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This study reports for the first time the variation of prolamin profiles among 51 pearl millet landraces representing seven populations prospected from contrasted bioclimatic areas of Tunisia. A total of 27 prolamins bands were detected, ranging from 11 to 245 kDa. Among them, 14 were polymorphic, resulting in a polymorphism rate of 51.85%. The bands with lower molecular weights are the most frequent. The biochemical marker M25.4 showed the highest value of Nei genetic diversity (h= 0.500), Shannon information index (I= 0.693), and effective number of alleles per locus Ne (2). At the population level, the polymorphism rates ranged between 50% (Mahdia) and 92.86% (Hammem Jebli, Kairouan, Medenine). The population of Kairouan showed the highest genetic diversity indices (I= 0.511 ± 0.054, h= 0.345 ± 0.041), while the lowest levels were recorded for the population of Mahdia (I= 0.268 ± 0.076, h= 0.177 ± 0.052). Analysis of molecular variance analysis indicated that the highest amount of genetic diversity was encompassed within the studied populations (89%). This was supported by low genetic differentiation (PhiPT = 0.110, p= .029) and Nei genetic distance values. The classification pattern using ward dendrogram and factorial analyses revealed the distinction of two clusters with a low genetic structure based on the geographic origins of landraces. The detected biochemical protein polymorphism could be a highly effective tool for the genetic resources characterization of pearl millet landraces, which will be further utilized in breeding investigations and taxonomic surveys of this cereal crop.

Using reliable salt tolerance markers is a key component in barley breeding programs. In this study, physiological and antioxidative markers of two Tunisian barley salinity tolerance contrasting genotypes Boulifa (B) and Manzel Habib (MH) were assessed at 0, 3, 6 and 9 days of 200 mM salt treatment. Salinity caused decrease in growth, degraded photosynthetic activity and reduced water-holding capacity in both genotypes with more pronounced negative effects in the salt-sensitive (MH) compared to the salt-tolerant (B) genotype. On the other hand, the lower oxidative damage in B compared to MH under salt stress could be explained by higher activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase (GPX) and glutathione reductase (GR). Additionally, a genotype-specific pattern of enzyme activity and corresponding gene expression was revealed in the two barleys under salt stress. In this context, a positive correlation was noted for the SOD. On the other hand, multivariate analysis marked SOD and APX as the most discriminating factors between both stressed genotypes. Our findings could be considered for selection in breeding programs for salt stress tolerance in barley.

The increasing anthropologic pressure and the modernization of agriculture have led to a forsaking of pearl millet traditional cultivars, inducing a progressive loss of the genetic variability encompassed in this locally adapted germplasm. Imperatively, national efforts based on robust data gleaned from genetic surveys have to be undertaken in order to set up suitable conservation priorities. In this study, in addition to the assessment of the genetic diversity and population structure among and within a set of seven pearl millet landrace populations from coastal North Africa, demographic and phylogenetic data, conservation priority scores were calculated according to Vane-Wright et al. (1991). To date, genetic diversity of pearl millet in North Africa is still poorly documented. The present survey reports for the first time the use of highly informative nSSR markers (PIC = 0.74) on Pennisetum glaucumlandraces representative of the Mediterranean coastline of North Africa. A high level of genetic diversity was obtained within the investigated landraces (He= 0.80) at the population level. FST, AFC-3D, and Bayesian clustering underlined significant differentiation and an apparent genetic structure, according to geographical origin. Phylogenetic considerations integrated with demographic and genetic information enabled conclusive inferences of highly prioritized populations for conservation. Populations Haouaria, Hammem Laghzez, Mahdia, and Medenine, representatives of the main pearl millet growing areas in Tunisia and cultivated in the North African littoral, should be strongly recommended for an ex situ conservation program. Dynamic on-farm conservation method is also required as it allows the local landraces to evolve in different environments, while maintaining their adaptation potentials.

