Location: Crops Pathology and Genetics ResearchTitle: Predicting stomatal closure and turgor loss in woody plants using predawn and midday water potential
|KNIPFER, THORSTEN - University Of California, Davis|
|BAMBACH, NICOLAS - University Of California, Davis|
|HERNANDEZ, MARIA - University Of California, Davis|
|BARTLETT, MEGAN - University Of California, Davis|
|SINCLAIR, GABRIELA - University Of California, Davis|
|DUONG, FIONA - University Of California, Davis|
Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2020
Publication Date: 8/6/2020
Citation: Knipfer, T., Bambach, N., Hernandez, M.I., Bartlett, M.K., Sinclair, G., Duong, F., Kluepfel, D.A., McElrone, A.J. 2020. Predicting stomatal closure and turgor loss in woody plants using predawn and midday water potential. Plant Physiology. 184(2):881-894. https://doi.org/10.1104/pp.20.00500.
Interpretive Summary: The relationship of predawn and midday water potential exhibits three distinct phases, and a method was developed that allows for a more time-effective and less labor-intensive way to determine the stress threshold of stomatal closure and turgor loss based on these curve characteristics.
Technical Abstract: Knowledge about process-specific stress thresholds provides crucial information about plant performance & survival under drought, but underlying measurements can be experimentally challenging and time-consuming. In this study we report on the triphasic nature of the relationship between predawn and midday water potential, and a method is described which permits determination of stomatal closure, turgor loss and efficiency of stomata regulation exclusively from measurements of water potential. Data collected on walnut trees showed that the relationship of midday versus predawn water potential can be divided into three distinct phases. A piecewise linear regression model was developed to calculate the boundaries between phases and corresponding slope values. Our model predicted that midday water potential was much more negative than predawn water potential during phase-I, reductions in midday water potential were minor while predawn water potential continued to decline during phase-II, and midday and predawn water potential reached similar values during phase-III. Corresponding measurements of leaf gas exchange and turgor revealed that the calculated boundaries between phase-I to -II and -II to -III coincided with the water potential thresholds for stomatal closure and turgor loss, respectively. In addition, the triphasic curve shape of predawn and midday water potential was found to be genotype- and species-specific and allowed to derive plant specific information about its leaf physiological responses under drought stress. The method developed here provides for a more time-efficient and less labor-intensive procedure to obtain water potential thresholds indicative for stomatal closure and turgor loss for plants experiencing water stress by drought.