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Abstract Detail

Environmental Physiology

Levine, Lanfang H. [1], Richards, Jeffrey [2], Wheeler, Raymond M. [3].

Attenuated Stomatal Response to ABA under Supraoptimal CO2.

Stomata are small pores on leaf surfaces formed by a pair of guard cells that integrate environmental stimuli (light, water and CO2) to regulate gas fluxes to and from the leaf. CO2 sensing is an intrinsic property of guard cells. It has been well established that there is an inverse relationship between CO2 concentration and stomatal aperture in non water-limited plants, i.e. increase in CO2 concentration results in a reduction of stomatal conductance. However, studies under extremely high or super-elevated CO2 (>4000 ppm) show that in many species, stomatal conductance increases during day and that stomata fail to close at night. It is not known whether this phenomenon is due to a failure in signal transduction pathways or inability of the guard cells to respond to the signal. The objective of this study was to investigate the ability of guard cells developed under super-elevated CO2 to respond to abscisic acid (ABA), a strong trigger for stomatal closure. Soybean plants were grown under a combination of high pressure sodium and metal halide lamps with a 12 light/12 dark photoperiod and a photosynthetic photon flux (PPF) of 450 µmol m-2 s-1. Carbon dioxide levels were controlled to either 1200 ppm CO2 or 10,000 ppm CO2. Twenty-one days after planting, two doses (25 µl each) of 1 mM ABA were administered to the petiolar groove of the fully developed 2nd trifoliate leaf. Stomatal conductance was monitored 2, 3, 4 and 5 hr post treatment using a steady state porometer. Results indicated that the ABA-induced closure of stomata in plants grown under 10,000 ppm CO2 was significantly less than those developed under 1,200 ppm CO2, implying CO2 and/or the consequence of long time exposure to super-elevated CO2 may interfere with ABA - signaling pathways.

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1 - Dynamac Corporation, Mail Code: DYN-3, Kennedy Parkway and 5th Street, Building # M6-1025, Kennedy Space Center, Florida, 32899, USA
2 - Dynamac Corp.
3 - Kennedy Space Center, NASA

Elevated CO2
Abscisic Acid
stomatal conductance

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P01047
Abstract ID:2099

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