Journal Article

Rapid recovery of photosystems on rewetting desiccation‐tolerant mosses: chlorophyll fluorescence and inhibitor experiments

Michael C.F. Proctor and Nicholas Smirnoff

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 51, issue 351, pages 1695-1704
Published in print October 2000 | ISSN: 0022-0957
Published online October 2000 | e-ISSN: 1460-2431 | DOI:
Rapid recovery of photosystems on rewetting desiccation‐tolerant mosses: chlorophyll fluorescence and inhibitor experiments

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In the mosses Racomitrium lanuginosum, Anomodon viticulosus and Rhytidiadelphus loreus, after a few days air dry, Fv/Fm 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 ΦPSII 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 Fv/Fm or ΦPSII; 3 mM chloramphenicol (CMP) had little effect on recovery of Fv/Fm, but resulted in substantial (though not total) depression of ΦPSII and 14CO2 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 Fv/Fm, 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 Fv/Fm 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.

Keywords: Anomodon viticulosus; bryophytes; desiccation tolerance; protein synthesis; Rhytidiadelphus loreus; Racomitrium lanuginosum.

Journal Article.  6508 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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