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The present work was carried out to quantify camelina germination niche under salinity and temperature ( T) stress using halotime and halothermal time models. Seed germination ( SG) time courses were recorded at six constant temperatures (5 °C, 10 °C, 15 °C, 20 °C, 25 °C, and 30 °C) and at each of the following levels of NaCl concentrations (0, 50, 100, 150, 200, and 250 mM). Halotime model could well describe the germination time courses across a range of NaCl concentrations ( R2 = 0.79–0.91). The median base NaCl concentration was approximately constant (231 mM) at suboptimal T followed by a linear decrease, with the rate of 17.4 mM °C−1, under supra-optimal T. However, the germination rate increased with increasing T, reaching its maximum at a fixed optimum temperature ( To = 20 °C), independent of NaCl concentration. Then it decreased linearly for T > To and intercepted the x-axis at the ceiling temperature values of 33.5 °C, 30 °C, 28 °C, 25 °C, and 22 °C under 0, 50, 100, 150, and 200 mM NaCl, respectively. Consequently, based on model estimation the adequate soil T for SG of camelina should be in the range of 0.4 °C–33.5 °C, and the To is 20 °C. Besides, the salinity should be less than 231 mM.

Fabaceae seeds are reported to be used for varying medicinal and pharmaceutical purposes. However, knowledge of the nutritive value of Astragalus tenuifoliosus seeds is largely based on very limited data and remains unexplored, we report here the protein content, phenolics as well as the antioxidant potential of plant seeds to give adequate information on its suitability as a new source of natural bioactive compounds. The protein content was determined using the Kjeldahl and Bradford assays. The phytochemical contents were evaluated, and the extracts were further subjected to high-performance liquid chromatography-electrospray ionization – mass spectrometry (HPLC-ESI-MS) analysis. The antioxidant potential was evaluated using the total antioxidant capacity and the free DPPH radical scavenging activity. The results obtained from the protein analysis showed that the total content was 59.43 % of the dry matter basis. The globulins constituted the dominant fraction and followed by albumins, glutelins, and prolamins. The phytochemical investigation showed considerable amounts of polyphenol, flavonoid and condensed tannin amounts. The LC-ESI/MS analysis revealed the presence of 18 phenolics including 8 phenolic acids and 10 flavonoids mostly predominated by quinic acid (255.4 µg g-1 DW), p-coumaric acid (65.39 µg g-1 DW), quercetin (97.21 µg g-1 DW), and cirsiliol (29 µg g-1 DW). The seeds possessed strong antioxidant potential evidenced by their DPPH radical scavenging activities and total antioxidant capacity. The obtained findings contribute to the limited bibliographic information concerning A. tenuifoliosus seeds and represent a starting point to evaluate its potential as a valuable source of proteins, natural antioxidants, and safe bioactive compounds. Resumen. Las semillas de las Fabaceae se utilizan para diversos fines medicinales y farmacéuticos. Sin embargo, el conocimiento del valor nutritivo de las semillas de Astragalus tenuifoliosus se basa en gran medida en datos muy limitados y sigue sin explorarse. Aquí se reporta el contenido de proteínas, fenoles y el potencial antioxidante de las semillas de plantas para brindar información adecuada sobre su idoneidad como nueva fuente de compuestos bioactivos naturales. El contenido de proteína se determinó utilizando los ensayos de Kjeldahl y Bradford. Se evaluaron los contenidos fitoquímicos y los extractos se sometieron a análisis de cromatografía líquida de alto rendimiento, ionización por electropulverización y espectrometría de masas (HPLC-ESI-MS). El potencial antioxidante se evaluó utilizando la capacidad antioxidante total y la actividad de captación de radicales libres DPPH. Los resultados obtenidos del análisis de proteína mostraron que el contenido total fue de 59.43% con base en el peso seco. Las globulinas constituyeron la fracción dominante, seguidas por las albúminas, las glutelinas y las prolaminas. La investigación fitoquímica mostró cantidades considerables de polifenoles, flavonoides y taninos condensados. El análisis medinate LC-ESI/MS reveló la presencia de 18 fenoles, incluidos 7 ácidos fenólicos y 11 flavonoides, predominando en su mayoría el ácido quínico (255.4 µg g-1 DW), el ácido p-cumárico (65.39 µg g-1 DW), la quercetina (97.21 µg g-1 DW), y el cirsiliol (29 µg g-1 DW). Las semillas poseen un fuerte potencial antioxidante, evidenciado por sus actividades de eliminación de radicales DPPH y su capacidad antioxidante total. Los hallazgos obtenidos contribuyen a la limitada información bibliográfica sobre las semillas de A. tenuifoliosus y representan un punto de partida para evaluar su potencial como fuente valiosa de proteínas, antioxidantes naturales y compuestos bioactivos seguros.

