Isolation And molecular characterization of xylella fastidiosa from different host plant species in Italy (Apulia region)

L'isolement en culture pure de la souche Xylella fastidiosa liée au syndrome de déclin rapide de l'olivier (OQDS), récemment observé dans les Pouilles (sud de l'Italie) a été tenté à partir des plantes symptomatiques naturellement infectée, principalement Olea europaea L., Polygala myrtifolia et Rosmarinus officinalis, en utilisant les méthodes d'impression et d'extraction de la sève. Avant l'isolement, RT-LAMP et qPCR ont été utilisés pour déterminer la présence de X. fastidiosa chez tous les hôtes. Des cultures bactériennes pures ont été obtenues à partir d'extraits d'Olea europaea L. et de Polygala myrtifolia étalés dans un milieu tamponné d'extrait de cystéine-levure (BCYE). Deux isolats d'olive ont ensuite été typés à l'aide du système de séquençage multilocus (MLST). Les résultats indiquent qu'Olea europaea a un grand potentiel d'isolement, et la méthode d'impression a présenté des résultats nettement meilleurs. MLST montre des points communs génétiques avec la souche De Donno (ST53) et confirme que nous avons toujours le même type de séquence ST53 dans la région.Pure culture isolation of the Xylella fastidiosa strain related to the olive quick declinesyndrome (OQDS), lately noticed in Apulia (southern Italy) was attempted fromnaturally infected symptomatic plants mainly Olea europaea L., Polygala myrtifolia and Rosmarinus officinalis using printing and sap extraction methods. Prior to isolation, RTLAMP and qPCR were used to determine the presence of Xylella fastidiosa in all hosts. Pure bacterial cultures were obtained from both Olea europaea L. and Polygala myrtifolia extracts plated in buffered cysteine-yeast extract (BCYE) media. Two olive isolates were subsequently typed using the Multilocus Sequencing System (MLST). Findings indicate that beside Olea europaea, Polygala myrtifolia seems to have a good potential for isolation, and printing method has presented significantly better results. MLST shows genetic commonality with De Donno (ST53) strain and ascertain that Apulia region still have the same sequence type ST53 in the region

Screening and Characterization of New Acetobacter fabarum and Acetobacter pasteurianus Strains with High Ethanol-Thermo Tolerance and the Optimization of Acetic Acid Production

The production of vinegar on an industrial scale from different raw materials is subject to constraints, notably the low tolerance of acetic acid bacteria (AAB) to high temperatures and high ethanol concentrations. In this study, we used 25 samples of different fruits from seven Moroccan biotopes with arid and semi-arid environmental conditions as a basic substrate to isolate thermo- and ethanol-tolerant AAB strains. The isolation and morphological, biochemical and metabolic characterization of these bacteria allowed us to isolate a total number of 400 strains with characters similar to AAB, of which six strains (FAGD1, FAGD10, FAGD18 and GCM2, GCM4, GCM15) were found to be mobile and immobile Gram-negative bacteria with ellipsoidal rod-shaped colonies that clustered in pairs and in isolated chains. These strains are capable of producing acetic acid from ethanol, growing on peptone and oxidizing acetate to CO2 and H2O. Strains FAGD1, FAGD10 and FAGD18 show negative growth on YPG medium containing D-glucose > 30%, while strains GCM2, GCM4 and GCM15 show positive growth. These six strains stand out on CARR indicator medium as isolates of the genus Acetobacter ssp. Analysis of 16S rDNA gene sequencing allowed us to differentiate these strains as Acetobacter fabarum and Acetobacter pasteurianus. The study of the tolerance of these six isolates towards pH showed that most of the six strains are unable to grow at pH 3 and pH 9, with an ideal pH of 5. The behavior of the six strains at different concentrations of ethanol shows an optimal production of acetic acid after incubation at concentrations between 6% and 8% (v/v) of ethanol. All six strains tolerated an ethanol concentration of 16% (v/v). The resistance of the strains to acetic acid differs between the species of AAB. The optimum acetic acid production is obtained at a concentration of 1% (v/v) for the strains of FAGD1, FAGD10 and FAGD18, and 3% (v/v) for GCM2, GCM4 and GCM15. These strains are able to tolerate an acetic acid concentration of up to 6% (v/v). The production kinetics of the six strains show the highest levels of growth and acetic acid production at 30 degrees C. This rate of growth and acetic acid production is high at 35 degrees C, 37 degrees C and 40 degrees C. Above 40 degrees C, the production of acid is reduced. All six strains continue to produce acetic acid, even at high temperatures up to 48 degrees C. These strains can be used in the vinegar production industry to minimize the load on cooling systems, especially in countries with high summer temperatures

