Journal Article

control of stomata by water balance

Buckley, Thomas N.

2005

Overview

It is clear that stomata play a critical role in regulating water loss from terrestrial vegetation. What is not clear is how this regulation is achieved. Stomata appear to respond to perturbations of many aspects of the soil-plant-atmosphere hydraulic continuum, but there is little agreement regarding the mechanism (or mechanisms) by which stomata sense such perturbations. This review discusses feedback and feedforward mechanisms by which hydraulic perturbations are putatively transduced into stomatal movements, in relation to generic empirical features of those responses. It is argued that a metabolically mediated feedback response of stomatal guard cells to the water status in their immediate vicinity ('hydro-active local feed-back') remains the best explanation for many well-known features of hydraulically related stomatal behaviour, such as transient 'wrong-way' responses and the equivalence of hydraulic supply and demand as stomatal effectors. Furthermore, many curious phenomena that appear inconsistent with feedback, such as 'apparent feedforward' humidity responses and 'isohydric' behaviour (water potential homeostasis), are in fact expected to emerge from the juxtaposition of hydro-active local feedback and the well-known hysteretic and threshold-like effect of water potential on xylem hydraulic resistance.

• Publisher: Blackwell Science,Blackwell Science Ltd,Blackwell
• Subject: Biological and medical sciences / Biomechanical Phenomena / cavitation / cytology / Feedback / feedforward / Fundamental and applied biological sciences. Psychology / Guard cells / homeostasis / Humidity / hydraulic resistance / Hydraulics / literature reviews / metabolism / Models, Biological / Plant cells / Plant Leaves / Plant Leaves - cytology / Plant Leaves - metabolism / plant physiology / Plant physiology and development / plant-water relations / Plants / soil-plant-atmosphere interactions / Stomata / Stomatal conductance / stomatal movement / supply balance / Tansley Reviews / Transpiration / Turgor pressure / vegetation / Water / Water - metabolism / Water and solutes. Absorption, translocation and permeability / water potential / Xylem