Quantification of germination niches under salt stress, temperature, and their interaction using population-based threshold models is important to predict seedling emergence patterns. Seeds of Sarcocornia fruticosa, Sarcocornia alpini, and Salicornia emerici were treated with various temperatures at different NaCl concentrations. Results indicated that the median base NaCl concentration was roughly steady (0.68, 0.73, and 0.70M, respectively) at sub-optimal temperature, then decreased linearly at supra-optimal temperature until the ceiling temperature (Tc). The estimated base, optimum and ceiling temperatures, in water, were − 0.5, 15 and 29°C for Sarcocornia fruticosa, − 2.5, 11 and 24°C for Sarcocornia alpini, and 9.5, 25 and 40°C for Salicornia emerici, respectively. At all species, the base temperature has not changed with the salinity while both optimum and ceiling temperatures decreased. Also, Salicornia emerici showed rapid and synchronized germination when salinity decreases during the rainy season coinciding with favorable temperatures compared with other species.

The design of the current study was to determine the functional properties of P. maritimum seeds by evaluating their mineral content, fatty acid composition, and biactive compounds. Results showed that seeds contained remarkable amounts of Na, K, Ca, Mg, Cu, Zn, and Fe. The oil yield was found to be 4.58% and contained higher unsaturated fatty acids predominated by linoleic and oleic acids. The colorimetric investigation revealed high total polyphenol (33.56 mg gallic acid equivalent/g), flavonoid (46.3 mg quercetin equivalent/g), and condensed tannin (22.3 mg catechin equivalent/g) contents. Furthermore, the LC-ESI/MS analysis revealed the presence of 13 phenolics mostly predominated by (+) catechin, quercetin-3-O-galactoside, gallic acid, and quinic acid. The seeds possessed strong antioxidant potential evidenced by ABTS and DPPH radical scavenging activities, total antioxidant capacity, and reducing power. The present findings suggest that P. maritimum seeds may be used as a potential source of biologically active natural products.

In Sabkha biotope, several environmental factors (i.e., salinity, drought, temperature, etc.) especially during dry season affect halophytes developments. To cope with these harmful conditions, halophytes use multiple mechanisms of adaptations. In this study, we focused on the effect of environmental condition changes over a year in the Sabkha of Ain Maider (Medenine - Tunisia) on the physiological and biochemical behavior of Limoniastrum guyonianum using a modeling approach. Our study showed that the model depicted well (R2 > 0.75) the monthly fluctuations of the studied parameters in this habitat. During the dry period (June to September), the salinity of the soil increased remarkably (high level of EC and Na+ content), resulting in high Na+ content in the aerial parts followed by a nutrient deficiency in K+, Ca2+, and Mg2+. As a result of this disruption, L. guyonianum decreased its water potential to more negative values to maintain osmotic potential using inorganic osmolytes (i.e., Na+) and organic osmolytes (i.e., sugars: sucrose, fructose, glucose, and xylitol, and organic acids: citric and malic acids). In addition, CO2 assimilation rate, stomatal conductance, transpiration rate, and photosynthetic pigments decreased significantly with increasing salinity. The phenolic compounds contents and the antioxidant activity increased significantly in the dry period as a result of increased levels of H2O2 and lipid peroxidation. This increase was highly correlated with soil salinity and air temperature. The maintenance of tissue hydration (i.e., moderate decrease of relative water content), the accumulation of sugars and organic acids, the enhancement of phenolic compounds amounts, and the increase of antioxidant activity during the dry period suggest that L. guyonianum possesses an efficient tolerance mechanism that allows the plant to withstand the seasonal fluctuations of climatic conditions in its natural biotope.

Polygonum aviculare and Polygonum maritimum, commonly known as knotgrass and sea knotgrass, have been widely used for several purposes. Leaves, stems, and roots of these species were evaluated for ...

The Halothermal time model (HaloTT) as a robust framework can accurately be used to simultaneously quantify the effect of both salt stress and temperature (T) on the dynamics of seed germination (SG) in different crops. The parameters of this model can be easily physiologically interpreted and explain how environmental factors interfere in regulating the SG response into seed population. A total of 75 seeds were used for germination tests. Five constant Ts, including 15, 20, 25, 30 and 35 °C, which at each of the following four levels of salinity (75, 150, 225 and 300 mM) were used. The effects of T and salinity on SG characteristics were studied using a HaloTT model. Also, cardinal temperatures were estimated and accumulation of Na+ and Cl− into the seeds were investigated. Results showed that the HaloTT model could quantify well the effect of salinity on SG of cucumber over sub- and supra-optimal Ts (R2 > 0.80). Based on the model, the cardinal Ts in water were 10.4, 28.7 and 38.5 °C. At To, the NaClb(50) was 337 mM equal to − 1.49 MPa when it was converted to the ψb(50). The thresholds decreased linearly at T ≥ To (slope of the linear model (kT) = 33.9 mM °C−1), then reached 0 mM at Tc while the ψb(50) increased linearly becoming less negative at T ≥ To (kT = 0.150 MPa °C−1), then reached 0 MPa at Tc. Seed Na+ and Cl− uptake increased significantly with T, and seed ψ was lower at each T under salt stress (depending on NaCl concentration), when compared to the control. Our results indicate that seed salt uptake was sufficient for germination at lower ψs under low and moderate salinity levels, and that SG is primarily controlled by the osmotic effect and, then, by the ion toxicity.

