Caratterizzazione morfologica e genetica di piante di Goji (Lycium barbarum L.) coltivate in Toscana e analisi nutraceutica dei frutti.

Lycium barbarum L., commonly known as Goji, is a shrub belonging to the Solanaceae family, which includes many of the most important agricultural species in the World, such as potatoes, tomatoes, peppers, aubergines and tobacco. Fruits, leaves, root bark and young shoots have been widely used in traditional Asian medicine for centuries and today represent a new frontier in medicine, nutraceuticals and functional foods, exploiting their beneficial properties. Thanks to these therapeutic capacities and its adaptability to different environments, L. barbarum has acquired economic significance worldwide in recent decades. It can grow on our peninsula and since the early 2000s many farms turned to this new cultivation with the aim of marketing a 100% Italian product. Since there is a lack of information on these plants grown in Italy, the aim of this PhD project was to study the genetic diversity and the morphological and nutraceutical characteristics of a set of plants derived from seed grown in an organic orchard located in Maremma, with the final aim of obtaining as much information as possible and making the most of their potential locally and on the Italian territory. From a morphological point of view, the plants present a great diversity in habit, vigory and shape and size of the fruits and leaves. Compared to literature, the number of seeds is not only much more variable, but also much higher on average, and appears to be a character dependent on external factors. The shape of the fruit, on the other hand, remains constant from year to year and helps in a more immediate way to discriminate between the plants; four fruit shapes were found (oval, flat apex, round, chili pepper). Four clusters of plants were created based on the shape of the fruit (morphotypes), and then they were sampled in subsequent fruiting seasons for nutraceutical characterization. For the molecular analysis, a set of microsatellite markers (SSR), never used before on this species in Europe, was developed. About 100 genomes were analyzed, seven of which belonged to accessions of known species (L. barbarum and L. chinense) from European Botanical Gardens. The analysis did not identify differences between the plants grown in the studied plantation, which constitute a homogeneous and separate population with respect to accessions with the reference genomes. Also, it derives from two different ancestral populations. Moreover, the morphotypes do not differ each other from a genetic point of view, and therefore cannot be traced back to different landraces or cultivars. From a nutraceutical point of view, the high presence of beneficial substances and antioxidants is confirmed, although in lower concentrations than the values recorded in the native Asian countries, but in line with those of the European literature. The various morphotypes do not have so substantial differences between them, suggesting that they belong to the same cultivar and that the difference in shape of the fruit does not influence the nutraceutical characteristics. Different years have instead led to significant differences, suggesting that climatic factors are decisive for these characteristics: the highest values of many compounds were recorded in 2019, that was the warmest and the wettest year. The fruiting season and its climatic trend also seem to have a decisive influence on the presence and concentration of some metabolites. This was important in understanding when fruits reached their highest nutraceutical potential: in fact, for the content of total antioxidants and flavonoids the best time seems to be the beginning of the fruiting season (July), while the total polyphenols and zeaxanthin have their peaks in September. This aspect can provide good indications for choosing the best time for harvesting based on the intended use of the product. In conclusion, this information could be used together with the descriptors list and the set of SSR markers to characterize other accessions grown in Italy and to design breeding and conservation programs and for the traceability and sustainable use of the resources deriving from these plants.