Selection strategies for increased salt tolerance in Medicago sativa must involve several growth stages, with the germination stage as a particularly important stage. At this stage, M. sativa is known to be more sensitive to salt than later growth stages. Cultivars differ significantly in their capacity to germinate under saline conditions. For this consideration and in order to analyze the response to salinity, initial screening at the germination stage for two varieties of M. sativa was undertaken. Seeds were germinated in Petri dishes under control treatment (0 mM NaCl) and four concentrations of NaCl (100, 150, 200 and 250 mM). Results from ANOVA showed that variation in root length (RL), fresh root weight (RFW) and shoot fresh weight (SFW) was explained by variety effect. The variation in hypocotyl length, (HL) SFW and RL was explained by the interaction of variety x treatment. Under salt stress, there was a major reduction (46, 66%) in final germination rate (GR) when seeds were geminated in 250 mM NaCl. The RL and HL were affected by salt stress and their respective values were reduced by more than 40% in 200 mM NaCl. The Californian variety was lesser affected by salt stress for RL and RFW while the local variety from El Hemma showed the lowest reduction for SFW. Further work is needed to asses these effects in later growth stages and in field conditions under salt stress.

In this study, we analyzed salt tolerance in two varieties of Medicago sativa at the vegetative stage. Gabès2355 and Californian varieties of M. sativa were cultivated under control treatment and under a range of salt concentrations (50 mM, 100 mM, 150 mM, and 200 mM NaCl) in a greenhouse. At harvest, ten quantitative characters related to aerial and root growth were measured for plants of both varieties. Results from ANOVA showed that the variation of the traits measured is explained by the effects of variety, treatment and the interaction of variety x treatment. The treatment factor represents the most pronounced effect. While the Californian variety was more sensitive than the Gabès variety under 50 mM NaCl, it was the most tolerant under higher concentrations of NaCl. Specific correlations between measured traits were noted under control treatment and salt stress. Further work is needed to evaluate the agronomic performances of both varieties in the field under salinity constraint.

ABSTRACT. Medicago ciliaris L., considered as a valuable genetic resource, is a good candidate for the improvement of marginal or degraded lands with low fertility or high salinity. In this study, the phenomorphological and genetic diversity were investigated in 14 Tunisian populations of M. ciliaris for the first time. Fourteen morphological traits showed significant differentiation between populations and high levels of diversity. Two amplified fragment length polymorphism primer combinations (E-AGC/M-CAA; E-AAG/M-CTG) were analyzed using an automated capillary electrophoresis system. A total of 528 loci were 2 C. Jabri et al.Genetics and Molecular Research 15 (3): gmr.15038595 generated, of which 54% were polymorphic. Allelic polymorphism ranged from 0.02 to 0.5. Significant variation between populations was found for gene diversity, mean number of alleles per locus and Shannon index for which mean values were 0.17, 0.26, and 1.57, respectively. Analysis of molecular variance revealed a high rate of genetic variation within populations. Principal component analysis and genotypic clustering discriminated M. ciliaris populations according to their geographical origin. M. ciliaris clustered into three main groups. The first group was associated with high inland and cold areas, the second was defined by low areas with mild winters while the third described low coastal areas. Similarity of morphological and molecular results indicated that either markers could be used for the study of genetic diversity in this species.

Due to its very important agronomic value and nutritional quality, Medicago sativa L. is considered as the queen of fodder and the first cultivated forage crop in the world. In field conditions, M. sativa is exposed to several biotic and/or abiotic constraints that affect its quality. In this regard, research is still underway to improve M. sativa resistance to many biotic stresses and, in this context, we analyzed the responses of a core collection of 10 varieties of M. sativa to Phoma medicaginis infection. Results from ANOVA showed that most growth parameters exhibited significant differences between the studied varieties. Nevertheless, only the number of healthy leaves among infection parameters varied significantly between the varieties. The local variety Gabès2355 exhibited the highest biomass. Positive correlations were found between the measured parameters. PCA based on the traits showing significant differences among the studied lines showed that the Gabès variety formed a separate group. Cluster analysis revealed that the studied varieties are classified into three major groups. The first group is formed by Gabès2353, the second group is composed of the Californian and El Hamma varieties, and the third group is constituted of the seven remaining varieties. Gabès2355 was the most tolerant to the Pm8 strain of P. medicaginis while Magna601 variety was the most susceptible. These two varieties will be useful to analyze the physiological and genetic determinants for M. sativa tolerance to P. medicaginis infection.

1 ABSTRACT To identify the suitable genetic resources of forage legumes for animal feeding, the characterization of their chemical and biochemical composition is crucial since forage quality is a limiting factor which affects animal health and performance and consequently human health. In this context, this study carried out for the first time the analyses of the antioxidant compounds and the secondary metabolites (total phenols and tannins and saponins) in whole fresh biomass, flowers and stems of eight populations of Medicago ciliaris L (echinus Medicago) collected in different bioclimatic areas of north Tunisia. The analysis of variance showed significant differences between populations for all parameters (P<0.05) except for anthocyanins (P>0.05). Significant correlations were found between carotenoids and chlorophylls a and b (r= 0.59, n=48; P<0.0001) and between lycopene and β-carotene (r=0.81, n=48; P<0.0001). Multivariate analysis showed that populations 306 and 326 had the highest contents of chlorophyll a and carotenoids while Pop3 had the highest content of lycopene, β-carotenes, saponines and total tannins. These populations will be integrated in a breeding program for quality improvement of forage and will serve for grazing of pods and straw in summer and grazing of green biomass in winter and spring accordingly to their richness in antioxidant compounds.