An alkali-soluble heteroxylan from seeds of Phoenix dactylifera L

Alkali-soluble polysaccharides, isolated from the seeds of dates, have been investigated using methylation and partial hydrolysis studies. The polysaccharides are shown to contain D-xylose and 4-O-methyl-D-glucuronic acid in a molar ratio of 5:1. An aldobiouronic acid from hemicellulose was characterized, and investigation revealed that the hemicellulose consists of a polymer of (1-->4)-linked D-xylopranosyl residues having branches of D-xylopyranosyl and 4-O-methyl-alpha-D-glucopyranosyluronic acid.     

A neutral beta-D-glucan from dates of the date palm,Phoenix dactylifera L

Polysaccharides extracted from Libyan dates with hot water and 0.05 M NaOH were fractionated and purified by ion-exchange and gel-filtration chromatography. According to the methylation and hydrolysis analyses, the results indicate the D-glucan to be linear and to contain both (1-->3)- and (1-->4)-linkages. The anomeric NMR measurements confirm that the sugar residues are beta-glycosidically linked. This is the first report on the isolation of a neutral beta-D-glucan from dates.     

Structure and biochemistry of endosperm breakdown in date palm (Phoenix dactylifera L.) seeds

Summary The zone of endosperm breakdown in the germinated date seed (Phoenix dactylifera L.) is a narrow area immediately adjacent to the surface of the enlarging cotyledon, or haustorium. The zone width is correlated with the amount of cell division in the adjacent region of the haustorium. The sequence of endosperm breakdown is: 1. protein bodies vacuolate, 2. storage cell walls become electron-transparent immediately adjacent to the protoplast of each endosperm cell, 3. all remaining cytoplasm and lipid bodies disappear, and 4. the remaining cell walls become electron-transparent and collapse against the haustorium surface. Two cell wall hydrolases are present—endo-mannanase (EC3.2.1.78) and -mannosidase (EC3.2.1.25). -mannosidase is detectable in the endosperm before germination. At germination, the major portion of activity is found in the softened endosperm. -mannanase is only detectable from germination and there is always hundreds of fold greater activity in the softened endosperm than elsewhere. Proteinase is detectable in trace amounts at germination in the softened endosperm but is also found in the haustorium at later stages. Isolated haustoria, incubated in extracted ivory nut (Phytelephas macrocarpa) mannan in buffer, cause no mannan breakdown. Haustoria, incubated in a solution of locust bean galactomannan, cause no decrease in galactomannan viscosity. Our observations suggest that although haustoria probably regulate mannan breakdown in the endosperm, they do not seem to secrete the hydrolytic enzymes concerned.     

Aflatoxin production on the pits (seeds) of the date palm (Phoenix dactylifera L.)

Pits —a by-product of the utilization of date fruits, are widely used as components of animal feeds, but an incident of aflatoxicosis in camels fed rations containing date pits has caused concern in the Gulf Region. This present study has shown that date pits can support aflatoxin production when inoculated withAspergillus parasiticus (IMI 91019b) and that variety and/or stages of maturation within a given variety can affect the final level of aflatoxin in the material. In one variety, Lulu, aflatoxin production was 44.5,38.7 and 21.0 ?g/g in pits taken from the first three stages of ripening namelyKimri, Khalal andRutab, but no significant aflatoxin production was noted at the fully-ripeTamr stage. Moisture content was considered to be the most important factor with respect to the capacity of the mould to synthesise aflatoxin in date pits.     

In Vitro Multiplication of Phoenix dactylifera (L)

A method of microcloning via somatic embryogenesis was established in date palm (Phoenix dactylifera L) cultivars. The method has potential for commercial application. Embryogenic cultures were initiated from soft primordial tissues of 2-3-year-old female suckers. The system was optimized first for the genotype ’sayar’ and then its applicability was tested to other genotypes. A method of pre-acclimation using pre-acclimation chambers has been devised, which improved hardening survival greatly. More than 80 clones obtained from the genotype ’sayar’ have been shifted to field for agronomic evaluation.     