The effects of salt stress on growth, organic and inorganic solute accumulation and chlorophyll florescence were studied on 3-month-old plants of six Tunisian wild grapevine accessions in order to identify salt tolerance mechanisms and select tolerant genotypes. Potted plants were grown under controlled conditions and irrigated for 14 days with 0, 100 and 150 mM NaCl Long Ashton nutrient solution. Salt begins to adversely affect plant growth and plant nutrition at 100 mM NaCl. Compared to control, shoot growth rates were 21.5% less for Khedhayria, Tebabaand Ouchteta, 33% for Djebbaand Zouarâaand 49% for Houamdia. They were assigned to stomatal and non-stomatal factors. Stomatal conductance decreased after 1 day at 150 mM NaCl in all accessions in response to reduced leaf water potential. Leaves in tolerant accessions were well hydrated through efficient osmotic adjustment, sufficient potassium flux and selectivity of K+versus Na+. In addition, salt tolerance of wild grapes was related to limiting Na+transport to lamina and to compartmentalization of Cl−on root and leaf vacuoles, improved in Tebabaand Khedhayriaby the uptake of K+. At the same time, disturbances of the PSII have been noted as non-stomatal factors, and the most important photoprotective mechanism against photosynthetic damages was non-photochemical energy dissipation. However, chlorophyll fluorescence parameters were more stable in Tebabacompared to Khedhayria,thus showing better salt tolerance. Based on our results, wild grapevine accessions could be classified from most tolerant to most sensitive as follows: Tebaba > Khedhayria > Ouchteta > Zouarâa > Djebba > Houamdia.

Hybridity and the genuineness of hybrids are prominent characteristics for quality control of seeds and thereby for varietal improvement. In the current study, the cross between two local barley genotypes (Ardhaoui: female; Testour: male) previously identified as susceptible/tolerant to salt stress in Tunisia was achieved. The hybrid genetic purity of the generated F1putative hybrids and the fingerprinting of the parents along with their offspring were assessed using a set of 17 nuclear SSR markers. Among the analyzed loci, 11 nSSR were shown polymorphic among the parents and their offspring. Based on the applied 11 polymorphic SSR loci, a total of 28 alleles were detected with an average of 2.54 alleles per locus. The locus HVM33presented the highest number of alleles. The highest polymorphism information content value was detected for the locus HVM33(0.6713) whereas the lowest PIC value (0.368) was revealed by the loci BMAC0156, EBMAC0970and BMAG0013with a mean value of 0.4619. The probabilities of identical genotypes PI for the 11 microsatellite markers were 8.63 × 10−7. Banding patterns among parents and hybrids showed polymorphic fragments. The 11 SSR loci had produced unique fingerprints for each analyzed genotype and segregate between the two parental lines and their four hybrids. Parentage analysis confirms the hybrid purity of the four analyzed genotypes. Six Tunisian barley accessions were used as an outgroup in the multivariate analysis to confirm the efficiency of the employed 11 nSSR markers in genetic differentiation among various barley germplasms. Thus, neighbor joining and factorial analysis revealed clearly the discrimination among the parental lines, the four hybrids and the outgroup accessions. Out of the detected polymorphic 11 nuclear SSR markers, a set of five markers (HVM33, WMC1E8, BMAC0154, BMAC0040and BMAG0007) were shown to be sufficient and informative enough to discriminate among the six genotypes representing the two parental lines and the four hybrids from each others. These five nSSR markers presented the highest number of alleles per locus (An), expected heterozygosity (He), PIC values and the lowest probabilities of identity (PI). These nSSR loci may be used as referral SSR markers for unambiguous discrimination and genetic purity assessment in barley breeding programs.

