Dissertations / Theses on the topic 'Date palm pollen (Phoenix dactylifera L)'

Philosophiae Doctor - PhD
In different parts of the world, medicinal plants have demonstrated a lot of health benefits to mankind and remains an important source for the discovery of new bio-active compounds. Libya is a typical example of a country where medicinal plants are widely used. Plant extracts of five Libyan medicinal plants were used in this study to investigate their in vivo effects on spermatogenesis and steroidogenesis in male rats and on ovulation and fertility in female rats. The In vitro effects of these plant extracts were also investigated on TM3 Leydig cells and MCF 7 breast cancer cells. A phyto-chemical analysis of the five Libyan medicinal plants (flaxseed, black seeds, radish seed, date palm pollen and nutmeg) was done. The results showed that date palm pollen had a higher antioxidant activity than all of the above mentioned plants. In addition to this, Nigella sativa was observed to possess high flavonol content as well as high antioxidant activity. Male rats exposed to flaxseed, radish seeds and date palm pollen showed no significant alterations in body weight gain, whereas date palm pollen (240 mg/kg, p < 0.05) promoted an increase in body gain. This study also revealed a significant increase in the relative testicular weight of animals exposed to either flaxseed (300mg/kg) or date palm pollen (120mg/kg). In addition, the relative weights of the seminal vesicles of all treated groups showed significant increased values. The level of serum testosterone showed a significant increase after exposure to radish seed (80mg/kg) and a significant dose- dependent increase for date palm pollen when compared to control (P< 0.05). In contrast, flaxseed caused a dose-dependent significant (p <0.01) decrease in testosterone level at radish seed (300mg/Kg). All plant extracts caused a significant increase in sperm concentration. Sperm vitality significantly (p < 0.05) increased by radish seed (80mg/kg), flaxseed (300mg/kg) and date palm pollen (120, 240mg/kg) respectively. Total progressive motility improved significantly at flaxseed (300 mg/kg) (p < 0.001) as well as date palm pollen (p < 0.01). Histological examination of the cross sections of the testis showed clear presence of all stages of spermatogenesis in all the treated groups. Rat epididymides showed normal morphological appearance and their lumen were filled with spermatozoa. The diameter of seminiferous tubules in male rats exposed to date palm pollen (120 and 240 mg/kg) was significantly higher (p < 0.001). The heights of the germ cell epithelia within the eminiferous tubules were also significantly increased in all treated groups. Liver and renal functions tests showed a significant decrease in Alanine transaminase (ALT) and creatinine in all treated groups (p < 0.05), and this demonstrates the lack of cytotoxic effects of date palm pollen, radish seed and flaxseed on the rats. However, these plant extracts produced a non-significant (p > 0.05) increase in Aspartate transaminase (AST) levels. Besides this, superoxide dismutase activity (SOD) in testis was increased significantly by radish seed (160 mg/kg), flaxseed (200 mg/kg) and date palm pollen (120 mg/kg). There was also improved catalase activity in testis of male rats exposed to radish seed and date palm pollen. Regarding male sexual behavior, the time to reach the female and the mount frequency decreased significantly in male rats exposed to flaxseed (300 mg/kg) and date palm pollen (120 and 240 mg/kg; p > 0.05) thus, these plant extracts exhibit aphrodisiac properties. In addition, exposure of male rats to date palm pollen (120 mg/kg) produced a significant (p < 0.01) increase in the number of embryos in untreated female rats. In the female rats, the body weight gain was not affected (p > 0.05). However, the relative uterus weights exposed to nutmeg (200 mg/kg) and date palm pollen (120 and 240 mg/kg) were significantly decreased (p < 0.05). In addition, the relative weights of ovaries after treatment with nutmeg (400 mg/kg) and black seed (400 mg/kg) showed significantly increased values (p < 0.01). Serum FSH was significantly increased (p > 0.05 or 0.01) when the female rats have been exposed to black seed (200 mg/kg), nutmeg (200 mg/kg) or date palm pollen (120 mg/kg). The LH level significantly (p < 0.01) decreased following exposure to black seed (200 mg/kg), date palm pollen (120 mg/kg). On the other hand, serum LH concentration was significantly increased in female rats exposed nutmeg (400 mg/kg; p > 0.05). The creatinine activity in female rat serum in all treated groups was significantly decreased (p < 0.05). Whereas the higher dose of date palm pollen (240 mg/kg) caused only a non-significant decrease. ALT activity in serum of female rat exposed to either black seed (400 mg/kg) or date palm pollen (120 and 240 mg/kg) was shown to decrease significantly (p < 0.05). Histology of the reproductive organs, kidney and liver in the female rats showed no obvious alterations in any of the treated groups. In addition, the number of embryos in female rats significantly increased (p < 0.01; p < 0.001) following exposure of female rats to black seeds 400 and date palm pollen 240 mg/kg, respectively. Incubation of TM3 Leydig cells with radish seeds for 24, 48 or 72 hours caused a significant (p < 0.01) decrease in mitochondrial dehydrogenase activity. Besides that, date palm pollen and flaxseed increased the mitochondrial dehydrogenases activity of TM3 Leydig cells. In addition, higher concentration of date palm pollen, nutmeg and black seed were cytotoxic to MCF7 breast cells. In testis slices testosterone secretion in vitro was significantly increased by flaxseed (500 μg/ml; p > 0·05) and date palm pollen (500 μg/ml; p > 0·01). MCf-7 cells treated with BS 10-50 μg/ml black seed and nutmeg 10-50μg/ml significantly increased cell proliferation. However, the treatment with date palm pollen produced only a weak estrogenic effect, which resulted in a concentration dependent significant increase as observed between 50-1000 μg/ml date palm pollen. In conclusion, in this study, we observed that date palm pollen, radish seed and flaxseed increased libido as well as steroidogenesis and spermatogenesis, improved hepato and nephron-protective effects. In female rats, the plant extracts NM, BS and date palm pollen potentiated the production of gonadotropic hormones. In addition to this, at lower concentrations these medicinal plants promoted cell growth, whereas at higher concentrations they inhibited cell proliferation of MCF- 7 breast cancer cells. The anti-oxidant effects of these plant extracts have been implicated for the above mention effects.