Seed-borne fungi of date-palm,Phoenix dactylifera L. from Saudi Arabia

Six different varieties of date-palm viz. Sukhari, Saggae, Rotana, Kholasi, Rashoodia and Nabtat Ali, were screened for seed-borne fungi. Eleven species belonging to nine different genera of fungi were isolated. The genera isolated were Alternaria, Eurotium, and Fusarium (two species), Aspergillus, Drechslera, Penicillium, Rhizopus, and Curvularia (one species each). This is the first record of seed-borne fungi from Phoenix dactyliera L. in Saudi Arabia.     

A galactomannan from Crotalaria medicaginea seeds.

A polysaccharide isolated from the seeds of Crotalaria medicaginea is composed of D-galactose and D-mannose in the molar ratio of 10:31. Structural studies were performed by methylation analysis, partial acid hydrolysis, chromic oxide oxidation, mild hydrolysis with dilute oxalic acid and 13CNMR analysis of the polymer.     

Propagation of Date Palm (Phoenix dactylifera L.) in vitro

Adventitious plantlets were obtained from lateral buds, shoottips, embryos, and pieces of stem and rachilla tissue of Phoenixdactylifera L. cultured on a modified Murashige and Skoog mediumcontaining 3 mg l^–1 N-(²-isopenty)adenine 0?1–100mg l^–1 -naphthaleneacetic acid or 2,4-dichlorophenoxyaceticacid, and 3 g l^–1 activated charcoal. Additions of auxinswere necessary to induce explants to produce callus, adventitiousplantlets, and roots. Plantlets were obtained from explantscultured 3–4 months in vitro. No difference in growthresponses between male and female explants was observed duringculture. Complex addenda of activated charcoal and polyvinylpyrrolidonewere tested in the nutrient media at various concentrationsto prevent explant browning. Activated charcoal fostered satisfactorygrowth by reducing the browning and inhibition of growth ofexplants.     

Isolation of generative cells from pollen of Phoenix dactylifera

Summary Generative cells in pollen of Phoenix dactylifera had a convoluted surface and a small cytoplasmic volume, and condensed chromatin in the nucleus. Treatment of hydrated pollen with pectinase followed by grinding in a hypotonic medium released the generative cells from pollen. Convolutions of the plasma-membrane surface in vivo were retained by generative cells in vitro. Generative cells had a much lower solute concentration than did vegetative cells, a property that explains why hypotonic shock was effective in releasing intact generative cells from pollen.     

Structure, Composition and Physiological State of the Endosperm of Phoenix dactylifera L

The date endosperm consists of living cells with the same generalcellular structure throughout the seed. The major storage products,as shown by histochemical staining, are lipid, stored as numeroussmall lipid bodies which fill the cytoplasm, and protein, aslarge but variably-sized protein bodies. Nuclei are presentbut lack large amounts of heterochromatin. Plastids and mitochondriaare present but infrequently seen and have poorly developedinternal membranes. No endoplasmic reticulum or dictyosomesare present before or after hydration. The cell wall is thickexcept in areas of pit fields and consists of three layers whichdiffer in their staining behaviour: middle lamella, thickenedwall and inner wall. Both the endosperm and embryo of the imbibedseed undergo aerobic respiration, but the embryo respires ata more rapid rate than does the endosperm. A small area of theendosperm around the distal pole of the cotyledon shows histochemicallydetectable levels of succinic dehydrogenase. Phoenix dactylifera L, date palm, endosperm, ultrastructure, histochemistry, respiration, succinic dehydrogenase     

Insights into the historical biogeography of the date palm (Phoenix dactylifera L.) using geometric morphometry of modern and ancient seeds

