Cessation of berry growth coincides with leaf complete stomatal closure at pre-veraison for grapevine (Vitis vinifera) subjected to progressive drought stress

Authors: KNIPFER, THORSTEN - University Of British Columbia; WILSON, NIK - University Of British Columbia; JORGENSEN-BAMBACH, NICOLAS - University Of California, Davis; BARTLETT, MEGAN - University Of California, Davis; McElrone, Andrew; CASTELLARIN, SIMONE - University Of British Columbia

Submitted to: Annals of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2023
Publication Date: 9/24/2023
Citation: Knipfer, T.M., Wilson, N., Jorgensen-Bambach, N., Bartlett, M.K., McElrone, A.J., Castellarin, S.D. 2023. Further examination of the plant water potential curve for characterization of drought responses: Sensitivity and broader application. Annals of Botany. 132:979-988. https://doi.org/10.1093/aob/mcad144.
DOI: https://doi.org/10.1093/aob/mcad144

Interpretive Summary:

Technical Abstract: The water potential (WP) curve was introduced by Knipfer et al. (Plant Physiology) as a cost-effective approach to categorize plant dehydration into three distinct phases and predict drought-induced stomatal closure and turgor loss from corresponding boundary values ('1 and '2, respectively). However, the sensitivity of this promising yet novel approach remains unknown which limits its broader application for physiological phenotyping and irrigation management. We used grapevine (Vitis vinifera ‘Syrah’) as a model system to (i) evaluate WP-curve dynamics over fruit development and removal, (ii) characterize the sensitivity of corresponding WP-curves to predict stomatal closure, (iii) investigate the link between stomatal closure, plant-soil hydraulic breakdown, and fruit shrinkage, and (iv) determine specific isohydricity in relation to stomatal closure. Our data show that WP-curves are unique to fruit development and removal resulting in distinct boundary values '1 and '2 and phase-specific slope (') values. We obtained unequivocal evidence that boundary '1 (separating dehydration phase I and II) predicts the '-thresholds of stomatal closure prior to and during fruit ripening. Boundary '1 coincided with the abrupt decline in predawn water potential under progressive soil drying (i.e. plant-soil hydraulic breakdown) and the onset of fruit shrinkage. Following drought-induced stomatal closure, ' -values obtained during Phase II allowed to resolve the transition from isohydric to anisohydric behaviors over fruit development, suggesting that drought-induced fruit water release predominantly contributes to buffering of xylem tension prior to ripening in this model organism. In conclusion, the WP-curve method represents a widely accessible and integrative approach to obtain advanced knowledge on plant-water relations under drought with future implications for physiological phenotyping and sustainable irrigation practices.