Application of RAPD markers in the identification and genetic relationship assessment among a number of salt - tolerant bread wheat (Triticum aestivum L.) lines.

number: 
608
English
Degree: 
Imprint: 
Biotechnology
Author: 
Rafat Hamdi Abdul Jaleel Al-Hadithi
Supervisor: 
Dr. Falah Attawi
Dr. Jaladat M. S. Jubrael
year: 
2002

The objective of this work was the detection of DNA polymorphisms among seven salt-tolerant bread wheat {Triticum aestivum L.) lines provided by the Iraqi Atomic Energy Organization, and one variety (Maxipac) known to be salt-sensitive as a control. This was achieved by the of Random Amplified Polymorphic DNA (RAPD) markers. DNA polymorphisms obtained using RAPD analysis were used to tentatively identify all samples tested, and to determine the genetic distance (GD) and the genetic relatedness among them. To achieve this, the following steps were carried out: - Genomic DNAs of bread wheat plants were extracted using CTAJB method. Genomic DNA yields obtained using this method ranged between (500 - 1000) ju g/3g of fresh plant tissues, with purity ranged between (1.8-2). After optimization conditions of RAPD reaction were setup (by varying the concentration of template DNA, Tag DNA polymerase and MgCl2) twenty three different decamer primers of arbitrary sequences were used for scanning for DNA polymorphisms among bread wheat variety / lines tested. Eleven primers have given detectable amplification products that scored in their number and their molecular weight in each primer individually. The total number of bands ranged between (3-8) bands for each primer individually. The molecular weight of amplified bands ranged between (0.15-15) Kbp according to the primer used. Twelve primers gave no detectable amplification products across bread wheat genotypes studied. Using DNA polymorphisms results obtained from RAPD experiments all variety / lines studied were tentatively characterized (Fingerprinted). The efficiency and the discriminatory power of each primer, for revealing DNA polymorphisms among genotypes studied, were calculated and it was found that, the primers efficiencies were ranged between nil (in primer OPO -01) to 1 (in primers OPA - 13 and OPK-04), and the discriminatory powers were ranged between nil (in primer OPO - 01) to 18% (in primer OPA - 12). DNA polymorphisms obtained using RAPD results were further used to calculate the genetic distance (GD) between variety / lines studied. The lowest genetic distance value was 0.10034 obtained between lines H5 and N3, while the highest value was 0.45815 between line N5 and Maxipac variety. The matrix of GD was used to generate a dendrogram that illustrate the genetic relatedness among variety / lines studied. Two major clusters were present, the first major group include all salt - tolerant lines tested, whereas the second major group included the salt – sensitive variety (Maxipac)