Search

Bioactive compounds in wheat have received a great interest in the last few years due to their nutritional and health benefits. Various analytical procedures were used to identify these compounds in wheat kernels. An ultra‐performance liquid chromatography coupled to electrospray ionization quadrupole‐time‐of‐flight mass spectrometry (UPLC–ESI‐QTOF‐MS/MS) was used for the screening of bioactive compounds in seven Tunisian durum wheat extracts. The aim of this study was to realize a screening of several classes of bioactive compounds in the same analysis and to identify specific metabolite markers for discriminating the durum wheat varieties. The UPLC‐ESI‐QTOF‐MS/MS allows the detection of 81 metabolites, belonging to different chemical families such as sugars, organic acids, amino acids, fatty acids, and phenolic compounds represented by benzoic and cinnamic acid derivatives, phenolic alcohols, flavones, lignans, and condensed tannins. Chemical profiles identified varied greatly between different wheat genotypes. As far as the authors know, this is the first time that different chemical classes were detected at the same time in durum wheat kernels using UPLC‐ESI‐QTOF‐MS/MS. This study gives the most complete map of metabolites in Tunisian durum wheat and proves that UPLC‐QTOF‐MS/MS coupled with chemometric analysis is a great tool for discrimination between durum wheat cultivars. [ABSTRACT FROM AUTHOR]

Abstract: Cereals contamination with mycotoxigenic species of Fusarium is considered as a major source of trichothecenes and other mycotoxin groups which cause severe yield losses and serious diseases in human and animal health. Early detection of Fusarium species could be for a great interest to prevent mycotoxin contaminating agro-products. We have established for the first time a direct polymerase chain reaction (DPCR) protocol to detect contamination with trichothecene-producing F. culmorum in wheat samples. We have successfully amplified fungal genomic DNA using specific primers targeting the trichothecenes biosynthetic Tri5 gene. We further investigated a versatile multiplex-DPCR on the basis of Tri5 gene and IGS (Intergenic Spacer of rDNA) specific sequence of F. culmorum for its identification at specie level and prediction of its potential trichothecenes production simultaneously. Our protocol allowed amplification directly from crude templates with no need of DNA extraction or purification methods and did not require any culture-based approach. These DPCR assays represent a reliable tool for high throughput screening, detection and rapid characterization of mycotoxigenic isolates as well as diverse applications in food industry. [Copyright &y& Elsevier]

An efficient protein extraction method is crucial to ensure successful separation by two-dimensional electrophoresis (2-DE) for recalcitrant plant species, in particular for grapevine ( Vitis vinifera L.). Trichloroacetic acid-acetone (TCA-acetone) and phenol extraction methods were evaluated for proteome analysis of leaves and roots from the Tunisian cultivar 'Razegui'. The phenol-based protocol proved to give a higher protein yield, a greater spot resolution, and a minimal streaking on 2-DE gels for both leaf and root tissues compared with the TCA-based protocol. Furthermore, the highest numbers of detected proteins on 2-DE gels were observed using the phenol extraction from leaves and roots as compared with TCA-acetone extraction. [ABSTRACT FROM AUTHOR]

We examined the variation and relationships between pathogenicity and a microsatellite-based haplotype in 79 Tunisian Rhynchosporium secalis isolates that were collected from the most commonly cultivated barley populations in Tunisia, Rihane cv. and local landraces, with the goal of finding genes that might be used to monitor resistance to scald. Isolates could be classified into three distinct virulence groups based on artificial inoculation of 19 differential cultivars with known scald resistance genes. The resistance gene BRR2 carried by the Astrix differential cultivar appeared to be the most effective in Tunisia. Pathotypes sampled from the Rihane host were more virulent than those sampled from local barley landraces. Because some differential cultivars that carried the same resistance genes showed different reaction patterns to 48 of the isolates, we postulated that other unknown resistance gene(s) specific to Tunisian isolates may be prevalent and could be used in Tunisian barley breeding programs. Microsatellite fingerprinting allowed the detection of 11 alleles linked to the virulence and pathogenic identification of 52% of the tested isolates. Thus, microsatellite analysis may provide a rapid tool for pathogen detection, without an inoculation step that requires long incubation periods before ultimate disease assessment. [ABSTRACT FROM AUTHOR]

Salt stress negatively impacts crop production worldwide. Genetic diversity among barley (Hordeum vulgare) landraces adapted to adverse conditions should provide a valuable reservoir of tolerance genes for breeding programs. To identify molecular and biochemical differences between barley genotypes, transcriptomic and antioxidant enzyme profiles along with several morpho-physiological features were compared between salt-tolerant (Boulifa) and salt-sensitive (Testour) genotypes subjected to salt stress. Decreases in biomass, photosynthetic parameters, and relative water content were low in Boulifa compared to Testour. Boulifa had better antioxidant protection against salt stress than Testour, with greater antioxidant enzymes activities including catalase, superoxide dismutase, and guaiacol peroxidase. Transcriptome assembly for both genotypes revealed greater accumulation of differentially expressed transcripts in Testour compared to Boulifa, emphasizing the elevated transcriptional response in Testour following salt exposure. Various salt-responsive genes, including the antioxidant catalase 3, the osmoprotectant betaine aldehyde dehydrogenase 2, and the transcription factors MYB20 and MYB41, were induced only in Boulifa. By contrast, several genes associated with photosystems I and II, and light receptor chlorophylls A and B, were more repressed in Testour. Co-expression network analysis identified specific gene modules correlating with differences in genotypes and morpho-physiological traits. Overall, salinity-induced differential transcript accumulation underlies the differential morpho-physiological response in both genotypes and could be important for breeding salt tolerance in barley. [ABSTRACT FROM AUTHOR]

