Location: Crops Pathology and Genetics ResearchTitle: The causes of leaf hydraulic vulnerability and its influence on stomatal conductance and photosynthetic rate in Arabidopsis thaliana
|SCOFFINI, CHRISTINE - University Of California|
|ALBUQUERQUE, CAETANO - University Of California, Davis|
|COCHARD, HERVE - Institut National De La Recherche Agronomique (INRA)|
|BUCKLEY, THOMAS - University Of California, Davis|
|FLETCHER, LEILA - University Of California|
|CARINGELLA, MARISSA - University Of California|
|BARTLETT, MEGAN - University Of California|
|BRODERSEN, CRAIG - Yale University|
|JANSEN, STEVEN - Ulm University|
|SACK, LAWREN - University Of California|
Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2018
Publication Date: 12/7/2018
Citation: Scoffini, C., Albuquerque, C., Cochard, H., Buckley, T., Fletcher, L., Caringella, M., Bartlett, M., Brodersen, C., Jansen, S., McElrone, A.J., Sack, L. 2018. The causes of leaf hydraulic vulnerability and its influence on stomatal conductance and photosynthetic rate in Arabidopsis thaliana. Plant Physiology. 178(4):1584-1601. https://doi.org/10.1104/pp.18.00743.
Interpretive Summary: Water scarcity threatens plant growth in natural and agricultural ecosystems worldwide. We studied how drought induced water stress alters the ability of leaves to transport water to the sites where it is exchanged for carbon dioxide in the model plant Arabidopsis. Using a variety of techniques including x-ray micro computed tomography, we found that changes in leaf mesophyll properties drive leaf and whole plant hydraulic decline with dehydration instead of air bubble blockages in leaf veins.
Technical Abstract: The influence of the dynamics of leaf hydraulic conductance (Kleaf) diurnally and during dehydration on stomatal conductance and photosynthesis remains unclear. Using the model species Arabidopsis (Arabidopsis thaliana ecotype Columbia-0), we applied a multitiered approach including physiological measurements, high-resolution x-ray microcomputed tomography, and modeling at a range of scales to characterize (1) Kleaf decline during dehydration; (2) its basis in the hydraulic conductances of leaf xylem and outside-xylem pathways (Kox); (3) the dependence of its dynamics on irradiance; (4) its impact on diurnal patterns of stomatal conductance and photosynthetic rate; and (5) its influence on gas exchange and survival under simulated drought regimes. Arabidopsis leaves showed strong vulnerability to dehydration diurnally in both gas exchange and hydraulic conductance, despite lack of xylem embolism or conduit collapse above the turgor loss point, indicating a pronounced sensitivity of Kox to dehydration. Kleaf increased under higher irradiance in well-hydrated leaves across the full range of water potential, but no shift in Kleaf vulnerability was observed. Modeling indicated that responses to dehydration and irradiance are likely attributable to changes in membrane permeability and that a dynamic Kox would contribute strongly to stomatal closure, improving performance, survival, and efficient water use during drought. These findings for Columbia-0 provide a baseline for assessing variation across genotypes in hydraulic traits and their influence on gas exchange during dehydration.