PHENOTYPIC DIVERSITY OF SOME OLIVE TREE PROGENIES ISSUED FROM A TUNISIAN BREEDING PROGRAM

This work was done to quantify and to evaluate the distribution of the genetic diversity observed within and between olive tree seedlings issued from a Tunisian breeding program. Forty-eight ‘Chemlali’ olive tree seedlings which were issued from free-, self-, and cross pollination of cultivar ‘Chemlali’ with ‘Coratina’ were characterized by combining 17 quantitative and 32 qualitative traits. Principal component analysis was used for the identification of the pattern of morphological variation. Variance analysis revealed significant differences between progenies. Variation coefficients ranged from 8.36 to 32.93% for ‘Chemlali’ ×’Coratina’ descendants, from 7.93 to 80.91% for ‘Chemlali’ free pollination descendants and from 10.38 to 74.88% for ‘Chemlali’ self pollination descendants. Shannon and Nei indices indicated also the variation between descendants within crossings. However, some seedlings showed tree, leaf, fruit and endocarp shapes and sizes which differs from the typical of ‘Chemlali’ cultivar. An increase of the fruit size and an improvement of the flesh to stone ratio were noted; thus the first three principal components explained 72% of the total observed variability. PC1 was mainly correlated to fruit and endocarp sizes and flesh to stone ratio; and PC2 was mainly correlated to fruit and endocarp shapes. Descendants’clustering was done according to the main discriminant parameter which is the fruit size. Most ‘Chemlali’ × ‘Coratina’ descendants were closely clustered. ‘Chemlali’ free and self pollination descendants were not closely grouped, but shows clear overlapping data, which suggests that these two types of pollination can induce a comparative morphological variability

Organic Acids, Sugars, and Anthocyanins Contents in Juices of Tunisian Pomegranate Fruits

Juices made from fruits of 30 Tunisian accessions of pomegranate were studied for their organic acids, sugars, and anthocyanin contents, using high performance liquid chromatography. Among the detected organic acids, malic acid was the major one (>50%) followed by citric acid (>22%), while among sugars, fructose and glucose were most present in pomegranate juice contributing 53.9 and 43.4% of the total sugar content, respectively. The total anthocyanin content ranged from 9-115 mg per litre of juice with the following ranges of the six compounds found: cyanidin-3,5-diglucoside (3.1-74.4 mg/L), delphinidin-3-glucoside (0.7-22.0 mg/L), cyanidin-3-glucoside (0.8-21.0 mg/L), pelargonidin-3-glucoside (0.5-16.1 mg/L), pelargonidin-3,5-diglucoside (0.0-11.8 mg/L), and delphinidin-3,5-diglucoside (0.0-5.4 mg/L). Based on the analyzed parameters, cluster analysis allowed grouping cultivars into two main clusters. One was made of sour cultivars and the second of the sweet ones. Principle component and cluster analyses suggested that the composition of the pomegranate fruits is determined by cultivar rather than cultivation location

Morpho-phenological variability in nine wild Rosy Garlic (Allium roseum L.) accessions from Tunisia