The antioxidant capacities of 11 populations of P. equisetiforme collected from the Saharan, arid, and semi-arid bioclimatic zones in Tunisia were investigated. Total phenolic content varied from 31 ± 5 to 113 ± 4 mg GAE/g dw. Flavonoid content varied from 29 ± 2 to 130 ± 10 mg QRE/g dw and condensed tannins ranged between 8 ± 1 and 33 ± 2 mg CTE/g dw. P. equisetiforme showed a high antioxidant potential, with the total antioxidant capacity varying from 10 ± 2 to 71 ± 3 mg GAE/g dw. The DPPH scavenging activity ranged from 12 ± 1 to 51 ± 6 mM TRE/g dw and the EC50 of reducing power ranged between 68 ± 5 and 210 ± 20 μg/mL. Plants collected from the Saharan climate showed the highest phytochemical and antioxidant activity. LC–ESI-MS analysis allowed identification of 19 compounds, of which quinic acid, gallic acid, (+)-catechin, epicatechin, quercetin-3-O-galactoside, quercetin-3-O-rhamnoside, and cirsiliol were identified as major compounds. High quantitative and qualitative variability in the phenolic acid and flavonoid fractions between the studied populations were observed. Overall, P. equisetiforme could be considered as a prospective source of useful natural antioxidants.

Retama raetam (Forssk Webb; Fabaceae) is a xerophytic shrub that is distributed from northern to southern Tunisia and which is of interest for medical use and for revegetation. To quantify seed germination responses of R. raetam to temperature (T) and water potential (ψ), and to determine cardinal Ts, a hydrothermal time model (HTT) was used. The experiment was conducted at six constant Ts (5, 10, 15, 20, 25, and 30 °C) at each of the following ψs (0, –0.3, –0.7 and −1 MPa; provided by PEG 6000). Results showed that germination rate (GR) and germination percentage (GP) were significantly influenced by ψ, T and their interactions (P

To cope with abiotic stresses, the halophytes use various tolerance mechanisms that are not all known for some species of halophytes. This work aimed to model the responses of two halophytes, Limonium pruinosum and Limonium tunetanum, to changing environmental conditions over a year in Sabkha biotope, Tunisia. Our findings indicated that the model could describe well the seasonal variations of all studied traits over a year in this region (R2 > 0.80). The pH, electrical conductivity (EC), and mineral composition (i.e., Sodium [Na+ ], potassium [K+ ], calcium [Ca2+ ], and magnesium [Mg2+ ] concentrations] in the soil significantly varied during the year (P

Canola is the second largely produced oilseed crop behind soybeans which is known as an important source of vegetable oil, being used in the food, feed, and biofuel feedstock. Seed aging is a serious problem in this plant particularly if the seeds are exposed to salinity stress during their germination stage. In this work, therefore, we applied both halotime and aging models to quantify the effect of the accelerated aging test period (AATP) and salinity (NaCl) on seed germination (SG) response of this plant. The seed moisture content (SMC) and electrical conductivity (EC) in response to AATP were also investigated. Based on our results, SG characteristics (i.e., germination percentage (GP) and germination rate (GR)) are significantly affected by AATP, NaCl, and their interactions (p 0.87). Based on the model parameters, the SG of canola was totally inhibited at 82.1 h AATP and 341.1 mM NaCl, respectively. Both SMC and EC increased significantly with the AATP, reflecting the loss of membrane integrity which is directly related to a decrease in SG and vigor. The parameters estimated in this study can be used for simulating canola SG as well as.

Seeds of Polygonum equisetiforme collected from 10 different Tunisian locations were evaluated for their crude protein content, oil content, fatty acid composition, phytochemical content, and antioxidant potential to enhance their industrial uses. The Kjeldahl method revealed that proteins (Nx6.25) varied from 10.20% to 13.50% on a dry weight basis. Oil contents, ranging from 2.6% to 5% on a dry weight basis, were characterized by a consistent fatty acid profile. Gas chromatography revealed the presence of mainly unsaturated fatty acids (ca. 80%). Oleic acid (ca. 38%), linoleic acid (ca. 30%), palmitic acid (ca. 15%), and α-linolenic acid (ca. 3.8%) were the major fatty acids. Total phenol content was measured using the Folin-Ciocalteu reagent and ranged from 13.36 to 33.85 mg GAE/g DW. The flavonoid content of the seed extracts was determined using the aluminium chloride method varied from 16.20 to 44.67 mg CTE/g DW. The total condensed tannin content detected using vanillin assay varied from 1.92 to 10.98 CTE/g DW. The assessment of the seed antioxidant potential was performed using the phosphomolybdenum assay and DPPH scavenging activity. The total antioxidant capacity (TAC) varied from 21.17 to 46.02 mg GAE/g DW. Indeed, the studied seed extracts were strong DPPH scavengers (14.33–35.37 mM TRE/g DW). Moreover, LC-ESI/MS analysis of P. equisetiforme extracts also showed the presence of nine phenolic acids and 12 flavonoids. Gallic acid, quinic acid, protocatechuic acid, (+)- catechin, and quercetin-3-O-galactoside were the main phenolic compounds. The present work highlighted the important nutritive value of the unexploitable P. equisetiforme seeds as natural antioxidants and a safe source of proteins, fatty acids, and phenolic compounds. P. equisetiforme can be considered a prospective source of useful natural bioactive molecules that could be used in functional food, pharmaceutical, and cosmetic industries.