Aim The main purpose of this work is to understand the origin, history, historical biogeography and mechanisms of date palm (Phoenix dactylifera L.) domestication. Location Seeds of uncultivated Phoenix individuals from isolated Oman populations, cultivated date palm varieties of various geographical origins and other related Phoenix species were analysed. Additionally, well‐preserved seeds from Egyptian archaeological sites (14th century bc to 8th century ad ) were compared with the morphometric reference model based on the analysis of modern material. Methods Elliptic Fourier transforms (EFT), a morphometric method applied to shape outline analysis, were used to characterize seed shape and to quantify morphological diversity in P. dactylifera and related species. Results Analysis of seed outlines by EFT (1) showed that P. dactylifera can be differentiated from other Phoenix species and (2) enabled the quantification of patterns of shape differentiation in the genus Phoenix at different taxonomic, geographical and chronological levels. Date palm agrobiodiversity, partitioned in distinct morphotypes, appeared to be complex in terms of geographical structure. Allocation of archaeological seeds to different modern Phoenix forms and date palm morphotypes allowed us to reveal ancient forms consumed and/or exploited in Egypt and finally to determine spatial and temporal changes in agrobiodiversity. Main conclusions Based on the morphological diversity quantified in P. dactylifera and related species, we characterized ancestral seed shape features present in uncultivated populations. The geographical distribution pattern of seed shapes points to human dispersal routes that spread cultivation from one or more initial ‘domestication centres’. Finally, this work provides a powerful tool to identify ancient forms as demonstrated by the analysis of well‐preserved Egyptian archaeological seeds, dating from the 14th century bc to the 8th century ad . Results open new and fascinating perspectives on the investigation of the origins and chrono‐geographical fluctuation of date palm agrobiodiversity.     

Purification and characterization of membrane-bound peroxidase from date palm leaves (Phoenix dactylifera L.)

Peroxidase from date palm (Phoenix dactylifera L.) leaves was purified to homogeneity and characterized biochemically. The enzyme purification included homogenization, extraction of pigments followed by consecutive chromatographies on DEAE-Sepharose and Superdex 200. The purification factor for purified date palm peroxidase was 17 with 5.8% yield. The purity was checked by SDS and native PAGE, which showed a single prominent band. The molecular weight of the enzyme was approximately 55 kDa as estimated by SDS–PAGE. The enzyme was characterized for thermal and pH stability, and kinetic parameters were determined using guaiacol as substrate. The optimum activity was between pH 5–6. The enzyme showed maximum activity at 55 °C and was fairly stable up to 75 °C, with 42% loss of activity. Date palm leaves peroxidase showed K_m values of 0.77 and 0.045 mM for guaiacol and H₂O₂, respectively. These properties suggest that this enzyme could be a promising tool for applications in different analytical determinations as well as for treatment of industrial effluents at low cost.     

Water-soluble galactomannan from the seeds of Lotus corniculatus L.: structure and properties

Galactomannan, a water-soluble heteropolysaccharide, was isolated from the seed of Far-Eastern population of ground honeysuckle Lotus corniculatus L. (yield, 1.65%). Analysis of this galactomannan showed that is consists of D-mannose and D-galactose residues (molar ratio, 1.22:1). Its aqueous solutions were characterized by specific rotation [alpha]D = +84.10 and characteristic viscosity [eta] = 559 ml/g. Analysis of this heteropolysaccharide using chemical and enzymatic procedures, as well as IR- and 13C-NMR spectroscopy, showed that its main chain comprises 1,4-beta-D-mannopyranose residues, 95.5% of which are substituted at C-6 with single residues of alpha-D-galactopyranose.     

In Vitro Flowering Induction in Date Palm (Phoenix dactylifera L.)

This article reports on a histological and morphological study on the induction of in vitro flowering in vegetatively propagated plantlets from different date palm cultivars. The study aimed to further explore the control of in vitro flower induction in relation to the photoperiodic requirements in date palm and to come up with a novel system that may allow for early sex determination through plant cycle reduction. In fact, the in vitro reversion of a shoot meristem from a vegetative to a reproductive state was achieved within 1–5 months depending on the variety considered. This reversion was accompanied by several morphological transformations that affected the apical part of the leafy bud corresponding mainly to a size increase of the prefloral meristem zone followed by the appearance of an inflorescence. The flowers that were produced in vitro were histologically and morphologically similar to those formed in vivo. The histological examination of the in vitro flowering induction process showed that the conversion into inflorescences involved the entire apical vegetative meristem of the plantlet used as a starting material and brought about a change in its anatomical structure without affecting its phyllotaxis and the leaf shape. Through alternating between hormone-free and hormone-containing media under different light/dark conditions, the highest flower induction rates were obtained with a basal Murashige and Skoog medium. A change in the architectural model of date palm was induced because unlike the natural lateral flowering, in vitro flowering was terminal. Such in vitro flower induction allowed a significant reduction in plant cycle and can, therefore, be considered a promising candidate to save time for future improvement and selection programs in date palm.     

