Globe artichoke (Cynara cardunculus L. var. scolymus) is a crop of historical, agricultural, and economic importance in the Mediterranean region, particularly in Italy, where considerable diversity of local varieties and plant materials has been maintained under different geographical conditions and traditional production systems. Although characterization of Italian germplasm has largely focused on the main varietal types and production areas, local accessions traditionally selected and vegetatively propagated by farmers persist in northern Italy. Their characterization is important for safeguarding agricultural heritage, assessing conserved diversity, establishing relationships among accessions, and identifying potentially redundant or genetically differentiated materials. Morphological and genetic characterization was conducted on 34 accessions from an ex situ collection of northern Italian globe artichoke conserved at Fondazione Riccagioia (PV). The aim was to assess morphological and genetic diversity within the collection and support the identification and management of the conserved accessions. Morphological characterization was performed using standardized descriptors based on the International Union for the Protection of New Varieties of Plants (UPOV) TG/184/4 guideline, focusing mainly on qualitative and pseudo-qualitative traits of the capitulum and outer bracts. Variation was examined through principal component analysis (PCA) and hierarchical clustering. Traits related to outer bract apex shape, spine development, apex coloration, outer bract base length, and capitulum shape contributed substantially to differentiation. Four morphological groups were recognized. Groups I, II, and III showed relatively well-defined patterns, whereas Group IV was more heterogeneous and included materials with intermediate states or accessions that did not clearly fit the other groups. Molecular characterization was performed using 20 Simple Sequence Repeat (SSR) loci across the 34 accessions with both morphological and genetic data, together with one reference sample (n = 35). All loci were polymorphic. The number of observed alleles per locus ranged from 2 to 9, with a mean of 4.85, while mean observed and expected heterozygosity were 0.498 and 0.551, respectively. Principal coordinates analysis (PCoA) and hierarchical clustering revealed genetic structure within the collection but did not reproduce the four morphologically defined groups. Comparison of the two approaches revealed different degrees of concordance. Group I showed the clearest association between morphological homogeneity and genetic proximity, although 20 SSR loci cannot establish whether the most closely related accessions represent clonal propagations of the same genotype or closely related genotypes. Group III combined morphological homogeneity with marked molecular dispersion. Group IV showed both morphological and genetic heterogeneity, while Group II contained subsets showing concordance between morphology and genetic proximity but was not molecularly homogeneous. Overall, morphological characterization and SSR analysis described different but complementary dimensions of diversity. Morphology revealed patterns associated mainly with the capitulum and its structures, whereas molecular markers identified genetic relationships not always reflected morphologically. These results provide a basis for future conservation and management of the ex situ collection and for higher-resolution studies of genetically close accessions.
Il carciofo (Cynara cardunculus L. var. scolymus) è una coltura di rilevanza storica, agricola ed economica nella regione mediterranea, in particolare in Italia, dove una notevole diversità di varietà locali e materiali vegetali è stata mantenuta in differenti condizioni geografiche e sistemi produttivi tradizionali. Sebbene la caratterizzazione del germoplasma italiano si sia concentrata sulle principali tipologie varietali e aree di produzione, nell’Italia settentrionale persistono accessioni locali tradizionalmente selezionate e propagate vegetativamente dagli agricoltori. La loro caratterizzazione è importante per salvaguardare il patrimonio agricolo, valutare la diversità conservata, stabilire relazioni tra le accessioni e identificare materiali potenzialmente ridondanti o geneticamente differenziati. È stata effettuata una caratterizzazione morfologica e genetica di 34 accessioni appartenenti a una collezione ex situ di carciofo dell’Italia settentrionale conservata presso la Fondazione Riccagioia (PV). L’obiettivo era valutare la diversità morfologica e genetica della collezione e supportare l’identificazione e la gestione delle accessioni. La caratterizzazione morfologica è stata effettuata utilizzando descrittori standardizzati basati sulle linee guida TG/184/4 dell’Unione Internazionale per la Protezione delle Nuove Varietà Vegetali (UPOV), concentrandosi sui caratteri qualitativi e pseudo-qualitativi del capolino e delle brattee esterne. La variabilità è stata esaminata mediante analisi delle componenti principali (PCA) e clustering gerarchico. I caratteri relativi alla forma dell’apice delle brattee esterne, allo sviluppo delle spine, alla colorazione dell’apice, alla lunghezza della base delle brattee esterne e alla forma del capolino hanno contribuito alla differenziazione. Sono stati riconosciuti quattro gruppi morfologici. I gruppi I, II e III hanno mostrato pattern relativamente ben definiti, mentre il Gruppo IV è risultato più eterogeneo e comprendeva materiali con stati intermedi o accessioni non chiaramente riconducibili agli altri gruppi. La caratterizzazione molecolare è stata effettuata utilizzando 20 loci Simple Sequence Repeat (SSR) sulle 34 accessioni per le quali erano disponibili