Desiccation‐tolerant (DT) plants can dry past −100 MPa and subsequently recover function upon rehydration. Vascular DT plants face the unique challenges of desiccating and rehydrating complex tissues without causing structural damage. However, these dynamics have not been studied in intact DT plants. We used high resolution micro‐computed tomography (microCT), light microscopy, and fluorescence microscopy to characterize the dynamics of tissue desiccation and rehydration in petioles (stipes) of intact DT ferns. During desiccation, xylem conduits in stipes embolized before cellular dehydration of living tissues within the vascular cylinder. During resurrection, the chlorenchyma and phloem within the stipe vascular cylinder rehydrated before xylem refilling. We identified unique stipe traits that may facilitate desiccation and resurrection of the vascular system, including xylem conduits containing pectin (which may confer flexibility and wettability); chloroplasts within the vascular cylinder; and an endodermal layer impregnated with hydrophobic substances that impede apoplastic leakage while facilitating the upward flow of water within the vascular cylinder. Resurrection ferns are a novel system for studying extreme dehydration recovery and embolism repair in the petioles of intact plants. The unique anatomical traits identified here may contribute to the spatial and temporal dynamics of water movement observed during desiccation and resurrection.
- Award ID(s):
- 1656876
- NSF-PAR ID:
- 10157420
- Date Published:
- Journal Name:
- Journal of Experimental Botany
- Volume:
- 71
- Issue:
- 3
- ISSN:
- 0022-0957
- Page Range / eLocation ID:
- 1139 to 1150
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Plain Language Summary can be found within the Supporting Information of this article. -
PREMISE Desiccation tolerance (DT) is a widespread phenomenon among land plants, and variable ecological strategies for DT are likely to exist. Using
Syntrichia caninervis , a dryland moss and model system used in DT studies, we hypothesized that DT is lowest in juvenile (protonemal) tissues, highest in asexual reproductive propagules (gemmae), and intermediate in adults (shoots). We tested the long‐standing hypothesis of an inherent constitutive strategy of DT in this species.METHODS Plants were rapidly dried to levels of equilibrating relative humidity (
RHeq ) ranging from 0 to 93%. Postrehydration recovery was assessed using chlorophyll fluorescence, regeneration rates, and visual tissue damage. For each life phase, we estimated the minimum rate of drying (RoDmin ) atRHeq = 42% that did not elicit damage 24 h postrehydration.RESULTS DT strategy varied with life phase, with adult shoots having the lowest
RoDmin (10‒25 min), followed by gemmae (3‒10 h) and protonema (14‒20 h). Adult shoots exhibited no detectable damage 24 h postrehydration following a rapid‐dry only at the highestRHeq used (93%), but when dried to lower RHs the response declined to <50% of control fluorescence values. Notably, immediately following rehydration (0 h postrehydration), shoots were damaged below control levels of fluorescence regardless of theRHeq , thus implicating damage.CONCLUSIONS Life phases of the moss
S. caninervis had a range of strategies from near constitutive (adult shoots) to demonstrably inducible (protonema). A new response variable for assessing degree of DT is introduced as the minimum rate of drying from which full recovery occurs. -
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