Tunisian barley (Hordeum vulgareL.) landraces, representing the oldest cultivated accessions, are growing in scattered populations across drought‐ and salt‐stressed environments and constitute a precious reservoir of potentially useful traits for breeding programs. The objective of this study was to elucidate genetic diversity and population structure of barley landraces across the landscape of Tunisia. Populations from 11 geographic zones were genotyped using 21 nuclear microsatellites. A high level of genetic polymorphism with 170 detected alleles was recorded among the studied genotypes. The average allelic richness was 8.095 alleles per locus. The index of genetic diversity (He) showed an average of 0.741. Genetic diversity was very high within populations, whereas differences among populations were difficult to detect. Only 0.15% of the DNA variation was apportioned among landraces (P< 0.001), whereas 99.85% of the DNA variation was maintained within these landraces. A high gene flow (Nm) was revealed among the investigated populations, which has been facilitated by exchange of barley seeds between Tunisian cereal farmers of different regions. Genetic diversity within Tunisian barley landrace germplasms may help to maintain adaptation to a broad range of environmental conditions and provide genetically diverse resources for barley breeders. Both ex situ (seed banks) and in situ (on‐farm) conservation strategies may be required to maintain barley landrace genetic resources.

The present study compared the effects of resveratrol and its dimer ε-viniferin on vascular endothelial cells (VECs) functions, and on the blood pressure and cardiac mass of spontaneously hypertensive rats (SHRs). Treatment of VECs with these compounds enhanced cell proliferation vianitric oxide generation and protected the cells from oxidative stress by suppressing increases in intracellular oxygen species. ε-Viniferin was more potent than resveratrol in most of these effects. ε-Viniferin, but not resveratrol inhibited angiotensin-converting enzyme activity in vitro. Three weeks of ε-viniferin treatment (5 mg/kg) reduced the systolic blood pressure and improved the whole cardiac mass and left ventricle mass indexes in SHRs. In contrast, resveratrol administration (2.5 mg/kg) failed to lower the blood pressure and significantly improve these mass indexes. These data suggest that ε-viniferin as well as resveratrol may be involved in protecting the functions of VECs and the heart.

Resveratrol is a strong candidate for explaining an irreversible correlation between red wine consumption and coronary heart disease. The present study examined the effect of ε-viniferin, a dehydrodimer of resveratrol, on vascular smooth muscle cells (VSMCs), because ε-viniferin functions are poorly understood in spite of its comparable content to resveratrol in red wines and grapes. Both ε-viniferin and resveratrol inhibited platelet-derived growth factor-induced cell proliferation, migration, and reactive oxygen species (ROS) production, in addition to inducing nitric oxide generation. ε-Viniferin was more effective than resveratrol in these effects, except for inhibiting ROS production. The compounds also increased the expression of the antioxidant enzyme, hemeoxygenase-1, viatranscription factor Nrf2. The phosphatidylinositol 3-kinase-Akt pathway was implicated in resveratrol-dependent nuclear Nrf2 accumulation, whereas extracellular signal-regulated kinase and p38 were involved in ε-viniferin-induced Nrf2 accumulation. These data suggest that ε-viniferin may function more effectively than resveratrol in different mechanisms and cooperatively with resveratrol in preventing atherosclerosis.