Knowledge about the extent of nutrient variability in local barley germplasm is an important prerequisite for efficient crop improvement. The present study is one of the first to assess the potential of Tunisian barley populations (named Testour, Gergis, and Enfidha) as sources of desirable traits for barley improvement and for the prevalence of Fusarium species and the mytoxin zearalenone (ZEN). Analysis of variance revealed highly significant differences between barley populations for nutrients density. The lowest phytate/zinc molar ratios were observed in Testour and Enfidha populations with 7.23 and 9.97, respectively. However, the bioavailability of iron of most barley populations (95.4%) was inhibited mainly by the high phytate content. Oleic acid (15.2–18.7%), linoleic acid (13.8–16.01%), and palmitoleic acid (4.7–14.2%) were identified as predominant fatty acid constituents in all three barley populations. Based on morphologic and molecular characterization, Fusarium graminearum and Fusarium culmorum were the predominant species that infected Testour, Gergis, and Enfidha populations. The concentration of zearalenone ranged between 0 and 140 µg kg−1. The highest levels of zearalenone, 92 μg kg−1 and 60 μg kg−1, were detected in Testour populations that were infected with F. graminearum and F. culmorum, respectively. These relatively low amounts of zearalenone in barley populations can be attributed to the Tunisian climate and the resistance of local genotypes. Testour and Enfidha barley populations could potentially be used to improve breeding programs for biofortification. [ABSTRACT FROM AUTHOR]

Background: Pearl millet (Pennisetum glaucum L.) has become increasingly attractive due to its health benefits. It is grown as food for human consumption and fodder for livestock in Africa and Asia. This study focused on five pearl millet populations from different agro‐ecological zones from Tunisia, and on characterization by morphological traits, total phenolic and flavonoid content, antioxidant activity, and occurrence of Fusarium. Results: Analysis of variance revealed highly significant differences between populations for the quantitative traits. The highest grain weights occurred in the pearl millet cultivated in Zaafrana and Gergis of Tunisia. Early flowering and early maturing populations cultivated in the center (Zaafrana, Rejiche) and south (Gergis) of Tunisia tended to have a higher grain yield. The Zaafrana population showed the highest value of green fodder potentiel (number and weight of leaves/cultivar and the weight of tillers and total plant/cultivar) followed by Gergis and Rejiche. The Kelibia population showed the highest total phenolic and flavonoid content. Rejiche exhibited the greatest antioxidant activity. Trans‐cinnamic, protocatechuic, and hydroxybenzoic acids were the major phenolic compounds in all the extracts. Three Fusarium species were identified in Tunisian pearl millet populations based on morphologic and molecular characterization. Fusarium graminearum and Fusarium culmorum occurred most frequently. The average incidence of the three Fusarium species was relatively low (<5%) in all populations. The lowest infection rate (0.1%) was recorded in the samples from Zaafrana. Conclusion: Chemometric analysis confirmed the usefulness of the above traits for discrimination of pearl millet populations, where a considerable variation according to geographical origin and bioclimatic conditions was observed. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

When constrained by in vitro culture conditions, microspores from Opuntia ficus-indica (L.) Mill. (Barbary fig) anthers were forced to stall out their gametophytic pathway and switch towards androgenesis. Five microspore stages were characterized based on cellular architecture. A relationship was also established between anthers and bud flower features. Anthers were cultured on three culture media containing 2,4-dichlorophenoxyacetic acid, thidiazuron and gibberellic acid at 22°C for 4 wk, followed by heat shock treatment at 32°C or 42°C for 2 wk, and the stressed material was recultured at 22°C for 24 wk in the dark. When anthers were heat shocked at 32°C and 42°C, the cultivated anthers swelled and burst, followed by the microspores flowing onto the explant surface. Androgenesis occurred directly and indirectly at uni- and binucleate stages. The micromorphology of multicellular, proembryos, globular, torpedo and cotyledonary-like-shaped structures from dehisced anthers was confirmed by environmental scanning electron microscopy. Furthermore, at 42°C, microscopic analysis demonstrated that the non-responsive microspores achieved pollen maturation and more rarely, the emission of a pollen tube. However, 11.4 to 14.4% of the mature pollen grains were converted into pollen embryos. The established system may serve, for the first time, as a protocol to produce microspore embryos in O. ficus-indica. Nevertheless, more efforts are needed to complete the development of diplo-haploid plantlets. [ABSTRACT FROM AUTHOR]

• Chemical characterization of Coriandrum sativm L. and Carum carvi L. seeds essential oils. • Antifungal and antiaflatoxigenic activities of Coriandrum sativm L., Carum carvi L. essential oils and their major terpene components. • Higher biological activities against Aspergillus flavus for Carum carvi L. EO and carvone. • Carvone presents a strong potential for use as biopreservative against aflatoxins contamination. With the purpose of searching for biological substances for controlling aflatoxins production in foodstuffs, we assessed the antifungal and antiaflatoxigenic activities of two essential oils (EOs) extracted from Carum carvi L., Coriandrum sativum L. seed and their major terpene component against Aspergillus flavus. The chemical profiles of Carum carvi , and Coriandrum sativum EOs were identified through Gas chromatography mass spectrometry analysis where carvone and linalool were respectively, recorded as the major terpene compound (78.85 and 72.34%). The effects of the EOs (0.1–0.7% (v/v)) and terpenes (100–2000 μg/mL) on the hyphal extension and aflatoxin B1 (AFB1) synthesis of A. flavus were tested by contact assay in Yeast Extract Sucrose medium. Carum carvi EO displayed a higher antimicrobial activity against A. favus than Coriandrum sativum EO with a minimum inhibitory concentration of about 0.4 and 0.7%, respectively. In the presence of 0.3% of EOs, 73.3 and 99.6% inhibition of AFB1 production was recorded, respectively, with Coriandrum sativm and Carum carvi. The antifungal and antiaflatoxigenic effects of carvone were also more significant than those of linalool (p < 0.05) with respectively, 64 and 16% of growth rate inhibition and 77.9 and 0.1% of AFB1 synthesis decrease recorded at 1000 μg/mL. Hence, the antifungal and antiaflatoxigenic activities of the two tested EOs were similar to their main terpene component. In conclusion, seed essential oils proved to be apotential natural source of antifungal and aflatoxin inhibition agent against Aspergillus flavus. [ABSTRACT FROM AUTHOR]

