Somatic Embryogenesis Of Date Palm Research Articles

Dataset of transcriptome assembly of date palm embryogenic calli and functional annotation.

Date palm (Phoenix dactylifera L.; 2n = 36; Arecaceae), cultivated in tropical and sub-tropical regions worldwide, is a staple food for people in the Middle East region and has economic value throughout the world. Tissue culture is considered as a feasible technique for the large-scale multiplication of elite date palm varieties. In this article, we report the transcriptome assembly from the embryogenic calli of Khalas variety of date palm. A total of 50,852,331 paired-end (PE) raw reads were acquired using an Illumina sequencing platform. Reference-based assembly, with date palm genome, resulted in 53251 transcripts. A total of 63888 Gene Ontology (GO) terms could be annotated from the assembled transcriptome. Also, transcription factor families and small RNAs were annotated from the assembled transcriptome. Results of the pathway analysis revealed that a total of 2584 transcripts were involved in various metabolic pathways. Transcripts with possible roles in somatic embryogenesis were also identified. The dataset provides insights into the expression pattern of various genes during early somatic embryogenesis in date palm.

Impact of Osmotica and Plant Growth Regulators on Somatic Embryogenesis of Date Palm

An efficient somatic embryogenesis system is reported for date palm cv. Al-Fayda, a genotype resistant to the bayoud disease. Callus induction was achieved from adventitious bud explants cultured for 6 months on semi-solid Murashige and Skoog (MS) medium containing 4.5 μM 6-(dimethylallylamino) purine (2iP) and various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) or picloram. The highest somatic embryogenesis frequency (89%) was obtained on MS medium supplemented with 225 μM 2,4-D. Subsequently, embryogenic cultures were transferred to agitated liquid MS medium (maturation medium) containing various concentrations of mannitol, polyethylene glycol (PEG) or sorbitol. The highest rate of somatic embryo maturation (71.4 mature embryos per 100 mg callus) was achieved on the medium supplemented with 40 g l-1 PEG. Mature somatic embryos were then transferred to MS medium supplemented with gibberellic acid (GA3) or 1-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP) at various concentrations. The highest frequency of germination and conversion (26%) was obtained on the medium containing 5 μM NAA and 5 μM BAP. The developed plants were then transferred to ex vitro conditions, where a survival rate of 77.02% was observed. The regeneration protocol established in the present investigation will be used for mass propagation of date palm cv. Al-Fayda.

Enhanced Indirect Somatic Embryogenesis of Date Palm Using Low Levels of Seawater.

Date palm tolerates salinity, drought, and high temperatures. Arid and semiarid zones, especially the Middle East region, need a huge number of date palms for cultivation. To meet this demand, tissue culture techniques have great potential for mass production of plantlets, especially using the indirect embryogenesis technique; any improvement of these techniques is a worthy objective. Low levels of salinity can enhance growth and development of tolerant plants. A low level of seawater, a natural source of salinity, reduces the time required for micropropagation processes of date palm cv. Malkaby when added to MS medium. Medium containing seawater at 500ppm total dissolved solid (TDS) (12.2mL/L) improves callus proliferation, whereas 1500ppm (36.59mL/L) enhances plant regeneration including multiplication of secondary embryos, embryo germination, and rooting.

Indirect Somatic Embryogenesis of Date Palm Using Juvenile Leaf Explants and Low 2,4-D Concentration.

This chapter describes an efficient protocol for large-scale micropropagation of date palm. Somatic embryo-derived plants are regenerated from highly proliferating suspension cultures. Friable embryogenic callus is initiated from juvenile leaves using slightly modified Murashige and Skoog (MS) medium supplemented with 0.1mg/L 2,4-dichlorophenoxyacetic acid (2,4-D). Suspension cultures consisting of proembryonic masses are established from highly competent callus for somatic embryogenesis using half-strength MS medium enriched with 0.1mg/L 2,4-D and 300mg/L activated charcoal. The productivity of cultures increased 20-fold when embryogenic cell suspensions were used instead of standard protocols on solidified media. The overall production of somatic embryos mostly exceeds 10,000units per liter per month. Partial desiccation of mature somatic embryos, corresponding to a decrease in water content from 90 down to 75%, significantly improved germination rates.

