AUTHOR=Dayer Silvina , Scharwies Johannes D. , Ramesh Sunita A. , Sullivan Wendy , Doerflinger Franziska C. , Pagay Vinay , Tyerman Stephen D. 

TITLE=Comparing Hydraulics Between Two Grapevine Cultivars Reveals Differences in Stomatal Regulation Under Water Stress and Exogenous ABA Applications

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00705

DOI=10.3389/fpls.2020.00705

ISSN=1664-462X

ABSTRACT=<p>Hydraulics of plants that have different strategies of stomatal regulation under water stress are relatively poorly understood. We explore how root and shoot hydraulics, stomatal conductance (<italic>g</italic><sub>s</sub>), leaf and root aquaporin (AQP) expression, and abscisic acid (ABA) concentration in leaf xylem sap ([ABA]<sub>xylemsap</sub>) may be coordinated under mild water stress and exogenous ABA applications in two <italic>Vitis vinifera</italic> L. cultivars traditionally classified as near-isohydric (Grenache) and near-anisohydric (Syrah). Under water stress, Grenache exhibited stronger adjustments of plant and root hydraulic conductances and greater stomatal sensitivity to [ABA]<sub>xylemsap</sub> than Syrah resulting in greater conservation of soil moisture but not necessarily more isohydric behavior. Correlations between leaf (Ψ<sub>leaf</sub>) and predawn (Ψ<sub>PD</sub>) water potentials between cultivars suggested a “hydrodynamic” behavior rather than a particular iso-anisohydric classification. A significant decrease of Ψ<sub>leaf</sub> in well-watered ABA-fed vines supported a role of ABA in the soil-leaf hydraulic pathway to regulate <italic>g</italic><sub>s</sub>. Correlations between leaf and root AQPs expression levels under water deficit could explain the response of leaf (<italic>K</italic><sub>leaf</sub>) and root (<italic>Lp</italic><sub>r</sub>) hydraulic conductances in both cultivars. Additional studies under a wider range of soil water deficits are required to explore the possible differential regulation of <italic>g</italic><sub>s</sub> and plant hydraulics in different cultivars and experimental conditions.</p>