Molecular polymorphism of cytoplasmic DNA in Ficus carica L.: Insights from non-coding regions of chloroplast DNA

The trnL (UAA) intron and the intergenic spacer between the 3′ exon of trnL (UAA) and trnF (GAA) sequences were used as genetic markers for differentiating Ficus carica cultivars and establishing refined genetic relationships. The study was based on 20 fig cultivars, collected from south and centre of Tunisia. Since, the intron was thought to be more variable among close relatives than is the chloroplast spacer. The size of these non-coding regions varied from 554 to 589 and from 989 to 1022 bases pairs for the intron and the combined sequences correspondingly. The average of GC content was 33.9% and 34.6% in the intron and the combined intron and spacer respectively. High values of A + T contents were detected in both data sets and may explain the high proportions of transversions founded. The observed variation pattern of plastid DNA provides evidence of an important genetic diversity. The overall transition/transversion bias (R) was 0.202 in the intron and 0.27 in the combined regions. The RI index of 0.592 indicates that these combined sequences have clearly more homoplasy then the intron (RI = 0.705) and spacer (RI = 0.777) sequences separately. Phylogenetic trees were generated based on maximum parsimony (MP) and neighbor-joining (NJ) analysis of the chloroplast sequences data. Results proved that a typically continuous genetic diversity characterizes the local fig germplasm. In fact, relationships inferred from the cpDNA analysis suggest several clades, which do not show geographical or tree sex correspondence. Although the level of apparent diversity is considerable, we may conclude that non-coding regions of chloroplast genome provide a new and practical opportunity to evaluate genetic diversity and to discriminate fig cultivars. Revealed cytoplasmic DNA markers are reliable to elaborate a molecular data base to conduct management and breeding programs on local fig germplasm.     

Genetic structure of Tunisian natural carob tree (Ceratonia siliqua L.) populations inferred from RAPD markers

? Seven RAPD markers were used to assess the genetic diversity and structure of ten Tunisian natural Ceratonia siliqua L. populations from different geographic and bioclimatic zones.

? The species maintain a high diversity within population as estimated by the percentage of polymorphic loci and Shannon’s index (P% = 76.31, $\bar H'_{pop} = 0.569$ ). The range of variation between populations was large. Populations from the upper semi-arid bioclimates, with more continuous distribution area showed the highest level of variation.

? A high genetic differentiation among populations (Φ_ST = 0.250 and $\bar G_{ST} = 0.347$ ), as a result of population isolation was revealed. Nevertheless, the genetic structure is in accordance with bioclimate indicating that ecological factors also should influence differentiation. Populations from the sub-humid, upper semi-arid and mean semi-arid zones clustered together and were distinct from those of the lower semi-arid ones.

? Conservation strategy should be made according to the level of polymorphism within population and bioclimate.

     

Inter-Simple Sequence Repeat fingerprints to assess genetic diversity in Tunisian fig (Ficus carica L.) germplasm

The genetic diversity of 18 Tunisian fig cultivars was investigated at the DNA level using the Inter Simple Sequence Repeat (ISSR) associated with the Polymerase Chain Reaction (PCR). Using a set of primers, the most informative ones were selected that were characterized by an important Resolving power value of 29.6. A total of 47 discernible fragments were scored from samples, with a mean of 11.7 fragments per primer. The 90.4% of sample that were polymorphic were scored as molecular markers to examine the Tunisian fig germplasm polymorphism at DNA level. A large genetic diversity as related to ISSR patterns was found within the local Tunisian fig germplasm. An UPGMA dendrogram exhibits the unstructured variability in this crop. Moreover, the principal component analysis shows that the observed diversity was typically continuous. Our data provide a large number of ISSR markers that are useful in the fingerprinting of Ficus carica L. cultivars, and in the understanding of the genetic relationships among these accessions.     

Effect of pollination intensity,frequency and pollen source on fig (Ficus carica L.) productivity and fruit quality

Yield and fruit quality in fig (Ficus carica L.) are highly dependent on cultural practices especially caprification (pollination). However, this technique remains not well controlled in Tunisia. This study was conducted during two successive years, 2009 and 2010, to investigate different pollination conditions, i.e. number of caprifigs and repetitions of caprification on fruiting of two cultivars Bouhouli (San Pedro type) and Zidi (Smyrna type). In addition, the efficiency of four pollen sources was evaluated to identify the most effective pollinator for female cultivar Zidi. The following parameters were recorded: fruit number per shoot, fruit set, productivity, fruit characteristics and vegetative growth.     

The black fig fly Silba adipata (Diptera: Lonchaeidae) as an emerging pest in Tunisia: preliminary data on geographic distribution,bioecology and damage

Phytoparasitica - Frugivorous fruit flies are considered among the most damaging pests of cultivated fruit crops. The most studied ones are those belonging to the Tephritidae family such as the...     