This study aims to compare the morpho-phenological variability of nine accessions of Allium roseum L. from different bioclimatic zones of central and southern Tunisia. Results showed the presence of a large morpho-phenological diversity among the studied accessions. The number of homogeneous groups formed after multiple comparisons of means, ranging from two (for the descriptor average number of leaves) to seven (for descriptors average length of the flower stalk and average length of the vegetative phase). A principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to determine the nature and degree of divergence among accessions and the total variation was explained to nearly 86.6 % for the three main components. The HCA showed that these accessions are grouped into three classes that show a certain affinity among accessions according to their geographical origin. The accessions with the highest leaf number (vigorous) and which have the longest vegetative phase are Sidi Bou Ali and Bir Ali. The latest provenances are: Sidi Bou Ali, Bir Ali, Lemaya and El Jem. These accessions are from the Sahel and central Tunisia. For both inflorescence number and vegetative vigour, it appears that accessions that have the highest reproductive and vegetative vigour are Sidi Bou Ali, Bir Ali and Lemaya originated from the Sahel and central Tunisia. The difference South-North is once again evident as regards the average number of seeds. Indeed, we note that the accessions from the South produced more seeds than the North. These results are of great interest for future breeding program for this species known for its culinary and therapeutic propertiesCette étude a pour objectif de comparer la variabilité morpho-phénologique de neuf accessions d'Allium roseum L. en provenance de différentes zones bioclimatiques de la Tunisie centrale et méridionale. Les résultats obtenus ont permis de mettre en évidence la présence d'une grande diversité morpho-phénologique entre les accessions étudiées. Le nombre de groupes homogènes, formés après comparaison multiple des moyennes, varie de deux (pour le descripteur nombre moyen des feuilles) à sept (pour les descripteurs longueur moyenne de la hampe florale et durée moyenne de la phase végétative). Une analyse en composantes principales (ACP) et une classification ascendante hiérarchique (CAH) ont permis de déterminer la nature et le degré de divergence entre les accessions et la variation totale a été expliquée à près de 86,6 % par les trois composantes principales. La CAH a montré que ces accessions se regroupent en trois classes qui mettent en évidence une affinité entre certaines accessions en fonction de leur origine géographique. Les accessions les plus feuillues (vigoureuses) et qui présentent la phase végétative la plus longue sont Sidi Bou Ali et Bir Ali. Les provenances les plus tardives sont: Sidi Bou Ali, Bir Ali, Lemaya et El Jem. Il s'agit d'accessions en provenance du Sahel et du centre du pays. Aussi, pour le nombre d'inflorescences et la vigueur végétative à la fois, il s'avère que les accessions qui présentent les plus fortes vigueurs végétative et reproductive sont celles de Sidi Bou Ali, Bir Ali et Lemaya. Il s'agit toujours d'accessions en provenance du Sahel et du centre du pays. La différence Sud-Nord est encore une fois évidente en ce qui concerne le nombre moyen de graines. En effet, on remarque que les accessions en provenance du Sud produisent plus de graines que celles du Nord. Ces résultats sont d'un grand intérêt pour un futur programme d'amélioration génétique chez cette espèce connue par ses propriétés thérapeutiques et culinaires

Dynamique de floraison et régime de reproduction chez le grenadier (

Introduction. En Tunisie, bien que des problèmes liés à la floraison et à la fructification se posent chez le grenadier (Punica granatum L.), aucune étude n'avait encore été menée sur cette espèce. Nos travaux ont donc cherché à étudier ces importantes étapes du cycle de reproduction de la plante chez certaines variétés locales de P. granatum exploitées dans les conditions tunisiennes. Matériel et méthodes. La dynamique de la floraison a été étudiée par le comptage régulier des fleurs formées sur branches des trois cultivars locaux : Gabsi, Kalaii et Garoussi. La chute des boutons floraux, des fleurs épanouies ou des jeunes fruits récemment noués a été comptabilisée pour l'arbre entier. Un suivi de la fertilité des fleurs et des essais d'autopollinisation par ensachage de rameaux de différentes longueurs ont été conduits sur le seul cultivar Gabsi. Résultats et discussion. La durée de la floraison a été de 8 semaines environ pour Gabsi et de 10 semaines pour Garoussi et Kalaii. Le maximum des fleurs a été obtenu entre la troisième et la cinquième semaine après le début de floraison. La majeure partie des fleurs est apparue sur du bois âgé d'un an ou plus. Le taux de rétention le plus élevé (8,4 %) a été enregistré chez le cultivar Gabsi. Les fruits ont surtout été obtenus à partir des fleurs hermaphrodites. Le calibre des fruits à la récolte a diminué au fur et à mesure que la date d'apparition des fleurs dont ils provenaient avait été tardive. Les rameaux courts ensachés n'ont pas retenu de fruits ; ceux de longueur moyenne ont permis un taux de nouaison de 2,3 % par rapport à la totalité des fleurs du rameau ; les rameaux de plus grande taille ont présenté un taux de 4,8 %. Conclusions. La floraison du grenadier est très échelonnée. Les cultivars étudiés ont différé en fonction de la date du début de floraison, de sa durée et de son intensité. Le régime de reproduction s'est révélé être l'allogamie préférentielle. L'étalement de la floraison et les particularités morpho-physiologiques des fleurs favoriseraient plutôt la pollinisation croisée

