Date palm (Phoenix dactylifera L.) is one of the most essential fruit crops grown in arid and semi-arid regions. It is widespread throughout the Middle East, North Africa, South Sahel, areas of Eastern 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 suitable for agriculture in arid environments. Furthermore, date palm cultivation generates significant opportunities for rural employment, provides a major source of income for farmers, and supports the livelihood and food security of rural areas (Mazri et al., 2015). The date palm can proliferate sexually via seeds or asexually via shoots. Seed propagation cannot be used for the commercial production of the best genotypes due to its heterozygous character (Tisserat, B. 1982), and due to the notable difference between seedlings and vegetatively propagated plants in the expression of production potential, maturation and of the value of the fruit, and harvest time. Offshoot propagation is a slow procedure, hampered by the limited number of shoots produced by a single date palm, the low survival rate and the risk of disease transmission. In vitro date palm propagation techniques represent a competent alternative to conventional methods. Indeed, date palm micropropagation allows the rapid and large-scale proliferation of uniform and healthy plants, without seasonal effects or risk of diseases and parasites 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 Shouldn't Be Banned"? Get an original essay The purpose of this review is to summarize the literature on date palm micropropagation through somatic embryogenesis and organogenesis and highlight the main factors influencing each stage of these two micropropagation techniques. In addition to this, the main problems encountered during micropropagation of date palm are described. Date Palm Propagation Methods: The available techniques of rapid date palm multiplication have helped to tremendously increase the demand for date palm fruits across the world (Jain et al., 2011). Traditionally, the date palm is proliferated both sexually through seeds and vegetatively through shoots produced from axillary buds located at the base of the trunk during the juvenile phase of the date palm. The progress of shoots is very slow and this hinders the vegetative propagation of the date palm plant. So far, there is no method available to accelerate the increase in shoot quantities and reduce development time. The use of offshoots preserves the type-true character of the reproduced genotypes. Furthermore, sexual propagation of date palm is not suitable for the commercial production of type-true value-added genotypes. It is due to the heterozygous character of date palm seedlings and also their dioecious nature (Jain, 2007a). Moreover, half of these offspring are collected from male trees that were not distinguished before flowering. Female plants produce variable and commonly lower quality fruit (Eke et al., 2005). In addition, the seed propagation method has another drawback: the growth and maturation of seedlings is extremely low, and this is one reason why date palm seedlings can start tobear fruit after 8-10 years of planting. Although shoot propagation is a true-to-type technique, it is not commercially practical for the following reasons: shoot production is limited to a relatively short vegetative phase of about 10 to 15 years; At this stage only a limited number of offshoots are formed (20 to 30 offshoots, depending on the variety); Some varieties harvest more shoots than others (some do not produce enough shoots).All); Offshoot survival rate is low; The use of shoots improves the spread of date palm diseases and pests; Propagation of offshoots is difficult, time consuming and therefore expensive. In vitro propagation of date palm: The use of in vitro techniques such as somatic embryogenesis and organogenesis is highly appropriate for large-scale plant multiplication of vegetatively proliferated crops. The success of these techniques is highly dependent on the genotype, however, they have proven to be successful practices for plant propagation in wide-ranging crops, including date palm (Jain, 2007a). Micropropagation by direct organogenesis is commonly used for rapid clonal propagation of the best genetic material of the date palm plant (Khierallah and Bader, 2007). The performance of micropropagated date palm appears to be better than conventionally grown plants in terms of yield, early flowering time, and relatively uniform in fruit value and physical properties. Aaouine reported plant redevelopment from 30 date palm genotypes by direct shoot organogenesis. The main concern with this method is somaclonal variation that depends on several factors including genotype, explants, and plant growth regulators (Jain, 2007a). Furthermore, it is extremely necessary to maintain the genetic fidelity of regenerated plants, which can be studied by many molecular markers. Micropropagation has the advantage of using low concentrations of plant growth regulators, consequently the callus phase is avoided. Direct regeneration of vegetative buds reduces the risk of somaclonal variation among regenerators. The length of the growing period is limited by numerous subcultures for maintenance and by the fact that shoot crops are intended for seedling production. However, before starting fresh crops from mother plants, the maximum number of subcultures must be determined. 