Metabolite analysis reveals distinct spatio-temporal accumulation of anthocyanins in two teinturier variants of cv. 'Gamay' grapevines (Vitis vinifera L.)

Main conclusion White-fleshed grape cv. 'Gamay' and its two teinturier variants presented distinct spatial-temporal accumulation of anthocyanins, with uncoupled accumulation of sugars and anthocyanins in 'Gamay Freaux'. In most red grape cultivars, anthocyanins accumulate exclusively in the berry skin, while 'teinturier' cultivars also accumulate anthocyanins in the pulp. Here, we investigated the teinturier cvs. 'Gamay de Bouze' and 'Gamay Freaux' (two somatic variants of the white-fleshed cv. 'Gamay') through metabolic and transcript analysis to clarify whether these two somatic variants have the same anthocyanin accumulation pattern in the skin and pulp, and whether primary metabolites are also affected. The skin of the three cultivars and the pulp of 'Gamay de Bouze' begun to accumulate anthocyanins at the onset of berry ripening. However, the pulp of 'Gamay Freaux' exhibited a distinct anthocyanin accumulation pattern, starting as early as fruit set with very low level of sugars. The highest level of anthocyanins was found in 'Gamay Freaux' skin, followed by 'Gamay de Bouze' and 'Gamay'. Consistently, the transcript abundance of genes involved in anthocyanin biosynthesis were in line with the anthocyanin levels in the three cultivars. Despite no evident differences in pulp sugar content, the concentration of glucose and fructose in the skin of 'Gamay Freaux' was only half of those in the skin of 'Gamay' and 'Gamay de Bouze' throughout all berry ripening, suggesting an uncoupled accumulation of sugars and anthocyanins in 'Gamay Freaux'. The study provides a comprehensive view of metabolic consequences in grape somatic variants and the three almost isogenic genotypes can serve as ideal reagents to further uncover the mechanisms underlying the linkage between sugar and anthocyanin accumulation.

Automated summary

The study investigated the accumulation of anthocyanins in white-fleshed grape cv. 'Gamay' and its teinturier variants, revealing distinct patterns of anthocyanin accumulation and uncoupled accumulation of sugars and anthocyanins in 'Gamay Freaux'. Despite no evident differences in pulp sugar content, the concentration of glucose and fructose in the skin of 'Gamay Freaux' was significantly lower, suggesting a unique metabolic profile in this variant. The findings provide insights into the metabolic consequences and the linkage between sugar and anthocyanin accumulation in grape somatic variants.