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Publication Type J
Authors Touchette, B. W., S. R. Schmitt and J. W. G. Moody
Title Enhanced thermotolerance of photosystem II by elevated pore-water salinity in the coastal marsh graminoid Sporobolus pumilus
Source Aquatic Biology
Author Keywords Photosynthesis Chlorophyll fluorescence Photosystem II Heat stress Salt stress chlorophyll-a fluorescence salt-marsh spartina-alterniflora osmotic adjustment high-temperature glycine betaine plant zonation heat tolerance stress photosynthesis
Abstract In coastal marsh ecosystems, high salinities, anoxic waterlogged soils, and elevated summer temperatures often promote physiological strain that results in only a few tolerant halophytic species. Although not well understood, plant physiological responses to multiple stressors can be complex and may involve intensifying or offsetting reactions. In this study, we investigated physiological responses to combined salinity and high temperature in the coastal marsh graminoid Sporobolus pumilus (syn. Spartina patens). Specifically, we considered changes in plant-water relations and Photosystem II (PSII) behavior (involving chlorophyll [chl] a fluorescence) in heat-shocked plants that were acclimated to different salinities (0, 15, and 30 psu). Higher salinities fostered lower stomatal conductance (g), lower leaf-water potential (Psi(leaf)) and lower tissue-water content (theta), as well as decreased potential quantum yield (F-v/F-m) and decreased excitation energy capture efficiencies of open reaction centers (F-v'/F-m'). Heat-shocked plants acclimated to freshwater only had decreased F-v/F-m and PSII performance index (PIABS). Interestingly, there were no changes in chl a fluorescent outputs in heat-shocked plants acclimated to moderate salinities, and minimal changes in plants acclimated to high salinities. Approximately 25% of the heat-shocked S. pumilus in freshwater revealed a K-step in their polyphasic chl a fluorescent transients (OJIP procedure); K-steps were not observed in salt-treated plants. This suggests that, for plants residing in freshwater, heat-shock promoted disturbances in the PSII reaction centers and, in some cases, disrupted the oxygen-evolving complex. These PSII disruptions were either absent or less intense in salinity-treated plants, indicating that acclimation to environmental salts may provide PSII thermostability in S. pumilus.
Author Address [Touchette, Brant W.] Elon Univ, Dept Biol, Elon, NC 27244 USA. [Touchette, Brant W.; Schmitt, Sarah R.; Moody, John W. G.] Elon Univ, Dept Environm Studies, Elon, NC 27244 USA. [Schmitt, Sarah R.] Appl Res Associates, Arlington, VA 22203 USA. Touchette, BW (corresponding author), Elon Univ, Dept Biol, Elon, NC 27244 USA.; Touchette, BW (corresponding author), Elon Univ, Dept Environm Studies, Elon, NC 27244 USA. btouchette@elon.edu
ISSN 1864-7790
ISBN 1864-7790
29-Character Source Abbreviation Aquat. Biol.
Year Published 2020
Volume 29
Beginning Page 111-122
Digital Object Identifier (DOI) 10.3354/ab00730
Unique Article Identifier WOS:000621198200002
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