Seed Epidermis Development and Histochemistry in Solanum melongena L. and S. violaceum Ort.

Structure, development and histochemistry of the seed epidermiswere studied inSolanum melongena L. andS. violaceum Ort. usinglight and scanning electron microscopy. The epidermal cellsat the endosperm mother cell stage of ovule development hadthickened outer periclinal walls, consisting of two layers,a thin inner layer, and a thick outer layer. The latter whichstained positively for pectic substances became further thickenedduring the course of seed development; more so inS. melongena.The inner layer of the outer periclinal wall also was thickenedby depositions of cellulose but remained comparatively thin.The development of the inner periclinal and anticlinal wallstook place by the uneven deposition of concentric layers. Thesesecondary wall thickenings which appeared as pyramids in transversesection stained for cellulose, lignin and pectin. Further unevensecondary thickenings near the outer part of the anticlinalwalls resulted in the formation of projections which were hair-or ribbon-like in appearance. InS. melongena, these projectionsprogressed only a short distance from the anticlinal wall. InS.violaceum, on the other hand, they grew much longer formingstriations on the inside of the outer periclinal wall. InS.melongena, partial removal of the outer periclinal wall by enzymeetching exposed to surface view a beaded appearance of the cellboundaries. Complete erosion of the outer periclinal wall revealedthe hair-like projections of the underlying anticlinal walls.InS. violaceum, enzyme treatment exposed the striations whichformed bridge-like structures over the curves in the anticlinalwalls. Solanum melongena ; Solanum violaceum; seed epidermis; seed structure; seed development; cell wall histochemistry; cell wall projections; cell wall striations     

Logarithmic Relationship between Moisture Content and Longevity in Sesame Seeds

The relationship between seed moisture content and seed longevityin sesame (Sesamum indicum L.) in hermetic storage at 50 °Cis logarithmic. The logarithmic relationship is maintained from15 per cent down to 2 per cent – the lowest moisture contenttested — but above 15 per cent this ‘air-dry’relationship no longer holds since further increase in seedmoisture content does not reduce longevity. Tentative estimatesof constant values for the improved seed viability equationare provided, and implications for long-term storage are discussed. Sesame, Sesamum indicum L., seed storage, improved viability equation, seed moisture content, seed longevity prediction     

Variation of Seed-coat Ornamentation in Striga hermonthica (Scrophulariaceae)

The surface features of the seed of the parasitic floweringplant Striga hermonthica were examined with the scanning electronmicroscope. The details of ornamentation were constant on seedsfrom one plant but varied within and between populations andare probably due to out-breeding. The variation was not relatedto geographical origin or to host-preference. Testa patternssimilar to those reported for other Striga species were foundin the samples. Striga hermonthica, Scrophulariaceae: Rhinanthoideae, hemi-parasite, testa, seed-coat, scanning electron microscope, genetic variation     

Viability and Germination of the Pollen of Sorghum [Sorghum bicolor (L.) Moench]

Previous studies have demonstrated that pollen of sorghum [Sorghumbicolor (L.) Moench] loses capacity to both germinate in vitroand to set seed in vivo soon after being shed. The current studyevaluates the capacity for dehydrated pollen to effect in vitrogermination, reduce tetrazolium chloride, and set seed on cytoplasmicmale sterile plants. Morphological changes during pollen germinationwere examined by scanning electron microscopy (SEM). Close to70% of the pollen germinated in 5 min, or less, when collectedat 80% relative humidity (RH) and stored in sealed glass vials.Pollen tubes elongated autotropically with atmospheric humidityapparently being a controlling factor in the process. Pollendehydrated at 50% RH and 25°C for 15-30 min neither germinatedin vitro, reduced tetrazolium chloride, nor set seed on malesterile plants. Rehydrating the pollen did not restore the capacityfor germination. SEM micrographs demonstrated that elongatingpollen tubes encircled the pollen grain and were contiguousto the surface. A fibrillar-like material existed on the exineof separated pollen grains at the point where the grains hadbeen previously attached.Copyright 1994, 1999 Academic Press Sorghum pollen, germination, seed-set, viability, scanning electron microscopy, Sorghum bicolor (L.) Moench     