Somatic embryogenesis is the mass production system of choice for date palm to increase the rates of vegetative propagation. However, the low rates of conversion to plants are common for somatic embryos. Up to 50% of plant productiqn in the Jimmah Tissue Culture Laboratory, Oman is lost during the stages of somatic embryo germination and conversion. Partial desiccation of date palm somatic embryos of the genotype Khalas Aldahra, either by dehydration for up to 4 hours or supplementation of the maturation Murashige and Skoog-based medium with sorbitol, sucrose and polyethylene glycol, increased significantly the percentage conversion to plants. In contrast, the addition of indol-3-butyric acid (IBA), a-naphthaleneacetic acid (NAA), 6-benzylaminopurine (BAP), abscisic acid (ABA), flurprimidol or activated charcoal to the germination medium did not improve the conversion of embryos to plants compared to the control. A protocol for cryopreservation of somatic embryos and embryogenic cultures of the genotype Buhabisha was developed in the current study using the vitrification method (incorporating PVS2 solution) and pretreatment with glycerol, sorbitol and dimethylsulfoxide as a cryoprotectant prior to freezing. Despite the fact that, there was a low percentage of survival of somatic embryos, the results from this study provided evidence that it is possible to cryopreserve somatic embryos and embryogenic callus of Omani date palms. A cell suspension protocol from the genotype Buhabisha was established in this study in order to utlilise more efficient micropropagation methods and to overcome the problems of the large size of somatic embryos that may lead to an efficient cryopreservation technique. NAA gave the best regeneration frequency of somatic embryos compared to 2,4-dichlorophenoxyacetic acid (2,4-D) or picloram. However, attempts to replace activated charcoal in the date palm cultures with either polyvinylpyrolidone or ascorbic acid were unsuccessful. The use of dialysis membrane to separate cell suspensions from activated charcoal was successful, but the generation of somatic embryos was low. Twenty one genotypes obtained from the Jimmah Research Station, Oman were screened and evaluated with microsatelIite markers to establish a DNA fingerprinting procedure. Simple Sequence Repeats (microsatellites) showed that date palm genotypes analysed had high genetic divergence. Importantly, somaclonal variation was not detected by DNA fingerprinting in tissue culture-derived plants of the genotype Khalas Aldahra.

Date palm (Phoenix dactylifera L.) is a diploid with 18 pairs of chromosomes and an estimated genome size of 658 Mb. It is a dioecious perennial monocot, with a long generation time (a period of 4-5 years until first flowering). Date palm is one of the major fruit crops grown in the Gulf countries and particularly in the Sultanate of Oman. Approximately 250 varieties of date palm are recorded throughout the country with evaluation and characterization based on morphological and reproductive traits (e.g. fruit color, fruit shape and fruit weight). Limited molecular characterization work has been undertaken for date palm germplasm in general and Omani date palm germplasm, in particular. The principal focus of this study was to: investigate the genetic diversity of Omani date palm germplasm and compare it with 'exotic' germplasm, to differentiate between female and male plants at the molecular level and to construct an initial genetic map for date palm. Samples were taken from eight parents of the available Omani date palm controlled crosses (Khalas 4, Khalas 13 male, Um-Alsela, Khori male, Bami, Naghal, Bahlani male, and Khasab) with 90 date palms from the BC1 and F1 populations, from 194 Omani date palm accessions (151 female cultivars and 43 male trees), together with samples from Italy (Sanremo and Bordighera), USDA-ARS, France, Iraq, Libya, Sudan and Iran. The F-statistics analysis showed that the genetic variation between female and male accessions based on random markers was only 2.1 %, while within the broader group of Omani female and male accessions the molecular variation was 97%, suggesting that the Omani female and male accessions have little consistent divergence, compared to the large-scale divergence within Omani germplasm, so male palm have been derived from most genetic origins in Oman. Additionally, the Principal Coordinates Analysis (PCA) and bootstrap consensus phenetic tree showed that the Omani accessions were closely related to each other and there was no clear genetic differentiation between female and male cultivars. A high degree of genetic variation was observed between germplasm from Oman, Italy, USDA-ARS, France, Iraq, Libya, Sudan and Iran as measured by Fst (19.7 %). The PCA showed that the Europe-Africa (Italy, France, Libya and Sudan) accessions are distinguished from West-Asia (Oman, Iraq and Iran) accessions and have their own autochthonous origin, a finding which was strongly validated by bootstrap consensus tree test. A medium density genetic map in date palm was constructed using 53 individuals from BC1 and 30 individuals from F1 populations. The BC1 map consisted of 270 markers (28 SSR and 242 SNP) distributed into 29 linkage groups with total genetic length of 1.486.7 cM, while the F1 map consisted of 591 markers (21 SSR and 570 SNP) distributed into 30 linkage groups with total genetic length of 2,385.6 cM. A total of 25 combined linkage groups were possible by combining both BC1 and F1 maps through common markers. A sex-link marker locus was developed and found to predict a high level of discrimination between male and female date palms among multiple varieties distributed across the wide range of cultivation, with an accuracy of 100% in the Omani crosses, 96% in the broad Omani material and 86% in the broadest date palm germplasm. This marker was also mapped in both BC1 and F1 at 42.8 cM and 4.9 cM in linkage groups 18 and 29, respectively and on combined group 19 at 42.8cM.

To meet the challenges of protein price increases from animal sources, the development of new, sustainable and inexpensive proteins sources (nonanimal sources) is of great importance. Date palm (Phoenix dactylifera L.) seeds could be one of these sources. These seeds are considered a waste and a major problem to the food industry. In this thesis we report a physicochemical characterisation of date palm seed protein. Date palm seed was found to be composed of a number of components including protein and amino acids, fat, ash and fibre. The first objective of the project was to extract protein from date palm seed to produce a powder of sufficient protein content to test functional properties. This was achieved using several laboratory scale methods. Protein powders of varying protein content were produced depending on the method used. Most methods were based on solubilisation of the proteins in 0.1M NaOH. Using this method combined with enzymatic hydrolysis of seed polysaccharides (particularly mannans) it was possible to achieve a protein powder of about 40% protein (w/w) compared to a seed protein content of about 6% (w/w). Phenol/TCA extraction gave the protein powder with the highest protein percentage of 68.24% (w/w) and this powder was used for subsequent functional testing. Several factors were found to influence seed protein extraction such as pH, temperature, the extraction time, the solvent to sample ratio and the solvent concentration. Optimum conditions for extraction were found to be pH 10, 45˚C and extraction time of 60 min. The results showed that use of enzymes to hydrolyse and remove seed polysaccharides improved the extraction of date seed protein. Optimal improvement was obtained using Mannaway, which hydrolyses mannans and galactomannans, which gave a powder with 34.82% (w/w) protein compared to the control of 11.15% (w/w) protein. The proteins in the extracted date seed protein were profiled using LC/MSMS. Three-hundred and seventeen proteins were identified. The proteins belonged to all major functional categories. The most abundant proteins were glycinin and β-conglycinin, the two major seed storage proteins of plants. The functional properties of extracted date seed protein were investigated using a range of tests. The thermal properties of date seed proteins were consistent with a powder containing high levels of conglycinin and β-glycinin. The solubility had a similar pH profile to soy protein, but differed in absolute solubility due to differences in non-protein composition. Similarly, water holding and oil holding capacity of date seed protein was lower than for soy protein, probably because of compositional differences. Date seed proteins were able to emulsify oils and had a comparable emulsifying ability and emulsion stability to soy protein isolate. The date seed protein was not a good foaming agent compared to soy protein or whey protein concentrate.

