A hot spot of olive biodiversity in the Tunisian oasis of degache

Tunisia is one of the world's largest producers of olive oil, and it preserves pools of olive genetic diversity that are still unexplored. A recent prospection and collection program of the National Gene Bank of Tunisia (NGBT) focused on the vast oasis of Degache, in the south west part of Tunisia, where 47 samples were collected and genetically characterized through simple sequence repeat (SSR) markers. Identification and authentication of genotypes were obtained through comparison with reference cultivars belonging to the Olive National Collection of Tunisia (IOC) and with cultivars from Algeria, Italia, Syria and Lebanon. Degache olive genotypes showed large genetic variability, a significant diversity from the reference germplasm, and a clear differentiation from modern varieties. The population structure analysis identified four gene pools characterizing genotypes from different area of origin. Two gene pools appear to be more represented in germplasm from southern Tunisia, where environmental conditions at critical plant development phases, are harsher. This suggests that this germplasm might present traits of adaptation useful for breeding to improve resilience to abiotic stresses. Our results will support ex situ and in situ conservation activities of Tunisian olive germplasm pursued by the National Gene Bank of Tunisia

Temperature field in a rotating roller subjected to interface heating

The thermal behaviour of a rotating roller, subjected to surface heat sources is studied in this paper using an analytical solution, developed for this purpose. The roller is composed of a solid cylinder, rotating with a constant angular velocity, and is heated at its peripheral surface by two different heat sources. The analytical solution is entirely explicit and does not necessitate any hypothesis neither on the speed nor on the physical or geometrical parameters of the roller. The characteristic parameters are presented in dimensionless forms and are used to analyse the temperature distribution as function of their variations. Thermal maps are also presented using the proposed solution. They show that the thermal gradients are localized at the vicinity of the friction zone, and that the thermal gradients zones decrease when the angular speed increases

Mise en évidence de l'adsorption de l'isopentane dans les pores de la zéolithe 5A

Sur zéolithe 5A, l'adsorption de l'isopentane et du n-pentane a été suivie en microbalance dans une gamme de températures variant de 50 à 420°C et pour une pression d'alcanes de 97 kPa. L'analyse de la phase adsorbée montre clairement que l'isopentane entre dans les pores de l'adsorbant et reste bloqué dans les cages a de la zéolithe, et ceci quelle que soit la température. À basse température (T = 50°C), chaque cage a peut être occupée par trois molécules d'isopentane. Les molécules d'isopentane peuvent facilement être désorbées par un traitement sous vide primaire à la température de l'adsorption. À haute température (T > 250°C), une partie de l'isopentane bloqué dans les pores est transformé en coke (oligomères et composés mono- et biaromatiques) par réactions successives sur les sites acides de la zéolithe (craquage, oligomérisation, cyclisation et transfert d'hydrogène). Ces molécules bloquées dans les cages a de la zéolithe limitent la désorption de l'isopentane

Diversity Assessment of Algerian Wild and Cultivated Olives (Olea europeae L.) by Molecular, Morphological, and Chemical Traits

Algeria has several genetic resources on olive trees, mainly made up of small indigenous cultivars, and a very important wild heritage. Twenty olive samples including eight cultivars and twelve wild trees from the province of Bejaia (Algeria) are characterized, by combining molecular data (13 SSRs), fruit and pit morphological traits, fatty acids composition, and phenolic compounds of the extra virgin olive oils (EVOOs). The genetic results based on PCoA, UPGMA, and AMOVA analyses demonstrate that olive cultivars and wild trees are mixed, suggesting kinship relationships between cultivated and wild olive trees and even cases of synonymy between some cultivars. PCA analysis on morphological traits shows a good separation of the two olive botanical varieties, the wild olive trees producing smaller fruits than those of the cultivated ones. Significant differences are also found in terms of fatty acids and phenol compounds composition of the EVOOs. Wild olive oils show the highest contents on phenolic compounds, mainly oleocanthal, as well as a considerable richness on oleic acid. The comparison of pairwise distances between olive trees obtained by genetic, morphological, fatty acids and phenolic compounds contents data using Mantel's test indicates a significant correlation among morphological characteristics, DNA polymorphism, and phenolic compounds. The results obtained in the present work contribute to reveal the diversity existing in the cultivated and wild olive trees of the region of Bejaia, shedding some light on the importance of Algerian olives germplasm. Practical Applications: Cultivated and wild olive diversity are assessed by genetic, morphological, fatty acids and phenolic composition. SSR marker analysis demonstrates the presence of a high genetic variation between the analyzed samples. A significant correlation of morphological characteristics with DNA polymorphism and phenolic compounds is found. A significant diversity in the wild and cultivated olive trees is observed. Kinship relationships between wild and cultivated Algerian olive trees are demonstrated using SSR markers, while the morphological parameters allow a good distinction between the two taxa. Significant differences are found for fatty acids and phenol compounds composition for the EVOOs; the wild olive oils present an interesting composition compared to the cultivated form

The coexistence of oleaster and traditional varieties affects genetic diversity and population structure in Algerian olive (Olea europaea) germplasm

The present work was aimed at assessing the genetic diversity of 42 local cultivars and oleaster genotypes from the area of Bejaia in Algeria. Fifteen highly polymorphic Simple Sequence Repeat markers were evaluated and proved to be very informative, producing a total number of 160 alleles with an average value of 10.7 per locus; the SSRs DCA09 and DCA16 were the most informative, distinguishing 17 and 19 genotypes, respectively. Phylogenetic and population structure analysis split the accessions in two main groups corresponding to most of oleasters and most of traditional varieties, respectively. Interestingly, ten traditional varieties resulted strictly related to the oleasters, indicating hybridization between the two botanical varieties. Genetic parameters and private alleles of groups confirmed this observation and indicated a wide genetic variability in Algerian olive germplasm. The results suggest the need to preserve and characterize this germplasm in order to limit the risk of losing potential important genetic traits present in the crop wild relatives.The present work was aimed at assessing the genetic diversity of 42 local cultivars and oleaster genotypes from the area of Bejaia in Algeria. Fifteen highly polymorphic Simple Sequence Repeat markers were evaluated and proved to be very informative, producing a total number of 160 alleles with an average value of 10.7 per locus; the SSRs DCA09 and DCA16 were the most informative, distinguishing 17 and 19 genotypes, respectively. Phylogenetic and population structure analysis split the accessions in two main groups corresponding to most of oleasters and most of traditional varieties, respectively. Interestingly, ten traditional varieties resulted strictly related to the oleasters, indicating hybridization between the two botanical varieties. Genetic parameters and private alleles of groups confirmed this observation and indicated a wide genetic variability in Algerian olive germplasm. The results suggest the need to preserve and characterize this germplasm in order to limit the risk of losing potential important genetic traits present in the crop wild relatives