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 F putative 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 HVM33 presented 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, EBMAC0970 and BMAG0013 with a mean value of 0.4619. The probabilities of identical genotypes PI for the 11 microsatellite markers were 8.63 × 10. 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, BMAC0040 and 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 ( A), expected heterozygosity ( H), 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. [ABSTRACT FROM AUTHOR]

Tunisian barley (Hordeum vulgare L.) 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. [ABSTRACT FROM AUTHOR]

For many years the needs of consumers, farmers and the seed industry have changed significantly. To meet these expectations, investments in research on durum wheat varieties are needed. In this context, five modern varieties of durum wheat (Karim, Razzek, Nasr, Khiar and Om Rabiaa), obtained through a selection program, harvested in northern Tunisia, have been investigated, deepening their technological and nutritional characteristics. The results obtained were evaluated using chemometric tools to visualize the interaction of these results with their calorific values. All wheat samples examined are characterized by low average grain glassiness values (0.67–10.65%), fatty acidity (≈0.05%) and moisture (≈10%), and high average values of thousandths weight (45.04–53.58 g), weight (≈84 kg h L−1) and monounsaturated fatty acids (20.34–25.62%). They also have appreciable quantities of gluten (from 26.49 to 42.22% of dry matter) and total protein (from 12.64 to 15.17% of dry matter) with an energy value of about 340 Kcal/100 g. According to UPLC-ESI-QTOF-MS analysis, dihydroferulic acid was shown to be the most abundant phenolic compound detected in all varieties, constituting approximately 30–40% of the phenolic compounds. The wheat variety strongly affects almost all technological and chemical parameters. Chemometric tools have allowed us to highlight the differences in the different varieties of wheat. In particular, the linear projections of the nutritional and technological characteristics of durum wheat were differentiated according to their calorific value, whereas the use of a heatmap was useful to create a hierarchical cluster of the wheat features. • Tunisian durum wheat has an ideal nutritional and technological quality. • Chemometric tools were effective in distinguishing wheat varieties. • Wheat variety strongly influences technological & chemical parameters. [ABSTRACT FROM AUTHOR]

The constitutive expression of a Vitis vinifera dehydrin ( DHN ) of the YSK 2 type ( VvDhn ) allowed for a more vigorous growth in transgenic tobacco plants than in wild-type (WT). In vitro , a very distinct germination kinetics and root development profile was observed both under optimal and stress conditions (control, mannitol, NaCl). Transgenic lines outperformed WT in germination success and precocity and root length. Furthermore, transgenic lines were able to germinate under 300 mM mannitol. Adult tobacco plants expressing VvDhn also displayed improved tolerance to both drought and salt stresses. The VvDhn lines under these constraints were significantly better than WT in terms of biomass and leaf number. Moreover, higher capacities to recover from drought were revealed. However, the major effect the VvDhn over-expression was observed under non limiting conditions. VvDhn interfered with the development program leading to higher biomass production (leaf, shoot and root) and to the production of higher number of leaves. The VvDhn gene show great promise for grapevine genetic improvement to drought and salinity tolerance. VvDhn gene can be used to screen and/or design for new grapevine rootstocks that together with viticultural management programs has the potential to cope successfully with a more adverse and unpredictable climate, which is highly demand by community. [ABSTRACT FROM AUTHOR]

To identify and isolate genes related to abiotic stress (salinity and drought) tolerance in grapevine, a candidate gene approach led to the isolation from Cabernet Sauvignon cultivar of a full-length cDNA of dehydrin gene. he latter, named VvDhn, which is highly and mainly induced in late embryogenesis in seeds, encodes for a protein of 124 amino acids with a predicted molecular mass of 13.3 kDa. Details of the physicochemical parameters and structural properties (molecular mass, secondary structure, conserved domains and motives, and putative posttranslational modification sites) of the encoded protein have also been elucidated. he expression study of VvDhn was carried out within plant organs and tissues as well as under drought and salt stresses. VvDhn was not detected in vegetative tissue, whereas it was only expressed during seed development (during late embryogenesis) at extremely high levels and was induced by salt and drought stresses as well as ABA application. Moreover, salt stress induced VvDhn expression in the tolerant variety (Razegui) but not the sensitive variety (Syrah), which did not display expression variation during stress; VvDhn expression level and salt-stress response depend on regulatory mechanisms that are efficient only in the tolerant variety. On the other hand, under drought stress VvDhn was induced in both tolerant and sensitive varieties, with higher levels in the tolerant variety. In addition, stress signal molecules such as ABA (applied alone or in combination with saccharose) induced VvDhn expression, even at low levels. Minimal knowledge about the role and functionality of this gene is necessary and constitutes a prerequisite for including VvDhn in grapevine abiotic stress tolerance improvement programs. [ABSTRACT FROM AUTHOR]

