Seasonal dynamics in grapevine physiological and transcriptomic responses to combined water and nitrogen limitation

Abstract

The increasing occurrence of drought events poses a major challenge for viticulture, as water deficit negatively affects vine yield and berry quality. Although grapevine responses to water deficit and nutrient supply have been widely characterized, their combined effects are still not well defined. This study investigated the physiological, ionomic, and transcriptomic responses of two Vitis vinifera L. cultivars subjected to water deficit and nitrogen (N) availability. Two-year-old Cabernet Sauvignon (near-anisohydric) and Grenache (near-isohydric) plants grafted onto SO4 rootstock were grown in soil-filled pots under semi-environmental conditions. Vines were either maintained well-watered or subjected to a controlled water deficit irrigation and received different N fertilization rates. Water deficit significantly reduced vegetative growth in both cultivars, with Grenache exhibiting a slower growth rate than Cabernet Sauvignon. At flowering, water availability emerged as the dominant factor regulating physiological performance, as water deficit reduced stomatal conductance (gs) and increased leaf nutrient concentrations. From veraison onward, N supply strongly modulated gs and leaf ionomic composition in Cabernet Sauvignon, with decreased nutrient accumulation under high N rates. Conversely, Grenache displayed a more stable physiological status and a delayed nutritional response, with major changes occurring mainly at maturity. Transcriptomic analyses revealed cultivar- and stage-specific activation of abiotic stress-related genes (including heat shock proteins and stress-responsive transcription factors), with greater modulation observed at maturity than at flowering. Notably, N treatment strongly influenced the transcriptomic response to water deficit. Overall, these results showed that grapevine responses to combined water and nutrient constraints are strongly dependent on genotype and phenological stage, and involve coordinated physiological, nutritional, and molecular adjustments. This integrative approach provides valuable insights for optimizing irrigation and fertilization practices, contributing to a more resilient and sustainable viticultural system.

Acknowledgements

This work was supported by PRIN 2022PNRR (PIANO NAZIONALE DI RIPRESAE RESILIENZA), M4C2, Inv. 1.1 and receive funding by the European Union – Next generation EU, Spatial characterization of molecular responses to water deficit and nitrogen limitation in grapevine roots – P20222XJKY, CUP G53D23007660001; Agritech National Research Center that received funding from the European Union Next- GenerationEU (PIANO NAZIONALE DI RIPRESAE RESILIENZA(PNRR) – M4C2, Inv. 1.4 – D.D. 1032 17/06/ 2022, CN00000022; Departmental Strategic Plan (PSD) of the University of Udine – Departmental Project on Artificial Intelligence (2020–25).