Browsing by Author "Sakr, Mahmoud"

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Behavior of Tunisian Local Barley Accessions Under Progressive Water Deficit: Physiological and Biochemical Approaches
(Journal of Phytology, 2010) Abdellaoui, Raoudha; Tarhouni, Mohamed; Chaabane, Ramzi; Ben Naceur, M’barek; El Faleh, Mouldi; Abdelli, Chedly; Ramla, Delila; Nada, Ahmed; Sakr, Mahmoud; Ben Hmida, Jeannette
Leaf water potential, percentage of membrane integrity and pigments chlorophyll content provide information on plant water status, on cell membranes integrity and on its photosynthetic capacity particularly under water stress conditions. These parameters were used to differentiate the behavior of 14 local barley accessions subjected to various intensities of stress (one week, two weeks and three weeks). The Principal Component Analysis (PCA) of the collected data at the end of each week revealed that the accessions behavior varies with the water deficit period. In fact, some are tolerant during the first and/or second week of stress and subsequently they are affected with a very substantial reduction in their chlorophyll pigments and their percentage of membrane integrity after three weeks. Others appear to be sensitive during the first week of stress and became tolerant under severe stress. This tolerance is manifested by the maintenance of membrane integrity, high content of chlorophyll pigments, significant proline accumulation and important specific activity of peroxidases. The study also showed that the 14 accessions exhibit two behavior types: i) significant decrease in leaf water potential with proline accumulation (constitutive osmotic adjustment) to keep cells turgid and ii) trivial drop of leaf water potential (osmotic adjustment of adaptive type). Moreover, variability in the different accessions behavior to water deficit seems to be linked to their geographical origin especially that supposed tolerant accessions are mostly from South and Central Tunisia characterized by severe aridity.
Genetic diversity analysis of North Africa’s barley using SSR markers
(Elsevier, 2012) Ben Naceur, Amani; Chaabane, Ramzi; El-Faleh, Mouldi; Abdelly, Chedly; Ramla, Dalila; Nada, Ahmed; Sakr, Mahmoud
It was demonstrated that some North Africa barley accessions have diverse tolerance sources for abiotic stresses and a good nutritional quality, but the studies done were incomplete since they were realized separately in each country apart. To implement a more complete analysis, 31 barley accessions originated from North Africa (Algeria, Tunisia and Egypt) were analyzed using 11 SSR markers selected from the seven barley linkage groups for studying the genetic diversity among these chosen barley accessions. Over the 11 SSR markers, a total of 478 reproducible bands were scored with an average of 2.13 alleles/primer and the average polymorphism information content of 0.5. Genetic distance analysis of the 31 accessions showed a large genetic diversity and high number of different groups. The most accessions are clustered according to their eco-geographical origin, according to their pedigree and agronomic characters or according to the caryopsis character (hulled or naked caryopsis). This high number of obtained groups is an invaluable aid in crop improvement strategies and confirms the opinion suggesting that North Africa could be a secondary center of origin of barley. The various growing conditions and the multiple uses of barley in each country may be the cause of the large variability of the barley germplasm in each region.