Periploca angustifolia (Labill.) is a multipurpose xerophytic shrub widely distributed in arid zones. It is used in rehabilitation programs; its exploitation and utilization require the understanding of its behavior under stress conditions such as drought. To evaluate drought response and at what level it becomes irreversible, a new analysis of physiological and biochemical performances of this threatened shrub was conducted to assess possible mechanisms of drought tolerance and how these relate to its ecological success. Eleven-month-old plants, grown under semi-controlled conditions, were subjected to a well-watered control treatment or progressive drought by withholding water for 7, 14 and 21 d with subsequent recovery for 7-d. After 7 days of drought, followed by rewatering period, no significant effect on all studied parameters was recorded for P. angustifolia . However, from 14 until 21 days of withholding irrigation, drought becomes irreversible causing plant damages, may be rewatering has no effect to reduce these damages. A water deficit of 21 days RWC (33%), chlorophyll a content (0.083 mg·g − 1 DW), transpiration 14.7%, as well as water and osmotic potential (− 3.40 and − 3.78 MPa) decreased significantly compared with control. While, proline content (0.25 μmol·g − 1 FW), soluble sugars (80.52 mmol·g − 1 DW) and vitamins C, E (1.9 mM·g − 1 FW) increased significantly that could indicate ability of osmotic adjustment in this species. Also the increases in RWC, water and osmotic potentials values after rewatering period indicate the good recovery of this plant. Based on these experiments, responses of P. angustifolia to water stress were typical of those of xerophytic plants.

The current study was carried out to check the influence of the gradient saline (0, 50, 150, 200, 250 and 300 mM NaCl) on Astragalus gombiformis Pomel. plants grown in pots in greenhouse conditions. The results demonstrated that salt levels above 50 mM substantially reduced the biomass accumulation in both roots and especially in shoots. Similarly, higher salinity (100–300 mM NaCl) resulted significant decline in net photosynthetic (-66.2%), transpiration (-80%), stomatal conductance (-87.7%), intercellular CO2 concentration (-78.1%) and chlorophyll a and b contents (-45.7 and -51%, respectively). Also, leaf relative water content (RWC) was reduced significantly with salinity exceeding 100 mM NaCl, while the leaf water potential (ΨW) decreased significantly as salinity rises. Salt stress increases Na+, Na+/K+ and decreases K+ concentrations in all tissues of A. gombiformis. Compensatory, an accumulation of organic osmolytes such as soluble sugars in response to higher salinity (150–300 mM NaCl) was observed, while proline content increased drastically with progressive salinity. The present study reveals that GPX and GR were highly used to protect from NaCl-induced H2O2. APX might to participate efficiently in restriction of oxidative damages under higher salinity (50–150 mM). The leaf anatomy showed an increase in upper epidermal thickness at higher salt level (300 mM), whereas the total leaf thickness and the mesophyll parenchyma area decreased with salinity exceeding 100 mM NaCl. The distance between vascular bundle and the xylem vessel diameter were reduced only at 300 mM. The stomatal density decreased with enhanced stomata size at 200–300 mM NaCl. Based on these physiological, biochemical and anatomical responses to salinity we conclude that A. gombiformis is unable to maintain the ionic homeostasis and to managing ROS stress at high salinity and therefore can tolerate only mild to moderate salinity.

Phytochemicals from Calicotome villosa seeds were evaluated during long-term storage. Total phenols were affected during storage, ranging from 34.6 (5-years-aged seeds) to 45.1 mg GAE/g DW (16-years-aged seeds). Flavonoids increased with the storage period varying from 21.4 (seeds collected at 2013) to 34.1 mg QRE/g DW (seeds collected at 2002). The total condensed tannins were low for all storage periods and the highest value was registered for 16-years-aged seeds (0.15 ± 0.01CTE/g DW). LC-ESI/MS analysis showed five phenolic acids and 11 flavonoids, which remained steady during the long-term storage. High-maintained storage protein content (50.2% DW) occurred in C. villosa seeds even under long-term storage (up to 16 years). Globulins were the major proteins (47.6% of total proteins). All these findings made C. villosa a source of natural antioxidants with high industrial value and could be used as a potential food source. PRACTICAL APPLICATIONS: In this research paper, we have evaluated and discussed the effect of long storage duration (5, 10, 13, and 16 years) on phenolic contents, antioxidant potential, and protein profiles of C. villosa seeds. The total phenolic content determined was not affected by storage duration, while the values of flavonoid content were enhanced. The storage length significantly increased the total condensed tannin content. However, the phenolic acids and flavonoid compounds remained stable. Moreover, high-maintained storage protein content (globulins, albumins, glutelins, and globulin) occurs in C. villosa seeds even under long-term storage. The obtained results showed that the quality of the seeds was not negatively affected by long storage duration. C. villosa seeds show the prospective potential applications in the food industry.

