Investigations of ABA Signalling Pathways in Stomatal Guard Cells.

Montgomery, Lucy Theresa (1998) Investigations of ABA Signalling Pathways in Stomatal Guard Cells. PhD thesis, UNSPECIFIED.

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Abstract

The effect of analogues of abscisic acid (ABA) on stomatal aperture and GUS activity driven by an ABA-responsive gene promoter (CDeT6-19) in guard cells was examined. The ABA analogues used were (-)-ABA, (+/-)-trans, trans-ABA, and (+)-and (-)-dihydroacetylenic abscisyl alcohol (PB1-63 and PBI-51, respectively). (+)-ABA and (+/-)-ABA were included in the investigations for comparison. (-)-ABA, hitherto believed to have little or no effect on stomatal aperture, significantly inhibited stomatal opening in Commelina communis, Vicia faba, Nicotiana tabacum and Arabidopsis thaliana. In contrast, PBI-51 [a competitive inhibitor of ABA-induced gene expression] had no effect on ABA-induced inhibition of stomatal opening (determined in both C. communis and N. tabacum) or ABA-induced promotion of stomatal closure (determined in C. communis only). Differences in the effectiveness of PBI-63, PBI-51 and (-)-ABA at inhibiting stomatal opening were discovered between plant species. These data demonstrate the importance of comparing the effect of ABA analogues on stomatal opening and CDeT6-19/GUS activity in guard cells in a single plant species. (+/-)-ABA enhanced CDeT6-J9/GUS activity in guard cells of A. thaliana but not N. tabacum. The ABA analogues that inhibited stomatal opening in A. thaliana also enhanced CDeT6-J9/GUS activity in guard cells of this species. The relative biological activity of the ABA analogues in detached epidermis of A. thaliana was (+)-ABA > (+/-)-ABA > (-)-ABA > PBI-63. PBI-51 and (+/-)-trans, trans-ABA had no effect on stomatal opening or CDeT6-19/GUS activity in guard cells of A. thaliana. Interestingly, a differential effect of 10 -5 M (-)-ABA on the two ABA-induced responses in A. thaliana was observed; 10 -5 M (-)-ABA enhanced CDeT6-J9/GUS activity in guard cells but had no effect on stomatal opening. Preliminary measurements of guard cell cytosolic free calcium ([Ca2+]i) showed that (-)-ABA induced oscillations in [Ca2+]i in guard cells of C. communis. In addition, these studies demonstrate the possibility of microinjecting guard cells of A. thaliana with fura-2 and provide a measure of resting [Ca2+]i in this species. The data presented in this thesis from A. thaliana suggest that the "receptor" utilized in the signalling pathway by which ABA inhibits stomatal opening is similar but not identical to that by which ABA enhances CDeT6-19/GUS activity in guard cells.

Item Type:
Thesis (PhD)
Additional Information:
Thesis (Ph.D.)--Lancaster University (United Kingdom), 1998.
Subjects:
ID Code:
133547
Deposited By:
Deposited On:
02 May 2019 16:35
Refereed?:
No
Published?:
Unpublished
Last Modified:
17 Sep 2020 07:07