Aquaporin Translation Tunes Plant Water Transport to External Conditions in Grapevine

Water stress challenges global crop productivity, particularly for perennial species such as grapevines, where effective water management is crucial for berry quality and yield. Aquaporins, a family of water channel proteins, play a key role in regulating water transport within plant cells, affecting water uptake and redistribution. Although the transcriptional response of aquaporin genes to water stress in grapevines has been documented, their translational regulation remains less explored. This study investigates the transcriptional and translational dynamics of three Plasma Membrane Intrinsic Proteins and three Tonoplast Intrinsic Proteins in leaves and roots of a grafted ‘Pinot Noir’ on ‘Kober 5BB’ rootstock during water deficit conditions and recovery. Aquaporin translation analyzed by polysome profiling and co-sedimentation analysis of their transcripts highlighted that water stress had a general negative effect, although significant only for VviTIP1-3. Conversely, recovery measured at 6 h after rewatering was characterized by a boost of translation reactivation for all but one aquaporins. Transcriptional profiling of the same aquaporins revealed significant down-regulation at prolonged stress in roots, highlighting the contribution of aquaporins to osmoregulation and drought tolerance. Moreover, transcriptional modulation resembles a long-term adaptative response to limit water loss. In the leaf, only two specific genes, VviPIP2-5 and VviTIP2-1, were modulated during water deficit and even more during recovery and positively correlated with stomatal conductance and leaf water potential. They represent important regulators of water homeostasis and good candidates for breeding programs. This study uncovered an additional level of aquaporin post-transcriptional control finely tuning vines to changing external conditions.