Despite the interest of legumes for food and feed purposes, the phytochemicals of Astragalus armatus (AA), A. caprinus (AC), and A. gombiformis (AG) have not been reported in-depth yet. Thus, the lipid contents, fatty acids composition, proteins, and bioactive compounds in the seeds of these species were investigated. Total lipids were ranged from 12.2 (AG) to 36.5 g 100 g-1 DW (AC) and consisted of linoleic acid, α-linolenic acid, and palmitic acid. The crude protein contents were in the range from 52.2 (AG) to 54.74 g 100 g-1 DW (AA). Globulin and albumin were the predominant soluble protein fractions. The seeds consisted significantly of different contents of total polyphenols (3.4–6.5 mg GAEg-1DW), total flavonoids (1.24–5.15 mg QEg-1DW), and total condensed tannins (12–23.2 mg CEg-1DW). The extracts mainly consisted of quinic acid, p-coumaric acid, and cirsiliol. All these findings can be assets for functional foods and/or food ingredients.

Drought is one of the most serious abiotic stresses limiting plant growth and crop productivity worldwide. The long arm of the barley chromosome 4H is often implicated in adaptation to drought. Therefore, the aim of the present study was to explore the polymorphism of microsatellite markers localized mostly on chromosome 4H in eight barley varieties (Hordeum vulgare L.) representing the wide range of drought tolerance. The differences in physiological responses related to drought stress classified these genotypes in two groups based on the Euclidean distances. The susceptible varieties are gathered in the same cluster recording an average Euclidean distance of 27.2, and an average dissimilarity of approximately 52.4 regarding the drought-tolerant group. Tolerance to drought stress of the Tunisian and Jordanian barley cultivars was associated with lower changing ratios of malondialdehyde contents, smaller decrease in leaf water content and significant increase in proline concentration compared to other analyzed genotypes. In simple sequence repeat (SSR) analyses, from a total of 17 analyzed SSR primers, 12 microsatellites showed clear patterns with high level of polymorphism. Among the 12 polymorphic SSR primers, four were found to be polymorphic across drought susceptible and drought-tolerant cultivars (Bmag808, EBMAC624, WMS6 and BMAC0577). High level of diversity was observed in the chosen genotypes through analyzing both physiological traits and SSR markers. A significant correlation was observed between the distance matrices based on SSR markers and physiological data, as determined by the Pearson’s correlation coefficient (r = 0.63; Mantel test P

Lotus creticus L. (Fabaceae) is largely grown in the Mediterranean zone and considered as a socioeconomic and ecologically valuable species in the rural and arid Tunisian regions. In the present work, we focused on the unexploited seeds of four ecotypes of this plant regarding their storage proteins, phytochemicals, and antioxidant potential. Both colorimetric assays and electrophoretic analysis revealed that L. creticus seeds are promising sources of protein and their total contents were in the range of 197.55–248.27 mg/g DW. Albumins constituted the major fraction and formed about 45.08% of total proteins, followed by globulins (27.32%), and glutelins (19.38%). The prolamin fraction presented only 8.22%. The methanolic extracts of the seeds were rich in phenolics. The total polyphenol and flavonoid contents were found to be in the range from 7.05 to 8.11 mg GAE/g DW and 11.83 to 14 mg QE/g DW, respectively, whereas the condensed tannin amounts ranged between 1.78 to 2.19 mg CTE/g DW. Moreover, the studied seeds extracts possessed high antioxidant potential as evidenced by their total antioxidant capacity (6.74–8.11 GAE/g DW), free radical DPPH scavenger activity (IC50 = 15.67–22.17 mg/mL), and reducing power (EC50 = 6.90–9.07 mg/mL) which were mainly due to the presence of several phenolics in the extracts. A total of 21 phenolics were identified and quantified using LC-ESI/MS method including 8 phenolic acids (31.81–33.83 μg/g DW) and 13 flavonoids (108.10–120.02 μg/g DW). Quinic acid, protocatechuic acid, epicatechin, hyperoside, and quercetin-3-O-rhamnoside were identified as the predominant compounds. Results so far have been very encouraging and proved that L. creticus seeds are an effective source of phenolics and proteins which could potentially be used for several industrial purposes.

Polygonum is the largest genus of Polygonaceae and 5 species are reported in Tunisia. In order to characterized flower, seed, and fruit development in Polygonum, flower and fruit of Polygonium equisetiforme (var. graecum and peyerinhoffi), P. aviculare and P. maritimum, collected from Tunisia, were examined. Flowers are composed of five oblong tepals. P. equisetiforme and P. aviculare have whitish-pink distylous flowers with dimorphism of style, filament and anther height, pollen diameter and stigma size. In contrast, P. maritimum shows white homostylous flowers. The floral vasculature showed that the tepals are inserted in one whorl and their traces arise independently in 3+2 manner. The eight stamens are arranged in a 5+3 manner and the staminal bundles arise independently in the two whorls. The epidermis and endothecium cells width were higher in P. maritimum and the lowest endothecium width was observed in P. aviculare. Polygonum aviculare and P. equisetiforme showed circular pollen with shallow colpi and trilobite pollen shape with deep colpi, while P. maritimum rarely showed shallow colpi. The ovule is anatropous with basal placentation in P. equisetiforme and P. aviculare and apical placentation in P. maritimum. The young seed coat was formed by an endotesta with thick-walled cells, a mesotesta and exotesta with thin-walled cells and a tegmen composed of radially elongated cells. The fruits of the studied species are trigonous with ovate-lanceolate shape. In P. aviculare, the exocarp is thicker compared to the two other species, in P. equisetiforme, the mature exocarp consists of smaller rectangular cells with narrow cavities, and in P. maritimum showed a thinner exocarpIn conclusion, P. equisetiforme and P. aviculare are a typically distylous species from the morphological point of view and we discussed the significance of heterostyly in Polygonaceae. From this first morpho-anatomical study of Polygonum species in North Africa, we can conclude mainly that there is no significant difference between P. equisetiforme var. graecum and var. peyerinhoffi supporting a taxonomic grouping of these two varieties.

