Diversité génétique des populations naturelles de Rosmarinus officinalis L. (Lamiaceae) en Tunisie

Rosmarinus officinalis L. is widespread in Central and North-Western Tunisia on sites belonging to sub-humid, semi arid superior and arid superior bioclimatic levels. This plant species reproduces exclusively by vegetative propagation. In all populations, regeneration from seeds is extremely rare because of abortion during nutlets maturation and the low rate of seedling establishment. The habitat destruction linked to human activities (vegetation clearing, overgrazing, over-collecting and oils exploitation) and the rarity of new plants establishment via seeds had led to a decrease in population number and size. Using starch gel electrophoresis, we analyzed the polymorphism of 19 Tunisian natural populations belonging to three bioclimatical stages (sub humid, semi arid superior and arid superior) to determine their genetic diversity and structuring. At ten polymorphic loci, the species maintained high levels of genetic variation within populations, despite its predominant vegetative reproduction and the low rate of seedling establishment. The high genotypical diversity of genets, in the starting population, and the outcrossing breeding system should act in favor of this high genetic variability. An average of 11.3% of the variation resides among populations, indicating a substantial level of interpopulational differentiation. A significant population differentiation was observed within each of the three ecological groups. The level of structuring varied in relationship with the population separation and the quality of sites. Differentiation between continuous groups was lower than that observed for discontiguous ones. Nei’s (1972) genetic distance values between pairs of populations were low (0.005< D< 0.232), particularly between close geographic populations. The UPGMA dendrogram, established through Nei’s genetic distances, exhibited two groups of populations. The first one includes populations of sub humid and semi arid superior. Populations within this group clustered according to their geographical proximity. The second group was represented by the arid superior populations geographically close. The high level of genetic similarities between populations and their high differentiation indicated recent population isolation mainly due to environmental (climatic and edaphic) and human (destruction of intermediate sites) factors. Efforts to preserve populations in situ must be made, particularly for the disturbed ones which had shown particular alleles. Moreover, conservation must rely on multiplication of individuals within each population and rehabilitation of forest, according to the bioclimate, with plant species linked to Rosmary populations. Ex situ conservation could be performed by collecting a high number of individuals within populations that showed particular alleles. These individuals should be multiplied via cuttings in multilocal conservatory parks in relationship with the bioclimate.En Tunisie, les populations naturelles de romarin (Rosmarinus officinalis L.) se développent, essentiellement au centre et au nord-ouest du pays, dans les étages bioclimatiques s’étendant du sub-humide à l’aride supérieur. Cette espèce se reproduit principalement par propagation végétative. Dans toutes les populations, la régénération à partir des graines est extrêmement rare du fait de la production d’un nombre élevé de nucules non viables et du faible taux d’installation des plantules. La destruction des habitats liée aux activités humaines (ouverture du milieu, surpâturage, collecte, distillation des huiles essentielles), associée au faible pouvoir de régénération d’individus à partir de semis, conduisent progressivement à une diminution du nombre et de la taille des populations. Dix-neuf populations de romarin, prospectées dans différents étages bioclimatiques de la Tunisie, ont fait l’objet d’une analyse du polymorphisme de huit systèmes isoenzymatiques afin d’évaluer leur diversité génétique et mesurer le niveau de leur différenciation. Pour les dix loci polymorphes détectés, l’espèce a présenté une diversité génétique intra-population importante, malgré la prédominance de son mode de reproduction végétative et le faible taux d’établissement des plantules. L’importante diversité génétique dans la population d’origine et les modalités de reproduction allogame pourraient expliquer cette variabilité génétique élevée. Une moyenne de 11,3 % de variation est répartie entre les populations ce qui indique un niveau de différenciation important entre les populations. Au sein de chacun des trois groupes écologiques, la différenciation des populations s’est révélée significative. L’éloignement géographique des populations, s’accordant généralement avec leur localisation bioclimatique et le degré de dégradation des habitats, joueraient un rôle important dans cette structuration. La structuration des populations appartenant à des étages bioclimatiques contigus s’est révélée moins importante que celle observée pour les populations se développant dans des étages séparés. Les valeurs des distances génétiques de Nei (1972), pour l’ensemble des paires de populations, se sont révélées être faibles (0,005< D< 0,232), particulièrement entre populations géographiquement proches. Le dendrogramme, établi à partir de ces indices, a montré la formation de deux ensembles réunissant respectivement (i) les populations du sub-humide et du semi-aride supérieur et (ii) les populations de l’aride supérieur. L’agrégation des populations au sein du premier groupe s’opère selon leur proximité géographique. La forte similarité génétique des populations et leur différenciation substantielle témoigneraient d’une récente isolation des populations sous l’influence des facteurs environnementaux (climatiques et édaphiques) et anthropiques (destruction des habitats intermédiaires). La conservation de l’espèce, in situ, doit concerner dans un premier temps les populations présentant des allèles particuliers. Elle doit s’appuyer sur la multiplication d’individus à l’intérieur de chaque population et la restauration de la végétation forestière, selon le bioclimat, par des essences associées normalement au romarin. La conservation ex-situ, pourrait être abordée par la collecte d’un maximum d’individus au sein des populations caractérisées par des allèles particuliers et leur multiplication dans des conservatoires multilocaux au niveau des différents étages bioclimatiques.Zaouali Yosr, Messaoud Chokri, Boussaid Mohamed. Diversité génétique des populations naturelles de Rosmarinus officinalis L. (Lamiaceae) en Tunisie. In: Ecologia mediterranea, tome 29 n°2, 2003. pp. 199-215

