dry matter (DM) andglucose and fructose (G + F) in selected grape berries cv. Dolcettoof varying initial size growing on leafed and defoliated vines.The first measurements at 2 d after veraison were obtained non-destructivelyfrom correlations with linear dimensions and deformability;the final measurements were made when the berries were harvested13 d later. The increments in DM and G + F per pericarp increased with initialberry size thus discounting an hypothesis of an equal amountof solutes supplied to all berries. The increments in weightof DM and G + F per increment of pericarp volume were constantin berries of different size, supporting an hypothesis of acontrol determined by concentration in the solution availablefor accumulation in all berries. Defoliation reduced the incrementsper pericarp and per g fr. wt. by about the same proportionand its effects were consistent with the above interpretations. Key words: Grape pericarp, sugar accumulation, phloem unloading, Vitis vinifera.     

The Plastids and Pigments of Fresh and Dried Chinese Gooseberries (Actinidia chinensis)

The pericarp of Chinese gooseberries is green due to the presenceof low concentrations of chlorophylls. On a f. wt basis thereis about 1.5 times more tetrapyrollic pigments (chlorophyllsand related compounds) in the outer pericarp than in the innerpericarp, whereas the carotenoid pigment values only showed1.25 times more in the outer than in the inner part of the fruit.The drying of Chinese gooseberries at 40 °C for 40 h resultedin the loss of at least half the tetrapyrollic pigments andof carotenoids. Chlorophylls a and b were converted to chlorophyllides,pheophytins and pheophorbides. Chloroplasts in the outer pericarp are clustered closely aroundthe nucleus and have a well-defined grana and inter-granal membranesystem. In the inner pericarp the chloroplasts are again clusteredaround the nucleus and there is a proliferation of inter-granalmembranes. In dried tissue the limiting membrane of chloroplastswas completely dispersed whereas some of the internal membranesremained intact. Actinidia chinensis Planch., Chinese gooseberry, Kiwi fruit, pigments, chloroplast structure     

FUNCTIONAL MORPHOLOGY OF THE RECTUM IN THE MARINE GASTROPOD LITTORINA SAXATILIS (OLIVI) (PROSOBRANCHIA:LITTORINOIDEA)

The ultrastructure of the rectum of the marine prosobranch gastropod,Littorina saxatilis suggests that it may have an additionalrole to the voiding of faecal pellets. It consists of two epitheliallayers, separated by a blood space. The inner epithelial layeris greatly folded and consists of metabolically highly activecells containing a wide variety of inclusions, and showing evidenceof secretory activity at their luminal surfaces. The outer epitheliumcontains a greater diversity of cell types, also with a largenumber of different inclusions present. Unlike some other prosobranchgastropods, a distinct rectal gland is absent in L. saxatilis.The entire rectal epithelium is glandular, and it appears thatthe rectal epithelial cells produce a number of secretions.This may indicate a role in absorption, the removal of materialfrom the blood, or the addition of a final covering to the faecalpellets. (Received 6 February 1989; accepted 6 March 1989)     

Inhibition of Ethylene Production by Fatty Acids in Fruit and Vegetable Tissues

Fatty acids of chain length from C₄ to C₁₂ inhibited ethyleneproduction in wounded albedo tissue of Hassaku (Citrus hassakuHort. ex Tanaka) fruit. Of the fatty acids tested, caprylicacid (C₈) and capric acid (C₁₀) were the most effective. Lauricacid (C₁₂) was less effective, and caproic acid (C₆) and butyricacid (C₄) were the least effective. Caprylic acid at 5 mM markedlyinhibited ethylene production in not only wounded albedo tissueof citrus fruit but also apple (Malus sylvestris Mill.) cortex,tomato (Lycopersicon esculentum Mill.) pericarp, cucumber (Cucumissativus L.) cortex, banana (Musa AAA group Cavendish subgroup)pulp, broccoli (Brassica oleracea L.) floret, spinach (Spinaciaoleracea L.) leaf, lettuce (Lactuca sativa L.) leaf and mungbean (Vigna radiata [L.] Wilczek) hypocotyl. Caprylic acid inhibitedethylene production at the step of conversion of l-aminocyclopropane-l-carboxylicacid to ethylene. The inhibition could be partially relievedby transferring the tissue to caprylic acid-free medium. (Received June 15, 1982; Accepted August 13, 1982)     

Population structure analysis provides insights into the infection biology and invasion strategies of Kretzschmaria deusta in trees

Infection biology and invasion strategies of Kretzschmaria deusta were investigated through the analysis of patterns of colonization and population diversity in three case studies, comprising different host species. Molecular analysis and isolation assays performed on stem sections at different heights indicated a prevalent heart rot mode of expansion. Random amplified microsatellites – RAMs and somatic incompatibility assays on isolates allowed detection, in one case, of a genet occupying the entire decay column and, in the other cases, of several different genets in each individual tree. Hypotheses on modes of arrival and entrance of K. deusta in trees are discussed on the basis of the distribution of genets and population genetics analyses. Significant correlation (Spearman ρ = 1.0; p < 0.001) between the number of genets and the number of areas delimited by pseudosclerotial plates (PSPs) on the decayed portions of stem sections suggests PSPs are interaction zone lines between different individuals of K. deusta occupying adjacent decay columns.