Clone-specific transcript profiling of 'Nebbiolo' grape berries unveils environmental responses mediated by sugar and secondary metabolite signalling

"During the last years, several research works were addressed to uncover how different grapevine cultivars respond to environmental conditions, nevertheless the molecular mechanisms tuning this phenomenon needs to be further deepened. In particular, little is known on the molecular processes underlying the interplay between clones of the same cultivar and vineyard. In order to investigate this point, we analyzed the transcriptome of berries collected over the ripening period from three 'Nebbiolo' clones (CVT 71, CVT 423, CVT 185, whose respective genome sequences have recently been released) grown in three different vineyards of the Langhe area (Piedmont, North-West Italy), in two years. Transcriptomic data obtained through RNA-sequencing analysis were integrated by: i) real-time RT-qPCR of candidate genes; ii) HPLC quantification of abscisic acid, flavonoid and stilbenoid contents; iii) agronomical parameters; and iv) climate conditions. This multidisciplinary approach was instrumental for exploring the whole complexity of the genotype-environment interaction and identifying the molecular changes controlled by clone, vineyard, phenological phase or a combination of them. The results showed that transcript categories associated to sugar mediated-signalling, anthocyanin biosynthesis and transport can be differently modulated among diverse clones of the same cultivar, thus influencing related yields in terms of berry quality and agronomical features. Conversely, genes involved in the production of secondary metabolites, typically playing a role in stress response such as stilbenoids, were significantly affected by the vineyard location, consistently with the accumulation patterns of different stilbenoids.We thus demonstrated that clone-specific molecular responses exert a key role in determining the agronomic performances of a grapevine variety in different environments. These results provide valuable indications also for directing viticulture practices aimed at enhancing the typicality of grapevine productions in light of both the cultivation area and clone choice."