Optimizing pear micropropagation and rooting with light emitting diodes and trans-cinnamic acid

Meta-Topolin riboside was selected as cytokinin for these experiments. The effects of combinations of monochromatic blue, red and far red LED light were compared to fluorescent light during the micropropagation and rooting of a recalcitrant pear (Pyrus communis L.). During the micropropagation phase, red light gave some particular advantages: maximal shoot length and leaf area were obtained. Under blue light, callus weight quadrupled compared to fluorescent light. Although far red was advantageous for shoot number, shoot quality was inferior because of hyperhydricity and chlorosis as indicated by a low Chlorophyll a+b and carotenoid content. The smallest leaf area was detected under fluorescent light. Blue+red showed significant improvements. Shoot cluster weight and shoot weight/callus weight' ratio was maximal, as well as shoot number and shoot length. Leaves were also dark green, showing a maximal Chlorophyll a+b and carotenoids content. Adventitious rooting of in vitro cultured pear plants was highly affected by different light spectra and the addition of a new rooting compound: trans-cinnamic acid. Without trans-cinnamic acid, limited rooting was observed under red, blue and blue+red light. In combination with trans-cinnamic acid, 100% rooting was achieved under red light

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

Tunisian previous termpomegranatenext term 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 previous termpomegranatenext term cultivars. Results showed that citric acid was predominant in sour previous termpomegranatesnext term, 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 previous termpomegranatenext term 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 previous termpomegranatenext term showed several characteristics that could be of great interest for food and nutraceutical industries

Molecular Polymorphisms in Tunisian Pomegranate (Punica granatum L.) as Revealed by RAPD Fingerprints

The genetic diversity among Tunisian pomegranate cultivars has been investigated. Using universal primers, the random amplified polymorphic DNA (RAPD) method was used to generate banding profiles from a set of twelve cultivars. Data was then computed with appropriate programs to construct a dendrogram illustrating the relationships between the studied cultivars. Our data proved the efficiency of the designed method to examine the DNA polymorphism in this crop since the tested primers are characterized by a collective resolving power of 12.83. In addition, the cluster analysis has exhibited a parsimonious tree branching independent from the geographic origin of the cultivars. In spite of the relatively low number of primers and cultivars, RAPD constitutes an appropriate procedure to assess the genetic diversity and to survey the phylogenetic relationships in this crop

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

Genetic Diversity and Structure of Tunisian Local Pear Germplasm as Revealed by SSR Markers

Growing pear has a long tradition in Tunisia, and numerous local cultivars possessing an excellent adaptability and resilience potential to climatic variation are present. This large adaptability is associated with an important genetic diversity, which is threatened to erosion. Appropriate measures have to be taken in order to properly evaluate and conserve this local material. Microsatellite markers were used to assess the level of genetic diversity among Tunisian pear germplasm, and compare it with some European varieties and wild pear species. 61 pear accessions representing eight groups (six groups from Tunisia, one from Northern Europe and another group composed of wild pear) have been genotyped using SSR markers derived from apple and pear. The pear accessions showed a significant polymorphism and 95 polymorphic alleles were found. The number of alleles per locus varied from 5 for CH04e03 locus to 14 for CH01d09 locus with an average of 9.4 alleles per locus. Moreover, the mean gene diversity (H-e) per locus ranged from 0.192 to 0.752. Genetic distance values and cluster analyses revealed high genetic similarities among the Tunisian groups. Factorial correspondence analysis (FCA) categorized the accessions into three independent groups where Tunisian local accessions agglomerated together distantly from European and wild pear accessions. Additionally, UPGMA dendrogram grouped accessions into two clusters, confirmed thereafter by the Bayesian model-based Structure analysis. The results showed 16 putative triploid accessions found in the local germplasm. This study provides valuable information to develop strategies of local pear conservation and use