| Abstract Detail
Integrative Plant Physiology Sherdan, Danielle M. [1], Outlaw, William H. [2]. Transpiration Rate Regulates Expression of Carbohydrate-associated Genes in Guard Cells. Stomata in the leaf epidermis regulate transpiration rate and CO2 uptake for photosynthesis by changing aperture size. In low humidity conditions, which favor high transpiration rates, stomatal aperture size is smaller, the sucrose concentration in the guard-cell apoplast is higher, and the sucrose concentration in the guard-cell symplast is lower than with low transpiration rates. We tested the hypothesis that transpiration-linked sucrose-concentration changes in and around guard cells regulate the abundances of carbohydrate-related transcripts in guard cells. Target transcripts with protein products involved in sugar transport or metabolism (e.g. RuBisCO and cell-wall invertase) in guard cells and whole leaves of Vicia faba under different relative humidity treatments were measured at selected time-points throughout the day utilizing real-time RT-PCR. We present diurnal- and transpiration-regulated gene expression specifically in guard cells. For example, the afternoon maximal expression of the hexose transporter in guard cells with low transpiration rates was two-fold higher than with high transpiration rates, whereas the maximal expression of the sucrose transporter and of cell-wall invertase were several-fold higher with high transpiration rates. Transpiration rate also affected transcript levels in whole leaves. For example, RuBisCO transcript levels were several-fold higher when the transpiration rate was low. In addition, we present the effects of transpiration rate on leaf conductance, photosynthesis rate, and xylem-sap sucrose. Interestingly, although some of the physiological effects of humidity persisted for several days, the effects on transcript abundances measured in the first days did not persist, possibly indicating acclimation.
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1 - Florida State University, Department of Biological Science, BIO Unit I, Chieftan Way, Tallahassee, FL, 32306-4370, USA
2 - Florida State University, Department of Biological Science
Keywords:
humidity
Photosynthesis
stomata
Transpiration
sucrose.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P04003
Abstract ID:332 |
