Browsing by Author "Chaabane, Ramzi"

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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.
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    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.
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    Molecular Characterization of Tunisian Barley (Hordeum Vulgare L.) Genotypes using Microsatellites (SSRs) Markers
    (European Journal of Scientific Research, 2009) Chaabane, Ramzi; El Felah, Mouldi; Ben Salah, Hammadi; Ben Naceur, M’Barek; Abdelly, Chedly; Ramla, Dalila; Nada, Ahmad; Saker, Mahmoud
    High level of polymorphism make simple sequence repeats (SSRs) the molecular marker of choice for diversity analysis in plant species. In this study 18 simple sequence repeats (SSRs) markers were used to characterize six Tunisian barley varieties (Faïz, Manel, Martin, Rihane, Roho, and Tej) as well as six landraces from different growing regions in Tunisia (Djerba, Gabes, Jendouba, kairouan, Kebili, Kerkennah). Amplification of SSRs loci were obtained for 17 primer pairs and only 11 among them showed clear polymorphic patterns. These 11 primers produced a total of 31 alleles. The number of alleles per marker ranged from 1 to 5 with an average of 2.81 alleles per locus. The data generated by these 11 primers were sufficient to discriminate the analysed barley genotypes. The UPGMA cluster analysis of the similarity data grouped the 12 studied genotypes into two groups according to their spike type (two-row and six-row barley), except for Manel verity witch is a six row type but it clustered among the two row group. These results will be useful for barley germplasm management in terms of biodiversity protection and design of new crosses