Salinity is one of the most common environmental stresses affecting grapevine productivity. In order to analyze the contribution of the dehydration-responsive RD22 gene of Vitis vinifera L. (VvRD22) to salt tolerance improvement, Agrobacterium-mediated transformation in the tobacco model plant (Nicotiana benthamiana) was carried out and transgenic lines were subjected to in vitro and ex vitro salt treatments for physiological response evaluation. Under in vitro salt stress, the transgenic lines exhibited higher seed germination and growth than the wild type (WT). The ex vitro assays after salt treatment showed better growth and higher chlorophyll content in VvRD22-expressing plants than in the WT. Ion analysis revealed less increase in the levels of sodium (Na+) in leaves and chloride (Cl-) in all organs within the transgenic lines compared to the WT. Interestingly, stabilized calcium (Ca2+) contents were registered in the leaves of transgenic lines. Moreover, the occurrence of an osmotic adjustment based on an overproduction of total soluble sugars was observed within the transgenic lines. These physiological responses suggest that the protective effect of VvRD22 transgenic expression is enabling other physiological mechanisms to function and subsequently contributing to the ability to cope with salt stress. The VvRD22 transgenic expression would be useful in engineering salt stress-tolerant grapevines. [ABSTRACT FROM AUTHOR]

Sorghum samples (n = 60) from Tunisian markets were analysed for the occurrence of 22 of both traditional and emerging mycotoxins. Samples were extracted with a QuEChERS-like method and mycotoxins were detected by LC-MS/MS. This method was validated and adequate analytical parameters were obtained. All samples had contamination with mycotoxins and several samples had higher contamination levels than European Union legislative limits (MLs). The most frequently found mycotoxins were ENB (100%), OTA (98%), ENA1(63%), ENB1(56%), BEA (48%), AFB1 (38%) and STG (33%). Mean contaminations were 30.7, 1.93, 33.2, 51.0, 15.4, 1.49 and 20.5 µg kg–1, respectively. While two samples were contaminated with FB2 and FB3 at mean values of 16.2 and 45.9 µg kg–1, respectively, one sample was contaminated with AFB2 and ZEA at levels of 0.82 and 45.0 µg kg–1, respectively. The results were used to estimate the daily intake of mycotoxins through sorghum consumption with regard to normal consumers (low-risk population) and high consumers such as babies (high-risk consumers) who are facing an alarming situation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cladodes from prickly O. ficus indica cultivars have a thick cracked epicuticular wax layer with an amorphous structure. [•] Spineless O. ficus indica cultivars have a less thick waxy layer with a rough crystalloid structure on their cladodes. [•] Persistent spines present a compact arrangement of oblong epidermal cells with a rough granular structure and filamentous prints. [•] Deciduous spines have a broken transversely fissured epidermis covering a parallel arrangement of fibres. [Copyright &y& Elsevier]

To characterize Aspergillus section Nigri strains involved in the ochratoxin A ( OTA) contamination of Tunisian wine and table grapes, a total of 33 strains were analysed. A molecular characterization of the isolates was performed by the amplification of internal transcribed spacer ( ITS1-5.8S rDNA- ITS2) region combined with amplicon sequencing. Analysis of similarity between the obtained sequences and those deposited in the GenBank database was performed. Twelve strains were confirmed to belong to the Aspergillus carbonarius species. Strains belonging to the Aspergillus niger aggregate group were classified by in silico RFLP assay into two patterns N and T, corresponding to A. niger and Aspergillus tubingensis. Among the 21 OTA producing isolates analysed, 13 showed the T-type pattern and 8 showed the N-type pattern. The presented method showed to be a reliable alternative to the classic RFLP method. Our findings unambiguously revealed that multiple aspergilli species isolated from wine and table grape in Tunisia are able to produce OTA. [ABSTRACT FROM AUTHOR]

This work aimed to determine patterns of pathogenicity in Pyrenophora teres f. teres and to identify potentially effective resistance sources that could be used as breeding material to control net blotch in Tunisia. Extensive pathogenic variability was detected in 85 isolates of P. teres causing net blotch of barley in Tunisia. Based on unweighted pair-group method with arithmetic averaging clustering and mean disease rating scores, three distinct virulence groups were identified. The isolates were classified into 23 pathotypes. Pathogenic variability within the groups was higher than that between the groups, a finding that can guide a rational choice of isolates for screening lines as part of a breeding program. Conversely, studying the relationship between geographic and pathotypic structure allowed us to detect a significant isolation by distance pattern, suggesting a regular and gradual dispersal of the pathogen over this spatial scale. Using specific resistance prop-erties of individual barley genotypes as virulence markers, all the dif-ferential barley genotypes were shown to be distinct, and no single source of resistance was totally effective against all isolates. [ABSTRACT FROM AUTHOR]

Abstract: This paper summarizes the results of a large study on the occurrence of ochratoxigenic fungi and Ochratoxin A from wine and table grapes in Tunisia. Our results revealed that Aspergillus section Nigri were the unique potential OTA producing fungi isolated from grapes. Isolates belonging to Aspergillus niger aggregate were the most abundant species followed by Aspergillus carbonarius isolates, then uniseriate aspergilli. A. carbonarius presented the highest percentage of OTA-positive strains (97%) whereas only 3% of A. niger aggregate isolates were OTA positive. Grapes were analysed for their OTA content and 58% of them contained detectable levels of OTA, between 0.05 and 5.85 μg/l. Only 4 samples out of 39 exceeded the OTA limit of 2 μg/l fixed by the EU for wine and grape juices. The most contaminated grapes were those from Raf–Raf region located in the North-Est and characterized by a humid climate. Grapes from the Regueb region, characterized by an arid climate, were rarely contaminated. Furthermore, A. carbonarius, which is the main OTA producer fungi on grapes, was rarely isolated in Regueb. [Copyright &y& Elsevier]

The article discusses comparative effects of phytochemical resveratrol and its dimer ε-viniferin on vascular endothelial cells (VECs) functions, blood pressure and cardiac mass of spontaneously hypertensive rats (SHRs). It mentions that ε-viniferin is more potent in exhibiting enhanced cell proliferation via nitric oxide generation and cells protection from oxidative stress. The other beneficiary effect mediated by its uptake includes reduction of systolic blood pressure in SHRs.

