title: Rapid recovery of photosystems on rewetting desiccation-tolerant mosses: chlorophyll fluorescence and inhibitor experiments.
abstract: In the mosses Racomitrium lanuginosum, Anomodon viticulosus and Rhytidiadelphus loreus, after a few days air dry, F:(v)/F:(m) reached, within the first minute of remoistening in the dark, two-thirds or more of the value attained after 40 min. A fast initial phase of recovery was completed within 10-20 min after which further change was slow. Initial recovery of Phi(PSII) in the light was somewhat slower, but was generally substantially complete within a similar time. Remoistening with 0.3 mM cycloheximide (CHX) or 3 mM dithiothreitol (DTT) made little difference to this short-term (40 min) recovery of either F:(v)/F:(m) or Phi(PSII); 3 mM chloramphenicol (CMP) had little effect on recovery of F:(v)/F:(m), but resulted in substantial (though not total) depression of Phi(PSII) and (14)CO(2) uptake. Effects of the protein-synthesis inhibitors and DTT were much more clearly apparent in longer-term experiments (>20 h) but only in the light. In the dark, the three inhibitors had at most only slight effects over periods of 60-100 h. In the light, CMP-treated samples of all three species showed a progressive decline of dark-adapted F:(v)/F:(m), falling to zero within 1-5 d (possibly due to blocking of the turnover of the D1 protein of PSII) and accelerated by DTT. CHX-treated samples showed a similar but slower decline. In the shade-adapted and relatively desiccation-sensitive Rhytidiadelphus loreus, slow recovery of F:(v)/F:(m) continued in the dark even in the presence of CMP and CHX for much of the 142 h of the experiment. The results indicate that in desiccation-tolerant bryophytes recovery of photosynthesis after periods of a few days air dry requires only limited chloroplast protein synthesis and is substantially independent of protein synthesis in the cytoplasm.
authors.affiliation: School of Biological Sciences, University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter EX4 4PS, UK.
authors.forename: M C
authors.initials: MC
authors.lastname: Proctor
authors.forename: N
authors.initials: N
authors.lastname: Smirnoff
mesh_terms: D000222:Adaptation, Physiological; D019068:Bryopsida / Q000378:metabolism / Q000502:physiology*; D002734:Chlorophyll / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003890:Desiccation; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D002734:Chlorophyll