Comparative study of pikeperch Sander lucioperca (Percidae; Linnaeus, 1758) eggs and larvae from wild females or from captive females fed chopped marine fish

Morphometric characteristics, proximal composition and fatty acids profiles of eggs and larvae at hatching and mouth opening were studied as indicators for assessing the potential differences between spawns obtained from wild or captive females of pikeperch (Sander lucioperca). Captive females were acclimated to hatchery conditions and fed to satiation with chopped marine fish for more than a year, guaranteeing that captivity covered the full cycle of gonad maturation. The number of larvae obtained from the spawnings did not differ between captive and wild females, but both mean diameter and mean weight of the eggs collected from the captive females were significantly larger. Proximal compositions were similar in eggs and larvae from both groups, but fatty acids (FA) profiles showed striking differences: polyunsaturated FA consisted mainly of linoleic acid in eggs and larvae from wild females, while they consisted mainly of long chains of n-3 series in eggs and larvae from captive females. The diet of captive females largely modified the FA profiles of eggs and of hatching or mouth opening larvae, but did not affect the growth potential of early larvae, demonstrating that they were able to satisfy their early physiological needs regardless of the striking differences in their FA.     

Seed and juice characterization of pomegranate fruits grown in Tunisia: Comparison between sour and sweet cultivars revealed interesting properties for prospective industrial applications

Tunisian pomegranate genetic resources consist of sweet and sour cultivars, showing large morphometric variability. In the present work we characterized seeds and juice contents of sugars and organic acids of 5 sour and 7 sweet pomegranate cultivars. Results showed that citric acid was predominant in sour pomegranates, while malic acid was the most prevalent in sweet ones. Paradoxically, sour cultivars have higher sugar content than the sweet ones. A strong correlation was found between sourness and citric acid content, which is assumed to be the major factor that determines sour taste in pomegranate fruits. Besides, some of the seed parameters showed a significant positive correlation with acidity. Sweet cultivars were appropriate for fresh consumption and juice production due to several attributes in addition to their sweetness. Equally, sour pomegranate showed several characteristics that could be of great interest for food and nutraceutical industries.     

MM3-ELISA evaluation of coproantigen release and serum antibody production in sheep experimentally infected with Fasciola hepatica and F. gigantica

During an experimental infection of sheep with Fasciola hepatica or F. gigantica, MM3-SERO and MM3-COPRO ELISA tests were applied to compare the kinetics of antibody production and coproantigen release between the 2nd and 32nd week post-infection (wpi). The Kato-Katz technique was used to measure the kinetics of egg shedding by both Fasciola species (eggs per gram of feces, epg). The kinetics of IgG antibodies for all sheep infected with F. hepatica and F. gigantica followed a similar pattern. Optical density (OD) increased rapidly between the 4th until the 12th wpi, when the highest values were reached and then decreased slowly until the 32nd wpi. Coproantigen levels increased above the cut-off value between 6 and 9 wpi in the F. hepatica group, and between 9 and 11 wpi in the F. gigantica group. The comparison between coproantigen levels and epg indicated that F. hepatica-infected sheep had detectable amounts of coproantigens 4–7 weeks before patency (egg shedding), while F. gigantica-infected sheep had detectable amounts of coproantigens 3–6 weeks before patency. When comparing the kinetics of coproantigen release vs the kinetics of epg, a similar pattern emerged, but with a two-week time-lag in epg, for both F. hepatica and F. gigantica infections. The amount of coproantigen release by each adult was not burden dependent for F. hepatica infection (burden of 33–66 adults), while it was for F. gigantica infection (burden of 17–69 adults). The results demonstrate the usefulness of the MM3-SERO and MM3-COPRO ELISAs as tools for the diagnosis of early as well as long-term fascioliasis infections, and suggest that they can potentially be applied to human fascioliasis even in countries where F. hepatica and F. gigantica co-exist. These tests can be employed not only in the diagnosis, but also in studies on epidemiology as well as pathogenesis and treatment in animals and humans since they allow post-treatment infection monitoring.     

Characterization of Tunisian pomegranate (Punica granatum L.) cultivars using amplified fragment length polymorphism analysis

The amplified fragment length polymorphism (AFLP) analysis of DNA was used to characterize 34 pomegranate cultivars. By using a combination of six primers, a total of 327 markers were scored with a mean of 57.5. The high percentage of polymorphic bands (ppb) of 94.7 and the resolving power (R_p) collective rate value of 129.14 were scored. Data proved that the tested primers were informative to discriminate among cultivars and to survey the genetic diversity in this fruit crop. It has been assumed that the local pomegranate germplasm is characterized by a typically continuous genetic diversity. The derived dendrogram proved that cultivars are clustered independently from their geographical origin and their denomination. In addition, AFLP permitted the generation of a nearly unlimited number of molecular markers that are reliable in differentiating the cultivars and/or the polyclonal varieties.