Assessment of Inter-Specific Diversity of the \u3cem\u3eHedysarum\u3c/em\u3e Genus in Tunisia

In Tunisia, many grassland and pasture species were menaced by genetic erosion. Thus, we were interested in the Hedysarum species which constitute a very important phytogenetic patrimony able to produce forage and restore destroyed pasture land especially in arid and semi-arid areas. In order to facilitate fodder improvement, we investigated the phenetic relationships among Hedysarum species using rDNA intergenic spacer (IGS) polymorphism

Relative efficiency of morphological characters and molecular markers in the establishment of an apricot core collection

In order to optimize the management of genetic resources, in most cases a representative sample of the germplasm collections needs to be developed. The establishment of a core collection is thus of major importance either to minimize the cost associated with the management of the associated germplasm or to apply analysis onto representative bases. In order to select a representative core collection among the Tunisian apricot germplasm of 110 accessions large, the Maximization strategy algorithm was used. This algorithm was shown to be the most convenient when using both morphological traits and molecular markers. Three core collections based on morphological characters, molecular markers or the combined data were compared. Our data indicate that both the molecular and the morphological markers have to be considered to obtain a core collection that represents the global diversity of the 110 accessions. Using this method, a subset of 34 selected accessions was found to represent accurately the 110 accessions present in the whole collection (75 to 100% for the morphological characters and 97% of the molecular markers). These results show that the combination of molecular and morphological markers is an efficient way to characterize the apricot core collection and provides an exhaustive coverage for the analyzed diversity on morphological and genetic bases

Analyse de la variabilité morphologique et enzymatique des formes cultivées et spontanées de Hedysarum coronarium L. en Tunisie

International audienc

Agronomic Evaluation and Genetic Variation of Tunisian Tall Fescue (Festuca arundinacea Schreb.)

Nine important agronomic traits were used to assess the genetic diversity of Tunisian tall fescue and to investigate the extent of genotype X environment (GE) interaction and its implications for breeding programs. These traits were studied for three consecutive years in thirty-five spontaneous populations and three cultivars. Panicle size contributed to seeds production, while the plant height at harvest and dry matter yield were selected for forage performance. Analysis of variance demonstrated that population attitude depended on the year and environmental conditions. Principal component analysis revealed significant similarities among some spontaneous populations and cultivars. The relationship between environmental conditions and agronomic traits revealed the influence of altitude, soil texture and minimum temperature on forage production, seed yield, and the architecture of plants, respectively. In addition, the local adapted ecotypes originating from Bizerte, Sidi Nsir, and Rass Rajel attained greater agronomic potentialities than control cultivars and were of considerable economic interest for the improvement of Tunisian tall fescue

Amplified Fragment Length Polymorphism (AFLP) is useful for finding markers associated with QTL for architectural trait in Hedysarum coronarium L.

Amplified fragment length polymorphism (AFLP) has been proposed as a valuable tool for finding mol- ecular markers linked to QTL controlling architectural trait. Segregation of polymorphic AFLP frag- ments was followed in F 2 offsprings Hedysarum coronarium derived from two native wild accesions crossing: Jebel Zit × El Haouaria, which had previously characterised by morphological and AFLP mark- ers. A comparison of profiles from the morphologically contrasted parental individuals and F 2 offspring has been assessed using five AFLP primer combinations. These generated 178 bands revealed by silver- stained denaturing polyacrylamide gels, of which 150 were polymorphic. Several AFLP markers appeared to be implied in the orthotropic form that can assist the selection and improve Hedysarum for- age crop

Loss of genetic diversity as a signature of apricot domestication and diffusion into the Mediterranean Basin

Background: Domestication generally implies a loss of diversity in crop species relative to their wild ancestors because of genetic drift through bottleneck effects. Compared to native Mediterranean fruit species like olive and grape, the loss of genetic diversity is expected to be more substantial for fruit species introduced into Mediterranean areas such as apricot (Prunus armeniacaL.), which was probably primarily domesticated in China. By comparing genetic diversity among regional apricot gene pools in several Mediterranean areas, we investigated the loss of genetic diversity associated with apricot selection and diffusion into the Mediterranean Basin. Results: According to the geographic origin of apricots and using Bayesian clustering of genotypes, Mediterranean apricot (207 genotypes) was structured into three main gene pools: ‘Irano-Caucasian’, ‘North Mediterranean Basin’ and ‘South Mediterranean Basin’. Among the 25 microsatellite markers used, only one displayed deviations from the frequencies expected under neutrality. Similar genetic diversity parameters were obtained within each of the three main clusters using both all SSR loci and only 24 SSR loci based on the assumption of neutrality. A significant loss of genetic diversity, as assessed by the allelic richness and private allelic richness, was revealed from the ‘Irano-Caucasian’ gene pool, considered as a secondary centre of diversification, to the northern and south western Mediterranean Basin. A substantial proportion of shared alleles was specifically detected when comparing gene pools from the ‘North Mediterranean Basin’ and ‘South Mediterranean Basin’ to the secondary centre of diversification. Conclusions: A marked domestication bottleneck was detected with microsatellite markers in the Mediterranean apricot material, depicting a global image of two diffusion routes from the ‘Irano-Caucasian’ gene pool: North Mediterranean and Southwest Mediterranean. This study generated genetic insight that will be useful for management of Mediterranean apricot germplasm as well as genetic selection programs related to adaptive traits