Morphological and Anatomical Studies of Linaria Species from South-west Spain: Seeds

Seeds of 24 taxa of Linaria from south-west Spain were examinedwith a scanning electron microscope and light microscope. Basedon seed features such as shape, surface ornamentation and cellshape, seven morphological types were recognized. Seeds of thedifferent types are described, illustrated and compared. A keyto distinguish the different species or groups of species isprovided. Copyright 1999 Annals of Botany Company Seed-coat, SEM, anatomy, Scrophulariaceae, Antirrhineae, Linaria .     

Scanning Electron Microscopic Studies on Seed Coat Patterns of Five Endangered Himalayan Species of Meconopsis (Papaveraceae)

Scanning electron microscopic studies of seed coat patternswere carried out on 16 populations of the endangered genus Meconopsis,the Himalayan poppy. Two different types of testa can be distinguishedin the five species of Meconopsis (M. horridula, M. paniculata,M. simplicifolia, M. sinuata, M. villosa ) investigated: (a)rugose, and (b) reticulate. The results indicate the absenceof intra- and inter-population variation in all five speciesof Meconopsis. However, seed coat patterns show a marked inter-specificdifference suggesting that they are species-specific.Copyright1995, 1999 Academic Press Himalayan poppy, Meconopsis horridula, Meconopsis paniculata, Meconopsis simplicifolia, Meconopsis sinuata, Meconopsis villosa, endangered species, seed coat patterns, scanning electron microscopy     

Stomatal Response of some Cultivated and Wild Tuber-bearing Potatoes in Warm Tropics as Influenced by Water Deficits

Leaf resistances of 14 cultivated potato genotypes (Solanumspp) and three tuber-bearing wild Solanum species were comparedwhen plants were grown under water stress at two tropical sitesFactors investigated were diurnal changes in leaf resistance,the effect of plant age, transient drought versus well-wateredconditions of potted and field-grown plants These measurementswere carried out in order to determine the stomatal behaviourof tuber-bearing genotypes and species Significant genotypic differences in leaf resistances were notedwithin the cultivated genotypes All genotypes had higher resistanceswhen water-stressed, but LT-7 appeared to have the lowest leafresistances Genetic differences in stomatal behaviour of tuber-bearingSolanum species were confirmed Abaxial stomatal resistancesof water-stressed plants of the species ranged between 1 74and 13 8 s cm^–1 Stomata of S chacoense were less affectedby drought (three-fold) than S tuberosum (four-fold) The greatesteffect was on S jungasense (five-fold) and on S raphanifoliumThese data show that stomata behaviour among tuber-bearing Solanumspecies is sufficiently different to warrant investigationsof drought-resistance in potato species under dry hot conditions Solanum tuberosum L., Solanum raphanifolium, Solanum chacoense, Solanum jungasense, leaf resistance     

Inheritance of Fusarium wilt resistance introgressed from Solanum aethiopicum Gilo and Aculeatum groups into cultivated eggplant (S. melongena) and development of associated PCR-based markers

The two eggplant relatives Solanum aethiopicum gr. Gilo and Solanum aethiopicum gr. Aculeatum (=Solanum integrifolium) carry resistance to the fungal wilt disease caused by Fusarium oxysporum f. sp. melongenae, a worldwide soil-borne disease of eggplant. To introgress the resistance trait into cultivated eggplant, the tetraploid somatic hybrids S. melongena + S. aethiopicum and S. melongena + S. integrifolium were used. An inheritance study of the resistance was performed on advanced anther culture-derived androgenetic backcross progenies from the two somatic hybrids. The segregation fitted a 3 resistant (R): 1 susceptible (S) ratio in the selfed populations and a 1R:1S ratio in the backcross progenies for the trait derived from S. aethiopicum and S. integrifolium. These ratios are consistent with a single gene, which we designated as Rfo-sa1, controlling the resistance to Fusarium oxysporum f. sp. melongenae. The allelic relationship between the resistance genes from S. aethiopicum and S. integrifolium indicate that these two genes are alleles of the same locus. Bulked Segregant Analysis (BSA) was performed with RAPD markers on the BC₃/BC₅ resistant advanced backcross progenies, and three RAPD markers associated with the resistance trait were identified. Cleaved Amplified Polymorphic Sequences (CAPSs) were subsequently obtained on the basis of the amplicon sequences. The evaluation of the efficiency of these markers in predicting the resistant phenotype in segregating progenies revealed that they represent useful tools for indirect selection of Fusarium resistance in eggplant.     