Les objectifs de ce travail visent à appréhender l'histoire évolutive et biogéographique du palmier dattier (Phoenix dactylifera L.), espèce d'une importance capitale pour les populations humaines des régions chaudes et arides d'Afrique du Nord et du Moyen-Orient, au moyen d'analyses génétiques et morphométriques. En effet, les origines de la domestication du dattier demeurent peu connues malgré les données archéologiques qui semblent attester de sa culture à partir de la fin du 4ème millénaire avant notre ère. L'analyse phylogénétique du genre Phoenix réalisée à partir de séquences chloroplastiques a permis d'identifier les parents proches du dattier. Des populations de dattiers sauvages sont reconnues pour la première fois grâce à des analyses de diversité et de structuration génétiques. De manière congruente, l'analyse morphométrique de contours de la graines s'appuyant sur la méthode des transformées elliptiques de Fourier met en évidence une nette différenciation entre les individus sauvages et cultivés. La caractérisation des changements de traits morphologiques de la graine liés à la domestication est exploitée pour définir le statut sauvage ou domestiqué de matériel mis au jour dans différents sites archéologiques du Pakistan et d'Egypte. En outre, l'étude génétique de dattiers d'origine diverses semble démontrer qu'au moins deux évènements de domestication ont eu lieu : l'un en Afrique et l'autre au Moyen-Orient. Finalement, les études génétiques et morphométriques, menées séparément ou conjointement selon le type et l'ancienneté du matériel analysé, permettent pour la première fois de discuter des origines, de l'histoire biogéographique et de la dynamique de l'agrobiodiversité du palmier dattier, dans le temps et dans l'espace
The objectives of this work are to understand the evolutionary history and biogeography of the date palm (Phoenix dactylifera L.), a species of importance to human populations in hot, arid regions of North Africa and the Middle East using genetic and morphometric analyzes. Indeed, the origins of the domestication of the date palm remain poorly understood despite the archaeological data that seem to attest its culture from the late 4th millennium BCE.Phylogenetic analysis of the genus Phoenix made ​​from chloroplast sequences identified close relatives of the date palm. Populations of wild date palms are recognized for the first time through analyses of genetic diversity and structure. Congruently, morphometric analysis of the seed outline based on the method of elliptic Fourier transform highlights a clear differentiation between wild and cultivated individuals. Characterization of changes in seed morphological traits related to domestication is used to define the status of wild or domesticated material excavated from various archaeological sites in Pakistan and Egypt. In addition, the date palm genetic study of various origins seems to indicate that at least two domestication events took place: one in Africa and one in the Middle East. Finally, genetic and morphometric studies, conducted separately or together depending on the type and age of the material analyzed, allow for the first time to discuss the origins, history and biogeographic dynamics of date palm agrobiodiversity, in time and space

Le palmier dattier (Phoenix dactylifera L.) a une grande importance écologique et socio-économique dans les zones arides et semi-arides du globe. Cette espèce présente une grande diversité (plus de 2.000 variétés identifiées) qui est menacée par la production à grande échelle de variétés élites. Il est nécessaire de développer des techniques permettant de conserver cette diversité et de gérer la production des variétés élites multipliées in vitro. La cryoconservation (azote liquide, -196°C) est la seule technique disponible à l’heure actuelle permettant la conservation à long terme, à coûts réduits et en sécurité de cette diversité. Dans ce travail, nous avons comparé l’efficacité de deux techniques de cryoconservation, la vitrification en goutte (DV) et la D cryo-plate (DP), pour la cryoconservation de masses proembryogènes (PEM) de deux variétés de palmier dattier, Sokary et Sultany. Avec la DV, la survie des PEM cryoconservées est nulle sans prétraitement au saccharose (3 jours avec 0,5M) et sans traitement avec la solution de vitrification PVS2. Après 15 à 120 min de traitement avec PVS2, la survie est comprise entre 90,9-98,6% et 85,6-88,0%, respectivement pour Sokary et Sultany. Avec un prétraitement au saccharose, 21,1% des PEM de la variété Sokary survivent à la cryoconservation sans traitement avec PVS2. Avec la DP, un effet positif du prétraitement au saccharose est observé sur la survie des PEM cryoconservés. Pour Sokary, la survie la plus importante (de 92,0 à 95,8%) après congélation est obtenue pour des durées de dessiccation comprises entre 60 et 120 min. La survie après cryoconservation est comprise entre 67,0 et 74,6% après des durées de 90 à 120 min de dessiccation pour Sultany. Avec les deux techniques expérimentées, l'intensité de croissance des PEM cryoconservées est supérieure chez Sokary par rapport à Sultany. L’étude histologique réalisée montre qu’en l’absence de prétraitement, c'est le traitement de loading qui induit la plasmolyse des cellules la plus importante, d'environ 26, 40 et 50%, respectivement pour les cellules méristématiques, les cellules embryogènes de la population I (PopI) et de la population II (PopII) par rapport à leur état initial. Le prétraitement au saccharose induit une plasmolyse d'environ 50% uniquement chez les cellules de PopII. Le traitement de loading et de vitrification n'entraîne pas de plasmolyse supplémentaire. Aucune plasmolyse n'est observée chez les cellules méristématiques et les cellules de PopI. En revanche, les mesures de la surface de l'ensemble des cellules montrent chez les cellules méristématiques une diminution significative de surface après le prétraitement au saccharose, mais aucune différence significative après le traitement de loading et de vitrification. Chez les cellules embryogènes de PopI, une diminution supplémentaire de la surface est observée après le traitement de vitrification. L’étude de la circularité des noyaux montre une déformation permanente des noyaux des cellules non prétraitées des trois types cellulaires, alors que seuls les noyaux des cellules de PopII présentent cet aspect chez les PEM prétraitées. Enfin, l'étude du degré de méthylation des PEM par immunolocalisation conclut à l'absence de différences significatives entre les PEM témoins non traitées et les autres conditions expérimentales. Cependant, les tissus différenciés présentent un pourcentage de noyaux méthylés plus important par rapport aux cellules embryogènes et aucun marquage n'est noté chez les cellules méristématiques. Nos résultats ont permis de préciser l’effet de la cryoconservation sur l’intégrité structurale et la physiologie des PEM de palmier dattier. Ils contribuent également à la sauvegarde de la biodiversité du palmier dattier