Arthrographis curvata and Rhodosporidium babjevae as New Potential Fungal Lipase Producers for Biotechnological Applications

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Alfalfa for a sustainable ovine farming system: Proposed research for a new feeding strategy based on alfalfa and ecological leftovers in drought conditions

In the past 10 years, the average demand for meat and milk across the world has significantly increased, especially in developing countries. Therefore, to support the production of animal-derived food products, a huge quantity of feed resources is needed. This paper does not present original research, but rather provides a conceptual strategy to improve primary production in a sustainable way, in relation to forthcoming issues linked to climate change. Increases in meat and milk production could be achieved by formulating balanced diets for ovines based on alfalfa integrated with local agricultural by-products. As the central component of the diet is alfalfa, one goal of the project is increasing the yield of alfalfa in a sustainable way via inoculating seeds with symbiotic rhizobia (i.e., Sinorhizobium meliloti). Seed inoculants are already present on the market but have not been optimized for arid soils. Furthermore, a part of the project is focused on the selection of elite symbiotic strains that show increased resistance to salt stress and competitiveness. The second component of the experimental diets is bio-waste, especially that obtained from olive oil manufacturing (i.e., pomace). The addition of agro-by-products allows us to use such waste as a resource for animal feeding, and possibly, to modulate rumen metabolism, thereby increasing the nutritional quality of milk and meat

Quels risques peuvent produire les changements climatiques sur la phénologie des arbres fruitiers en Méditerranée? Un diagnostic durant un passé récent comme feuille de route stratégique pour une arboriculture durable en avenir

International audienceL’objectif de ce travail est de comprendre l'impact du changement climatique, en particulier l’augmentation des températures, sur la phénologie des arbres fruitiers ayant une valeur socio-économique importante dans la méditerranée (Meknès et Tassaout au Maroc, Nîmes et Montpellier en France et Forli en Italie). Trois espèces ont été étudiées : l’olivier, le pommier et l'amandier. Trois approches méthodologiques complémentaires ont effectuées: statistique, expérimentale et modélisation. L’analyse des données de température a montré un réchauffement climatique significatif dans les trois régions pendant la période rassemblant les mois octobre-mai. Ce réchauffement a engendré une précocité de floraison chez les arbres fruitiers, avec une sensibilité remarquable chez l’olivier et le pommier. Le processus physiologique propre à chaque espèce pendant à la fois la période de dormance et de croissance explique, en partie, les différences régionales observées dans les dates de floraison entre sites (Maroc et France) et espèces (pommier et amandier). Les tendances des stades phénologiques simulées par modélisation chez le pommier sont en concordance avec celles observées au champ. Cette approche (modélisation) est un outil puissant pour la prévision phénologique dans le contexte des changements climatiques et il peut servir dans les processus de la décision managériale

Identification de différents modes de dormance chez un arbre fruitier suivant les conditions environnementales et le génotype cultivé : quel enseignement en terme d'adaptation ?

