BIODIVERSITÀ DI CASTANEA SPP.: EROSIONE GENETICA E STRATEGIE DI CONSERVAZIONE

The long coevolution between chestnut and human populations has led to the spread in the world of a rich and varied genetic diversity. Its flexibility and adaptability to different pedoclimates and the wide genetic variability has determined the spread of many varieties in the wild carriers of genotypes with specific qualities in terms of use, needs cold, water requirements and resistance to diseases. Shape and behavior are highly variable, and the genus Castanea in fact includes trees of the first magnitude, erect and slender but also some species of small size, dwarf shrubs and stolonifers. They generally prefer deep, light, acid soils, temperate climates, rainfall ranging between 700 and 1500 mm per year and have spread widely in the northern hemisphere and in particular in three distribution areas: - Europe and the countries bordering on the Mediterranean, where it is grown Castanea sativa; - Asia with C. crenata, C. mollissima, C. seguinii and C. henryi; - North America is located in C. dentata. These are flanked by smaller species such as C. davidii, C. pumila, C. floridana, C. ashei, C. alnifolia and C. paucispina. Currently this rich biodiversity is critically endangered and hundreds of ecotypes and varieties are at risk of being lost due to problems of plant health (canker, Chryphonectria parasitica, ink disease, Phytophthora spp., gall wasp, Dryocosmus kuriphilus) and anthropological (chestnut degradation and climate changes) (degradation of chestnut and Climate Change) which over the years had a significant effect on the course of chestnut populations in the world. The nature of fungal diseases have led to a selective pressure during the past centuries leading to the destruction of numerous areas chestnut or even, as in the case of Castanea toothed, to the almost complete disappearance of them. The progressive degradation and abandonment of chestnut grove has contributed to the loss of many agricultural systems based on this crop. Since the '90s, however, noted a process of rediscovery and revaluation of chestnut thanks to new entrepreneurs; however they must take account of current problems such as climate change and the gall wasp, which pose serious risks in the loss of biodiversity . In this regard, several programs of research and testings have attempted to develop strategies for the conservation of the species in order to protect genes for use in breeding programs but also for the development of varieties that risk to be lost. The study of germplasm is made possible through a series of actions to the identification, characterization and conservation of genotypes and this work is very long and costly but it is necessary to safeguard the biodiversity of the chestnut. First, in the description of the collections are examined phenological and morphological traits that allow to differentiate the accessions and to determine their potential usefulness. However, these traditional methods of identification are not sufficient to determine the genetic diversity of the collections and to improve the germplasm due to environmental influence; so over the years we have joined the traditional methods molecular markers that allow you to identify certainty the different cultivars through DNA analysis. These research activities are ongoing in a number of international research institutes, including the University of Turin, engaged in the study and conservation of genetic material through the creation of a field collection.