The date palm (Phoenix dactylifera. L) has a great ecological and socioeconomic importance in arid and semi-arid areas of the globe. This species displays a great diversity, with over 2,000 identified varieties, which is threatened by the large scale production of elite varieties. It is necessary to develop techniques allowing to conserve this biodiversity and to manage the production of in vitro propagated elite varieties. Cryopreservation (liquid nitrogen [LN], -196°C) is currently the only technique available ensuring the safe and cost-effective long-term conservation of this diversity. In this work, we compared the efficiency of two cryopreservation techniques, droplet-vitrification (DV) and D cryo-plate (DP), for the cryopreservation of proembryonic masses (PEMs) of two varieties of date palm, Sokary and Sultany. With DV, recovery of cryopreserved PEMs was nil without sucrose pretreatment (3 days, 0.5 M) and without treatment with PVS2 vitrification solution. After 15 to 120 min of PVS2 treatment, recovery was between 90.9-98.6% and 85.6-88.0% for Sokary and Sultany, respectively. Sucrose pretreatment led to 21.1% recovery of cryopreserved PEMs of variety Sokary without PVS2 treatment. Regrowth intensity of PEMs cryopreserved was generally lower in the Sultany variety compared to the Sokary variety. With DP, a positive effect of sucrose pretreatment on recovery of cryopreserved PEMs was observed. For Sokary, the highest recovery of PEMs (92.0 to 95.8%) after LN exposure was achieved for desiccation periods between 60 and 120 min. Recovery of cryopreserved PEMs of variety Sultany was between 67.0 and 74.6% after desiccation periods between 90-120 min. With DP, the regrowth intensity of cryopreserved PEMs was higher for variety Sokary compared to Sultany. The histological study performed showed that in absence of pretreatment, it was the loading treatment which induced the highest cell plasmolysis, with values of 26, 40 and 50% for meristematic, embryogenic PopI and PopII cells, respectively, compared to their initial state. Sucrose pretreatment induced a 50% plasmolysis only in PopII cells. The loading and vitrification treatments did not cause any additional plasmolysis. No plasmolysis was observed in meristematic or PopI cells. By contrast, the measurement of the surface of all cells revealed a significant decrease in the surface of meristematic cells after pretreatment, but no significant difference after the loading or vitrification treatments. In embryogenic PopI cells, an additional decrease in the cell surface was observed after the PVS2 treatment. The study of nuclei circularity showed a permanent deformation of nuclei of non-pretreated cells of the three cell types. In pretreated PEMs, only the nuclei of PopII cells displayed deformation. Finally, the study of the methylation degree in PEMs by immunolocalization revealed the absence of significant differences between the untreated controls and other experimental conditions. However, the differentiated tissues exhibited a higher percentage of methylated nuclei compared to embryogenic cells, while no stained nuclei were observed in meristematic cells. Our results allowed clarifying the effect of cryopreservation on the structural integrity and on the physiology of date palm PEMs. They also contribute to safeguarding of date palm biodiversity

La compréhension des mécanismes moléculaires impliqués dans la détermination du sexe chez les plantes à fleurs est primordiale d’un point de vue fondamental et appliqué. Des processus liés à la biosynthèse des hormones, tel que l’éthylène, ou la régulation de l’expression génique via des petits ARN et des facteurs de transcription ont été associés à l’unisexualisation des fleurs chez des espèces dioïques. Cependant, les déterminants contrôlant le sexe chez les plantes sont encore largement méconnus. Le palmier dattier, Phoenix dactylifera L, est une espèce dioïque dont le dimorphisme sexuel est observé très tôt au cours du développement des fleurs. Des gènes différentiellement exprimés (DEGs) ont été identifiés pendant les stades précoces du développement floral mâle et femelle. Pour cela, un transcriptome de référence rassemblant des données d’expression relatives aux deux sexes a été généré. L’analyse d'enrichissement GO des DEGs, a révélé des processus biologiques communs aux mâles et aux femelles, associés au développement reproducteur et à la réponse aux stimuli. Ce résultat indique que des mêmes processus peuvent solliciter des gènes différents au cours du développement floral précoce en fonction du sexe. Cette analyse a également mis en évidence que le développement des fleurs mâles requiert des processus biologiques spécifiques impliqués dans la régulation cellulaire et l'expression des gènes. En outre, deux DEGs femelles, une S-adenosylmethionine synthase et une Flap endonuclease et un DEG mâle, un élément transposable, ont été identifiés dans les régions non-recombinantes du génome du palmier dattier.Cette étude est la première analyse globale des processus biologiques associés à l’acquisition du dimorphisme sexuel. Elle contribue également à la compréhension de la détermination du sexe chez le palmier dattier, et plus largement à la connaissance de ces processus chez les espèces dioïques