Des tests de forçage durant la dormance ont été appliqués à des bourgeons végétatifs et floraux de pommier dans deux sites à climats doux (Nord du Maroc, Sud du Brésil) et un site à climat tempéré (Sud de la France). Des tests similaires ont été conduits pour l’amandier dans le Nord du Maroc. Des différences d’intensité et de cinétique de dormance ont été identifiées en lien avec les différences régionales de satisfaction des besoins en froid et différents niveaux de besoins des génotypes étudiés. La diversité observée des modes de dormance suggère que des génotypes adaptés aux climats doux (amandiers, pommiers à faibles besoins en froid) se caractérisent par une aptitude des bourgeons végétatifs à demeurer dans un état de faible dormance et une aptitude des ébauches florales à croître rapidement, garantissant l’absence d’anomalies phénologiques ultérieures à la feuillaison et la floraison

Differentiated dynamics of bud dormancy and growth in temperate fruit trees relating to bud phenology adaptation, the case of apple and almond trees

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresInternational audienceFew studies have focused on the characterization of bud dormancy and growth dynamics for temperate fruit species in temperate and mild cropping areas, although this is an appropriate framework to anticipate phenology adaptation facing future warming contexts which would potentially combine chill declines and heat increases. To examine this issue, two experimental approaches and field observations were used for high- and low-chill apple cultivars in temperate climate of southern France and in mild climates of northern Morocco and southern Brazil. Low-chill almond cultivars offered an additional relevant plant material for comparison with apple in northern Morocco. Divergent patterns of dormancy and growth dynamics were clearly found in apple tree between southern France and southern Brazil. Divergences were less pronounced between France and Morocco. A global view outlined main differences in the dormancy chronology and intensity, the transition between endordormancy and ecodormancy and the duration of ecodormancy. A key role of bud rehydration in the transition period was shown. High-chill cultivars would be submitted in mild conditions to heterogeneous rehydration capacities linked to insufficient chill fulfillment and excessive forcing linked to high temperatures. This would favor bud competitions and consequently excessive flowering durations and weak flowering. Low chilling requirements in apple and almond would conversely confer biological capacities to tolerate superficial dormancy and abrupt transition from endordormancy to ecodormancy without important heterogeneous rehydration states within buds. It may also assume that low-chill cultivars can also tolerate high temperatures during ecodormancy as well as extended flowering durations

Response of almond flowering and dormancy to Mediterranean temperature conditions in the context of adaptation to climate variations

International audienceDetermining the flowering and the dormancy phases in fruit trees is a crucial process because of their substantial role in some agricultural practices and crop managements. However, few of these studies were conducted on almond flowering and dormancy, particularly in mild climate areas. This study aimed to simulate the dormancy phases, closely involved in the determination of flowering time of almond species in response to temperature variations. To reach this objective, Partial Least Squares analysis was used. In this regard, climatic and flowering data were collected from Ain Taoudjate in Morocco during the period from 1974 to 2014. In fact, a significant temperature increase was highlighted, inducing a decrease in amounts of chill during the studied period. Using Partial Least Squares analysis, a good fit of data was obtained, particularly using mean and maximal temperatures. Two relevant periods controlling the flowering process were highlighted in Tuono cultivar, in concordance with the sequential model in prediction of flowering times. The first long chilling period started from October 01st to January 11th. During this period, temperatures correlated positively with flowering dates, inducing consequently a delayed flowering dates because of low and slow accumulation of chilling requirements. However, the second short forcing period extended from January 18th to March 09th, during which flowering dates were negatively correlated with temperatures. In fact, the accumulation of certain threshold of Growing Degree Hours and Chill Portions during the two periods respectively could delay flowering, particularly in the context of chilling privation in the coming future, causing a serious problem for fruit trees. Significantly, temperatures during the chilling period seemed to affect effectively the flowering dates of almond than temperatures during the forcing period. In this investigation, we demonstrated that Partial Least Squares showed a good fit in explanation of the flowering process and can be used for prediction of dormancy phases and flowering process