Prehydration Mitigates Damage Accrued From Prolonged Periods of Desiccation in Cultured Shoot Apices of Syntrichia ruralis

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Journal of Bryology

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© British Bryological Society 2020. Introduction.: We hypothesised that a prehydration period (exposure to humid air) should mitigate the damaging effects of short or long periods of desiccation in a desert moss, Syntrichia ruralis. Methods.: Cultured uniclonal shoots of S. ruralis were dried rapidly, equilibrated at 42% relative humidity (RH), allowed to remain at this RH for 1–50 days, and either (1) prehydrated (24 h at 100% RH) then rehydrated with liquid water, or (2) rehydrated directly using liquid water without a prehydration treatment, and assessed using chlorophyll fluorescence and visual damage. Key results.: At both 20 min and 24 h postrehydration, all chlorophyll fluorescence measures (F m, F v/F m, ΦPSII, qP) were higher in shoots that were prehydrated. Prehydrated S. ruralis shoots also had less visual leaf damage 7 d postrehydration. Duration-dry (DD) had an overall negative effect for all fluorescence measures on shoots immediately after rehydration, an effect that dissipated at 24 h postrehydration in three of the four fluorescence measures (F m, F v/F m, ΦPSII). Leaf damage was not influenced by Duration-dry. Although no interaction was detected between Prehydration and Duration-dry treatments, the benefits of prehydration were accentuated based on fluorescence metrics F v/F m and ΦPSII, when shoots are exposed to longer drying periods. Conclusions.: A prehydration treatment implemented just prior to hydration with liquid water significantly mitigated shoot damage accrued from a prior rapid drying event and DDs of up to 50 d at 42% RH. Based on photosynthetic efficiency, prehydration conferred greater effects at longer DDs. Experiencing humid conditions prior to rainwater mitigates damage incurred during prolonged desiccation.


Chlorophyll fluorescence; Constitutive; Desiccation tolerance; Equilibrating relative humidity; Inducible; Suprasaturation


Botany | Plant Sciences



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