Unraveling molecular mechanisms involved in sex determination in flowering plants is of outstanding basic and applied interest. Several studies on dioecious species have highlighted the molecular basis of sex determination, such as cell death and ethylene biosynthesis pathway. Sex determination mechanisms in plants are, however, still largely unknown. The date palm, Phoenix dactylifera L, is a dioecious species where sexual dimorphism is observed very early in development of flowers. Differentially expressed genes (DEGs) were identified during the early stages of the male and female flower development. A reference transcriptome including male and female data was constructed to gain insight into this process in the dioecious palm Phoenix dactylifera L. Differentially expressed genes (DEG) were subsequently identified between males and females in the early flower development stages in which the first morphological gender difference occurs in date palms.Gene ontology enrichment analysis of DEG revealed biological processes shared between males and females involved in reproductive development and response to stimulus, indicating that same processes could require different genes during early flower development in date palm. This analysis also suggested that date palm triggers biological processes specifically involved in cellular regulation and gene expression to develop male flowers. Furthermore, two female DEGs related to DNA methylation S-adenosylmethionine synthase and DNA metabolism Flap endonuclease, and one male DEGs, a transposable element were found in non-recombinant date palm regions. This study provided the first insight into biological processes involved in sex determination in date palms and more widely to knowledge of this process in dioecious species

Le palmier-dattier constitue une des rares cultures à vocation alimentaire adaptées aux conditions climatiques extrêmes (sécheresse, salinité), telles que rencontrées à Djibouti. Dans un contexte de ressources en eau fortement limitées, la connaissance des modalités de l’alimentation hydrique du palmier dattier est essentielle. L’objectif de ce travail de recherche est d’acquérir cette connaissance, dans le contexte pédoclimatique de Djibouti, par la réalisation d’un suivi in situ du fonctionnement hydrique du système sol-palmier, à l’échelle d’un individu, et la quantification du puits racinaire du palmier-dattier. Un palmier-dattier, pleinement développé, a été instrumenté à l’échelle de la cuvette d’irrigation, à l’aide de plusieurs tubes d’accès de sonde à neutrons, pour le suivi de la teneur en eau volumique du sol, et de plusieurs tensiomètres, répartis de 10 à 160 cm de profondeur. Trois expériences d’infiltration/redistribution a été réalisées successivement, la première sans altérer le fonctionnement du système sol-palmier, la seconde après avoir coupé le palmier, tout en permettant l’évaporation de la surface du sol, la dernière après avoir couvert la surface du sol afin d’empêcher l’évaporation. Les résultats mettent en évidence une forte hétérogénéité des propriétés hydriques du sol, avec une stratification liée au contexte sédimentaire littoral. L’impact du puits racinaire sur la dynamique hydrique du sol est observé jusqu’à 80 cm de profondeur. Pour la période fraîche, les besoins en eau du palmier dattier sont estimés à 130 L par jour, avec une fréquence d’irrigation d’une fois toutes les 2 semaines. Pour la première fois, le coefficient cultural du palmier dattier (kc = 1,39) a été établi dans les conditions climatiques de Djibouti. Les résultats obtenus contribueront à une meilleure gestion de l’irrigation et à une meilleure maîtrise du risque de salinisation du sol dans le contexte pédoclimatique de la République de Djibouti
Date palm is one of the few food crops adapted to the extreme weather conditions (drought, salinity), such as encountered in Djibouti. In the context of highly limited water resources, knowledge of the date palm water requirements is essential. The objective of this research was to determine the date palm water requirements, in the Djibouti pedoclimatic context, using in situ monitoring of water transport in the soil-plantatmosphere system, at the scale of a single date palm tree, and to quantify the date palm root water uptake. A fully developed date palm tree was instrumented at the irrigation basin scale, using several access tubes for neutron probe for monitoring the soil volumetric water content, and several tensiometers, installed from 10 to 160 cm depth. Three infiltration/redistribution experiments have been performed successively, the first without alteration of the soil-plant system, the second after cutting off a date palm tree while allowing the surface evaporation, the last with covering the soil surface to avoid evaporation. The results show large heterogeneity in soil hydraulic properties, with stratification linked to the coastline sedimentary context. The root water uptake is observed up to 80 cm depth. The date palm water requirements in the fresh period are estimated at 130 liters per day with a frequency of irrigation of one time every two weeks. For the first time, the date palm cultural coefficient has been established in the Djibouti climatic conditions (kc = 1.39). The obtained results will contribute to better management of irrigation and to improve the control of soil salinization in the pedoclimatic context of the Republic of Djibouti

La production de dattes ne cesse d’augmenter d’une saison à une autre ce qui engendre des pertes essentiellement lors des étapes de manutention et de commercialisation. De plus, l’étape de manutention post-récolte joue un rôle important dans le maintien de la qualité des dattes. Dans ce cadre et afin de préserver les qualités organoleptique et nutritionnelle des dattes après récolte tout en améliorant leur valeur commerciale, des essais de conservation et de traitement post-récolte ont été mis en place. L’effet de la conservation des dattes en fonction de la température, du temps, de l’utilisation d’atmosphère modifiée lors du stockage et d’un traitement thermique sur la fermeté, la couleur, et les teneurs en sucres, acides organiques, polyphénols et parois cellulaires a été étudié. Les dattes du cultivar ‘Deglet Nour’ récoltées en 2017 et 2018 au stade Tamr ainsi que les dattes communes ‘Arichti’, ‘Bouhattam’, ‘Bser Hlou’ consommées à un stade de maturité précoce (stade Khalal) ont été conservées à -18, 0, 2 et 4 °C pendant 3, 6 et 9 mois et à 2 °C pendant 30 et 60 jours, respectivement. La spectroscopie Moyen Infrarouge (MIR) en tant que méthode non destructive et non ciblée a permis de mettre en évidence l’effet de l’année de récolte par rapport à la composition chimique et de discriminer les échantillons de dattes ‘Deglet Nour’ conservés à 4 et 2 °C. Le rendement en parois cellulaires assimilées aux fibres, ainsi que les procyanidines représentant 98% des polyphénols totaux sont stables durant la conservation du cultivar ‘Deglet Nour’ et du cultivar ‘Arichti’ quel que soit la température et la durée de conservation. En revanche, ces composants sont ceux qui sont les plus affectés par les conditions de conservations dans le cas des cultivars ‘Bouhattam’ et ‘Bser Hlou’. Ce