Is infiltration of the apoplast a problem?
Although infiltration of the apoplast may be a relatively rare naturally occurring event during flooding or water logging, wherever it happens, it has fatal consequences. The apoplast is very sensitive to the slightest mechanical and chemical disturbances, as well as to alterations in the ion content and to oxygen shortage. Whereas the rapid and transient increase in pH by almost 2 units following local nano-infusion is probably caused by mechanical stress, i.e. by displacing the gas and subsequent wetting the apoplast surface, the longer-lasting increased pH (about pH 6) may in fact be due to oxygen shortage through which the H+ pump activity gets reduced, with the consequence that no or very few H+ ions are exported. This interpretation is supported by control tests (Fig. 2) in which the activity of the H+ pump was manipulated by FC (stimulation) or cyanide (deactivation). From the light/dark responses shown in Fig. 3B, it is also obvious that an infiltrated apoplast will not be full
