Innocenza Chessa

Genetic diversity and relationships between wild and cultivated olives (Olea europaea L.) in Sardinia as assessed by SSR markers

The genetic relationships within and between wild and cultivated olives were examined and clarified in an isolated and restricted area, such as the Mediterranean island of Sardinia. Wild (21 individuals) and cultivated olive trees (22 local cultivars from a germplasm collection and 35 ancient trees) were genotyped by means of 13 SSR loci. Five cases of synonymy were observed and nine distinct genotypes were identified in the collection. Five novel genotypes were also detected among the ancient trees. Differences on the allelic composition and heterozygosity levels were found between wild and cultivated trees. Model-based clustering method classified the olive trees into two major gene pools: (a) wild genotypes and (b) local cultivars from the collection and from heritage olives. Regarding the cultivated plant material, we observed that: (a) most of the Sardinian cultivars shared the same allelic profiles with the ancient cultivated trees and (b) the majority of these cultivars and all the novel genotypes were not related to any other cultivars included in this study. These findings as well as the detection of unique alleles and a certain wild genetic background at some cultivars revealed by the Bayesian analysis may indicate their autochthonous origin. The synonymy cases found between local cultivars and Italian mainland cultivars indicate interchange of genetic material among these growing areas, suggesting thus a possible allochthonous origin. The information obtained can assist in the management of an olive collection and sheds some light on the survival of true oleasters and the origin of Sardinian cultivars.

Analysis of diversity in the fruit tree genetic resources from a Mediterranean island

A large number of genotypes of different fruit tree species have been described in Sardinia, where the plant species have evolved by adaptation to the Mediterranean environment. In this work results are summarized of a long-term survey carried out in the island by the authors since the early 1980s. Ten fruit tree species have been surveyed and collections of the traditional varieties were established. Some are major staple crops such as olive and grape, others such as almond, cherry, plum, fig, apple and pear are nowadays less cultivated, and still others have been more recently introduced like apricot and cactus pear. Data on the level of inter and intra-species diversity are given, as illustrated by representative morphological traits. The results of isozymes and RAPD-PCR analysis on the species Ficus carica genotypes are included, to assess genetic relationship among accessions. Observations on composition, as well as on state of conservation of selected traditional varieties are reported, and the main causes of genetic erosion are listed.

Pollen emission from olive trees and concentrations of airborne pollen in an urban area of North Sardinia

In this study the seasonal and daily variations in olive airborne pollen concentrations were measured in the atmosphere of Sassari (Italy) and the olive pollen emission was monitored in the countryside during the flowering period in 1995 and 1996, in order to detect the patterns of change in the atmosphere. The intensity and the timing of pollination was also studied in relation to phenological stages occurrence. In addition, the influence of the main meteorological parameters on pollen emission and airborne pollen dispersal in the city was assessed. Airborne pollen reached its highest concentration a few days before the peak of pollen emission in 1995 but several days after it in 1996 (6 days). Analysis of hourly concentrations shows that the maximum emission and dispersion recorded during the observation period occurred in the middle of the day. Significant regressions were found between hourly temperature and air humidity values and hourly pollen concentrations recorded in the olive grove for almost every day studied, indicating a negative correlation between humidity and pollen concentration and a positive correlation between pollen concentration and temperature. On the other hand, no significant correlation was observed between the meteorological parameters and pollen concentration recorded in the urban area.

Primary and secondary characterization of a Vermentino grape clones collection

Vermentino is one of the main grape variety cultivated in the west Mediterranean region, mainly in France (Provence and Corsica) and in Italy (Sardinia, Tuscany and Ligury). Due to the high quality of its monovarietal wines, Vermentino has increased its importance in the last two decades, while previously has been regarded as a minor variety covering small surfaces. Through clonal selection Vermentino clones have been patented and diffused among growers in Corsica and in Italy. On a collection of 14 Italian and Corsican Vermentino clones, ex situ preserved in Sardinia, ampelographic data, phenological stages, and agronomic characteristics, such as yield, bud fertility, bunch and berry weight, pH, acidity and SST of must, were recorded from 2004 to 2005. The description of the Vermentino genotypes evidenced the identities and the distinctive traits within the clones collection, increasing the information on their agronomic performance in a common area of cultivation.

Opuntia sp. Adaptability to the Mediterranean Environment

The relationships between Opuntia sp. and the Mediterranean environment of the island of Sardinia were studied based on the identification of the limiting ecological factors, using statistical techniques and GIS software. In 100 test-sites, representative of the area variability, Opuntia sp. populations were morphologically and genetically characterized. GIS application was implemented to analyze, update and encode all collected data, thus enabling thematic maps to be drawn. FloraMap, a specific GIS application, was successfully used to predict the Opuntia sp. distribution in Sardinia.