dernier est le cultivar le plus ferme et le plus apprécié par les consommateurs, en raison notamment de l’augmentation des teneurs en sucres réducteurs affectant son goût sucré lors de la conservation. De ce fait, une conservation des dattes ‘Deglet Nour’ à -18 °C pourrait être une solution pour un stockage à long terme, par contre en raison des coûts énergétiques élevés, 2 °C est la température optimale de conservation. En outre, afin de bien valoriser les dattes communes et prolonger leur durée de vie, la durée de conservation peut être prolongée pour le cultivar ‘Arichti’, une optimisation de la température de conservation pour le cultivar ‘Bser Hlou’ et ‘Bouhattam’ sera cependant nécessaire. Les dattes précédemment citées ont été également conservées dans différents types d’emballages à atmosphère modifiée (EAM) à 2 °C pendant 3, 6 et 9 mois pour le cultivar ‘Deglet Nour’ et pendant 30 et 60 jours pour les cultivars ‘Arichti’, ‘Bouhattam’ and ‘Bser Hlou’. D’une façon générale, ces résultats ont montré que les EAM ont le même impact que la température et la durée de conservation sur la qualité des dattes. Par conséquent, leur utilisation dans les industries de conditionnement de dattes va entrainer des coûts supplémentaires sans effets bénéfiques. L’impact d’un traitement d’hydratation sur les qualités organoleptique et nutritionnelle des dattes a également été évalué. Le traitement des dattes ‘Deglet Nour’ de trois usines de conditionnement différentes, à une vapeur d’eau saturée à 60-62 °C pendant 4 heures a montré qu’elles deviennent plus souples comme attendu, tandis que les paramètres nutritionnels sont resté stables. La spectroscopie Moyen Infrarouge (MIR) a permis de discriminer les dattes des trois usines et il est suggéré qu’elle soit adoptée par les stations de conditionnement comme une nouvelle technique prédictive et non destructive. Ce résultat confirme que le traitement d’hydratation pourrait être fortement recommandé pour valoriser les dattes sèches de faible valeur commerciale, cependant il doit être optimisé pour les dattes très sèches
The production of dates is increasing every season, causing losses especially during post-harvest handling andmarketing. Post-harvest handling plays an important role in maintaining date palm. In order to preserve organolepticand nutritional quality of date palm fruits after harvest with improving their commercial value, storage experiments andpost-harvest treatments have been assayed.The effect of different storage conditions of temperature, time and modified atmosphere, as well as the effectof heat treatment of dates, on firmness, colour, sugars, organic acids, polyphenols and cell walls and compositions havebeen studied.‘Deglet Nour’ date palm fruits of two harvest seasons (2017 and 2018) as well as common date cultivars‘Arichti’, ‘Bouhattam’ and ‘Bser Hlou’ consumed at early maturity stage (Khalal stage), were stored at -18, 0, 2 and 4°C for 3, 6 and 9 months and at 2 °C for 30 and 60 days, respectively. Mid Infrared Spectroscopy (MIR) as a nontargetedmethod allowed to highlight a year effect on 'Deglet Nour’ chemical composition and to discriminate samplesstored at 4 and 2 °C regarding to major components (moisture, sugar, organic acids...). Cell wall yields (assimilated tofiber) as well as procyanidins, accounting for 98% of total polyphenols, were stable during ‘Deglet Nour’ and ‘Arichti’cultivars storage regardless of temperature and time conditions. However, these same components were the mostaffected by storage conditions for ‘Bouhattam’ and ‘Bser Hlou’ cultivar. This latter, was the softest cultivar and themost appreciated by consumers, may be because of reducing sugars increase affecting its sweet taste. Thus, stored fruitsat -18 °C could be the solution for a long-term storage but due to its high energetic costs, 2 °C must be the optimaltemperature. Moreover, in order to valorize common dates palm and prolong their shelf life, storage time could beprolonged for ‘Arichti’ cultivar with temperature storage ptimization for ‘Bser Hlou’ and ‘Bouhattam’ cultivars.Date palm fruits mentioned above, were also stored under Modified Atmosphere packaging (MAP) at 2°Cduring 3, 6 and 9 months for ‘Deglet Nour’ and during 30 and 60 days for commons cultivars (‘Arichti’, ‘Bouhattam’and ‘Bser Hlou’). In general, differences were observed on physical and chemical parameters using different MAPstreatments for ‘Deglet Nour’date palm fruits. Dates became darke with MAPT and MAPA storage. Dates palm storedunder this latter MAP bag showed an increase on procyanidins, some cell walls compositions, fructose and citric acid.Firmness loss of this cultivar was delayed with MAPZ storage with polyphenols stability. This latter bag type conservedfirmness and colour of the three studied cultivars (‘Arichti’, ‘Bouhattam’ and ‘Bser Hlou’) were stabe with no differencecomparing to control (without MAP). Organic acids, cell walls yield and composition, polyphenols were also stableduring storage. Only sugars contents of every cultivars had different behaviour.These results showed that MAP bags had very lower benefical effects than storage time and temperature on ‘date palmquality. So, their use in date processing industries could have more costs with no apparent effects.The organoleptic and nutritional quality of ‘Deglet Nour’ date palm was also evaluated before and afterhydration treatment commonly used in date prcessing units (DPU), in order to become more commercially valued andto minimize waste generated along the date palm fruit supply chain. Hydration treatment under saturated steam at 60-62°C for 4 hours impoved date fruits texture as expected while nutritional parameters were quite stable. Mid InfraredSpectroscopy (MIR) allowed to discriminate samples from the three DPUs suggesting to be adopted in DPU as a newpredictive and no destructive technique. So, hydration treatment could be highly recommended to valorize fruit byproducts.However, it needs to be optimized for the very hard-type dates