Effects of meta-topolin derivatives and temporary immersion on hyperhydricity and in vitro shoot proliferation in Pyrus communis

Although micropropagation in temporary immersion systems might increase plant growth and multiplication, it can also cause specific problems such as hyperhydricity and losses by contamination. A new commercial temporary immersion bioreactor, SETIS™, was used to micropropagate two Tunisian pear cultivars, ‘Arbi’ and ‘Mahdia 6’. The latter cultivar was endogenously contaminated by Sphingomonas. Hyperhydricity was inevitable when 5 µM benzyladenine was applied. However, the symptoms could be reduced by lowering the immersion frequency to 3 times per day. Applying 5 µM meta–Methoxy topolin riboside (MemTR) or meta–Topolin riboside (mTR) completely inhibited hyperhydric shoot formation. Moreover, the addition of Plant Preservative Mixture was effective to control Sphingomonas and allowed the plants to proliferate. For both pear cultivars, the highest number of shoots per explant was induced by 5 µM MemTR, whereas the highest leaf area was obtained with 5 µM mTR. The longest shoots were obtained with 5 µM mTR for ‘Arbi’ and 5 µM MemTR for ‘Mahdia 6’. Key message Methoxy topoline-riboside (MemTR) and meta-topoline-riboside (mTR) were used as alternatives to benzyladenine to prevent hyperhydricity during the micropropagation of pears in a new temporary immersion system. These cytokinins also increased the number of good quality shoots, characterized by large leaves and longer shoots

Fatty acid profile of Cystoseira C. Agardh (Phaeophyceae, Fucales) species from the Tunisian coast: Taxonomic and nutritional assessments

A screening of the total lipids and fatty acids (FAs) of 11 brown algae species of the genus Cystoseira (Phaeophyceae, Fucales) from the Tunisian coast is presented and discussed. Cystoseira species showed low total lipid content, ranging from 19.8 to 68.2 mg·g–1 dry weight. Fourteen major FAs were detected in the lipid extract of Cystoseira. The FA profile of lipid extracts was characterized by high amounts of saturated FAs (SFAs) ranging from 40.51% to 57.91% of total FAs, with predominance of the lipid fraction of palmitic acid (>30% of total FAs). The arachidonic acid (C20:4n-6) levels were found to be significantly high, ranging from 8% to 16% of total FAs. Multivariate analyses of FA composition showed low geographic differentiation, providing further evidence of intraspecific diversity. Cystoseira crinita, Cystoseira schiffneri, Cystoseira amentacea var. stricta, and Cystoseira sedoides stood out for their low polyunsaturated fatty acid (PUFA)/SFA ratios, low n-6/n-3 PUFA ratios, high unsaturation, and low atherogenicity and thrombogenicity indices, suggesting high nutritional value

Total phenolic content and antioxidant activity of six wild Mentha species (Lamiaceae) from northeast of Algeria