Abstract: Randomly amplified polymorphic DNA markers (RAPD) were employed to assess the level of genetic stability of long term micropropagated prickly pear (Opuntia ficus-indica) plantlets. Thirteen micropropagated plantlets were chosen from a clonal collection of shoots that originated from a single mother shoot. This clonal collection had been maintained under in vitro culture conditions for at least 5 years, as achieved for the time by axillary branch multiplication in Opuntia ficus-indica. Twenty arbitrary primers were used to compare RAPD patterns between in vitro raised material and the mother plant. Only 11 primers were found to yield distinct and reproducible amplification products resulting in a total of 87 amplified products, out of which 82 bands were monomorphic across all the plantlets and 5 showed polymorphisms. Cluster analysis performed on the basis of similarity indices indicated that all micropropagated plantlets and their mother plant grouped together in one major cluster with a 91% level of similarity. Low level of genetic variation has been detected, as polymorphic bands accounted for just 2.79% of the total genetic variation. This very low level of genetic variation, despite more than 5 years of in vitro culture, demonstrates the genetic stability of Opuntia ficus-indica and indicates that the axillary branch multiplication method is highly reliable for the multiplication of genetically true-to-type plant material. The high degree of clonal fidelity detected here, recommend the use of axillary-branching micropropagation technique for the safe in vitro conservation of prickly pear interesting genetic resources. [Copyright &y& Elsevier]

For the first time, genetic variability and differentiation among five annual caraway (Carum carvi) populations originating from Tunisia, Germany and Egypt were examined. Random Amplified Polymorphic DNA (RAPD) marker data were obtained and analysed with respect to genetic diversity, population structure and gene flow. Fourteen primers generated a total of 136 discernible and reproducible bands across the analyzed populations, out of which 56 were polymorphic. The UPGMA cluster analysis permitted the discrimination of all the genotypes and their sorting into 3 main groups. Tunisian caraway populations diverged significantly from German and Egyptian ones. Population clustering was made dependently from geographic origin. This has been further explained at the DNA level as we were able to select a set of RAPD fingerprints unique to each of the studied populations. Furthermore, dimensional graph derived from factorial analysis of RAPD frequency data, allowed significant grouping of the genotypes into five sub-plots, representing each one population. Shannon's index values showed that variation ranks between rather than within populations. These results indicated that considerable genetic differences among C. carvi populations were registered. [ABSTRACT FROM AUTHOR]

Abstract: In this study, 51 samples of cereals (wheat, Barley, maize and Sorghum) and by-products (mainly pasta and couscous) purchased from Tunisian supermarkets were examined for contamination with the emerging Fusarium mycotoxins: Enniatins ENs (EN A, EN A1, EN B and EN B1), beauvericin (BEA) and fusaproliferin (FUS). The extraction of the samples was performed with methanol using an Ultra-turrax homogenizer. Mycotoxins were analyzed with a liquid chromatography (LC) coupled to a diode array detector (DAD). The frequencies of contamination of total samples with ENs were 96%. EN A1 was the most common EN found with the highest prevalence of 92.1%, levels ranged between 11.1 and 480 mg/kg. EN B was evidenced in 35 samples and levels ranged from 1.5 to 295 mg/kg. EN B1 was detected in 20 samples (39.2%) and levels varied from 4.8 to 120.1 mg/kg and EN A was detected in 14 samples with contamination levels ranging between 19.6 and 121.3 mg/kg. The maximum concentration of total ENs in a single sample was 683.9 mg/kg (sorghum). The analytical results also showed that all the analyzed samples were free of BEA and FUS. The present work is the first one ever drafted on the presence of the emerging Fusarium mycotoxins in Tunisian cereals and derived products. [Copyright &y& Elsevier]

The article discusses research which examines the effectiveness of ϵ-viniferin in red wine for inhibiting vascular smooth muscle cell (VSMC) migration and proliferation. The study showed that ϵ-viniferin is more effective in inhibiting VSMC proliferation compared to its monomer resveratrol. It revealed that nitric oxide compounds increased the expression of the antioxidant enzyme.

The photoperiodic response is one of the adaptation mechanisms to seasonal changes of lengths of day and night. The circadian clock plays pivotal roles in this process. In Arabidopsis, LHY, CCA1, ELF3, and other clock proteins play major roles in maintaining circadian rhythms. lhy;cca1 double mutants with severe defects in circadian rhythms showed accelerated flowering under short days (SDs), but delayed flowering under continuous light (LL). The protein level of the floral repressor SVP increased in lhy;cca1 mutants under LL, and the late-flowering phenotype of lhy;cca1 mutants was partially suppressed by svp, flc, or elf3. ELF3 interacted with both CCA1 and SVP, and elf3 suppressed the SVP accumulation in lhy;cca1 under LL. These results suggest that the unique mechanism of the inversion of the flowering response of lhy;cca1 under LL may involve both the ELF3–SVP/FLC-dependent and -independent pathways. In this work, elf3-1 seeds were mutagenized with heavy-ion beams and used to identify mutation(s) that delayed flowering under LL but not long days (LDs) or SDs even without ELF3. In this screening, seven candidate lines named suppressor of elf3 1 (self1), sel3, sel5, sel7, sel14, sel15, and sel20 were identified. Genetic analysis indicated that sel20 was a new deletion allele of a mutation in the blue light receptor, CRY2. A late-flowering phenotype and decrease of FT expression in the elf3;sel20 double mutant was obvious under LL but not under SDs or LDs. These results indicated that the late-flowering phenotype in the double mutant elf3;sel20 as well as in lhy;cca1 was affected by the presence of darkness. The results suggest that CRY2 may play more essential roles in the acceleration of flowering under LL than LDs or SDs. [ABSTRACT FROM PUBLISHER]