Flow Cytometric Determination of Nuclear Replication Stage in Seed Tissues

Flow cytometric determination of DNA levels in embryos of fullymatured seeds of various plant species revealed large amountsof 2C DNA signals, indicating that most cells had arrested thecell cycle at the presynthetic G₁ phase of nuclear division.The accumulation of cells at G₁ was found both in orthodox andin recalcitrant (i.e. Castanea sativa) seed species. As recalcitrantseeds are characterized by the absence of maturation drying,the arrest of the cell cycle in the presynthetic phase may notbe linked to the seed water status. Apart from the 2C signal, 4C values were found in the embryoof some seed species (e.g. Raphanus sativus) indicating thatcells were arrested in G₂ Cells arrested in G₂ were primarilylocated in the root-tip region of the embryo. In addition, combinationsof higher C values (i.e. 8C, 12C, 16C and 64C) were observedin the endosperm of Solanum melongena and Lycopersicon esculentum,and in the root-tip cells of Phaseolus vulgaris and Spinaciaoleracea. These mixtures of polyploid nuclei (also called 'polysomaty')may arise from a developmentally controlled cellular endoreduplicationand indicates that in each cell type of the seed the amountof DNA is regulated both spatially and temporally.Copyright1993, 1999 Academic Press Endive, Cichorium endiva, lettuce, Lactuca sativa, egg-plant, Solanum melongena, pepper, Capsicum annuum, tomato, Lycopersicon esculentum, radish, Raphanus sativus, bean Phaseolus vulgaris, spinach, Spinacia oleracea, chestnut, Castanea sativa, beech, Fagus sylvatica, pine, Pinus nigra, DNA content, flow cytometry, seed, nuclear replication stage, C levels, storage     

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     

Ovicidal activity of Sesamum indicum (L.) oil against Spodoptera littoralis (Boisd.)

In the research for alternative tools and botanical products to control Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae). Sesamum indicum (L.) (Lamiales: Pedaliaceae) oil was assayed as an ovicide. The mortality increased with existence of fatty acids. Chemical analysis of S. indicum oil using GLC analysis showed palmitic acid as the major fatty acid (51.27%), while the major hydrocarbon and sterols were found to be heneicosane (58.63%) and β-sitosterol (2.60%), respectively. Generally, the values of LC₅₀s indicated that one-day-old egg masses are more susceptible than three-day-old eggs. Also, the leaf dip technique is more efficient than the spraying one. Results showed several features of chorionic surface deformation treated with sesame and KZ oils than control using scanning electron microscopy. Meanwhile, the tested oils caused significant reduction in both total soluble protein and transaminase enzymes as compared to control. Additionally, the oils elongated the incubation period and larval duration than control.     

Regulation of Sterol Biosynthesis in Solanum Species

Regulation of sterol synthesis was studied in Solanum species.A significant negative correlation was found between sterolcontent and rate of sterol synthesis from (1-¹⁴C) acetate inplant organs of Solanum nigrum and cell cultures of S. dulcamara.Exogenous cholesterol significantly inhibited the rate of sterolsynthesis from (¹⁴C) acetate in cell cultures of S. dulcamarawithout affecting synthesis from (³H) mevalonate. Exogenouscholesterol stimulated the rate of total lipid synthesis fromboth (¹⁴C) acetate and (³H) mevalonate. Thus, cholesterol inhibitedconversion of acetate to mevalonate; this is taken as evidenceof a negative feedback control on sterol synthesis. Key words: Feedback control, Phytosterol biosynthesis, Plant cell culture, Solanum species     