Effects of growth regulators and types of culture media on somatic embryogenesis in date palm (Phoenix dactylifera L. cv. Degla Beida)

In the present study, we aim to develop a complete production scheme for the propagation of Algerian date palm Phoenix dactylifera L. (cv. Degla Beïda) by somatic embryogenesis. The scheme consists of four main steps: induction of callus, multiplication of nodules on solid and liquid media, initiation of somatic embryogenesis in agitated liquid medium and maturation and germination of proembryos on solid media. Our results showed that hormonal treatments (10mg/L 2,4-D, 1mg/L BAP) and (50mg/L 2,4-D, 1mg/L BAP) combined with 300 and 1500mg/L of activated charcoal, respectively, promoted initiation and multiplication of nodular calli on solid media. The best multiplication factor (9.75) was obtained from these calli when they were further cultivated in liquid medium containing 1mg/L 2,4-D. Moreover, liquid medium without growth regulators promoted the development of relatively homogeneous embryogenic suspensions. The return to solid medium without growth regulators during the maturation phase improved the yield of somatic embryos and their subsequent germination.

Somatic Embryogenesis of Date Palm (Phoenix dactylifera L.) Improved by Coconut Water

Somatic Embryogenesis of Date Palm (Phoenix dactylifera L.) Improved by Coconut Water

Comparison Effects of Sucrose and Date Palm Syrup on Somatic Embryogenesis of Date Palm (Phoenix dactylifera L)

The effect of different concentration of date palm syrup (2, 4, 6, 8 and 10%) and sucrose at concentration of 30 and 60 g/l in addition to the control (without carbon source) on the micro propagation of date palm Suckary were investigated. The results indicated that date syrup was taken up from the media as shown by the increase in total dry weight of culture. Addition of sucrose at 60 g/l produced the highest number of somatic embryos and longest shoot equal to that produced by date syrup at concentration of 6% without significant differences. On the other side, sucrose at 30 g/l improved the germination of somatic embryos followed by date syrup at 6%. Regarding fresh and dry weights, adding 6% date palm syrup was superior in this respect. Tissues grown on medium supplement with 10% of date syrup caused severe reduction in number of somatic embryo possibly due to the osmotic stress. In addition, tissues grown on medium containing 2% of date syrup had the lowest number of embryos. Date palm tissues are capable of utilizing date syrup as the sole carbon source for vegetative growth. It can be concluded that, adding date syrup locally known as 'Dibs' to the culture medium of date palm at concentration of 6% can be used totally as a replacement of sucrose which was the normally sugar used in most of plant tissue culture medium. This is the first report on the use of date syrup on somatic embryogenesis of date palm cv. Suckary.

Optimization of biotin and thiamine requirements for somatic embryogenesis of date palm (Phoenix dactylifera L.)

This study was conducted to examine the effect of biotin and thiamine concentrations on callus growth and somatic embryogenesis of date palm (Phoenix dactylifera L.). Embryogenic callus derived from offshoot tip explants was cultured on hormone-free MS medium containing biotin at 0, 0.1, 1, or 2 mg l−1 combined with thiamine at 0.1, 0.5, 2, or 5 mg l−1. Embryogenic callus weight, number of resultant embryos, and embryo length were significantly influenced by thiamine and biotin concentration. The optimum callus growth treatment consisted of 0.5 mg l−1 thiamine and 2 mg l−1 biotin. This treatment also gave the highest number of embryos. Embryo elongation was greatest at 0.5 or 2 mg l−1 thiamine combined with 1 mg l−1 biotin. Embryos from all treatments germinated and regenerants exhibited normal growth in soil. This study provides an insight into the importance of optimizing various culture medium components to overcome in vitro recalcitrace of date palm.