The regeneration ability of a Tunisian barley accession originated from Kerkena islands was monitored through somatic embryogenesis and organogenesis. To prevent or to reduce normal germination, longitudinally bisected as well as base-wounded mature caryopses were cultured on a modified Chée and Pool-based medium (CP) enriched with different phytohormonal combinations. The greatest embryogenesis response was obtained when base-wounded caryopses were cultured on CP enriched with 2 mg/l chlorophenoxyacetic acid + 2.5 mg/l kinetin (76.85%). The same combination coupled to longitudinally bisected caryopses led to the embryogenic induction at the hypocotyl base of the germinated caryopses (61.9%). Embryogenic calluses differentiated into globular, heart-shaped, torpedo, and fully differentiated stages of somatic embryos on hormone-free Murashige and Skoog-based medium. Rooted plantlets were successfully transferred to soil and grown to maturity in the greenhouse and produced fertile seeds within 3 mo. On the other hand, organogenesis was achieved on CP enriched with 2 mg/l 2,4-dichlorophenoxyacetic acid + 2.5 mg/l kinetin. Histological aspects and scanning electron microscopy of both regeneration methods confirmed further the embryogenic and organogenic nature of the established processes. This efficient plant regeneration system provides a foundation for generating transgenic plants and germplasm preservation of 'Kerkena' barley accession. [ABSTRACT FROM AUTHOR]

Abstract: Salt stress adversely affects the growth of grapevine plants. In order to understand the molecular basis of salt stress response in grapevine plants, suppression subtractive hybridization (SSH) and microarray based screening approaches were combined. Two leaf-specific subtractive cDNA libraries were constructed from grapevine plants subjected to a moderate, incremental salt stress treatment. SSH were performed 6h and 24h after NaCl peaked at 100mM using cDNAs prepared from leaves of a salt tolerant cultivar (Razegui) as testers and cDNAs from unstressed leaves as drivers. Then, a pre-screened subset of cDNA clones from these SSH libraries were used to construct a Vitis vinifera cDNA array, in order to verify the expression changes of the genes upon salt treatment. Expression profiles were compared between the salt tolerant and a susceptible cultivar (Syrah) under both control conditions and after salt stress treatment. Seven cDNA clones were identified which were up-regulated by salt stress in two independent growth experiments and confirmed by RNA blot analysis. The transcript expression patterns of the selected genes differed between the contrasting grapevine cultivars tested with respect to stress-regulation. The possible relationship of individual cDNAs with salinity tolerance mechanisms is discussed. [Copyright &y& Elsevier]

Abstract: The effect of three alternating temperatures cycles (20/30, 20/37 and 25/42°C) and photoperiod on growth and Ochratoxin A (OTA) production of six isolates of Aspergillus carbonarius on synthetic nutrient medium were investigated. The different temperature regimes affected significantly both the mycelial growth and the OTA production. The best growth and OTA production were recorded at 20/30°C. The isolates from the region of Baddar produced the highest OTA yields. A 24h light cycle generally enhanced the growth of A. carbonarius. Growth rates cycles of 11h/13h light/darkness and 24h darkness were often similar for individual isolates, such conditions enhanced OTA production in two of the six isolates tested. [Copyright &y& Elsevier]

Proteomic and transcriptomic analyses of pathogenesis-related proteins, PR10, were carried out by subjecting adult plants of the salt-tolerant grapevine cv. Razegui to 100 mM NaCl for 6 and 24 h under controlled greenhouse conditions. Within 6 h of salt exposure, an increase in levels of RzPR10 was observed in the roots. PR10 mRNA levels in leaves were significantly different than those in roots; moreover, significant differences for mRNA levels were found between treated and control plants. Within 24 h of salt treatment, roots exhibited the highest levels of RzPR10 protein, but no differences were observed for mRNA levels in both leaves and roots. Overexpression of Vvpr10 cDNA, under the control of the Gal promoter, in the yeast Saccharomyces cerevisiae revealed that growth of transformed cells on a minimal medium containing 500 mM NaCl is similar to that of cells cultivated on NaCl-free medium. This indicated that Vvpr10 gene was functional in yeast and conferred tolerance to high salt concentrations. [ABSTRACT FROM AUTHOR]

This study investigated the effects of temperature (15 to 37 °C) and water activity (0.90 to 0.99) on the growth and production of ochratoxin A (OTA) by Aspergillus carbonarius cultured on synthetic nutrient medium (SNM) after 5 and 10 d of incubation. Total of 8 ochratoxigenic A. carbonarius, isolated from vineyards located in different regions of Tunisia, were used. Growth data were modeled by the flexible model of Baranyi and growth rates at each set of conditions were obtained. For both growth and OTA production, optimal water activity was 0.99; however, optimal temperature varied. The optimal temperature for growth was 30 °C. At 37 °C, the growth rate decreased significantly ( P < 0.05). Maximum toxin production occurred at temperatures in the range of 15 to 25 °C with the optimum one depending on the isolate tested. Significant amounts of OTA were produced after only 5 d of incubation. Our results showed that A. carbonarius isolated from Tunisian grapes behave as those from European and Australian grapes, as reported in the literature, although some differences in trends for growth and OTA production were observed. [ABSTRACT FROM AUTHOR]

