الفهرس 
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Abstract
This investigation was carried out at the Agriculture Genetic Engineering Research Institute (AGERI), ARC, Giza-Egypt and the Department of Genetics, Faculty of Agriculture, Ain Shams University, during the period 2011-2017. Two Egyptian cultivars of Sweet potato (Ipomoea batatas (L.) Lam) were tested in this study.
The main objectives were
1- Selected the most important and common local cultivars of sweet potato (Abees and Mabrouka) in Egypt.
2- Study and evaluate in vitro regeneration of sweet potato cultivars using different methods.
3- Genetic transformation using Agrobacterium method.
4- Transformation using gene gun (Biolistic gene gun).
5- Determination of putative transformed plants using Histochemical analysis and PCR.
The results could be summarized as follows
1- Choose the shoot tip explants were very successfully for regeneration process.
2- Use of cytokinins were very important factor for regeneration, the use of BA only at concentration of 1.0mg/l with Abees cv., and 5.0mg/l kinetin only with Mabruka cv. were produced shoots and roots intensively and successfully.
3- When the BA used with either NAA or IAA, only roots were produced.
4- Abees cv. was the most responded cultivar which give the highest regeneration frequency 26.3 %. While, Mabruka cv. gave 13.3 %.
5- The responded explants were shoot tips while the other explants (leaves and stem) were completely unresponded to shoot formation.
6- The addition of silver nitrate to the regeneration media was studied as an important factor which was found to be effective in stimulating regeneration in various plants species due its role in inhibiting the ethylene level which produced during in vitro plant tissue culture but this did not proved in Sweet potato Egyptian cv. However, the addition of silver nitrate to the regeneration media was enhanced the root formation in both shoot tips and stem explants, but no results indicated with leaves explants.
7- Results indicated that the medium constituent (MS basal salt mixture supplemented with 30 g/l sucrose and 2.2 g/l Phytagel, and pH was adjusted to 5.6-5.7) was the best medium for root formation.
8- Mabruka cv. most responded cultivar which gives the highest root frequency 85.9% in regeneration medium containing 1.0mg/l BA. While, Abees cv. give 23.9% in regeneration medium containing 3.0mg/l BA.
9- The concentration of 4mg/l bialaphos was chosen as a selection marker to select the transformed tissues in the Egyptian Sweet potato cv.
10- The ideal optical density of Agrobacterium suspension culture determined through histochemical explant analysis. The results showed that the highest number of GUS expression was observed using suspension of 0.3 O.D600.
11- Also, to increase the Agrobacterium transformation efficiency, the shoot tips explants were inoculated for 30 min with bacterial su.spension with wounding the explants using immersed scalpel.
12- The explants were co-cultivated on regeneration media (MS media with 3% sucrose, 1.0 mg/l of BA with Abees cv. and 5.0mg/l kinetin with Mabruka cv., 2.2g/l Phytagel, 4 mg/l bialaphos and 200 mg/l cefotaxime) at 28 ºC for 2 days which was found to be better.
13- Experiment was performed to determine the effects of different bombardment pressure (900 and 1100), as an acceleration pressures during bombardment, on the transformation efficiency of two Egyptian Sweet potato cv., it was shown that 1100 give the best results followed by 900.
14- The putatively transformed plants were histochemically analyzed using GUS histochemical analysis which proved the presence of the GUS gene. Also, those plants were analyzed on the molecular level of DNA using the polymerase chain reaction.
15- The integration and expression of GUS and bar genes in the positive transgenic Sweet potato plants tested using PCR confirmed by the presence of 1050 bp partial GUS gene fragment and 400 bp partial bar gene in transgenic.
FUTURE WORK
The presently available regeneration and transformation protocol will allow us to draw any strong future prospects to enhance the Sweet potato properties as tuber quantity and quality and resistance of biotic and abiotic stresses through genetic transformation.