The present study was designed to study the effect of drought on several physiological and biochemical parameters three-month-old Astragalus gombiformis Pomel. plants, submitted to water deficit (5, 10, 15, and 20 days of withheld irrigation). The results show that water deficit treatments reduced the biomass accumulation (DM) in both organs parts especially in the shoots. In addition, leaf water potential (ΨW) and leaf relative water content (RWC) decreased significantly with drought stress. Net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), and internal CO2 concentration (Ci) decreased only after 10 days of water deficit. However, chlorophyll a and b remained unchanged in all treatments, suggesting that photosynthetic rate was reduced mainly due to stomatal closure. After prolonged drought stress (20 days), A. gombiformis exhibited increased accumulations of total soluble sugars and proline. Indeed, the lower but significant increases of malondialdehyde occurred only after 20 days of water deficit, explaining the higher aptitude of this species to adjust osmotically. Under prolonged stress (20 days), α-tocopherol concentrations increased by 30 % and ascorbic acid increased by 61 %. In contrast, the accumulation of total polyphenol was unchanged under water deficit, suggesting their minor role as antioxidants in A. gombiformis plants. The lower increase in malondialdehyde content suggest that A. gombiformis was able to maintain leaf cell integrity because of the efficient osmoprotection and antioxidant defense systems. Indeed, the accumulation of α-tocopherol and ascorbic acid showed that these compounds might to participate efficiently in restriction of oxidative damages caused by the H2O2 generation.

Stipa lagascae R. & Sch. (perennial bunchgrass) is one of the most promising steppic species for arid and desert lands of Tunisia. The present study was designed to study the effect of drought on root and leaf anatomy, water relationship, and the growth of three- month-old S. lagascae plants, submitted to water deficit (5, 10, 15, 20, 30 days of withheld irrigation) and grown in pots in greenhouse conditions. The results show that water deficit treatments reduced the biomass accumulation (MS) and leaf water potential (Ψw) of plants. However, leaf relative water content (RWC) decreased significantly only at severe drought. The root’s anatomical features showed reduced root cross-sectional diameter under water deficit. Conversely, epidermis was unaffected by water stress. Moderate and/or severe water deficit (20–30 days) reduced significantly the cortex thickness, cortical cell size, stele diameter, xylem vessel diameter and the stele/root cross-sectional ratio, while the number of cortical cells increased for severe water deficit. The cuticles and mesophyll of S. lagascae was thickened by moderate to severe drought and the entire lamina thickness was increased significantly by 5.8% only after 30 days of water deficit while epidermis was unaffected by water deficit. However, severe water deficit (30 days) decreased the width and the length of the bundle sheath. At the same time, the mesophyll cells size and both the xylem and phloem vessels diameter diminished by 12, 16.8 and 17.5%, respectively. Leaf rolling occurs as a response to water deficit and its level increases as the drought period is progressing in plants while reduced bulliform cells size occurred only at severe water deficit. Our findings suggest a complex network of root and leaf anatomical adaptations such as a reduced vessel size with lesser cortical and mesophyll parenchyma formation and increased leaf rolling. These proprieties are required for the maintenance of water potential and energy storage under water stress which can improve the resistance of S. lagascae to survive in extremely arid areas.

The present study was designed to study the effect of drought on root, stem and leaf anatomy of Astragalus gombiformis Pomel. Several root, stem and leaf anatomical parameters (cross section diameter, cortex, root cortical cells, pith, leaf lamina and mesophyll thickness) were reduced under moderate to severe water deficit (20–30 days of withheld irrigation). The stele/cross section root ratio increased under moderate water deficit. The root’s and stems vascular systems showed reduced xylem vessel diameter and increased wall thickness under water deficit. In addition, the root xylem vessel density was increased in these drought conditions while it was unchanged in the stems. The stomata density was increased under prolonged drought conditions whereas the stomata size was untouched. The leaf vascular system showed reduced xylem and phloem tissue thickness in the main vein under moderate to severe water deficit. However, in the lamina the vascular tissue and the distance between vascular bundle were unaffected. Our findings suggest a complex network of anatomical adaptations such as a reduced vessel size with increased wall thickness, lesser cortical and mesophyll parenchyma formation and increased stomata density. These proprieties are required for the maintenance of water potential and energy storage under water stress which can improve the resistance of A. gombiformis to survive in arid areas.

