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ABA Contents in the Guard-Cell Symplast and Guard-Cell Apoplast Are Not Correlated with Stomatal Aperture Size under Three Conditions of Water Sufficiency

Title: ABA Contents in the Guard-Cell Symplast and Guard-Cell Apoplast Are Not Correlated with Stomatal Aperture Size under Three Conditions of Water Sufficiency.
Name(s): Meng, Fanxia, Ph. D., author
Outlaw, William H., Jr., professor directing dissertation
Logan, Timothy M., outside committee member
Bass, Hank W., committee member
Bates, George W., committee member
Epstein, Lloyd M., committee member
Keller, Laura R., committee member
Department of Biological Science, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2007
Publisher: Florida State University
Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Guard cells respond to environmental stimuli by opening and closing stomata, which balance CO2 uptake and water conservation. Stomatal closure under water deficiency and the involvement of abscisic acid (ABA) in this response are well-known. However, whether ABA plays a role in stomatal regulation under some water-sufficient conditions, such as diurnal changes, humidity shift (i.e. transpiration-rate change) and brief flooding, is not clear. Using an enzyme-linked immunosorbent assay (ELISA) with sub-femtomole sensitivity for ABA assays, we studied the relationships of stomatal aperture size with the ABA contents in the symplast and apoplast of guard cells, as well as those in the leaf and the leaf apoplast in Vicia faba under the following three conditions. (1) Diurnal changes. Stomata opened in the morning, reached a maximum opening at 1400 h, and closed at 1800 h. Neither the leaf nor the leaf apoplastic ABA content strongly correlated with stomatal aperture sizes. The ABA contents of the guard-cell compartments did not change over the course of the day, providing evidence that ABA is not involved in diurnal stomatal regulation. (2) Humidity-induced transpiration-rate changes. The transpiration rate of intact plants and that of detached leaves infused with 1µM ABA was decreased by shifting RH from 60% to 90%. The ABA contents of the four compartments were not changed by this humidity shift, in spite of an increase of 2–3 µm in stomatal aperture sizes. Thus, the guard-cell-apoplastic ABA content is not affected by transpiration rate, and ABA may not participate in the stomatal response to transpiration rate. (3) Brief flooding. Stomata closed after brief (4-h) flooding, when the leaf and the leaf apoplastic ABA increased 2–3 fold and the xylem pH increased 0.2 pH units. The leaf ABA increase did not correlate strongly with stomatal aperture size and the xylem ABA delivery rate remained unchanged. The ABA contents in the guard-cell compartments of flooded plants were not different from those of non-flooded plants. Therefore, ABA may not be an initiator of stomatal closure under brief flooding, and xylem alkalinization probably does not induce leaf ABA redistribution to guard cells.
Identifier: FSU_migr_etd-2485 (IID)
Submitted Note: A Dissertation Submitted to the Department of Biological Science in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy.
Degree Awarded: Spring Semester, 2007.
Date of Defense: December 1, 2006.
Keywords: Abscisic Acid, Guard Cell, Transpiration Rate, Flooding, Vicia Faba Humidity, Diurnal Changes, Stomata
Bibliography Note: Includes bibliographical references.
Advisory Committee: William H. Outlaw, Jr., Professor Directing Dissertation; Timothy M. Logan, Outside Committee Member; Hank W. Bass, Committee Member; George W. Bates, Committee Member; Lloyd M. Epstein, Committee Member; Laura R. Keller, Committee Member.
Subject(s): Biology
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Host Institution: FSU

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Meng, F. (2007). ABA Contents in the Guard-Cell Symplast and Guard-Cell Apoplast Are Not Correlated with Stomatal Aperture Size under Three Conditions of Water Sufficiency. Retrieved from