Some Current Aspects of Stomatal Physiology

The growth and gas exchange response of soil‐planted Norway spruce [Picea abies (L.) Karst.] and red oak (Quercus rubra L.) exposed to elevated CO2 and to naturally occurring drought

“…Both Beadle, Jarvis & Neilson (1979) and Barton, Lee & Jarvis (1993) found increased stomatal conductance in the presence of CO, for Sitka spruce. Mansfield, Hetherington & Atkinson (1990) in a review of stomatal responses to CO, describe how a lack of response or opening in the presence of COj was considered exceptional, but that this view was established from experiments where plants were grown with very little variation in growth conditions.…”

Electrical signaling, stomatal conductance, ABA and Ethylene content in avocado trees in response to root hypoxia

“…Whiley and Schaffer 4 postulated that stomatal closure in avocado trees exposed to root hypoxia resulting from soil flooding was due to a build-up of CO 2 in the leaf, which has been associated with stomatal closure in plants. 32,33 This was based on studies where flooding-induced reductions of gs in avocado trees were observed concomitantly with decreases in net CO 2 assimilation and increased intercellular CO 2 concentration in leaves. 2 Although the precise timing and sequence of hypoxia-induced reductions in gs and net CO 2 assimilation have not been elucidated in avocado trees, reductions in net CO 2 assimilation may occur before reductions in gs resulting in an increased intercellular CO 2 concentration.…”

The control of specificity in guard cell signal transduction

“…Alterations in stomatal pore diameter are brought about by turgor changes of the guard cells (Assmann 1993). Guard cells are a good model for the study of signal transduction in plants because they respond in an easily quanti¢able manner to a range of important environmental stimuli such as light, CO 2 concentration, temperature, plant hormones (Mans¢eld et al 1990;Assmann 1993) and the activity of the circadian clock (Webb 1998). As these cells are tractable to a range of single cell techniques we know a great deal about the control of the ion £uxes which underlie guard cell turgor alterations (MacRobbie 1997).…”

“…A. R. Webb and A. M. Hetherington, unpublished observations). In addition to these experiments, a host of data from investigations based on pharmacological intervention (reviewed by Mans¢eld et al (1990)) demonstrates that inhibiting components of calcium-based signal transduction pathways results in impaired stomatal movements in response to a variety of signals. Finally, arti¢cial elevation of guard cell [Ca 2+ ] cyt either by the release of caged calcium (Gilroy et al 1990;McAinsh et al 1995), the addition of InsP 3 (Gilroy et al 1990) or of cyclic ADPribose (cADPR) (Leckie et al 1998b) invariably results in reductions in guard cell turgor.…”