Date palm (Phoenix dactylifera L.) is one of the most essential fruit crops grown in arid and semi-arid regions. It is widespread in the Middle East, North Africa, southern Sahel, parts of East and South Africa, Europe and the United States (Mazri et al., 2015), with approximately 150 million trees worldwide (Mazri et al., 2015). The date palm is refined for its high yield and the high nutritional value of its fruits, to preserve ecosystems threatened by desertification and create a microclimate conducive to agriculture in an arid environment. Furthermore, date palm cultivation generates considerable rural employment opportunities, constitutes a main source of income for farmers and confirms the livelihoods and food security of rural areas (Mazri et al., 2015). The date palm can proliferate sexually by seeds or asexually by branches. Propagation by seed cannot be used for commercial production of the best genotypes due to its heterozygous character (Tisserat, B. 1982), and due to the considerable difference between seedlings and vegetatively propagated plants in the expression of production potential, fruit ripening and value, and harvest period. Branch propagation is a slow procedure that is hampered by the limited number of branches produced by a single date palm, low survival rate and the risk of disease transmission. Date palm propagation using in vitro techniques presents an effective alternative to conventional methods. Indeed, the micropropagation of the date palm allows the rapid and large-scale proliferation of uniform and healthy plants, without seasonal effects or risk of spreading diseases and pests during the exchange of plant material (Quiroz-Figueroa et al., 2006) . Say no to plagiarism. Get a tailor-made essay on “Why violent video games should not be banned”?Get an original essay The aim of this review is to summarize the literature on date palm micropropagation through somatic embryogenesis and organogenesis and to highlight the main factors affecting each stage. of these two micropropagation techniques. Furthermore, the main problems encountered during date palm micropropagation are described. Date Palm Propagation Methods:- Available techniques for rapid multiplication of date palm have contributed to a considerable increase in the demand for date palm fruits worldwide (Jain et al., 2011). Traditionally, the date palm proliferates both sexually through seeds and vegetatively through offshoots produced from axillary buds located at the base of the trunk during the juvenile phase of the date palm. The progression of the branches is very slow, which hinders the vegetative propagation of the date palm. Until now, there is no technique to accelerate the increase in the quantities of releases and reduce the time required for their development. The use of branching preserves the true-to-type character of the genotypes reproduced. Furthermore, sexual propagation of date palm is not suitable for commercial production of true-to-type and value-added genotypes. This is due to the heterozygous nature of date palm plants but also to their dioecious nature (Jain, 2007a). Additionally, half of this progeny consists of male trees that cannot be distinguished until flowering. Female plants produce variable and generally lower quality fruits (Eke et al., 2005). Furthermore, the method ofSeed propagation has another disadvantage: the growth and maturation of the plants is extremely poor, and this is one reason why date palm plants may begin to fruit after 8 to 10 years of planting. Although sucker propagation is a true-to-type technique, it is not commercially practical for the following reasons: Sucker production is limited to a relatively short vegetative phase of about 10 to 15 years; Only a limited number of branches are formed during this phase (20 to 30 branches depending on the variety); Some varieties harvest more offshoots than others (some don't produce offshoots at all); The survival rate of offspring is low; The use of branches improves the spread of date palm diseases and pests; The propagation of ramifications is difficult, long and therefore costly. In vitro propagation of date palm: The use of in vitro techniques such as somatic embryogenesis and organogenesis are very suitable for large-scale plant propagation of vegetatively proliferating crops. The success of these techniques is highly dependent on genotype, but they have been found to be successful in plant propagation in many