A Preliminary Study on the Effects of Nitrogen Supply on the Growth In Vitro of Nine Potato Genotypes (Solanum spp)

Cultures of nine potato genotypes (seven Solanum tuberosum oneS. sparsipilum and one S. oplocense genotypes) were examinedfor their response to growing on medium containing either 60mol m^–3, 40 mol m^–3 or 20 mol m^–3 nitrogen.Genotypes differed in their response to nitrogen. Reducing thenitrogen regime tended to produce taller plants with longerinternodes, shoots had larger leaves but contained less chlorophyll.No change in fresh weight or number of nodes was observed. Genotypex nitrogen interactions were significant for chlorophyll content,shoot length and internode length. Results suggest that thechanges observed were as a result of changes in the total nitrogenlevel rather than changes in the ammonium : nitrate ratio. Thisstudy suggests that for certain potato genotypes, nitrogen levelsin MS medium are too high for producing desirable microplantsin terms of leaf area and shoot length Key words: Solanum tuberosum, S. sparsipilum, S. oplocense, micropropagation, morphogenesis     

Effect of Sporophytic Heterozygosity on the Male Gametophyte of the Tetraploid Potato (Solanum tuberosum L.)

Quantitative variation for pollen stainability was examinedin both tetraploid x diploid and tetraploid x tetraploid familiesof potato (Solanum tuberosum L.). The diploid parents, whichwere highly heterozygous, produced first division restitution(FDR) 2n pollen. The families used were not affected by cytoplasmic-geneticmale sterility. Significant differences between families werefound. FDR 2n pollen producing diploid clones had progenieswith a significantly higher pollen stainability than those derivedfrom crosses between tetraploid parents. This was related tothe level of heterozygosity in the sporophyte. In FDR 2n pollen,80% of the heterozygosity and a large fraction of epistasispresent in the diploid parent was transmitted to its tetraploidprogeny. This is important for the production of open pollinated,true potato seed, because pollen stainability is significantlycorrelated with fruit set (r = 0·85).Copyright 1994,1999 Academic Press FDR 2n pollen, gametophytic heterozygosity, true potato seed     

Pollen Wall Structure Using a New Stripping-Sputtering Device for Scanning Electron Microscopy

A new method has been developed to elucidate pollen wall architecture by the separation of wall layers and the use of scanning electron microscopy (SEM). Separation of wall layers at natural boundaries, breakage across the wall and metal-coating of the specimen have been achieved by controlled ramming of free scattered ions produced by a novel “ion separating and coating – model A” instrument. The stripping treatment reveals interfaces and cross profiles of pollen walls and the sputtering treatment results in metal coating for examination with SEM. An advantage of the method is that it provides intact interfaces that are not eroded or damaged. The application of the method is exemplified by SEM analyses of pollen grains of Gossypium hirsutum L., Zea mays L., Sesamum indicum L. and Brassica napus L. var. oleifera. Interfaces between the tectum, column, foot, nexine-2 and intine layers of the pollen wall were all portrayed in G. hirsutum and to a great part in the other species. In G. hirsutum, it was possible to document the attachment point of surface spines, the appearance of individual baculae and the irregular labrum-operculum but regular inner labrum-aperture structure. No tectum was found in S. indicum. In all four species it was not possible to separate the intine from the sporoplast. The numbers of apertures were 20, 1, 10–14 and 3 in G. hirsutum, Z. mays, S. indicum and B. napus, respectively. The dumbell-shaped arrangement of apertures in G. hirsutum, the gear-shaped oblate sporoplast of S. indicum and the abundance of micropores on the intine of B. napus are characteristic features.     

