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

Abstract

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.

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

“…Similarly to other crops, current olive cultivation is the result of a continuous rearrangement of the genetic base involving selection, genetic material exchange and the creation of new diversity (Chessa and Nieddu 2005). At the same time, the crop cultivation may have been strongly influenced by the numerous civilizations which in turn invaded or visited the island for commercial trading, although the exact geographical origin of cultivars and the introduction chronology are not easy to establish.…”

“…Historical documents evidence that olive cultivation in Sardinia dates back to the eigth to seventh century BC (Milella 1957(Milella , 1961, while the first naming of local varieties were reported at the time of Spanish colonization (Chessa and Nieddu 2005). Most of the island's olive cultivation have been traditionally managed and are still based on several local cultivars.…”

The assessment of biodiversity loss over time: wild legumes in Syria

“…Another approach frequently applied for the direct genetic erosion assessment is based on the comparison between the number of various subspecific units (subspecies, varieties, landraces) at different time points or different localities. Thus, temporal or spatial comparison of the number of land races cultivated allows for the genetic erosion assessment in crop species, even if the historical plant material is not available (Chessa and Nieddu 2005;Hammer et al 1996;Teklu and Hammer 2006).…”

Diversity and spatial distribution of Opuntia spp. in the Mediterranean Basin

“…Most of the species richness in the Sardinian rural landscape is associated with small-scale farming and persisting traditional management, while a horticultural-intensive industry has developed in the few flat areas (Chessa and Nieddu, 2005). The surface of the island is mainly mountainous, reaching its highest peak at 1834 m; some alluvial plains and Aeolian dunes are present.…”

“…Thus, each of the larger islands in the Mediterranean has its own distinctive set of native species and of woody plant crops (Chessa and Nieddu, 2005). Most islands were colonised soon after the last glacial period, around 11 000 years ago, and evidence of human colonisation stretches as far back as 20 000 years ago in Sardinia (Blondel and Aronson, 1999).…”