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 selected date palm cultivars and describes the advantages and limitations of date palm micropropagation; The main advantages are year-round plant availability, quality control, rapid plant production of elite cultivars and cold storage of elite genetic material. Advantages and Disadvantages of Somatic Embryogenesis (Jain, 2007b) Advantages of Somatic Embryogenesis: Somatic embryos originate from a single cell and minimize or eliminate chimera depending on the plant species. Somatic embryonic cell suspension is ideal for the induction of mutations due to the production of direct mutant somatic embryos. Somatic embryos behave like a zygotic embryo during germination. The single somatic embryo can be encapsulated to develop into a somatic seed that could germinate like a normal seed. This aspect still requires further research for use on a commercial scale.The most suitable approach in woody species for plant regeneration. Somatic embryos can be produced in a bioreactor that could be automated for large-scale production of somatic embryos. Somatic embryos are suitable for long-term preservation by cryopreservation. Disadvantages of Somatic Embryogenesis: - Somatic embryogenesis is highly genotype dependent and therefore modification of culture medium may be necessary for different genotypes. The germination rate of somatic embryos is very poor in most cultures. Somatic embryo cultures can lose their properties if they are not subcultured regularly on fresh culture medium, and this increases the possibility of obtaining genetic variability. Date palm explant selection organogenesis: The choice of an explant and its disinfection process can influence the success of micropropagation including date palm. Shoot tips and adventitious shoots in lateral buds contain more meristematic tissues than other organs and therefore are frequently used in date palm tissue cultures ( Mazri and Meziani, 2015 ). Aregeneration 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". Date palm tissue culture can also be achieved using inflorescence-derived explants, as reported for 'Banshee' and 'Gulistan'. Reynolds and Murashige (1979) induced somatic embryogenesis from zygotic embryos obtained from green fruits harvested 2-3 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 the explant: the main disinfectant agent used for shoot tips is sodium hypochlorite (NaOCl) at a concentration between 5% and 25% and for spikelets, mercuric chloride (HgCl2) at a concentration of 0.1%. Furthermore, the use of antioxidants such as ascorbic acid 150 mg/l (for 30 minutes), polyvinylpyrrolidone 4% (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 disinfection of shoot tip explants (Khierallah et al., 2007). Khan and Tabassum (2012) used an effective protocol to eliminate the infection from shoot tips: treatment with 5% (w/v) NaOCl containing a drop of a surfactant (Tween-20/100 ml), gently shaken to 30 minutes, rinsed three times in sterile distilled water (SDW; 5 minutes for each rinse), disinfect the surface with 0.2% (w/v) HgCl2 for 10 minutes and then rinse three times with SDW. Leaf primordia of 6 cm long shoot tips were removed and used as explants, and 2 cm long shoot tips with 2–4 intact leaf primordia also served as explants. A similar protocol was used by Othmani for the leaves adjacent to the axillary shoot tips of cv. “Boufeggous.” Fki first washed the young leaves with tap water and surface sterilized them with 0.01% HgCl2 for 1 hour, rinsed three times with SDW, then cut them into explants 5-10, 10-15 and 15-20 mm long . Ledo described a disinfection procedure for zygotic embryos from 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 fruit. After being washed under running water, the fruits were immersed in 40EC water and the seeds were removed on a laminar flow bench, immersed in 70% ethanol for 2 minutes, then in 2% NaOCl for 20 minutes under stirring and finally washed four times with SDW (Khokhar, MI et al., 2017). Adventitious bud initiation: The formation of adventitious buds on date palm explants depends on many factors such as substrate components, genotype, and time period of harvesting the plant material. Various culture media have been suggested for the formation of adventitious buds, depending on the cultivar. From offshoot-derived explants, Beauchesne et al. suggested half-strength Murashige and Skoog (MS) medium supplemented with 1-5 mg/L 2-naphthoxyacetic acid (NOA), 1 mg/L NAA, 1 mg/L indole-3acetic acid (IAA), and 0, 1-3 mg/ 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 2ip and 1 mg/L 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 scarce. Loutfi and Chlyah indicated that shoot primordia formed primarily 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 offshoot removal period, Beauchesne et al. suggested a period that starts from the end of the date harvest and lasts until the beginning of flowering. Aissam reported that explants made between October and February show the highest rate of bud formation, while Zaid et al. reported that the best period for in vitro culture of shoot-derived explants is from the beginning of flowering. Shoot multiplication Many factors influence shoot multiplication in date palm, particularly the basal formulation of the growing medium, genotype and PGRs. Abhmane said the main base formulation used is MS at full or half strength, supplemented with PGR at low concentrations compared to the bud-early stage. Zaid et al. reported that for shoot bud multiplication, NAA, NOA, IAA, BAP, and kinetin could be used at 0.5–5 mg/L. Beauchesne et al. suggested mid-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 1-5 mg/L kinetin. For the cultivar Khalas, 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 BAP for date palm cv. Maktoom while Khan and Bi Bi found that MS medium containing 0.5 mg/L BAP and 0.5 mg/L kinetin produced the highest number of shoots per explant in cv. Dhaka. In a previous work on the CV. Then, we found that the best medium for sprout bud multiplication was half-strength MS medium supplemented with 0.5 mg/L NOA and 0.5 mg/L kinetin, which yielded an average of 23, 5 shoot buds per explant after 3 months of multiplication. Mazri recommended the.