Histochemical and ultrastructural changes in the haustorium of date (Phoenix dactylifera L.)

Summary During imbibition ofPhoenix dactylifera embryos, all cotyledon cells show the same changes: protein and lipid bodies degrade, smooth endoplasmic reticulum (ER) increases in amount, and dictyosomes appear. At germination, the distal portion of the cotyledon expands to form the haustorium. At this time, epithelial cells have a dense cytoplasm with many extremely small vacuoles. Many ribosomes are present along with ER, dictyosomes, and mitochondria. The parenchyma cells have large vacuoles and a small amount of peripheral cytoplasm. Between 2 and 6 weeks after germination, epithelial cells still retain the dense cytoplasm and many organelles appear: glyoxysomes, large lipid bodies, amyloplasts, large osmiophilic bodies, and abundant rough and smooth ER which appear to merge into the plasmalemma. A thin electron-transparent inner wall layer with many small internal projections is added to the cell walls. Starch grains appear first in the subsurface and internal parenchyma and subsequently in the epithelium. Lipid bodies, glyoxysomes, protein, and osmiophilic bodies occur in the epithelial and subepithelial cell layers but not in the internal parenchyma. At 8 weeks after germination, the cytoplasm becomes electron transparent, vacuolation occurs, lipid bodies and osmiophilic bodies degrade, and the endomembranes disassemble. After 10 weeks, the cells are empty. These data support the hypothesis that the major functions of the haustorium are absorption and storage.     

A Histological Study of Development of Adventive Embryos in Organ Cultures of Phoenix dactylifera L.

Callus cultures from axillary buds of 2–4-year-old offshootsof Phoenix dactyl'fera L have yielded plantlets adventitiouslyAdventive embryos originated from meristematic cytoplasm-richcells located in the epidermal and adjacent sub-epidermal portionsof the periphery of callus on a basal medium supplemented with2, 4-D and isopentenyladenine The formation of adventive embryosis described Morpho-genetically competent cells proliferateinto globular proembryos which differentiate into bipolar structures.Transfer to a medium devoid of hormones enhances embryo developmentand promotes plantlet growth Comparative studies were made betweenzygotic and adventive embryos in various stages of development Phoenix dactylifera L, date palm, Palmae, adventive embryogenesis, histological development     

Development of male-specific SCAR marker in date palm (Phoenix dactylifera L.)

Genetics of control mechanisms that underlies sex differentiation in date palm is not known. Sex of the plants becomes known only at the time of first flowering, which takes around 5 years. In comparison, molecular diagnosis (if available/feasible) promises quick and reliable identification of sex types very early when plantlets are growing in seedbeds. To develop such an assay, genomic DNA from 45 individual plants (25 female and 20 male) belonging to different varieties of date palm was subjected to PCR amplification using 100 random amplified polymorphic DNA (RAPD) and 104 intersimple sequence repeat (ISSR) primers. Initially, two bulk genomic DNA samples (each made by pooling DNA from ten male and female plants, separately) were used. A primer showing sex-specific band in bulked samples was further used for amplification of the genomic DNA of the individual samples of that bulk. Only one RAPD primer, OPA-02, amplified a fragment of ~1.0 kb in all the individual samples of male genotypes, whereas this fragment was absent in all the female genotypes. This male-specific fragment was cloned and sequenced (GenBank accession no. JN123357), and a sequence-characterized amplified region (SCAR) primer pair was designed that amplified a 406-bp fragment in both female and male genotypes and a unique fragment of 354 bp in only male genotypes. The SCAR marker was further validated using 25 female and ten male date palm plants belonging to different varieties collected from different locations.     

Mineral composition of the exine of two male date palms (Phoenix dactylifera L)

The mineral composition of the exine of two male date palms “Deglet-noor” and “Takerboucht” was examined with Electronic Probe X Micro Analysis. Fresh pollen grains were (1). dried naturally and untreated, (2). lyophilized, (3). Gamma-ray irradiated, and analysed. Their composition is compared. A slight distinction between these two male date palms is established.