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Title: Responses of stomatal guard cells to methyl jasmonate
Author: Evans, N. H.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2001
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Previous studies had indicated that the jasmonate family of plant growth regulators (PGR's) might promote stomatal closure, although the mechanistic basis of any effect was not determined. In this study, patch-clamp electrophysiology was used to examine potassium transport across the plasma-membrane of Vicia faba guard cell protoplasts and demonstrated methyl jasmonate (Me-JA) has concentration-dependent effects on transport. At 0.1 μM, Me-JA reduced the conductance of the inward-rectifying potassium channel and increased the conductance of the outward-rectifying potassium channel. This would facilitate the efflux of potassium from the guard cell cytoplasm and a loss of guard cell turgor, indicating how Me-JA might act to promote stomatal closure. In radioactive flux studies, Me-JA promoted the efflux of vacuolar 86Rb+ from Commelina communis guard cells, suggesting it had the ability to mobilise K+ from the major ion store in the turgid guard cell. The results of bioassay experiments supported the conclusions drawn from patch-clamp and radioactive flux work, demonstrating that Me-JA could act to promote stomatal closure in C. communis epidermal peels. In patch-clamp, radioactive flux and bioassay studies, the frequency and magnitude of the Me-JA response varied considerably, suggesting it may have been dependent upon the physiological address of the guard cells. Calcium buffering failed to eliminate Me-JA-induced changes in plasma-membrane K+ channel conductance but nicotinamide inhibited the vacuolar efflux response, suggesting the Me-JA signal is relayed to the tonoplast via a calcium-dependent mechanism.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available