Current Status of Biodiversity Assessment and Conservation of Wild Olive (Olea europaea L. subsp. europaea var. sylvestris)

Oleaster (Olea europaea L. subsp. europaea var. sylvestris) is the ancestor of cultivated olive (Olea europaea L. subsp. europaea var. europaea) and it is spread through the whole Mediterranean Basin, showing an overlapping distribution with cultivated olive trees. Climate change and new emerging diseases are expected to severely affect the cultivations of olive in the future. Oleaster presents a higher genetic variability compared to the cultivated olive and some wild trees were found adapted to particularly harsh conditions; therefore, the role of oleaster in the future of olive cultivation may be crucial. Despite the great potential, only recently the need to deeply characterize and adequately preserve the wild olive resources drew the attention of researchers. In this review, we summarized the most important morphological and genetic studies performed on oleaster trees collected in different countries of the Mediterranean Basin. Moreover, we reviewed the strategies introduced so far to preserve and manage the oleaster germplasm collections, giving a future per-spective on their role in facing the future agricultural challenges posed by climatic changes and new emerging diseases

Optimization of insect odorant receptor trafficking and functional expression via transient transfection in HEK293 cells

Insect odorant receptors show a limited functional expression in various heterologous expression systems including insect and mammalian cells. This may be in part due to the absence of key components driving the release of these proteins from the endoplasmic reticulum and directing them to the plasma membrane. In order to mitigate this problem we took advantage of small export signals within the human HCN1 and Rhodopsin that have been shown to promote protein release from the endoplasmic reticulum and the trafficking of post-Golgi vesicles, respectively. Moreover, we designed a new vector based on a bidirectional expression cassette to drive the functional expression of the insect odorant receptor co-receptor (Orco) and an odor-binding odorant receptor, simultaneously. We show that this new method can be used to reliably express insect odorant receptors in HEK293 cells via transient transfection and that is highly suitable for downstream applications using automated and high-throughput imaging platforms

Applications of microsatellite markers for the characterization of olive genetic resources of tunisia

Among the countries of the Mediterranean Basin, Tunisia is located at the crossroad for the immigration of several civilizations over the last two millennia, becoming a strategic place for gene flow, and a secondary center of diversity for olive species. Olive is one of the principal crop species in Tunisia and now it strongly characterizes the rural landscape of the country. In recent years, collecting missions on farm and in situ were carried out by various institutes, with special emphasis given to ex situ collections serving as a reference for the identification of olive germplasm. Simple Sequence Repeats (SSRs) represent the easiest and cheapest markers for olive genetic fingerprinting and have been the tool of choice for studying the genetic diversity of this crop in Tunisia, to resolve cases of homonymy and synonymy among the commercialized varieties, to identify rare cultivars, to improve knowledge about the genetic variability of this crop, to identify a hot spot of olive biodiversity in the Tunisian oasis of Degache, and to enrich the national reference collection of olive varieties. The present review describes the state of the art of the genetic characterization of the Tunisian olive germplasm and illustrate the progress obtained through the SSR markers, in individuating interesting genotypes that could be used for facing incoming problems determined by climate changes

How to choose a good marker to analyze the olive germplasm (Olea europaea l.) and derived products

The olive tree (Olea europaea L.) is one of the most cultivated crops in the Mediterranean basin. Its economic importance is mainly due to the intense production of table olives and oil. Cultivated varieties are characterized by high morphological and genetic variability and present a large number of synonyms and homonyms. This necessitates the introduction of a rapid and accurate system for varietal identification. In the past, the recognition of olive cultivars was based solely on analysis of the morphological traits, however, these are highly influenced by environmental conditions. Therefore, over the years, several methods based on DNA analysis were developed, allowing a more accurate and reliable varietal identification. This review aims to investigate the evolving history of olive tree characterization approaches, starting from the earlier morphological methods to the latest technologies based on molecular markers, focusing on the main applications of each approach. Furthermore, we discuss the impact of the advent of next generation sequencing and the recent sequencing of the olive genome on the strategies used for the development of new molecular markers

New insight into the identity of italian grapevine varieties: The case study of calabrian germplasm

Calabria is a region located in Southern Italy and it is characterized by a long tradition of viticulture practices and favorable pedoclimatic conditions for grapevine cultivation. Nevertheless, less than 2% of cultivated land is dedicated to grapevine growing in Calabria. The characterization of local grapevine accessions is crucial to valorize the local and peculiar Italian products and boost the Calabrian winemaking sector. With this purpose, we performed a deep characterization of two widespread Calabrian grapevine varieties—Magliocco Dolce and Brettio Nero, of which very little is known. In particular, a genetic and morphological analysis, a berry physico-chemical and polyphenolic compositions assessment, and oenological evaluation of monovarietal wines were carried out. Our results allowed us to demonstrate that Magliocco Dolce and Brettio Nero are unique and distinct varieties with peculiar morphological and chemical characteristics and show the suitability of these two varieties in high-quality wine production. Moreover, the obtained molecular profiles will be useful for authentication and traceability purposes

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

Recovery, assessment, and molecular characterization of minor olive genotypes in Tunisia

Olive is one of the oldest cultivated species in the Mediterranean Basin, including Tunisia, where it has a wide diversity, with more than 200 cultivars, of both wild and feral forms. Many minor cultivars are still present in marginal areas of Tunisia, where they are maintained by farmers in small local groves, but they are poorly characterized and evaluated. In order to recover this neglected germplasm, surveys were conducted in different areas, and 31 genotypes were collected, molecularly characterized with 12 nuclear microsatellite (simple sequence repeat (SSR)) markers, and compared with 26 reference cultivars present in the Tunisian National Olive collection. The analysis revealed an overall high genetic diversity of this olive’s germplasm, but also discovered the presence of synonymies and homonymies among the commercialized varieties. The structure analysis showed the presence of different gene pools in the analyzed germplasm. In particular, the marginal germplasm from Ras Jbal and Azmour is characterized by gene pools not present in commercial (Nurseries) varieties, pointing out the very narrow genetic base of the commercialized olive material in Tunisia, and the need to broaden it to avoid the risk of genetic erosion of this species in this country

Spatio-temporal distribution of Erysiphe necator genetic groups and their relationship with disease levels in vineyards

International audienceThe discovery of genetically distinct Erysiphe necator groups (A or B), with high phenotypic similarities, raises important questions about their coexistence. For plant pathogens, niche partitioning, allowing the coexistence on the same host (i.e. the same resource), might result from separation in space and/or time. We used a landscape genetic approach to study the geographic distribution of genetic groups of E. necator (distinguished by a SNP in the β-tubulin gene) at the spatial scale of the Languedoc-Roussillon region (southern France) and to assess the temporal succession of groups along the course of the 2007 epidemic. Spatial distribution revealed a high heterogeneity between vineyards: from 100% B to 100% A, with 62% and 38% of vineyards showing a majority of A and B isolates, respectively. Temporal isolation seems to be the major mechanism in the coexistence of the two genetic groups: all isolates collected towards the end of the epidemic belonged to group B, whatever the initial frequency of genetic groups. Our results confirm that both A or B isolates can lead to flag-shoot symptoms, and showed that group A isolates tend to disappear during the course of the epidemic, whereas group B isolates may be active during the entire epidemic and involved in further production of cleistothecia, when recombination takes place. For the first time, the relationship between the frequency of genetic groups and disease levels on leaves and clusters at the end of the epidemic was evaluated. We showed a strong relationship between the disease severity and the genetic composition of E. necator populations: the damage was more important when the epidemic was initiated by B isolates