الفهرس 
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Abstract
SUMMARY
This study was conducted at the Department of Genetics, Faculty of Agriculture, Ain Shams University, Shubra Al Khaymah, Egypt and the Department of Genetic Resources, Desert Research Center, El-Matareya, Egypt from 2014 to 2018.
The objectives of this study were to (1) identify some genes controlling salinity tolerance (oxidative and osmotic stress) in mangroves using NCBI (2) studying the gene expression of these genes at Nabq protectorate in Red sea conditions through the following steps:
1- Searching for some gene sequences for salinity tolerance (oxidative and osmotic stress) in mangroves using NCBI database.
2- DNA barcoding of mangrove in Nabq protectorate.
3- Studying the levels of four genes expression using quantitative-PCR.
4- Isolation and sequencing of 3’-UTR regulation sites of the genes controlling salinity tolerance (oxidative and osmotic stress).
The major results obtained can be summarized as follows:
1- DNA barcoding by internal transcribed spacer (ITS), a DNA sample was amplified from mangrove by the ITS1 and ITS4 primers), the PCR product exhibited a single band of the target size (545bp). BLASTn search results of Avicennia marina; 18S ribosomal RNA geneas a partial sequence; complete sequence of internal transcribed spacer 1 (ITS1), 5.8S ribosomal RNA gene and internal transcribed spacer 2 (ITS2)); and 26S ribosomal RNA geneas a partial sequence, confirmed our results.
2- Quantitative gene expression for the four genes amFer1, amSod1, amUbc2 and amCat1 were validated using qPCR to reveal the differential expression under the natural abiotic stress conditions (salinity, oxidative and osmotic stresses) in Avicenna marina transcript levels.
The results showed over-expression of the mRNA of ferritin (amFer1) gene transcript, followed by slight increase in mRNA of superoxide dismutase (amSOD1) and even slight increase in ubiquitin conjugation2 (amUBC2) compared with the actin gene. At the same time gene expression of catalase (amCAT1) was down-regulated.
3- Molecular characterization of the 3’-UTR-structured region of each gene and molecular characterization and comparability in the five databases (NCBI, T-coffee, clustal-w2, EMBOSS Needle and weblogo.3) confirmed the high homologies of amCat genes (99%), amFer (99%) amSOD (98%) and UBC2 (100%). It was evident that the variation in the 3’-UTR region is very limited because it is harboring conserved regulatory region that controls the efficiency and half-life time of mRNA and thus it is reflected on the gene expression.
The results confirm that these genes have important roles in controlling salt, oxidative and osmotic stress in the Egyptian gray mangrove plant under the red sea conditions within the Nabq protectorate in South Sinai.
These results would help geneticists and crop breeders as they could provide important bases for future investigations to functionally analyze and exploit the complex gene network behind its outstanding recourses. This could provide such genes to enhance abiotic stress tolerance through gene transfer to some strategic crops such as wheat, maize and rice.