VALORISING TUSCAN VARIETIES OF SWEET CHERRY (PRUNUS AVIUM L.) THROUGH AN INTEGRATED APPROACH: GENE EXPRESSION ANALYSIS COUPLED TO METABOLOMICS AND PROTEOMICS

A strong interest is given to sustainable agricultural practices valorising the local biodiversity of territories and promoting, at the regional level, products deriving from locally-grown non-commercial varieties. These varieties designate plants that were grown in the past, but that have not been subject to a market-driven pressure, thereby falling out of agricultural interest. Ancient varieties are considered wild, since they can thrive in soils where the human input is minimal and are sources of interesting agronomic characters, notably higher resilience to adverse environmental conditions. Italy has started conservation programs aimed at preserving the local biodiversity via ex situ collections; in this respect Tuscany is at the forefront, with a regional law (law 64/04) created for the recovery and preservation of local varieties of woody and herbaceous plant species. The fruits produced by ancient varieties can diversify the options offered by local markets and are equally rich sources of functional molecules with nutraceutical value. With a view to valorize non-commercial regional sweet cherry varieties of Tuscany, the present PhD thesis characterised the Tuscan repertoire of Prunus avium L., by using complementary approaches comprising genotyping, gene expression analysis, as well as metabolomics and proteomics. The fruits of sweet cherry are rich sources of health-promoting compounds. Among the beneficial phytochemicals are different classes of phenolic compounds produced via the phenylpropanoid pathway, an important hub of plant secondary metabolism. The content of phenolic compounds was measured in six ancient P. avium varieties from Tuscany (Benedetta, Carlotta, Crognola, Maggiola, Moscatella and Morellona) sampled at the stage of commercial harvest (ca. 60 dpa, days post anthesis). The results cover three consecutive years of sampling (2016-2017-2018) to highlight the variations in functional molecule content linked to the environmental conditions encountered during the years. Higher levels of phenolic compounds were quantified in the Tuscan sweet cherries, as compared to the fruits of the commercial variety Durone. In particular, the varieties Crognola and Morellona are the top-producers of phenolics. The expression analysis reveals the presence of different expression patterns of the genes involved in the early and late steps of the phenylpropanoid pathway, both among the genotypes and the years. Finally, the soluble proteomes of the two highest producers of functional molecules, i.e. Crognola and Morellona, reveal differences in proteins related to cell wall remodelling, redox balance and stress response. In conclusion, the results presented draw attention on the nutraceutical potential of ancient P. avium varieties from Tuscany and stress the importance of a multidisciplinary approach encompassing gene expression and metabolomic analyses.