انتاج التمور في ارتفاع مستمر من موسم الى اخر مما يجعل مراكزالفرز و التخزين تتخلص من كميات هائلة من التمور المتضررة أثناءعمليات الفرز والتسويق. هذه العمليات تلعب دورا هاما في الحفاظ على جودة التمور. ومن أجل الحفاظ على الجودة الغذائية للتمور بعد الجنيمع تحسين قيمتها التسويقية، تم القيلم بتجارب التخزين وبعض معالجات ما بعد الجني.وقد تم دراسة تأثير ظروف التخزين المختلفة من درجة الحرارة، مدة الخزن وتقنية الجو الهوائي المعدل، وكذلك تأثير معالجة التمور الجافةعلى الصلابة، اللون، السكريات، الأحماض العضوية، البوليفينول وجدران الخلايا النباتية (الالياف) ومكوناتها.تم تخزين تمور ’ دقلة النور’ لصابة 2017 و 2018 والأصناف الأخرى من التمور الأقل انتشارا مثل ’ الارشتي’، ’ بو حتم’، ’ بسر حلو’18 درجة مائوية وفي 2 درجة مائوية لمدة - ,0 ,2 , التي تستهلك في مرحلة متقدمة من النضج (خلال)، لمدة ثلاثة، ستة وتسعة أشهر في 430 و 60 على التوالي. اثبت التحليل الطيفي بالأشعة تحت الحمراء الوسطى ان سنة الجني لها تاثير على العناصر الكيميلئية للتمور’ دقلةالنور’ وقامت بتمييز التمور المخزنة في 2 و 4 درجة مائوية بالنسبة لاهم مكوناتها (الماء، السكريات، الأحماض العضوية...). اثبت النتائجان جدران الخلايا النباتية (الالياف) وان أكبر مكونات البوليفينول (بروسيانيدين) كانت مستقرة اثناء تخزين تمور’ دقلة النور’ و ’ الارشتي’،بغض النظر عن درجة حرارة ومدة التخزين. نفس هذه العناصر كانت الأكثر تاثرا بعوامل التخزين بالنسبة لاصناف’ بو حتم’ و ’ بسرحلو’. هذا الصنف الأخير كان الأكثر ليونة مع تغير بنية جدران الخلايا على الرغم من انه أكثر صنف قابلية لدى المستهلك، من الممكنبسبب ارتفاع كمية السكريلت السريعة التي اثرت على مذاقه الحلو.فبحيث ان تخزين التمور ’ دقلة النور’ في - 18 درجة مائوية من الممكن ان يكون أحسن حل على مدى طويل، لكن نظرا لتكاليفة الطاقيةالباهضة، تخزين التمور في 2 درجة مائوية يجب ان يكون أفضل حل. بصفة عامة لم يكن هناك خسائر هامة للقيمة الغذائية بالنسبة لاصنافالتمور الاخرى اثناء التخزين، مما يجعل التمديد في مدة التخزين ممكنا بالنسبة اصنف’ الارشتي’ مع البحث عن درجة حرارة تخزين ناجعةالصنف ’ بسر حلو’ و’ بو حتم’.تم ايضا تخزين انواع التمور المذكورة اعلاه بتقنية الجو الهوائي المعدل في 2 درجة مائوية لمدة ثلاثة، ستة وتسعة أشهربالنسبة ’ لدقلةالنور’ ولمدة 30 و 60 يوم بالنسبة للاصناف الأخرى. بصفة عامة هناك اختلافات في العناصر الفيزيلئية والكيميلئية ’ لدقلة النور' المخزنةفي كل أنواع تقنيات الجو الهوائي. ' دقلة النور' المخزنة في أكياس ترندلايف و ايباك. أصبحت داكنة الون.دقلة النور المخزنة في أكياس ' سجلت ارتفاعا في مكونات جدران الخلايل, بروسيانيدين, الفروكتوز و حامض السيتريك. تخزين' دقلة النور'في أكياس زويباك اخرت في ليونتها مع استقرار في البوليفينول. هذه النتائج اثبتت ان تخزين التمور في اكياس الجو الهوائي المعدل لم تكنذو نجاعة عالية مقارنة بعوامل الحرارة والمدة الزمنية.لون وصلابة التمور من اصناف ’ الارشتي’، ’ بو حتم’، ’ بسر حلو’ اثبتت استقرارها بعد تخزينها في أكياس زويباك, لكن بعدم ايجاد فرقمقارنة بالتمور المخزنة بدون اكياس الجو الهوائي المعدل, مثلها مثل بقية العناصر الفيزيلئية والكيميلئي بصفة عامة. هذا يثبت ان استعمالهافي مصانع تخزين التمور ليس له جدوى اقتصادية واضحة.تم دراسة مدى تاثر القيمة الغذائية لتمور ’ دقلة النور’ الجافة على إثر معالجتها وترطيبها بالطريقة الهعتدة في اغلب مصانع تخزين التمور62 درجة مائوية لمدة 4 ساعات - لتكون ذات قيمة تسويقية عالية ولتقليص كمية الخسائر. تقنية ترطيب التمور على طريقة البخار في 60اثبتت نتائج ناجعة كما كان متوقع مع المحافضة على استقرار المكونات الغذائية. طريقة معالجة التمور بترطيبها هي طريقة متصوح بهالكنها غير ناجة للتمور الأكثر جفافا التي تحتاج تطوير في هذه التقنية

La Maladie de la Feuille Cassante du Palmier dattier (Phoenix dactylifera L.) constitue un cas d'émergence d'une maladie à fort impact économique causée par un agent étiologique inconnu. Notre stratégie a visé à élaborer une approche sans à priori de l'émergence pouvant être transposée à n'importe quelle situation de ce type. En nous appuyant sur des caractérisations successives des compartiments viraux, bactériens et fongiques de tissus sains et malades, nous avons cherché à mettre en évidence des différences de composition spécifiques et de distribution de ces flores sur 2 campagnes de prélèvements réalisées en 2010 et 2012. Alors que la microscopie électronique à transmission nous a permis de visualiser des structures d'origine virale probable au niveau des chloroplastes du parenchyme chlorophyllien, une étude moléculaire de séquençage de gènes ribosomaux nous a permis de corréler l'apparition de ces structures a de profondes modifications qualitative et quantitative de la microflore endophyte. Ainsi il nous est apparu que la symptomologie de la maladie était corrélée à une modification profonde de la distribution spécifique de la microflore endophyte, visible à la fois au niveau du compartiment fongique et bactérien, suggérant la complète disparition de la pression de sélection exercée par le palmier sain sur sa flore et mise en évidence dans les 2 cas, par un shift d'une répartition de type Poisson vers une répartition normale. Dans le compartiment fongique, une claire déplétion des Pleosporaceae, associées à la plante saine pouvait ainsi être liée à une apparition de nouvelles familles (Trichocomaceae et Mycosphaerellaceae). De même, parmi les bactéries, une disparition des Rhizobium et Ensifer sp associés au compartiment racinaire de la plante saine a ainsi pu être mise en évidence, ces espèces pouvant servir ultérieurement d'indicatrices de bonne santé des palmiers. Dans une deuxième partie de notre travail nous avons cherché à utiliser des éléments de la flore endophyte mais également de substances naturelles dans la lutte biologique contre d'autres pathogènes du palmier. Ainsi, un antagonisme a été mis en évidence entre une souche endophyte d'Arthrobacter agilis et un pathogène majeur, Fusarium oxysporum sp Albedinis
The Brittle Leaf Disease of the Date Palm Tree (Phoenix dactylifera L.) constitutes a case study of an emerging disease of economic impact caused by a yet uncharacterized etiologic agent. Our strategy was to develop an approach that could be indistinctly transposed to any situation of this type. While basing our investigations on the successive characterization of the diversity of viral, bacterial and fungal endophytic compartments of healthy and diseased Palm trees, we aimed at enlightening differences in species composition but also distribution over two sampling campaigns performed in 2010 and 2012. While transmission electronic microscopy allowed us to visualize structures of probable viral origin affecting chloroplasts of the chlorophyllic cell layer, a molecular approach based on ribosomal gene sequencing allowed us to evidence correlations between the occurrence of such structures and deep modifications of the structure of the palm date tree associated endophytic flora suggesting a strong depletion of the ability of the palm to control its associated endophytes. This was evidenced in both fungal and bacterial compartments by a shift from a Poisson like diversity distribution towards a Gaussian distribution in the flora associated to MFC affected palms. In the fungal compartment, Pleosporaceae, that dominated in healthy palms were replaced by an opportunistic flora of Trichocomaceae and Mycosphaerellaceae. Among bacteria, the disappearance of Rhizobium and Ensifer species, typically associated to the root compartment of healthy palms was enlighten, suggesting that these species could indeed be used as biomarkers of healthy plant status. In a second part of this study, we investigated the potential use of cultivable palm endophytes, but also natural compounds for biocontrol applications. In particular, we evidence the antagonistic potential of Arthrobacter agilis, a palm endophyte, against a major palm date disease agent, Fusarium oxysporum sp. Albedinis

