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Cultivation of faba bean (Vicia faba L.) in Tunisia is largely based on improved varieties of the crop. However, a few farmers continue to produce local cultivars or landraces. The National Gene Bank of Tunisia (NGBT) recently launched a collection project for faba bean landraces, with special focus on the regions of the North West, traditionally devoted to cultivating grain legumes, and where around 80% of the total national faba bean cultivation area is located. The seed phenotypic features of the collected samples were studied, and the genetic diversity and population structure analyzed using simple sequence repeat markers. The genetic constitution of the present samples was compared to that of faba bean samples collected by teams of the International Center for Agricultural Research in the Dry Areas (ICARDA) in the 1970s in the same region, and stored at the ICARDA gene bank. The results of the diversity analysis demonstrate that the recently collected samples and those stored at ICARDA largely overlap, thus demonstrating that over the past 50 years, little genetic change has occurred to the local faba bean populations examined. These findings suggest that farmers serendipitously applied international best practices for in situ conservation of agricultural crops.

ABSTRACT:The genetic diversity of a set of 21 hexaploid wheat germplasm from the National Agronomic Institute of Tunisia were investigated by applying 26 agro morphological traits and 10 wheat microsatellites molecular markers (Simple Sequence Repeat). The morphological variability was analyzed using the Principal Component Analysis (PCA) and the cluster analysis based on ward's method and square Euclidean distance. Eighteen microsatellites primer pairs were tested for all genotypes, among them 10 primers generated polymorphic and reproducible profiles. They revealed a total of 414 reducible bands among which 373 were polymorphic. The polymorphic information content (PIC) values per locus varied from 0,33 to 0,94 with an average of 0,72. Genetic similarity values between genotypes, calculated by the molecular derived data, were used to produce a dendrogram. The genotypes were clustered in four clear groups according to their origin, pedigree and in some cases to phenotypic characters similarities.

An experimental study was carried out under semi controlled conditions at National Agronomic Research Institute of Tunisia in Ariana experimental station. Eight main Tunisian Durum wheat (Triticum turgidum L.) varieties were grown under salinity conditions. The objectives of this research were to compare the behaviour of the varieties under salt stress. Many agronomic and physiological traits were evaluated under both saline (10 g NaCl/l) and non saline conditions (control). Results showed that salinity negatively affected all of the studied parameters. The tiller number, chlorophyll contents, height growth rate, shoot dry weight, spikes per plant, 1000-grain weight and total grain yield were significantly affected by salinity. However the plant height, spikelets per spike and grains per spike were much less affected by salinity. Correlation studies showed significant positive and negative correlations between salt tolerance indexes of different evaluated parameters. These results strongly suggest that the number of fertile tillers and shoot dry weight might be useful for salinity tolerance improvement programs of the analyzed genotypes.

Our study focuses on the molecular analysis of the genetic diversity within 15 Tunisian durum wheat varieties and the assessment of the efficiency of some available markers to select valuable genotypes for technological proprieties of semolina (i.e. parameters related to SDS-sedimentation, mixing time and breakdown resistance of mixograph, grain protein content and yellow colour). While several markers were validated, others were not informative within the genotypes used. A high level of polymorphic information content (PIC) was detected, with an average of 5.2 polymorph alleles per locus and 0.6 average. Old varieties have high protein content however; modern varieties display strong gluten strength. Our results thus open the opportunity to choose valuable parents on the base of pedigrees, technological properties and genetic distances; and lead us to select efficient markers for the Regional Indigenous Land Strategy (Rils) selection strategy.

