Variability in Responses to Phoma medicaginis Infection in a Tunisian Collection of Three Annual Medicago Species

Spring black stem and leaf spot, caused by Phoma medicaginis, is an issue in annual Medicago species. Therefore, in this study, we analyzed the response to P. medicaginis infection in a collection of 46 lines of three annual Medicago species (M. truncatula, M. ciliaris, and M. polymorpha) showing different geographic distribution in Tunisia. The reaction in the host to the disease is explained by the effects based on plant species, lines nested within species, treatment, the interaction of species × treatment, and the interaction of lines nested within species × treatment. Medicago ciliaris was the least affected for aerial growth under infection. Furthermore, the largest variation within species was found for M. truncatula under both conditions. Principal component analysis and hierarchical classification showed that M. ciliaris lines formed a separate group under control treatment and P. medicaginis infection and they are the most vigorous in growth. These results indicate that M. ciliaris is the least susceptible in response to P. medicaginis infection among the three Medicago species investigated here, which can be used as a good candidate in crop rotation to reduce disease pressure in the field and as a source of P. medicaginis resistance for the improvement of forage legumes

Studies on Arabic Dialectology and Sociolinguistics

This volume contains over fifty articles related to various fields of modern Arabic dialectology. All the articles are revised and enhanced versions of papers read on the 12th Conference of the Association Internationale de Dialectologie Arabe (AIDA) held in Marseille in June 2017. Since its first conference in Paris in 1993, AIDA members gather every two years in different country. The collection of the AIDA proceedings offer an updated insight of the development of the field. During the past few decadesthe the study of Arabic dialects has become an important branch of research covering a wide range of subjects from phonological analyses, morphosyntax, semantics to pragmatics, sociolinguistics, folk linguistics, studies on literacy and writings, cultural and artistic practices, etc. As many articles of this volume illustrate, the study of Arabic dialects explores different aspects of the languages and cultures of the contemporary Arab world. A remarkable feature is the growing and constant participation of young scholars from all around the globe

Morpho-phenological diversity among natural populations of Medicago polymorpha of different Tunisian ecological areas

Medicago polymorpha is a herbaceous legume that can be a useful pasture plant, in particular, in regions with a Mediterranean climate. The genetic variation in 120 lines of M. polymorpha sampled from five regions in Tunisia was characterized on the basis of 16 morpho-phenological characters. Results from analysis of variance (ANOVA) showed that differences among populations and lines existed for all traits, with population explaining the greatest variation for measured traits. The populations of Enfidha and Soliman were the earliest flowering, while those of El Kef, Bulla Regia and Mateur were the latest. El Kef and Mateur exhibited the highest aerial dry weight while the lowest value was found for Soliman. Moderate to lower levels of heritability (H²) were registered for investigated traits. There was no significant association between pairwise population differentiation (QST) and geographical distances. Studied lines were clustered into three groups with 59 for the first group, 34 for the second group, and 27 lines for the third group. The lines of the first two groups showed the largest length of stems while those of the second group had the highest number of leaves. The variation of quantitative traits among populations was influenced by the altitude, temperature and relative humidity. Overall, the high levels of within population variation and the lack of correlation between population differentiation and geographical distances suggest a potentially important rate of long-distance seed dispersal and confirm the role played by natural selection in the population structure of Tunisian populations of M. polymorpha.Keywords: Medicago polymorpha, populations, quantitative traits, population differentiation, environmental parameter

Genetic Variation in Responses to Salt Stress in Tunisian Populations of <i>Medicago ciliaris</i>

Soil salinity is one of the most serious environmental factors affecting crop productivity around the world. We used a morpho-physiological approach to investigate the salt responses of four Tunisian natural populations of Medicago ciliaris. Forty-six lines of M. ciliaris were grown under a control treatment and 100 mM NaCl. We measured 11 quantitative traits of shoot and root growth during harvest. An analysis of variance showed that the variations in salt response can be explained by the effects of the population, line, treatment, and interactions between the population and treatment and the line and treatment. Most of the measured traits showed significant differences between the studied populations under the control treatment and salt stress. High to moderate broad-sense heritabilities (H2) were noted for most of the parameters under the control treatment and salt stress, implying that salt tolerance is highly heritable. Most correlations between the measured traits under the two treatments were positive, of which the strongest correlations were recorded between characteristics related to development. The 46 studied lines formed three groups in both conditions, while their genetic structure was dependent on the treatment factor. The results from this study can provide a basis for identifying and breeding salt-tolerant lines of M. ciliaris

Genetic Variation in Responses to Salt Stress in Tunisian Populations of Medicago ciliaris

Soil salinity is one of the most serious environmental factors affecting crop productivity around the world. We used a morpho-physiological approach to investigate the salt responses of four Tunisian natural populations of Medicago ciliaris. Forty-six lines of M. ciliaris were grown under a control treatment and 100 mM NaCl. We measured 11 quantitative traits of shoot and root growth during harvest. An analysis of variance showed that the variations in salt response can be explained by the effects of the population, line, treatment, and interactions between the population and treatment and the line and treatment. Most of the measured traits showed significant differences between the studied populations under the control treatment and salt stress. High to moderate broad-sense heritabilities (H2) were noted for most of the parameters under the control treatment and salt stress, implying that salt tolerance is highly heritable. Most correlations between the measured traits under the two treatments were positive, of which the strongest correlations were recorded between characteristics related to development. The 46 studied lines formed three groups in both conditions, while their genetic structure was dependent on the treatment factor. The results from this study can provide a basis for identifying and breeding salt-tolerant lines of M. ciliaris