This study was carried out to evaluate the effect of long-term natural aging on germination ability and several biochemical characteristics regarding soluble sugars and polyphenol matter contents and radical scavenging activity of Periploca angustifolia Labill. (Asclepiadaceae) stored seeds for 1, 3, 7, 10, 11 and 15-years, dry storage compared to freshly collected seeds. The long-term aging caused an important decrease of germination percentage, seed vigor index, seeds’ viability, moisture content and seed vigor except for seeds stored for seven-years. The latter showed the highest percentages of germination and viability, seed vigor index and seed vigor under a 7.3% moisture content when compared to the oldest seeds (15-years old) which presents the lowest moisture content. In our study, aged seeds showed the lowest radical scavenging percentage activity and amounts of polyphenol, keeping free radicals and peroxides at high levels causing thereby seeds deterioration. P. angustifolia seeds undergo a process of after-ripening under the storage conditions, possibly depending on the low, but steady water loss down to an optimal storage water content of approx. 7.3%, thereafter undergoing some deterioration as indicated by reduced amounts of soluble sugars by polyphenol contents and experimentally tested antioxidant activities, which is in line with increased membrane leakages as indicated by increased electrical conductivities of solution from experimentally soaked seeds. Keywords : Periploca angustifolia Labill, polyphenol, germination African Journal of Biotechnology Vol. 12(15), pp. 1760-1768

Aegilops geniculata Roth (Poaceae) is a potential source of genetic variation for wheat improvement. In order to distinguish and evaluate different genetic of Aegilops and Triticum using RAPD markers, thirteen Aegilops geniculata populations and three durum wheat varieties (Triticum durum Desf.) were collected from different regions of Tunisia (North and central). Aegilops geniculata Roth populations (Goussa, Djebel Abderahmen, Tabarka, Djebel Ressas), (Bizerte, Zaghouan), (Mekna, Ain Zana), (Djebel Oust, Souk jemaa, Sbeitla), (Djebel Serj, Nefza) constitute different groups. Complement gene locus were amplified by nineteen RAPD primers witch produced 212 bands, that 182 bands (about 86%) were polymorphic. The results revealed that genetic diversity within populations was relatively high. Nei’s genetic diversity (H) and Shannon’s index (I) were 0.324, 0.484 respectively. Global AMOVA showed that genetic variation within populations accounted 80% occurring (ΦPT =0.205 p

The essential oils of three wild species of Calligonum (C. azel, C. arich and C. comosum) growing in the Tunisian desert were obtained by hydrodistillation and were analyzed by GC-FID and GC-MS in order to discern the differences and similarities between the chemical composition of the essential oils of these species. A total of 110 compounds, which accounted for 94.0 – 99.7 % of the total composition of the essential oils, have been identified. The main constituents were viridiflorol (9.6 %) in C. azel, hexadecanoic acid (20.1 %) in C. arich and 9-octadecenoic acid (19.8 %) in C. comosum. Based on their chemical composition, two chemotaxonomic groups may be established: C. azel on one hand, C. arich and C. comosum on the other hand.

Genetic diversity of three durum wheat cultivars (Triticum durum Desf.) and thirteen Aegilops geniculata Roth accessions belonging to different regions of Tunisia (in North and Central) was evaluated using random amplified polymorphic DNA (RAPD) markers. Nineteen arbitrary universal primers were used for the amplification of random DNA sequences. Data were analysed with the SIMQUAL program using the NTSYS-pc. Phylogenetic diagram was drowning using the UPGMA algorithm. Results indicate an important inter—specific polymorphism between Aegilops and durum wheat. Ae. geniculata accessions revealed a high level of polymorphism (71.27%) than wheat cultivars (39.76%). Two main groups were represented by cluster and principal component analyses. The first group is formed by Ae. geniculata accessions and the second is constituted only by durum wheat cultivars. Consequently, RAPD markers separate clearly Ae. geniculata accessions and durum wheat cultivars.

Soil and water salinity is a major environmental problem in the dry Mediterranean regions, affecting rangeland production. This study investigated the effects of salinity on the wild perennial grass (Poaceae) species Stipa lagascae R. & Sch., a potential forage plant that could be used to rehabilitate degraded rangelands in dry areas. In a laboratory, 3-month-old S. lagascae seedlings were subjected to increasing salt treatments (0–400 mm NaCl) for 45 days. Physiological and biochemical parameters such as leaf water potential (Ψw), leaf relative water content (RWC), proline, total soluble sugars, Na+, K+ and Ca2+ contents, and catalase, ascorbate peroxidase and glutathione reductase activities were measured. Total soluble sugars and proline concentrations increased and Ψw and RWC decreased with increasing salt concentrations. Lower salt concentrations induced a non-significant degradation of chlorophyll pigments. Shoot Na+ content increased with a salinity level, whereas shoot K+ and Ca2+ concentrations decreased and the K+ : Na+ ratio was lower. The salinity threshold, above which S. lagascae showed signs of damage, occurred at 300 mm. Plants have evolved reactive oxygen species (ROS) scavenging enzymes including catalase, ascorbate peroxidase and glutathione reductase, which provide cells with an efficient mechanism to neutralise ROS. The tolerance strategies of S. lagascae to moderate salinity seem to include osmotic adjustment through total soluble sugars and proline accumulation, and highly inducible antioxidative defence. Further investigations are necessary to study the effect of salt stress on distribution of ions (Na+, K+, Ca2+, Mg2+, Cl–, NO3–, SO42–) and osmotic adjustment. Photosynthesis and water-use efficiency parameters could be also useful tools.

