Cell expansion in the filamentous gametophyte of the fernOnoclea sensibilis L. |
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Authors: | Todd J Cooke Richard H Racusen |
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Institution: | (1) Department of Botany, University of Maryland, 20742 College Park, MD, USA |
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Abstract: | Filamentous gametophytes of the fernO. sensibilis were exposed to paired combinations of light of different qualities, hormones and cations in the attempt to elucidate the underlying processes that regulate cell expansion. Simultaneous treatments with high-pH buffers or the auxin antagonistp-chlorophenoxyisobutyric acid abolished blue-light-mediated expansion but did not influence growth in red light. In contrast, the red-light response was preferentially altered by the ethylene absorbant KMnO4 or the Ca2+ chelator ethyleneglycol-bis(-aminoethyl ether) N,N-tetraacetic acid. The Ca2+ ionophore A23187 caused a significant reduction in cell expansion under both blue and red irradiation. A marked promotion of expansion was mediated by high concentrations of indole-3-acetic acid, but this effect was dependent on the presence of low-pH buffers. The ethylene-generating agent 2-chloroethylphosphonic acid decreased the magnitudes of both photoresponses; this inhibition was further enhanced by high Ca2+ concentrations. These findings and those with other plants are interpreted in terms of two independent control mechanisms for cell expansion: 1) a blue light photoreceptor-auxin-hydrogen ion system, and 2) a phytochrome-ethylene-calcium ion system.Abbreviations APW-X
artificial pond water (the associated number designates pH)
- CEPA
2-chloroethylphosphonic acid
- EGTA
ethyleneglycol-bis(-aminoethyl ether)N,N-tetraacetic acid
- IAA
indole-3-acetic acid
- PCIB
p-chlorophenoxyisobutyric acid |
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Keywords: | Blue light photoreceptor Cell expansion Gametophyte (fern) Onoclea Phytochrome Pteridophytes Tip growth |
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