Ploidy Variation in Solanum brevidens Plants Regenerated from Protoplasts Using an Improved Culture System

Plating efficiency of cultured protoplasts of Solanum brevidensincreased to c. 10% after the addition of 5•0 mol m^–3glutamine to the culture medium. Growth of protoplast-derivedcolonies at densities of 20 colonies cm^–3 was obtainedby lowering the auxin content alter 4–6 d. A sample of50 protoplast-derived plants was examined for chromosomal variation.Twelve plants were diploid (2n=24), 26 were tetraploid (2n=48)and 12 were aneuploid at the tetraploid level (2n=48?). Tetraploidand aneuploid plants had broader leaves and set fewer or noseeds compared to the diploid regenerants which were similarin gross morphology and seed set to control plants. Key words: Solanum brevidens, protoplasts, plant regeneration, variation     

An Improved Method Involving Hydroponic Culture for the Production of Sexual Hybrids between Dihaploid Solanum tuberosum and Diploid S. microdontum

Dihaploid Solanum tuberosum and diploid S. microdontum plantswere grown in soil and hydroponics under glasshouse and growthroom conditions. A high light intensity was necessary for flowerinduction in both species and the dihaploid flowered only whengrown in hydroponics. Premature berry abscission was retardedby tuber removal and prevented by the addition of indole aceticacid to the nutrient solution. Seeds from prematurely abscisedberries germinated poorly in soil, but germinated almost aswell as those seeds from indole acetic acid-treated plants whenplaced on Murashige and Skoog (1962) based culture medium. Thehybrid plants were intermediate in morphology, compared to theparents, possessed heterotic vigour and were male fertile. Germinatinghybrid seeds on a colchicine-containing medium led to poorlygrowing plants with ploidy chimeras. Hybrid plant ploidy levelswere doubled by regenerating plants from stem/leaf explantson the tuber disc regeneration medium of Jarret et al. (1980). Key words: Solanum tuberosum, S. microdontum, sexual hybridization, hydroponic culture, tissue culture     

Inhibiting Effect of Ammonium Ion in Protoplast Culture of Some Asteraceae Plants

Protoplasts with high division activity were obtained reproduciblyfrom mesophyll cells of axenic shoot culture of three wild speciesof Asteraceae, Artemisia vulgaris L., Chrysanthemum indicumL. and Ch. zawadskii Herbich, by means of a suitable combinationof enzymes with a gentle pipetting treatment. Ammonium ion was found to inhibit cell division in the protoplastculture of these Asteraceae species but to accelerate it inthe case of tobacco. The inhibiting effect of ammonium ion wasdrastic on the protoplast of Artemisia but moderate on thatof Ch. indicum and Ch. zawadskii. The total concentration ofthe major inorganic elements had little effect on the divisionfrequency of protoplasts in these species. ³Present address: Kirin Brewery Co., Ltd., Plant Research Center,Kitsuregawa, Tochigi-ken 329-14, Japan. (Received October 12, 1983; Accepted December 20, 1983)     

Morphology, Anatomy and Ontogeny of Female Cones in Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae)

The developmental morphology and anatomy of the female conesof Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae)are described and illustrated, based on observations, histology,scanning electron microscopy (SEM) and nuclear magnetic resonance(NMR) imaging. Ovulate development is typically podocarpaceous.Ovules are unitegmic, and horizontal or inclined upwards throughoutontogeny; the pollination drop is inverted because of the declinatemicropyle. Ontogeny of the epimatium-ovule complex is acropetal,the epimatium developing first. A terminal, distal sterile bractcreates a pollen-scavenging area. During development, the wholecone re-orientates through some 270°, and the seed realignsapprox. 60° with respect to the receptacle axis. The ‘receptacle’or podocarpium supporting the seed is formed by gradual fusionof initially free bracts. The structures adnate to these bractsrepresent homologues of ovuliferous scales; they bear vestigialepimatia which may develop into supernumerary ovules or non-functionalepimatia. Thus, female cones ofA. pancheri are vestigially multi-ovulate.NMR imaging effectively and non-invasively revealed the three-dimensionalarrangement of vascular bundles and resin canals in the cones.Copyright 2001 Annals of Botany Company Acmopyle pancheri(Brongn. & Gris) Pilg., anatomy, developmental morphology, gymnosperms, histology, nuclear magnetic resonance (NMR) imaging, ontogeny, ovules, Podocarpaceae, scanning electron microscopy (SEM), seed cones