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King Abdulaziz University (2010)

Genetic Fingerprinting of Some Native Barley in Kingdom of Saudi Arabia

Al Aboud, Nora Mohammed

Titre : Genetic Fingerprinting of Some Native Barley in Kingdom of Saudi Arabia

البصمة الوراثية لبعض أصناف الشعير البلدي بالمملكة العربية السعودية

Auteur : Al Aboud, Nora Mohammed

Université de soutenance : King Abdulaziz University

Grade : Master 2010

Résumé
Genetic improvement of any crop species depends upon the existence, nature and extent of the genetic variability available for manipulation .This study was conducted on six samples of barley (Hordeum vulgare) collected from different regions of Saudi Arabia (Taif, Hail, Qassim, Asir, Al Baha and Jazan) in order to test the ability of these samples to tolerate different levels of salt stress, and then to determine the fingerprint at the level of protein, as well as at the level of DNA, and to study the variation and the genetic relationship between samples using the technique of RAPD-PCR . Results indicated that the presence of a direct correlation between the small and dwarf shoot of the samples and increasing salt concentration which is probably due to a metabolic defect as a result of salt stress . It also showed significant decrease of the fresh weight of the treated seedlings, this reduction was evident in the seedlings treated with concentration of 12000 ppm . The highest rate of decrease in wet weight were recorded in the sample from Hail, Qasim, Jizan, Asir, Al Baha and Taif, respectively. Salt stress caused significant decrease in seedlings dry weight of all samples that increase by increasing salt concentration. Jazan sample was the least affected, where it recorded the lowest decline in both concentrations, this decline is probably due to inhibition of plant cell division as a result of salt stress . Despite the disparity of the total content of amino acids in the leaves of the studied samples seedlings, but they all showed that Aspartic acid was the most abundant acid. On the other hand, proline was the least among the list of amino acids recorded in the samples. Moreover, the studied samples agreed that the group of neutral amino acids constituted the largest in terms of total acid content followed by acidic, basic, and then aromatic group. Salt stress leads to accumulation of amino acids in the leaves of the samples, which could be of preventive value. The highest rate of amino acids accumulation under the influence of stress salt was seen in the sample from Jazan at a concentration of 4000 parts per million, and in Qassim sample at a concentration of 12000 ppm. Increase in the content of amino acids may be associated with plant tolerance to salinity . Gel electrophoresis of protein samples did not show clear differences in the patterns of protein bands that have been obtained, the number of basic bands were the same in all samples at the weight of 55, 27, 23 and 16 kDa. However, salt stress induced the emergence of a number of new bands that is likely belong to heat shock proteins (HSPs), which are activated under stress conditions. Changes in pattern of protein bands is the result of changes in gene expression caused by salt stress . By using eight RAPD-PCR primers, we were able to obtain 91 genetic bands that represent the sources of variation between the study samples. The two primers OP-N1 and OP-H1 showed a higher ability to detect a high rate of variation between the studied samples .The average variation rate obtained by the eight primers was 92.86%. Cluster analysis based RAPD-PCR data analysis divided barley varieties in the studied samples into two groups . We found the highest degree of genetic similarity between samples from Al Baha and Jazan (65.3%) , also similar degree of genetic convergence (65.1%) was found beteween samples from Asir and Taif, while samples from Al Baha and Taif were the most divergent from each other genetically .

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Page publiée le 21 décembre 2014, mise à jour le 3 novembre 2017