الفهرس 
Molecular Genetic Studies on Drought Tolerance in Cotton Plants by Poly-Ethylene-Glycol (PEG)Only 14 pages are availabe for public view
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Abstract
Cotton is an important economic crop in the world, where it plays an important role
in the national income in terms of fibers used in the manufacture of textiles and cotton
seeds from which oil is extracted and its residues used for animal feed. This research was
carried out for the development of drought-tolerant cotton plant using tissue culture
technique. Four cotton cultivars were used in this research, all of which are under
Gossypium barbadese spp. They are, Giza 86, Giza 92, Giza77, and Hybrid 2. Seeds were
grown on MS medium and leaves were used to study tissue culture technique.
The effect of drought was also studied on callus induction from cultivars using two
concentrations of Polyethylene Glycol (PEG). The callus was put on the germination
media for producing the green callus and shoot. Finally, molecular studies were used to
determine the genetic variability among the selected cotton genotypes.
1- Six MS medium (D, D1, D2, D3, D4 and D5) were different in the concentration of the
hormone, were used in growing seeds for each genotype on these media.
2- After producing the Callus, the best medium for each genotype was selected
3- Callus is used to estimate its tolerance to drought induced with the following
concentrations (50-100g/l) of polyethylene poly ethylene glycol (PEG).
4- The callus growth was followed after the PEG treatment, which causes dehydration,
callus was transferred to the regeneration medium
5- Green callus and Shoot were produced.
6- Molecular techniques; RAPD-PCR and DDRT-PCR, were done.
Results of tissue culture:
1- Medium (D4) containing (0.1mg / l 2, 4-D + 0.1mg / l KI) was the best medium for
producing callus for G86 and G92 genotypes.
2- The medium (D) containing (0.1 mg / l BA + 0.5mg / l 2, 4-D) the best medium
given callus for H2 (G86*G45) and G92 genotypes.
3- The best genotypes that given callus induction was Giza 86 on medium D4.
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4-Two types of calli were found, the first callus was yellowish and friable, called
embryogenic calli, while the second was white and hard, and called non embryogenic
calli.
Results of the impact of callus to dryness using (PEG) as follows:
1- The effect of (PEG) on callus of three different Egyptian cotton varieties and one cotton
Hybrid was studied using two concentrations of PEG (50-100 g / L), for 21 days and
then transferred to the a new medium and the cycle lasted 63 days.
2- Different degrees of tolerance of drought for the four genotypes were observed. The
genotype Giza86 showed the highest tolerance, while the genotype Giza 92 produced
the lowest tolerance on PEG 10 %.
3- The color of calli were changed from white to yellow on the concentration of 50 g / l
PEG and the color turned to brown to the concentration of 100 g / l PEG.
Effect of regeneration medium:
1-Callus was developed from each of the four cultivars on the four media (D6, D7, D8
and D9), which different in the concentrations of the hormones to produce shoot.
2- The four cultivars failed to give shoots on the four medium regenerations.
3- They were placed in four other medium (D10, D11, D12 and D13) differed in the
concentration of hormones.
4- It was found that the genotype hybrid2 gave shoots on the medium D13 and all
genotypes produced green calli on the media D10andD13.
Results of PCR techniques:
1-The DNA was extracted from non-treated PEG samples (4 samples) and treated ones for
all cotton cultivars (8 samples).
2- RNA was extracted from the four genotypes treated with polyethylene glycol 5% and
10%.
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3- RAPD analysis for all cultivars, were done using twelve random primers.
4- RAPD results the OPG-1, OPF-03 gave the highest percentage of hereditary
differences between Giza 86, Giza 92 and H2 cultivars and when the phylogenetic tree
was used to clarify the degree of relationship, Giza92, Giza86 was found to be the
highly related.
5- Differential display reverse transcriptase polymerase chain reaction (DDRT-PCR) was
also done using seven specific primers, with the four cultivars.
6- Results of DDRT-PCR found that the primer P3 gave the highest percentage of genetic
differences in the varieties Giza 86 on 10% PEG and Giza 92 on 5% and 10% PEG.
7- The other primers did not give any result.