Molecular cloning and expression of a vacuolar Na⁺/H⁺ antiporter gene (AgNHX1) in fig (Ficus carica L.) under salt stress

Soil salinity can be a major limiting factor for productivity in agriculture and forestry and in order to fully utilize saline lands productively in plantation forestry for fig production, the genetic modification of tree species for salt tolerance may be required. Na+/H+ antiporters have been suggested to play important roles in salt tolerance in plants. Here, we isolated AgNHX1 a vacuolar Na+/H+ antiporter from a halophytic species Atriplex gmelini and introduced it into fig (Ficus carica L.) cv. Black Mission via Agrobacterium-mediated transformation. Leaf discs explants of fig were co-cultivated for 2 days with Agrobacterium tumefaciens strain LBA 4404 harboring the binary vector pBI121 containing the AgNHX1 gene and the hpt selectable marker gene which encodes hygromycin phosphotransferase. Explants were cultured on MS medium containing 30 mg L−1 hygromycin, 3 % sucrose, 0.2 mg L−1 kinetin and 2.0 mg L−1 2,4-dichlorophenoxyacetic acid solidified with 2.5 g L−1 phytagel in darkness for callus formation. The calli were cultured on MS medium containing 2.0 mg L−1 zeatin riboside in combination with 0.4 mg L−1 indole acetic acid in the light for plant regeneration. Putative regenerated transformant shoots were confirmed by polymerase chain reaction (PCR) and Southern hybridization for the AgNHX1 gene. Reverse transcriptase polymerase chain reaction analysis indicated that the gene was highly expressed in transgenic plants, but the degree of this expression varied among transformants. Overexpression of the AgNHX1 gene conferred high tolerance to salt stress and transgenic fig plants overexpressing AgNHX1 developed normally under salinity conditions compared to those of non-transgenic plants. Salt treated transgenic plants contained high proline and K+ but less Na+ compared to non-transgenic control plants

In vitro Propagation of Date Palm Cultivars Magdoul and Safwai through Somatic Embryogenesis

The success of genetic conservation, cloning and possible genetic transformation requires an effective micropropagation protocol in vitro. For date palm (Phoenix dactylifera L.), there seems to be a lot of reported genotypic variation influencing optimum in vitro protocols. Two different cultivars of date palm Safawi and Magdoul were investigated to establish efficient protocol for callus induction, somatic embryogenesis, shoot proliffaration in vitro and plant acclimization ex vitro. The highest value of callus induction and relative water content (RWC) was reached at 25.0 mg L-1 2, 4-D and 5.0 mg L-1 2iP; 10 mg L-1 2, 4-D and 8.0 mg L-1 2iP for cvs. Safawi and Magdoul, respectively. The highest percentage of callus producing somatic embryos were 92.25% and 96.18% obtained on MS medium fortified with 6.0 mg L-1 2iP with 1.0 or 3.0 mg L-1 NAA for cvs. Safawi and Magdoul, respectively. High root formation occured on 2 and/or 2.5 mg L-1 NAA alone or with of 0.5 mg L-1 IBA. Regenerated plantlets were successfully acclimatized ex vitro with a 55-70% survival rate. The present article gives an update of the current approaches of date palm micropropagation with emphasis on the plant regeneration through somatic embryogenesis. It highlights key factors that influence in vitro differentiation and evaluated somatic embryos from embryogenic lines established from two cultivars with respect to their ability to germinate and be converted into plantlets

Cryopreservation of Embryogenic Callus of Date Palm (Phoenix dactylifera) cv. Magdoul through Encapsulation-Dehydration Technology

To overcome the genetic deterioration and the extinction of date palm genotypes and species as result of environmental challenges, it has become necessary to develop techniques that allow the remaining genetic resources to be persevered under in-vitro conditions for long period without a substantial decline in the vitality, genetic stability and low survival. The development of an effective cryopreservation method for date palm (cv. Magdoul) via an encapsulation-dehydration method for long term conservation was researched in this study. Embryogenic callus, obtained from shoot tip culture, was used as explants and exposed to different concentration of sucrose (0.0, 0.5, 0.75, 1.0 and 1.5 M) combined with dehydration time (0–10 days) and different drying time (1–10 h). It was found that using sucrose at 0.75 M was more effective compared with using 1.0 and 1.5 M. Among the drying time tested, 4 h gave the best result for survival. The interaction treatment between sucrose, dehydration and moisture content (MC) was studies. After different periods of time in liquid nitrogen, the greatest values of survival (74.4%) and regrowth (71.25%) after 6 weeks of storage were obtained when 0.75 M sucrose for three days followed by 4 h dehydration period with a 39.50% MC was applied. The present results indicated that encapsulation-dehydration can be applied as a simple and effective protocol to a diverse range of cv. Magdoul genetic resources using embryogenic calli. © 2020 Friends Science Publisher

Micropropagation of virus-free plants of Saudi fig (Ficus carica L.) and their identification through enzyme-linked immunosorbent assay methods

© 2018, The Society for In Vitro Biology. Viral infection is one of the most serious biotic stresses, which disturbs the growth and productivity of many horticultural crops, including that of fig (Ficus carica L.). The production of plants free of viruses, such as fig mosaic virus (FMV), has become a priority in many plant breeding programs. In this study, leaves from plants of two fig cultivars, Kodato and Dattora, infected with FMV were collected from both Mecca and Al-Taif, Saudi Arabia. Transmission electron microscopy of ultrathin leaf sections showed double membrane bodies, characteristic of FMV particles, only in the mesophyll cells of infected samples. Protein analysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of a protein band with a molecular weight of 35 kDa, which corresponded to the viral coat protein; and FMV was confirmed by Western blot and enzyme-linked immunosorbent assay (ELISA) tests. To obtain virus-free plants, apical shoot culture was applied. A comparison of various artificial media with different concentrations of growth regulators was evaluated to optimize shoot formation, shoot multiplication, and root formation, and was followed by plant acclimation ex vitro. Direct ELISA analysis of shoots micropropagated from meristem tip explants indicated that there were virus-free shoots, when compared to infected plants (positive control), while there were no significant differences between these explants and healthy samples (negative control). This study demonstrated that in vitro micropropagation of Saudi F. carica infected with FMV virus led to the successful elimination of the virus