Date palms (Phoenix dactylifera L.) and papayas (carica papaya L.) are two commercially important plantation crops. Their economic potential in South Africa and worldwide is increasing. However, due to disease, pests and socio-economic reasons, planting material is in short supply. Micropropagation provides a method for rapidly propagating selected superior cultivars for commercial and environmental interests. A satisfactory process for the regeneration of elite cultivars should result in individuals phenotypically and genetically identical to the explant from which they were derived. However, due to somaclonal variation generated during in vitro culture, the true-to-typeness is questionable. For this reason a southern African survey for off-types on date palms produced using somatic embryogenesis was conducted. Plant growth variations such as leaf variegation, seedless fruit, broad leaves, compact growth habit and parthenocarpic fruit were recorded and possible explanations for each phenomenon given. Factors influencing the date palm initiation process such as decontaminating agents, plant growth regulators, explant type and nurse cultures were investigated. A double decontamination process with 2.6% and 1.3% sodium hypochlorite was most effective at reducing contamination. Alternative plant growth regulators, TIBA and NAA were ineffective as a substitute to 2,4-D for somatic embryogenesis. The size of the explant and "nurse cultures" played an important role in explant growth and initiating callogenesis. A "nurse culture" reduced the time in culture significantly. The problem areas in the three commercial tissue culture techniques used for date palms were outlined. In the second part of the study, factors influencing initiation, multiplication and rooting of papaya were determined. Presoaking with antibiotic, Rifampicin, and various fungicides had a positive effect on decontaminating papaya explants, while Bronocide™ had little effect. Various methods and materials were used to optimize papaya multiplication and rooting in vitro. The growth and multiplication of papaya was optimal at 50 g l ¯¹ sucrose. Gelling agent, Gelrite, increased multiplication rates significantly but had a negative effect on overall growth causing plants to become vitrified. The addition of activated charcoal reduced vitrification but also reduced multiplication rate. Activated charcoal greatly improved overall growth of papaya and reduced leaf senescence. No vitrification was observed in multiplying papaya cultures where agar and Gelrite combinations were used, but multiplication rate was reduced compared to cultures grown on Gelrite alone. callus removal from the bases of papaya at subculturing reduced multiplication rate and influenced elongation, growth and leaf senescence. Lower concentrations magar and Gelrite improved rooting percentages, but did not provide good support. Damaged roots and lower rooting percentages were observed on plantlets treated with IBA for four weeks compared to those exposed for only two days. A one hour pulse with a higher concentration (5 mg l ¯¹) of IBA greatly improved rooting percentage and further eliminated a second subculture onto an IBA-free medium after two days. Good, strong roots with root hairs were produced on vermiculite medium containing equal volumes of DS salts and vitamins. Modified lids with cotton-wool plugs also reduced leaf abscission. In vitro grafting using stericrepe proved impractical, while grafting in vitro unrooted papaya plants onto ex vitro seedlings was more successful, using wedge and slant grafts. Grafts sealed with pegs and Parafilm™ were less effective.
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2000.

Date palm (Phoenix dactylifera L.) is a fruit-bearing tree with numerous potential sustainable applications. Since ancient times, it has been considered a stable, secure, and sustainable food. This work provides comprehensive metabolic profiling of both parts, flesh and seed, of four P. dactylifera cultivars; Ajwa, Anbara, Sukkari, and Degelt Nour, which originated from two countries, Saudi Arabia, Tunisia. The analysis performed using mass spectrometry-untargeted metabolomics approaches, included a combination of LC-MS and GC-MS coupled to multivariate statistical analysis to reveal the differences in metabolite compositions among date varieties. The LC-MS seed results showed several classes of metabolites that belong to the flavonoids, phenolic acids, and amino acids derivatives, including citric acid, malic acid, lactic acid, hydroxyadipic acid, caffeic acid, which were at high concentrations in AJS followed by DNS and ARS. The LC-MS flesh analysis displayed that DNF had a high level of Isoquercitrin (flavonoid compound) and sinapic acid, and AJF was high concentrations level in hydroxyadipic acid and ascorbic acid. GC-MS concluded that seed samples of four date varieties are richer in metabolites classes than the flesh samples. The metabolites contributed to the seed metabolite compositions included several classes of amino acids, hydrocinnamic acids (caffeic, ferulic and sinapic acids), antioxidant phenolics, and long-chain fatty acids. The PCA and its loading analysis demonstrated the discriminating metabolites that were responsible for date varieties segregation, as HCA displayed the metabolic patterns and groups of metabolites that drive the clustering of the date samples, two groups of dates clustered together (AR and AJ) and (SR and DN). These clusterings are based on the similarities and differences observed in the metabolite compositions of the studied date samples that could be explained by differences in various metabolic responses and the environmental conditions, genotypes and geographical regions. This extensive date palm information would increase the potential of date fruits and seeds as low-cost sources of natural diet that may provide nutritious and bioactive components in the food and pharmaceutical fields to produce value-added products.