dati morfologici e genetici, insieme a un campione di riferimento (n = 35). Tutti i loci erano polimorfici. Il numero di alleli osservati per locus variava da 2 a 9, con una media di 4,85, mentre l’eterozigosità osservata e quella attesa medie erano rispettivamente 0,498 e 0,551. L’analisi delle coordinate principali (PCoA) e il clustering gerarchico hanno evidenziato una struttura genetica nella collezione, senza tuttavia riprodurre i quattro gruppi definiti morfologicamente. Il confronto tra i due approcci ha evidenziato diversi livelli di concordanza. Il Gruppo I ha mostrato la relazione più evidente tra omogeneità morfologica e prossimità genetica, sebbene 20 loci SSR non consentano di stabilire se le accessioni geneticamente più vicine rappresentino propagazioni clonali dello stesso genotipo o genotipi strettamente correlati. Il Gruppo III ha mostrato omogeneità morfologica associata a una marcata dispersione molecolare. Il Gruppo IV ha evidenziato eterogeneità morfologica e genetica, mentre il Gruppo II comprendeva alcuni sottoinsiemi concordanti tra morfologia e prossimità genetica, senza risultare complessivamente omogeneo a livello molecolare. Nel complesso, la caratterizzazione morfologica e l’analisi SSR hanno descritto dimensioni diverse ma complementari della diversità. La morfologia ha evidenziato pattern associati principalmente al capolino e alle sue strutture, mentre i marcatori molecolari hanno identificato relazioni genetiche non sempre riflesse a livello morfologico. Questi risultati forniscono una base per la futura conservazione e gestione della collezione ex situ e per studi a maggiore risoluzione sulle accessioni geneticamente vicine.
Analisi morfologica e genetica di una collezione ex situ di carciofo
LÓPEZ MICELI, MARIO ALBERTO
2025/2026
Abstract
Globe artichoke (Cynara cardunculus L. var. scolymus) is a crop of historical, agricultural, and economic importance in the Mediterranean region, particularly in Italy, where considerable diversity of local varieties and plant materials has been maintained under different geographical conditions and traditional production systems. Although characterization of Italian germplasm has largely focused on the main varietal types and production areas, local accessions traditionally selected and vegetatively propagated by farmers persist in northern Italy. Their characterization is important for safeguarding agricultural heritage, assessing conserved diversity, establishing relationships among accessions, and identifying potentially redundant or genetically differentiated materials. Morphological and genetic characterization was conducted on 34 accessions from an ex situ collection of northern Italian globe artichoke conserved at Fondazione Riccagioia (PV). The aim was to assess morphological and genetic diversity within the collection and support the identification and management of the conserved accessions. Morphological characterization was performed using standardized descriptors based on the International Union for the Protection of New Varieties of Plants (UPOV) TG/184/4 guideline, focusing mainly on qualitative and pseudo-qualitative traits of the capitulum and outer bracts. Variation was examined through principal component analysis (PCA) and hierarchical clustering. Traits related to outer bract apex shape, spine development, apex coloration, outer bract base length, and capitulum shape contributed substantially to differentiation. Four morphological groups were recognized. Groups I, II, and III showed relatively well-defined patterns, whereas Group IV was more heterogeneous and included materials with intermediate states or accessions that did not clearly fit the other groups. Molecular characterization was performed using 20 Simple Sequence Repeat (SSR) loci across the 34 accessions with both morphological and genetic data, together with one reference sample (n = 35). All loci were polymorphic. The number of observed alleles per locus ranged from 2 to 9, with a mean of 4.85, while mean observed and expected heterozygosity were 0.498 and 0.551, respectively. Principal coordinates analysis (PCoA) and hierarchical clustering revealed genetic structure within the collection but did not reproduce the four morphologically defined groups. Comparison of the two approaches revealed different degrees of concordance. Group I showed the clearest association between morphological homogeneity and genetic proximity, although 20 SSR loci cannot establish whether the most closely related accessions represent clonal propagations of the same genotype or closely related genotypes. Group III combined morphological homogeneity with marked molecular dispersion. Group IV showed both morphological and genetic heterogeneity, while Group II contained subsets showing concordance between morphology and genetic proximity but was not molecularly homogeneous. Overall, morphological characterization and SSR analysis described different but complementary dimensions of diversity. Morphology revealed patterns associated mainly with the capitulum and its structures, whereas molecular markers identified genetic relationships not always reflected morphologically. These results provide a basis for future conservation and management of the ex situ collection and for higher-resolution studies of genetically close accessions.| File | Dimensione | Formato | |
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Descrizione: This thesis assesses morphological and genetic diversity in Northern Italian globe artichoke germplasm conserved ex situ at Fondazione Riccagioia. UPOV descriptors and 20 SSR markers were used to characterize accessions and support their conservation
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https://hdl.handle.net/20.500.14239/36670