333 Molecular and Morphological Variation among and within Populations of Cynara scolymus L. cv. ‘Spinoso sardo’ S. Lanteri, L. Ledda and M.G. Mameli Dipartimento di Scienze Agronomiche e Genetica Vegetale Agraria Università degli Studi di Sassari via E. De Nicola, 07100 Sassari Italy I. Di Leo and E. Portis DI.VA.P.R.A. settore Genetica Agraria Università degli Studi di Torino via L. Da Vinci, 44 Grugliasco Torino Italy Keywords: globe artichoke, RAPD, genetic variability, morphological/yield variation. Abstract The aim of this study was to measure molecular variation, using RAPD, as well as checking morphological and yield variation of artichoke heads in five populations of ‘Spinoso sardo’, the most widely grown and economically important cultivar in Sardinia (Italy). Considerable variation was observed for most of the morphological and yield characters studied. Analysis of molecular data showed significant dissimilarities between population. High level of variation within population was also detected, possibly as a consequence of the multiclonal composition of the populations but might also be due to mutations occurring over time (chromosomal aberrations, aneuploidy, polyploidy etc) which have been selected and vegetatively propagated together with non-variant plants. Our results show the need to apply clonal selection to narrow the broad genetic variability within the cultivar and provide uniform and selected material to farmers. They in turn provide useful information for the definition of the cultivar ideotype and address important questions on the most suitable strategies for germplasm preservation and cultivar fingerprinting. INTRODUCTION Italy is the richest source of artichoke variation (Bianco, 1990) and numerous distinct clonal cultivars, best adapted to local environments and local tastes, are grown. Artichoke breeding history is limited to a few studies on the inheritance of the main characters (Pècaut, 1993; Lòpez Anido et al., 1998), and breeding programs have traditionally aimed at improving earliness, head yield and quality based on interclonal hybridization (Miller, 1975; Scarascia Mugnozza and Pacucci, 1976; Tesi, 1976) and intraclonal selection (Deidda, 1967; Abbate and Noto, 1981; Pècaut, 1983). Today commercial production of artichokes is mainly based on the perennial cultivation of vegetatively propagated clones, which are usually highly heterozygous and segregate widely when progeny tested (Foury, 1969; Pécaut, 1993). On the whole there is a lack of information available on the level of variation within artichoke cultivars (Tivang et al., 1996); furthermore the literature reporting the pattern and extent of RAPD variation in artichoke cultivars is extremely limited. The aim of this study was to measure molecular, morphological and yield variation among and within five artichoke populations of ‘Spinoso sardo’, the most widely grown and economically important cultivar in Sardinia (Italy). ‘Spinoso sardo’, together with ‘Violetto di Sicilia’, ‘Violet de Provence’ and ‘Blanca de España’ belongs to traditional varieties which, when forced by means of irrigation and fertilization, begin production in autumn (Porceddu et al., 1976). The highest income for farmers comes from the first heads in autumn, sold locally as well as in northern Italy, where it is particularly appreciated for fresh consumption. Proc. IV th IC on Artichoke Ed.: V.V. Bianco et al. Acta Hort. 681, ISHS 2005