Date palm (Phoenix dactylifera L.) is one of the most importan tree crops in the deserts

No abstract

Nanotechnology is one of the most important recent trends to improve the production of secondary metabolites in tissue culture for wide commercial use. Therefore, in this study, the effects of magnetite nanoparticles (MNPs) of different sizes (10.77, 20.5, and 29.3 nm) and different concentrations (0.5, 1, and 2 ppm) on the growth and production of active constituents in Ginkgo biloba L callus were investigated. The best medium for callus growth and proliferation of Ginkgo biloba L was MS medium supplemented with 1 ppm naphthalene acetic acid (NAA), 1 ppm kinetin, and 0.5 ppm MNPs with a size of 10 nm, which gave the maximum fresh weight of callus and percentage increase in fresh weight after two subcultures. The maximum accumulation of ginkgolide A and bilobalide was obtained when the callus was stimulated by MNPs 10 nm at 2 ppm. This study also focused on the estimation of phenolic compounds by HPLC and free radical scavenging (antioxidant activity) with 2, 2-diphenyl-1-picrylhydrazyl (DPPH) for their indirect effect on the production of active constituents. In addition, MNPs of different sizes had a significant effect on the number of phenolic compounds, with maximum values recorded at (2 ppm + size 10.77 nm). The major components were quercetin, kaempferol, p-coumaric acid, rutin and Caffeic acid. Moreover, the highest percentage of antioxidant activity (DPPH) was recorded when the callus was treated with (2 ppm + size 10.77 nm), which reached 77.29%. This study highlights the importance of MNPs in the production of ginkgolides A and bilobalides from Ginkgo biloba L. and focuses on the relationship between their size and concentration. Moreover, to obtain a good and durable source of active compounds of medicinal and industrial importance at a large scale and at the lowest cost.

n vitro medium term conservation of tropical plant germplasm is widely used for most plant species. Changes in the physical or chemical conditions had been used as a strategy for reducing the in vitro plant metabolism and prolonging the cultivation period. Embryogenic callus cultures of Oshkingbeel and Friahy date palm cultivars were derived from shoot tip explants using Murashige and Skoog (MS) medium supplemented with 10 mg/l dichlorophenoxy acetic acid (2,4-D) and 3 mg/l 2isopentenyladenine (2iP). Cultures were stored at two temperature (20 and 27±2°C) in complete darkness. Cultures were also subjected to different osmotic agents (sucrose and sorbitol) at different concentrations (0.087, 0.1, 0.2 or 0.4 M), which were added to medium supplemented with 10 mg /l 2,4-D and 3 mg/l 2iP. Every three months of storage up to 15 months, cultures were evaluated for percentage of survived and germinated embryos. After 15 months, the temperature of 20°C was more effective for the in vitro conservation of both cultivars concerning survival percentage and number of germinated embryos. At this temperature, after 15 months of storage, the highest survival percentage was 86.7 and 93.3% for cvs Oshkingbeel and Friahy, respectively. For osmotic agents, after 15 months, the highest survival percentage (66.7 %) was recorded with sorbitol at 0.4 M or sucrose at 0.2 M for cv Fraihy, whereas 60% of cv Oshkingbeel cultures were able to survive when preserved on medium containing 0.2 M sucrose. Sorbitol at its different concentrations and 0.2 M sucrose were the most appropriate treatments for maintaining the cultures and increasing the number of germinated embryos of cvs Oshkingbeel and Fraihy cultures after the tested storage periods.

Shoot tip and leaf primordial explants of Phoenix dactylifera L. cvs. (Sewi and Oshkingbeel) were cultured in modified MS medium supplemented with various combinations between different growth regulators cytokinins (2iP or BA) and Auxins (2, 4-D or NAA). Friable callus was produced from shoot tip and leaf primordial explants. The highest percentage of callus initiation was achieved on modified MS medium supplemented with 100 mg/L 2,4-D and 3 mg/L 2iP for shoot tip and leaf primordial explants. The highest percentage of embryogenic callus was achieved on modified MS medium supplemented with 10 mg/L 2,4-D, 5 mg/L NAA, 3 mg/L 2iP and 3.0 g/L activated charcoal which gave 87.5% and 75% for Sewi and Oshkingbeel cvs., respectively. Somatic embryos formation were obvious on modified MS medium plus 0.1 mg/L NAA which gave the highest average number (5.16, 4.94) for Sewi and Oshkingbeel, respectively after three subcultures. Greatest embryonic elongation resulted at 0.5 mg/L 2iP + 0.5 mg/L kinetin + 40 g/L sucrose in solid full strength MS medium. Also, the highest value of leaves number was shown on the same medium. The complete plantlets developed from individual embryos (5-10 cm) were transferred to rooting MS medium supplemented with 1 mg/L NAA with good growth in solid and liquid media. Rooted date palm plantlets from both cultivars were transferred to plastic pots (5cm diameter) containing peat-moss, sand and vermiculite at equal volume. Acclimatization percentage decreased gradually during four months in the first acclimatization stage. Date palm plantlets produced from the first acclimatization stage were transferred to plastic pots (20 cm diameter) containing peatmoss, washed sand and vermiculite at equal volume for more growth and development to be ready to cultivate in the field. Although survival percentage was low during the first acclimatization stage, it was very high in the second acclimatization stage and date palm survival percentage became constant after another six months with good growth.