Carbon metabolism in in vitro cultures of date palm: the role of carboxylases (PEPC and RubisCO)

While describing major trends of carbon metabolism during the initiation and expression of somatic embryogenesis in date palm (Phoenix dactylifera L., cv. Deglet Nour), we have investigated the role of two carboxylases, namely PEPC (Phosphoenolpyruvate carboxylase, EC 4.1.1.31) and RubisCO (Ribulose 1,5-bisphosphate carboxylase/oxygenase, EC 4.1.1.39), in embryogenic and non-embryogenic cultures. The detection of PEPC activity on polyacrylamide native gels after electrophoresis revealed the presence of 3 active isoforms in crude extracts from the embryogenic (E) callus strain, whereas only a single band was present in the non-embryogenic (NE) one. The level of PEPC specific capacity was of the same order (3.9 ± 1.2 μmol CO2 h−1 mg−1 TSP) in both types of cultures. Further changes in carboxylase (PEPC and RubisCO) activities during the growth and development of somatic embryo–derived plantlets were also analysed. The PEPC/RubisCO ratio was found to progressively decrease (from 17.7 to 0.2) throughout the in vitro development of plantlets, due to a substantial depletion of PEPC activity, which decreased from 5.3 to 1.2 μmol CO2 h−1 mg−1 TSP. Concomitantly, RubisCO assumed greater importance (from 0.3 to 5.3 μmol CO2 h−1 mg−1 TSP ) and became the main route for inorganic carbon fixation. Western blot analysis using polyclonal antibodies raised against PEPC and RubisCO purified from tobacco leaves confirmed this trend in terms of relative enzyme abundance.

Influence of physical conditions of nutrient medium and sucrose on somatic embryogenesis of date palm

Shoot tips and leafy bud fragments removed from offshoots of adult date palms (Phoenix dactylifera L.) were cultured on a nutrient medium containing the Murashige and Skoog inorganic salts, 453 μM 2,4-dichlorophenoxyacetic acid, 14.8 μM N6-(2-isopentenyl)adenine and 3 g l-1 activated charcoal to develop nodular callus after 8 months of culture. Callus was cultured in agar-solidified and stationary or shaken liquid media containing half-strength MS inorganic salts, 3 g l-1 activated charcoal and different sucrose concentrations to study the influence of these factors on somatic embryogenesis. The best conditions for embryo development were culturing in liquid medium shaken at 100 rpm for a period of 2 weeks without sucrose, followed by culture on 3% sucrose.

Somatic embryogenesis and analysis of peroxidases inPhoenix dactylifera L

To determine some physiological parameters implicated in somatic embryogenesis in date palm (Phoenix dactylifera L.), peroxidases have been studied. Activated charcoal commonly used in date palm tissue culture as an essential antibrowning factor decreased cellular protein contents and peroxidase activities. During the first months of culture, the conventionally used medium (100 mg dm-3 of 2,4-dichlorophenoxyacetic acid, 3 g dm-3 charcoal) reduces 2 to 3 and 4 to 6 times protein contents and peroxidase activities, respectively, in comparison with the same one containing only 5 mg dm-3 of 2,4-D and with or without 150 mg dm-3 charcoal. In addition, the standard procedure decreased the embryogenic potential which is positively related to the intra- and extracellular (excreted into culture medium) peroxidase activities. In medium with embryogenic calli, extracellular peroxidase activity was three times as high as the activity determined in the same medium with non-embryogenic calli. There were two basic isoforms and four to five acidic bands characterizing the embryogenic calli. It can be suggested that peroxidases play a key role in somatic embryogenesis of date palm and the charcoal used at 3 g dm-3 constitute a perturbating factor for this process.

Somatic embryogenesis from shoot tip and immature inflorescence of Phoenix dactylifera cv. Barhee

A method of clonal propagation via somatic embryogenesis of date palm, cultivar Barhee, which has potential for large scale commercial application as well as for developmental studies on embryos is described. Cultures were initiated from shoot tip and immature inflorescence explants, both of which were capable of development into embryogenic callus. When the embryogenic callus was cultured in liquid suspension on a rotary shaker, hundreds of embryos developed from milligram quantities of callus in a fairly synchronous manner. Scanning electron microscopy showed globular, heart-shaped and torpedo-shaped embryos. Green leaves emerged from a white cotyledonary sheath.