The preservation of embryogenic lines derived from several endangered local grapevine cultivars was studied. Embryogenic calluses were obtained from immature anthers of eight cultivars, sampled on both fruity-cuttings and field grown vines. Anthers at the 'separated flower' stage, derived from fruity-cuttings, resulted in an increased induction of somatic embryogenesis, compared to those derived from the field. Pro-embryogenic calluses were induced on Chùe and Pool (1987) basal medium, supplemented with 9 μM of 2,4-dichlorophenoxyacetic acid (2,4-D) and 11.35 μM of thidiazuron (TDZ) under dark conditions. Different anther zones (filament, abaxial, adaxial, lateral zones and entire anthers) were involved in somatic embryogenesis induction. The percentages of granular and yellowish pro-embryogenic call uses ranged between 15.6% and 34.8% in 'Kahli Kerkennah' and 'Muscat Raf-raf' cultivars, respectively. Although, morphological diversifications of pro-embryogenic calluses (several necrosis and spontaneous maturation) were observed on the induction medium after 5 subcultures. The reduction of 2,4-D and TDZ levels to 4.52 μM and 2.89 μM respectively, induced granular and yellowish embryogenic material. Thus, Chée and Pool (1987) (CP) enriched with 4.52 μM of 2,4-D and 2.89 μM of TDZ revealed to be the most appropriate for long-term maintenance. In fact, all the cultivars presented high and regular embryo maturation rates after 12, 24, 36 and 48 months of cultivation on this medium, under light conditions. After 4 years, they still exhibit high germination and regeneration abilities. Germination of somatic embryos was achieved on Murashige and Skoog (1962) basal-medium, with rates ranging from 69% to 96%. Only 5% of somatic embryos were concerned by morphological variations. The regenerated plantlets presented a normal phenotype under controlled greenhouse conditions, compared to mother plants. [ABSTRACT FROM AUTHOR]

Abstract: To identify and isolate genes related to abiotic stresses (salinity and drought) tolerance in grapevine, a candidate gene approach was developed and allowed isolating a full-length cDNA of rd22 gene from the Cabernet Sauvignon variety. The latter, named Vvrd22, is a dehydration-responsive gene that is usually induced by the application of exogenous ABA. Details of the physicochemical parameters and structural properties (molecular mass, secondary structure, conserved domains and motives, putative post-translational modification sites…) of the encoded protein have also been elucidated. The expression study of Vvrd22 was carried out at the berry growth stages and at the level of plant organs and tissues as well as under both drought and salt stresses. The results showed that Vvrd22 is constitutively expressed at a low level in all analyzed tissues. Moreover, salt stress induced Vvrd22 expression, particularly for the tolerant variety (Razegui), contrary to the sensitive one (Syrah), which did not display any expression variation during the stress, which means that Vvrd22 is involved in salt stress response and that its expression level depends on regulatory mechanisms that are efficient only for the tolerant variety. On the other hand, under drought stress, Vvrd22 is induced in an identical manner for both tolerant and sensitive varieties. In addition, stress signal molecules such as ABA (lonely applied or in combination with sucrose) induced Vvrd22 expression, even at a low level. A minimal knowledge about the role and the functionality of this gene is necessary and constitutes a prerequisite condition before starting and including Vvrd22 in any program of improvement of grapevine''s abiotic stress tolerance. To cite this article: M. Hanana et al., C. R. Biologies 331 (2008). [Copyright &y& Elsevier]

Summary: Salt stress is one of the major abiotic stresses in agriculture worldwide, especially in the Mediterranean area. We report here a proteomic approach to investigate the salt stress-responsive proteins in grapevine (Vitis vinifera). Two-dimensional electrophoresis (2-DE) was used to analyze the proteome of the salt-tolerant Tunisian grapevine cultivar Razegui, subjected to a supply of 100mm NaCl over 15d. Analysis of 2-DE gels derived from stressed plants revealed more than 800 reproducibly detected protein spots, with 48 proteins displaying a differential expression pattern, including 32 up-regulated, 9 down-regulated and 7 new protein spots induced after salt treatment. The presence of stress-responsive proteins in the different plant organs suggests that salt spreads systemically. Edman degradation analysis and database searching aided us in identifying a major protein GP. Database analysis revealed that this peptide has a 98% sequence similarity with a pathogenesis-related (PR) protein 10 (V. vinifera). A full-length cDNA encoding the GP protein was isolated from grapevine salt-stressed leaves and sequenced. The predicted protein contained 158 amino acids and showed 98% identity with PR10 protein of of V. vinifera (accession no. Cac16165). [Copyright &y& Elsevier]

Abstract: In order to quickly and efficiently evaluate the grapevine''s salt tolerance, salinity tests were conducted on some grapevine varieties and rootstocks under in vitro conditions. Plant materials used in the salinity test were propagated using the axillary buds culture method. Single-node shoots were subjected to seven different NaCl concentrations (0, 20, 50, 100, 150, and 200 mM NaCl) in MS medium for 45 days. The different growth parameters analysed were: survival capacity, length of shoot, bud formation, and rooting capacity. Our results showed that salinity reduced in vitro growth and development of grapevine. Proliferation, growth, rooting and viability of explants decreased due to the increase in NaCl concentration. First symptoms of stress (leaves necrosis) appeared after 10 days of treatment with 80 mM NaCl, which may lead to total desiccation. It was determined that severity of salt treatment injury varied depending on the genotype and NaCl concentration. A positive correlation was found between the vigour of plants in saline medium and their faculty to tolerate salt. The most tolerant grapevine genotypes to salt treatment were Sejnene and Asli, followed by the moderately sensitive Saouadi and Sakasly genotypes, and last Razegui, 1103P, 41B, and SO4, which were particularity sensitive. Thus, grapevine''s salt tolerance seems to be linked to the genetic background. To cite this article: L. Hamrouni et al., C. R. Biologies 331 (2008). [Copyright &y& Elsevier]