crops, including date palm (Jain, 2007a). Micropropagation by direct organogenesis is commonly used for rapid clonal propagation of the best date palm germplasm (Khierallah and Bader, 2007). The performance of micropropagated date palm appears better than that of conventionally grown plants in terms of harvest, early flowering period and relatively uniform fruit value and physical properties. Aaouine reported a plant reorganization of 30 date palm genotypes by direct shoot organogenesis. The main concern of this method is somaclonal variation which depends on different factors including genotype, explants and plant growth regulators (Jain, 2007a). Furthermore, it is absolutely necessary to maintain the genetic fidelity of the regenerated plants, which can be studied by numerous molecular markers. Micropropagation has the advantage of using low concentrations of plant growth regulators, which allows the callous phase to be avoided. Direct regeneration of vegetative buds reduces the risk of somaclonal variation between regenerants. The length of the cultivation period is limited by many subcultures for maintenance and by shoot cultures for seedling production. However, the greatest number of transplants should be determined before starting fresh crops from the mother plants. This is done to prevent or reduce somaclonal variation. Currently, only a few laboratories use this technique to commercially produce date palm plants in vitro, mainly in Morocco, Saudi Arabia and the United Arab Emirates. A micropropagation technique has been used commercially in some date palm cultivars, describing the advantages and limitations of date palm micropropagation; the main advantages are year-round availability of plants, quality control, rapid production of elite cultivar plants and cold storage of elite germplasm. Advantages and Disadvantages of Somatic Embryogenesis (Jain, 2007b) Advantages of Somatic Embryogenesis: Somatic embryos originate from a single cell and minimize or eliminate chimeras depending on the plant species. Somatic embryo cell suspension is ideal for induction of mutations through the production of direct mutant somatic embryos. Somatic embryosbehave like a germinating zygotic embryo. The single somatic embryo can be encapsulated to develop into a somatic seed which could germinate like a normal seed. This aspect still requires further research for use on a commercial scale. The approach most suited to woody species for plant regeneration. Somatic embryos can be produced in a bioreactor which could be automated for large-scale production of somatic embryos. Somatic embryos are suitable for long-term storage by cryopreservation. Disadvantages of Somatic Embryogenesis:- Somatic embryogenesis is highly genotype dependent and hence modification of culture medium may be required for different genotypes. The germination rate of somatic embryos is very low in most cultures. Somatic embryogenic cultures can lose their properties if they are not subcultured regularly on fresh culture medium, which increases the risk of obtaining genetic variability. Organogenesis of the date palm Selection of explants: The choice of an explant and its disinfection process can affect the success of micropropagation in particular of the date palm. Shoot tips and adventitious shoots of lateral buds contain more meristematic tissues than other organs and are therefore frequently used in date palm tissue cultures (Mazri and Meziani, 2015). A successful regeneration of many date palm genotypes was achieved when shoot tips were used as explants: 'Jihel' and 'Iklane', 'Mordarsing' and 'Khanizi', 'Nabout' and 'Khasab' (Al-Khayri , 2007), and "Khalasah", "Zardari", "Banshee", "Zart", "Muzati" and "Shishi". Tissue culture of date palms can also be performed using inflorescence-derived explants, as has been reported for 'Banshee' and 'Gulistan'. Reynolds and Murashige (1979) induced somatic embryogenesis from zygotic embryos obtained from green fruits harvested 2 to 3 months after pollination. Pinker also used zygotic embryos to induce somatic embryogenesis in 'Khistawi', 'Zahdi', 'Barban', 'Asabe' and 'Elarous'. Somatic embryos are useful for micropropagation and large-scale production of date palm plants and can also be used to obtain true-to-type genotypes. Disinfection and preparation of explants: - The main disinfectant agent used for shoot tips is sodium hypochlorite (NaOCl) at a concentration ranging from 5% to 25% and