1. The pH of the Apoplast: Dynamic Factor with Functional Impact Under Stress 
Christoph-Martin Geilfus 
Molecular Plant 
Volume 10, Issue 11, Pages (November 2017)
DOI: /j.molp
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2. Figure 1
A Working Model Showing that the pH of the Apoplast Is a Dynamic Factor with Functional Impact Under Stress.
Abiotic stress events such as salinity (solid curve), drought (dotted curve), and the biotic stressor powdery mildew (Blumeria graminis) (dash-dot curve) alkalinize the apoplast. The apoplastic proton concentration decreases only temporally. Duration and magnitude differ between the stressors. Under conditions of salinity and drought, the transient increase in the pHapo reduces the stomatal aperture or is suggested to inhibit stomatal opening via effects exerted through ABA (green box; only shown for drought). The transient alkalinization that is caused by the mycorrhiza fungus Piriformospora indica increases the resistance of Hordeum vulgare against powdery mildew infections (not shown in this model). Indications are increasing that the decrease in the free apoplastic proton concentration counteracts growth due to a pHapo shift away from the range that favors cell-wall loosening (yellow box; only shown for drought). Growth retardation would be favorable under conditions of water scarcity because growth is a process that consumes water.
Molecular Plant  , DOI: ( /j.molp )
Copyright © 2017 The Author Terms and Conditions