Abstract: In this work, we report for the first time on the analysis of genetic diversity within a set of 36 Tunisian Opuntia ficus indica (L.) Mill. ecotypes using RAPD markers. Random decamer primers were screened to assess their ability to detect polymorphisms in this plant crop. Thirty-nine RAPD markers were revealed and used to survey the genetic diversity at the DNA level and to establish relationships. Consequently, considerable genetic diversity was detected and the UPGMA analysis permitted the discrimination of all the genotypes and enabled their sorting into thirteen groups. The accession ‘R Sbiba inerme’ was significantly divergent from all tested genotypes. In addition, as shown by the clustering the tested genotypes did not significantly diverge, though originating from different localities. Since RAPD markers proved to be useful for germplasm discrimination as well as for discovery of patterns of variation in Barbary fig, the opportunity of this study was discussed in relation to the setting up of rational decisions concerning the management of a national reference collection that ought to allow the preservation of all studied genotypes. [Copyright &y& Elsevier]

Abstract: The occurrence of ochratoxin A (OTA) and the identification of the ochratoxigenic microbiota in Tunisian grapes were studied for the first time. Black aspergilli were the dominant genus among the filamentous fungi isolated from grapes and were the only potential OTA-producing fungi found. The most abundant species were member of Aspergillus niger aggregate (63%) and Aspergillus carbonarius (36%). Uniseriate aspergilli were rarely present (1%). Of the A. carbonarius isolates, 97% were OTA positive but only 3% of the A. niger aggregate isolates were OTA positive. During grape maturation, the frequency of black aspergilli increased due to increase of the numbers of A. carbonarius. Musts (n =24) obtained from grapes collected at the different sampling times were analyzed for their OTA content. Up to 37% of the musts contained OTA at levels varying between 0.59 and 2.57 μg/l. The amounts of OTA in musts increased as grapes matured. These results indicate that A. carbonarius is the main cause of OTA contamination of Tunisian grapes. [Copyright &y& Elsevier]

Barley is characterized by a rich genetic diversity, making it an important model for studies of salinity response with great potential for crop improvement. Moreover, salt stress severely affects barley growth and development, leading to substantial yield loss. Leaf and root transcriptomes of a salt-tolerant Tunisian landrace (Boulifa) exposed to 2, 8, and 24 h salt stress were compared with pre-exposure plants to identify candidate genes and pathways underlying barley's response. Expression of 3585 genes was upregulated and 5586 downregulated in leaves, while expression of 13,200 genes was upregulated and 10,575 downregulated in roots. Regulation of gene expression was severely impacted in roots, highlighting the complexity of salt stress response mechanisms in this tissue. Functional analyses in both tissues indicated that response to salt stress is mainly achieved through sensing and signaling pathways, strong transcriptional reprograming, hormone osmolyte and ion homeostasis stabilization, increased reactive oxygen scavenging, and activation of transport and photosynthesis systems. A number of candidate genes involved in hormone and kinase signaling pathways, as well as several transcription factor families and transporters, were identified. This study provides valuable information on early salt-stress-responsive genes in roots and leaves of barley and identifies several important players in salt tolerance. [ABSTRACT FROM AUTHOR]

The current study assesses the natural occurrence of mycotoxins and fungal metabolites in Tunisian Pearl millet. Investigations using a multi-mycotoxin liquid chromatography/electrospray ionization-tandem mass spectrometric (LC/ESI–MS/MS) method were carried out on a total of 220 pearl millet samples collected from farmers (n = 144) located in four different agroecological zones in Tunisia and from retail shops (n = 76). Results revealed fifty-seven regulated and emerging metabolites contaminating 91.4% of grain samples. Among major mycotoxins, both aflatoxin B1 (AFB1) and ochratoxin A (OTA) were the most prevalent at rate of 8.6% each and occurring at an average level of 106 and 69.4 μg/kg, respectively. All positives samples were significantly exceeding the European thresholds (5 and 3 μg/kg, respectively). Lower incidence (5.9%) of Zearalenone (ZEA) contaminated samples at levels below the authorized limits (100 μg/kg) was recorded. Pearl millet grains from the south coastal zone (CT.S) had significantly the highest mean AFB1 contamination (p < 0.05). Meanwhile, OTA was encountered only in CT.S zone. Furthermore, commercial samples showed higher OTA and ZEA mean concentrations than farmers samples (p < 0.05). As regards emerging mycotoxins, Fusarium mycotoxins including beauvericin (BEA), equisetin (EQUS), monoacetoxyscirpenol (MAS) and diacetoxyscirpenol (DAS) were detected in 43.2%, 43.2%, 11.4% and 10.5% of positive samples, respectively. Furthermore, 12.7%, 50.9%, 53.2% and 14.1% of grains were contaminated with Alternaria mycotoxins namely alternariol (AOH), alternariolmonomethyl ether (AME), tentoxin (TEN) and tenuazonic acid (TA), respectively. The majority of emerging Fusarium and Alternaria mycotoxins mean levels were significantly higher in grains from north coastal area (p < 0.01). The present study highlighted a wide range of mycotoxins in Tunisian pearl millet with a different mycotoxin patterns within the agroecological zones. • Analysis of a comprehensive range of mycotoxins in pearl millet by LC/MS/MS. • 201/220 pearl millet samples were detected positive for at least one metabolite. • AFB1 and OTA positive samples were highly contaminated in the coastal south zone. • Emerging Fusarium and Alternaria mycotoxins were higher in the coastal north zone. [ABSTRACT FROM AUTHOR]