Ionome Dynamics in Grapevine Leaves

Despite extensive studies, global patterns governing the accumulation of essential and non-essential elements in grapevine leaves remain insufficiently understood. Therefore, a comprehensive literature survey of 148 studies (selected according to PRISMA 2020 guidelines) was compared with authentic elemental analyses of young and mature leaves of the white cultivar Rhein Riesling and the red cultivar Cabernet Sauvignon to identify the major drivers of grapevine leaf ionome composition. In unstressed grapevine leaves, macroelements followed the concentration order Ca > K > Mg > P, whereas microelements decreased in the order Fe > Mn > Cu > B > Zn > Mo. Seasonal development was associated with opposite trends between Ca and Mg versus K and P. Geographic origin and berry color were associated mainly with differences in Ca, P, Mn, Cu and Fe concentrations. In our authentic samples, potentially toxic elements occurred at substantially lower concentrations than commonly reported in the literature (mainly Pb, Co, As, Cd, Cs, Al, Sr, Ba, Li and Zr). Mature leaves accumulated higher levels of non-essential elements than young leaves, although bioaccumulation from soil remained generally low. Correlation analyses further demonstrated cultivar-dependent relationships among elements, particularly involving Mg. Multivariate analyses revealed that leaf developmental stage represented the primary factor shaping elemental composition, while cultivar-specific effects constituted a secondary but detectable source of variation. Our results identify phenological stage as a dominant factor controlling ionomic composition and suggest that Mg-, Fe-, Zn-, and Cu-associated processes may contribute to the regulation of the accumulation of toxic elements in grapevine leaves.