Declining root water transport drives stomatal closure in olive undermoderate water stress

9 páginas.-4 figuras.- 45 referencias.- Additional Supporting Information may be found online in theSupporting Information section at the end of the article http://dx.doi.org/10.1111/nph.16177

Efficient water transport from soil to leaves sustains stomatal opening and steady-statephotosynthesis. The aboveground portion of this pathway is well-described, yet the roots andtheir connection with the soil are still poorly understood due to technical limitations. Here we used a novel rehydration technique to investigate changes in the hydraulic pathwaybetween roots and soil and within the plant body as individual olive plants were subjected to arange of water stresses. Whole root hydraulic resistance (including the radial pathway from xylem to the soil–rootinterface) constituted 81% of the whole-plant resistance in unstressed plants, increasing to>95% under a moderate level of water stress. The decline in this whole root hydraulicconductance occurred in parallel with stomatal closure and contributed significantly to thereduction in canopy conductance according to a hydraulic model. Our results demonstrate that losses in root hydraulic conductance, mainly due to a disconnectionfrom the soil during moderate water stress in olive plants, are profound and sufficient to inducestomatal closure before cavitation occurs. Future studies will determine whether this coreregulatory role of root hydraulics exists more generally among diverse plant species

Thisstudy was supported by funds from an Individual Fellowship fromthe European Union’s Horizon 2020 research and innovationprogramme under the Marie Skłodowska-Curie grant agreementno. 751918-AgroPHYS to CMR-D and from the AustralianResearch Council, Discovery Projects, DP170100761 to TJB

Peer reviewed