Objective: To investigate the total phenolics, flavonoids and tannins content and the in vitro antioxidant activities of methanolic extracts of six wild Mentha species which are Mentha aquatica, Mentha arvensis, Mentha piperita, Mentha pulegium, Mentha rotundifolia and Mentha villosa. Methods: The Folin–Ciocalteu method was used to determine the total phenols content while flavonoids were estimated according to the aluminum chloride colorimetric method. To evaluate tannins content, vanillin and HCl were added to methanolic extracts. The antioxidant potential was measured by 1,1-diphenyl-2-picrylhydrazyl radical scavenging, ferrous ion chelating and the inhibition of β-carotene bleaching assays. Results: The methanol extracts of Algerian mints were rich in phenolic compounds and exhibited powerful antioxidant activity ranging from 7.5 μg/mL to 44.66 μg/mL, which varied significantly among species. Mentha aquatica stood out with efficient antioxidant ability which was correlated to the high total phenolics content, followed by Mentha arvensis and Mentha piperita with very close values, comparing to Mentha pulegium, Mentha rotundifolia and Mentha villosa with lowest values. Conclusions: These results show that methanolic extracts of Mentha species from Algeria have a great potential of polyphenols which can be used as a natural food preservative and antioxidant source

Genetic variation of Tunisian Myrtus communis L. (Myrtaceae) populations assessed by isozymes and RAPDs

The genetic variation of six Tunisian Myrtus communis L. (Myrtaceae) populations was assessed using nine isozymes coding for 17 putative loci and 79 RAPD markers, amplified by five decamer random primers. The analysed populations belonged to three bioclimatic zones (lower humid, sub-humid and upper semi-arid). A high genetic diversity within populations was detected both by isozymes and RAPDs. The level of variation differed according to bioclimate. Populations collected from sub-humid bioclimate showed more polymorphism than those grown in the upper semi-arid zone. For all populations, the genetic diversity revealed by RAPDs was more pronounced than that detected with isozymes. A high differentiation among populations related to bioclimate and geographic distance was revealed by both methods. Population's structure based on RAPD markers was more concordant with bioclimatic zones in comparison with isozymes. Differentiation between ecological groups was higher than that revealed within groups. Conservation programs should take into account the level of genetic diversity within population revealed by the two complementary classes of markers according to bioclimate.Variabilité génétique des populations tunisiennes de Myrtus communis L. (Myrtaceae) estimée par des marqueurs isoenzymatiques et moléculaires (RAPD). La variabilité génétique de six populations tunisiennes de Myrtus communis L. (Myrtaceae) a été estimée à l'aide de neuf systèmes isoenzymatiques contrôlés par 17 loci et 79 marqueurs RAPD amplifiés par cinq amorces. Les populations analysées appartiennent à trois étages bioclimatiques différents : humide inférieur, sub-humide et semi-aride supérieur. Une diversité génétique intrapopulation importante a été détectée. Le niveau de polymorphisme varie selon le bioclimat. Les populations du sub-humide sont plus polymorphes. Pour l'ensemble des populations, la diversité génétique révélée par les RAPDs est plus importante que celle détectée par les isozymes. Une forte différenciation entre les populations, selon le bioclimat et l'éloignement géographique, a été révélée par les deux méthodes. La structuration des populations selon les marqueurs RAPD concorde mieux avec le bioclimat. La différenciation entre les populations appartenant à des groupes écologiques différents est plus importante que celle entre populations d'un même groupe. Les programmes de conservation de l'espèce doivent tenir compte aussi bien du degré de la diversité génétique intrapopulation révélé par les deux types de marqueurs que du bioclimat

Thin‐layer chromatography‐bioautographic method for the detection of arginase inhibitors

International audienc

Efficacy of Tissue Culture in Virus Elimination from Caprifig and Female Fig Varieties (Ficus carica L.)