Genetic diversity among 26 cucumber (Cucumis sativusL. var. sativus) accessions from five African countries [Algeria (1), Egypt (21), Ethiopia (2), Kenya (1), and Libya (1)] present in the U.S. National Plant Germplasm System (NPGS) were examined by assessing variation at 71 polymorphic random amplified polymorphic DNA (RAPD) loci. Genetic distances (GD; simple matching coefficient) were estimated among these African accessions and a reference array (RA) of 21 accessions representative of the genetic variation in cucumber. GD among African accessions ranged between 0.41 and 0.97. GD among accessions in the reference array ranged between 0.36 and 0.88. Multivariate analysis identified three distinct groupings (1–3) of African accessions; Group 1 contained 21 accessions (Egypt, Ethiopia and Libya), Group 2 consisted of two accessions (Kenya, Algeria), and Group 3 possessed three accessions (Egypt). These groupings were distinct from each other (P > 0.001). Accessions in Group 1 differed genetically from all other accessions examined (P > 0.01), and accessions in Groups 2 and 3 were uniquely associated with several RA accessions. While GD among accessions in Group 1 ranged between 0.52 and 0.90, distances among Group 2 accessions varied between 0.93 and 0.97. The GD between the two accessions in Group 3 was 0.65. An accession from Syria (PI 181874) and from one Turkey (PI 199383) were genetically more similar to accessions in Group 1 than to other accessions in the RA. Likewise, accessions in Group 2 were genetically similar to two RA accessions from China and a European glasshouse cucumber line, and Group 3 accessions showed genetic affinities with the U.S. market class cultivar Dasher II. Data suggest that some Egyptian accessions (Group 1) possess unique genetic variation, that this germplasm has potential for broadening the genetic base of commerical cucumber, and that further collection of African germplasm is likely to enhance genetic diversity of cucumber in NPGS.

The genetic diversity among 126 exotic (108) andreference array (RA) melon (CucumismeloL.) accessions (18) was assessed byvariation at 49 random amplified polymorphic DNA marker bands(putative loci) using 29 10-mer primers. Africanaccessions of unknown melon market classes were compared to the RAaccessions from a broad range of C.melosubsp. melogroups(Cantalupensis, Conomon, Inodorus and Flexuosus). Althoughdifferences in groupings occurred after multidimensional scaling andcluster analysis, both analyses placed African accessions into twogroups, which were separate from RA groupings. One African group of33 accessions containing accessions from Zimbabwe (5),Zambia (24), Mali (1), one of two Senegalaccessions and two of three South African accessions examined. Thesecond group, which consisted of 67 accessions containing collectionsfrom Egypt (40), Tunisia (6), Libya(13), Morocco (1), Algeria (2),Ethiopia (1), Niger (1), Sierra Leone(1), S. Africa (1), Zambia (1) andZimbabwe (1). Depending on the multivariate analysistechnique employed, accessions from Kenya, Senegal and Ghana formedeither unique groupings or were grouped with accessions(Cantalupensis) from the RA. Both analyses indicate thatthe genetic differences inherent between the African gene pools isassociated with the geographic proximity of African countries(northern vs. central-southern Africa) in thegermplasm array examined. Moreover, these data indicate that thegenetic diversity of U.S. and European commercial RA germplasm(Cantalupensis and Inodorus) could be enhanced by theintroduction of genetic variation from African accessions, and thatit would be advantageous to acquire more accessions from thisgeographically and ecologically varied region to ensure the retentionof existing genetic diversity.

An efficient in vitro regeneration system using epicotyl segments was developed and then used for optimizing genetic transformation of the Tunisian 'Maltese half-blood' (Citrus sinensis) variety using phosphinothricin (PPT) resistance as a selectable marker. The maximum regeneration efficiency was achieved after incubating epicotyl explants (excised in an oblique manner) in MT culture media containing BAP (4 mg/l) and IAA (0.3 mg/l) hormonal combination in the dark for 3 weeks before their transfer to light. Data from the genetic transformation assays indicated that the highest number of regenerated-transformants was reached when the selection phase was conducted in MT culture media containing PPT (0.25 mg/l) and Carbenicillin (500 mg/l) for 3 weeks in the dark followed by 8 weeks of light. After that, transformed buds were maintained for eight additional weeks in the same culture media but with reduced PPT concentration (0.125 mg/l) before decreasing Carbenicillin dose (250 mg/l) at the second half of this last incubation period which allowed both a good shoot proliferation and an optimal rooting efficiency. Based on molecular analyses, the transgenicity of 21.42% of the regenerated vitroplants was confirmed. The developed regeneration and transformation procedures of the elite ‘Maltese half-blood’ variety can be used for orchard renewal as well as for functional studies and genome editing purposes to develop new cultivars with the desired genetic traits.