The durum wheat (Triticum turgidum L. ssp. durum Desf.) landraces constitute a useful natural germplasm to increase the genetic diversity in the modern durum cultivars. The Tunisian durum germplasm constitutes 28 accessions conserved in Genebank of Tunisia, which are still unexplored. In this study, a comparative genetic analysis was performed to investigate the relationships between the Tunisian durum lines and the modern cultivars and detect divergent loci involved in breeding history. The genetic diversity analyses carried out using nine morphological descriptors and the 25K single-nucleotide polymorphism (SNP) array allowed us to distinguish two groups of Tunisian landraces and one of durum cultivars. The analysis of molecular variance and diversity indices confirmed the genetic variability among the groups. A total of 529 SNP loci were divergent between Tunisian durum landraces and modern cultivars. Candidate genes related to plant and spike architecture, including FLOWERING LOCUS T (FT-B1), zinc finger CONSTANS, and AP2/EREBPs transcription factors, were identified. In addition, divergent genes involved in grain composition and biotic stress nucleotide-binding site and leucine-reach repeats proteins and disease resistance proteins (NBS-LRR and RPM) were found, suggesting that the Tunisian durum germplasm may represent an important source of favorable alleles to be used in future durum breeding programs for developing well-adapted and resilient cultivars.

Faba bean (Vicia faba L.) is a legume crop cultivated for its nutritious seeds that are an important worldwide source of human food and feed. Seeds characterization is a prerequisite step for faba bean quality improvement. The morphophysical characterization of the seeds of twenty-four local faba bean accessions following the UPOV descriptors and the AOAC International standards was carried out and assessed with an approach based on Euclidean statistical model. “205 Bulk” was the unique accession harboring white hilum color seed which is linked to low convicine grain content. Irregular seed shape was the most observed character among the studied accessions except “Badii” displaying an elliptical seed shape; therefore, seed shape did not allow discrimination within our Tunisian germplasm. Interestingly, the physical characters of the seeds showed significant diversity between the accessions for all the measured parameters. A highly significant variability was observed for axial, length, and width dimensions of seeds, with “Memdouh” being the longest and largest seed accession, whereas “01-02” was the shortest and narrowest. Classification of the studied faba bean germplasm accessions based on morphophysical characters using clustering by Euclidean distance revealed three different groups. Moreover, multivariate PCA analysis further classified the faba bean accessions into four main clusters. Correlation study performed by using Spearman’s test established positive correlations within physical parameters of seeds such as between mean length and mean width of seeds. Therefore, using morphophysical parameters screening, valuable phenotypes have been selected for deeper physiological characterization and further breeding programs.

The gluten quality is one of the main factors affecting the quality of durum wheat. It depends primarily on its storage proteins composition (glutenins and gliadins). In order to set up and initiate a technological quality improvement program of durum wheat we have conducted a prospection of the different protein sequences of gliadin in different databases for Triticum, then the filtration steps and assembly by appropriate software have been conducted to reduce the number of redundant sequences. On the other hand, we have isolated a gene from Iride "Gli-A1" encoding a γ-gliadin protein associated with gluten strength and viscoelasticity of the dough, we performed an in silico molecular and structural analysis in order to define its putative functional properties. The latter could be a valuable candidate as molecular marker for selecting high nutritive value of durum wheat and/or for genetic improvement of durum wheat quality. R. Ben Ayed et al. J Fundam Appl Sci. 2017, 9(3), 1497 L'amélioration de la qualité technologique du grain est un objectif majeur des programmes d'amélioration. En effet, la structure et la composition de l'endosperme mature, y compris la teneur en protéines, la dureté du grain et la qualité de l'amidon, sont des facteurs importants dans la détermination de l'utilisation finale de la farine de blé. Jusqu'à présent, ces études ont porté sur deux aspects de qualité qui sont principalement déterminés par le grain (composition des protéines): la force de la pâte et la texture du grain (dureté) [6]. Plusieurs études ont signalé la production de plantes transgéniques de blés surexprimant plusieurs gènes HMW-GS chez le blé tendre [7 ; 8 ; 9] ainsi que LMW-GS chez le blé dur [10 ; 11 ; 12]. Dans tous les cas, des modifications des propriétés visco-élastiques de la pâte dérivée ont été observées [13]. Du blé commercial a été conçu avec succès avec la sur-expression de la sous-unité HMW du gène R. Ben Ayed et al. J Fundam Appl Sci. 2017, 9(3)