Fig mosaic disease (FMD) is a viral disease that spreads in all Tunisian fig (Ficus carica L.) orchards. RT-PCR technique was applied to leaf samples of 29 fig accessions of 15 fig varieties from the fig germplasm collection of High Agronomic Institute (I.S.A) of Chatt-Mariem, to detect viruses associated to FMD. Analysis results show that 65.5% of the accessions (19/29) and 80.0% (12/15) of the fig varieties are infected by FMD-associated viruses. From all fig accessions, 41.4% of them are with single infection (one virus) and 24.1% are with multi-infections (2 virus and more). Viruses infecting fig leaf samples are Fig mosaic virus (FMV) (20.7%), Fig milde-mottle-associated virus (FMMaV) (17.25%), Fig fleck associated virus (FFkaV) (3.45%), and Fig cryptic virus (FCV) (55.17%). A reliable protocol for FCV and FMMaV elimination from 4 local fig varieties Zidi (ZDI), Soltani (SNI), Bither Abiadh (BA), and Assafri (ASF) via in vitro culture of 3 meristem sizes was established and optimized. With this protocol, global sanitation rates of 79.46%, 65.55%, 68.75%, and 70.83% respectively for ZDI, SNI, BA, and ASF are achieved. For all sanitized varieties, the effectiveness of meristem culture for the elimination of FCV and FMMaV viruses was related to meristem size. Meristem size 0.5 mm provides the highest sanitation rates ranging from 70% to 90%

Sanitary Selection of Virus-Tested Fig (Ficus carica) Cultivars in Tunisia

Field surveys were carried out during autumn 2011 and spring 2012, in different fig orchards located at Rafraf, Takelsa, Mornag, Djebba, Sousse, and Sfax to select virus-free plants. A total of 202 trees representing 26 fig cultivars were prospected and sampled. Total nucleic acids were extracted from leaf veins and tested by RT-PCR for the presence of FMV,FLMaV-1, FLMaV-2, FMMaV, FCV, and FFkaV using specific primers. PCR results indicate that all these viruses were present in the Tunisian fig orchards. The average of infection level determined by RT-PCR was 63.86%. FMV was proved to be the most widespread virus (37.12%), followed by FLMaV-1 (11.9%), FFkaV (11.4%), FCV (8.9%), FMMaV (8.4%), and finally FLMaV-2 (5.9%). Among the 26 tested cultivars, only 7 (Marghrebi, Boukhobza, Zagfar, Assafri, Kahli, Chetoui, Delgane) were free from the tested viruses. By the contrary, the sanitary status of the main Tunisian cultivars Bayoudhi, Bouhouli, Soltani, Zidi and Bither, seemed heavily degraded (75, 70.37, 69.23, 66.03, and 46.15% of infection, respectively). Seven cultivars (Wahchi, Khartoumi, Thguegli, Besbessi, Bidh-Bghal, Njeli and Khedhri) were totally infected. This study allowed the identification of at least one “virus-tested” candidate clone from 19 different fig cultivars which can represent the potential mother plants for propagating materials in order to establish new fig nurseries and orchards

The Neuroprotective Effect of Clove Essential Oil Against 6-Ohda-Induced Cell Death in Sh-Sy5y and A Rat Model of Parkinson's Disease

International audienceParkinson's Disease (PD) is the second most prevalent neurological disorder. Natural therapies are becoming more popular for preventing disease onset. Clove Essential Oil (CEO), a potent antioxidant derived from Syzygium aromaticum buds, was tested in vitro (SH-SY5Y) and in vivo (PD rat model) for its ability to protect against 6-OHDA-induced cell death. Twenty-four hours of SH-SY5Y cells' exposure to 6-OHDA (100µM) drastically decreased cell viability. At doses lesser than 20µg/ml, CEO and its main component Eugenol (EG) had no cytotoxic effect on SH-SY5Y. CEO and EG at doses of 2.5-20µg/ml provided significant neuroprotection against 6-OH-DA-induced cell death. A PD rat model was generated by injecting 6-OHDA (21µg/animal) unilaterally into the striatum. An assessment of motor performance can predict neuronal cell loss in the Substancia Nigra Compacta (SNc). Compared to 6-OHDA-lesioned, CEO-treated (10mg/Kg) rats' locomotor performance (actimetry and cylinder tests) improved significantly one and two weeks after 6-OHDA-lesion. Tyrosine Hydroxylase (TH) cell count showed a significant decrease in cell death in ipsilateral SNc in both CEOtreated and 6-OHDA-lesioned rats when compared to contralateral. In contrast to the 6-OHDA-lesioned group, the ipsilateral SNc of the CEO-treated group showed a significant high TH cell number. In the present study, the neuroprotective effect of CEO was demonstrated both in vitro and in vivo against 6-OHDA cytotoxicity. Therefore, CEO could be used as a food supplement for PD prevention