for spikelets, mercuric chloride (HgCl2) at a concentration by 0.1%. In addition, the use of antioxidants such as 150 mg/l ascorbic acid (for 30 min), 4% polyvinylpyrrolidone (Aslam and Khan, 2009), citric acid at a concentration of 150 mg/l with 150 mg/l ascorbic acid (soaked overnight), or caffeine anhydrous are widely used during the disinfection of shoot explants (Khierallah et al., 2007). Khan and Tabassum (2012) used an effective protocol to eliminate infection from shoot tips: treatment with 5% (w/v) NaOCl containing one drop of a surfactant (Tween-20/100 ml), gently shaken for 30 min, rinsed three times. times in sterile distilled water (SDW; 5 min each rinse), surface disinfected with 0.2% (w/v) HgCl2 for 10 min, then rinsed three times with SDW. Leaf primordia from 6 cm long shoot tips were collected and used as explants and 2 cm long shoot tips with 2–4 intact primordial leaves also served as explants. A similar protocol was used by Othmani for leaves adjacent to the apex ofAxillary shoots of the CV. “Buffeggous.” Fki first washed the young leaves with tap water and surface sterilized them with 0.01% HgCl2 for 1 h, rinsed three times with SDW, and then cut them into explants of 5-10 , 10-15 and 15-20 mm long. Ledo described a procedure for disinfecting zygotic embryos of mature (wine-colored, -2.17 g) and immature (green, -1.68 g) fruits of the "a?ai" palm, a species of Euterpe palm grown for its fruits. After being washed in running tap water, the fruits were immersed in water at 40 °C and the seeds were excised on a laminar flow bench, immersed in 70% ethanol for 2 min, then in 2% NaOCl for 20 min with stirring, and finally washed four times. with SDW (Khokhar, MI et al., 2017). Initiation of adventitious buds: The formation of adventitious buds on date palm explants depends on many factors such as the components of the medium, the genotype and the period of collection of the plant material. Different culture media have been proposed for the formation of adventitious buds, depending on the cultivar. From explants derived from suckers, Beauchesne et al. suggested half-strength Murashige and Skoog (MS) medium, supplemented with 1 to 5 mg/L 2-naphthoxyacetic acid (NOA), 1 mg/L NAA, 1 mg/L indole-3acetic acid (IAA ) and 0.1 to 3 mg/L. L 6-(dimethylallylamino) purine (2iP). Khierallah and Bader recommended MS medium supplemented with 2 mg/L 2ip, 1 mg/L BAP, 1 mg/L NAA, and 1 mg/L NOA for cv. Maktoom. Al-Mayahi suggested MS medium supplemented with 1 mg/L BAP and 0.5 mg/L thidiazuron (TDZ) for cv. Hillawi. For CV. Zaghlool, Bekheet used MS medium supplemented with 2 mg/L of 2ip and 1 mg/L of NAA while Hussain et al. used MS medium supplemented with 4 mg/L IBA and 1 mg/L BAP for CVS. Asil, Hussaini and Zaidi. According to Al-Khateeb, low concentrations of PGR promote bud formation while high concentrations induce abnormal growth without bud formation. Studies on the formation of adventitious buds from inflorescence explants are very rare. Loutfi and Chlyah indicated that shoot primordia are formed mainly on Greshoff and Doy medium supplemented with 0.5 mg/L NAA, 2 mg/L BAP and 1 mg/L 2iP. In a recent literature review, Abhmane reported that the combination of one auxin and two cytokinins is effective for bud formation on inflorescence explants. Regarding the period of elimination of offspring, Beauchesne et al. suggested a period from the end of harvest dates to the start of flowering. Aissam reported that explants collected between October and February have the highest rate of bud formation, while Zaid et al. reported that the best period for in vitro culture of branch-derived explants is at the start of flowering. Shoot multiplication Many factors influence date palm shoot multiplication, including the basal formulation of the culture medium, genotype and PGR. Abhmane mentioned that the main basal formulation used is MS at full or half concentration, supplemented with PGR at low concentrations relative to the bud initiation stage. Zaid et al. reported that for bud multiplication, NAA, NOA, IAA, BAP and kinetin could be used at 0.5 to 5 mg/L. Beauchesne et al. suggested half-strength MS medium supplemented with 2 mg/L NOA, 1 mg/L NAA, 1 mg/L IAA, 0.5 mg/L BAP, 1 mg/L 2iP and 1 to 5 mg /L of kinetin. For Khalas cultivar, Aslam and Khan used 7.84 µM BAP for high bud multiplication. Khierallah and Bader recommended MS medium with a combination of 1 mg/L NAA, 1 mg/L NOA, 4 mg/L 2iP and 2 mg/L.