Retama raetam is a stem-assimilating, C3, evergreen, medicinal plant species, desert legume common to arid ecosystems around the Mediterranean basin. This study addresses the genetic diversity and relationship among and within three populations collected from different habitats in southern Tunisia by Random Amplified Polymorphic DNA (RAPD). Estimates of the percentage of polymorphic bands, Shannon's diversity information index and Nei's gene diversity index were determined. Results showed that population from the Island Djerba has the lowest Nei's gene diversity; this also was for Shannon diversity index. An analysis of molecular variance indicated that the majority of variation existed within populations (68%) and that there was significant differentiation among populations (phiPT = 0.316, p < 0.001). Genetic distance (phiPT based values) between pairwise populations ranged from 0.098 to 0.505 and the differentiation between pair-wise populations was significant when individual pairs of populations were compared. Based on the coefficient of gene differentiation (Gst), gene flow (Nm) was estimated and was found to vary from 0.490 to 4.609 between pair-wise populations and 1.42 among populations. The results of UPGMA cluster analysis and PCoA analysis indicated that most variation occurred within populations and that genetic differentiation had happened between populations. These findings are important for a better understanding of the adaptive strategy of R. raetam in southern Tunisia and will be useful for conservation managers to work out an effective strategy to protect this important species.

A collection of nine Tunisian faba bean (Vicia faba) populations belonging to three botanical classes (Var. minor, var. equina and var. major) was evaluated using twenty seven agro-morphological traits. Analysis of variance, correlation coefficients and principal components analysis (PCA) were performed based on MVSP 3.13 program. Significant differences between populations were noted for most agromorphological traits in four main groups. The first group, positively correlated to the two axes, isrepresented by ‘Bachaar’ belonging to V. faba. var. minor, the second group, including V. faba. var. minor population (‘Massri’ and ‘Badï’), is positively correlated to the PC1 and negatively correlated to the PC2 while the third group, is composed of two V. faba var. major (‘Malti’ and ‘Batata’) and were positively and negatively correlated to the PC2 and PC1, respectively. Finally, the fourth group negatively correlated to the two axes, gathers the remaining population (‘Chahbi’, ‘Chemlali’, ‘Aguadulce’ and ‘Super Aguadulce’). The dendrogram based on Nei's genetic distance of the 9 populations using UPGMA method, show some genetic drift between populations.Key words: Faba bean, agromorphological traits, principal components analysis, UPGMA method.

This study used sequence specifc amplifcation polymorphism (SSAP) markers to investigate the genetic diversity and population genetic structure of nine Tunisian Vicia faba populations belonging to the minor and major faba bean’s sub-species. Three primers were used (PDR1, Tps19 and Tvf4) in this study. These primers gave good SSAP marker profiles, high number of bands obtained per gel and a high percentage of polymorphic bands as confirmed in a previous study. Indeed, these primers provided a total of 173 amplified bands, with 123 of them being polymorphic. Shannon indexes ranges from 0.166 to 0.248 with an average of 0.207. The genetic diversity within population of 0.743 was clearly higher than that of among population genetic diversity (Dst = 0.138), indicating an out-crossing predominance in the studied populations. The Dst value showed that 15.6% of the total genetic variation resided among populations, a little lower than that of out-crossing species. The dendrogram grouping the populations by unweighted pair-group method with arithmetic averages (UPGMA) method revealed three main clusters. The local major faba bean ‘Batata’ was the most divergent population and was separated from other population.Key words: Vicia faba, SSAP marker, Genetic diversity, Tunisia.

Seven isozyme systems (Sod, 6-Pgd, Me, Est, Skdh, Fdh and Gdh) representing nine loci were used to study the genetic diversity of nine faba bean populations. Seven loci revealed polymorphic bands and showed the same quaternary structure as that found in several species. They revealed a high number of phenotypes. Indeed, from 3 to 9 phenotypes per locus were investigated in this study. The percentage of polymorphic loci (P = 59.3 %) was higher than that mentioned in the autogamous species (P = 20.3 %) and less than the optimum (P=96 %) indicated for allogamous plants. Total genetic diversity (H T) and within population genetic diversity (H S) were estimated with the isozyme markers. The contribution of among population genetic diversity (D ST) to total genetic diversity was 22%. Enzyme markers pointed out an average inbreeding level for whole population (F IT) and within population (F IS). Within population genetic diversity represents 78% of total diversity. Intra-population genetic diversity (H S = 0.206) was ranged with the respect of allogamous species and was clearly higher than that of among population genetic diversity (D ST = 0.057) indicating an out-crossing predominance in the studied populations. The expected heterozygosity was higher than that observed heterozygosity at the allogamous species was confirmed in this study. Although, the mean estimated gene flow was less than 1(Nm=0.814), the dendrogram based on Nei's genetic distance of the 9 populations using UPGMA method showed some genetic drift between populations. © 2011 The Genetics Society of Korea and Springer Netherlands.