Hydraulic and chemical signalling in the control of stomatal conductance and transpiration.

Abscisic acid (ABA) transported in the xylem from root to shoot and perceived at the guard cell is now widely studied as an essential regulating factor in stomatal closure under drought stress. This provides the plant with a stomatal response mechanism in which water potential is perceived in the root as an indication of soil water status and available water resources. There is also ample evidence that stomata respond directly to some component of leaf water status. This provides additional information about water potential gradients developing between root and shoot as the result of water transport, allowing for a more stable regulation of shoot water status and better protection of the transport system itself. The precise location at which leaf water status is sensed, however, and the molecular events transducing this signal into a guard cell response are not yet known. Major questions therefore remain unanswered on how water stress signals perceived at root and leaf locations are integrated at the guard cell to control stomatal behaviour.

[1]  Maurizio Mencuccini,et al.  Control of stomatal conductance by leaf water potential in Hymenoclea salsola (T. & G.), a desert subshrub , 1998 .

[2]  S. Assmann,et al.  ABA‐deficient (aba1) and ABA‐insensitive (abi1‐1, abi2‐1) mutants of Arabidopsis have a wild‐type stomatal response to humidity , 2000 .

[3]  M. Jackson,et al.  External Pressures Based on Leaf Water Potentials Do Not Induce Xylem Sap to Flow at Rates of Whole Plant Transpiration from Roots of Flooded or Well-drained Tomato and Maize Plants. Impact of Shoot Hydraulic Resistances , 2000 .

[4]  K. Mott,et al.  Stomatal responses to non-local changes in PFD : evidence for long-distance hydraulic interactions , 2000 .

[5]  William J. Davies,et al.  Root Signals and the Regulation of Growth and Development of Plants in Drying Soil , 1991 .

[6]  H. Jones,et al.  A Positive Root-sourced Signal as an Indicator of Soil Drying in Apple, Malus x domestica Borkh. , 1990 .

[7]  M. Jackson,et al.  Decreased root hydraulic conductivity reduces leaf water potential, initiates stomatal closure and slows leaf expansion in flooded plants of castor oil (Ricinus communis) despite diminished delivery of ABA from the roots to shoots in xylem sap , 2001 .

[8]  J. Passioura,et al.  Water Transport in and to Roots , 1988 .

[9]  J. Passioura,et al.  Root signals control leaf expansion in wheat seedlings growing in drying soil , 1988 .

[10]  Jianhua Zhang,et al.  Stomatal closure is induced rather by prevailing xylem abscisic acid than by accumulated amount of xylem‐derived abscisic acid , 1999 .

[11]  Nicanor Z. Saliendra,et al.  Influence of leaf water status on stomatal response to humidity, hydraulic conductance, and soil drought in Betula occidentalis , 1995, Planta.

[12]  E. Steudle,et al.  Root hydraulic conductance: diurnal aquaporin expression and the effects of nutrient stress. , 2000, Journal of experimental botany.

[13]  S. Wilkinson,et al.  Factors that regulate abscisic acid concentrations at the primary site of action at the guard cell , 1998 .

[14]  M. Canny.  Tansley Review No. 22 What becomes of the transpiration stream? , 1990, The New phytologist.

[15]  N. Livingston,et al.  Hydraulic control of stomatal conductance in Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] and alder [Alnus rubra (Bong)] seedlings , 1996 .

[16]  Ernst Steudle,et al.  THE COHESION-TENSION MECHANISM AND THE ACQUISITION OF WATER BY PLANT ROOTS. , 2001, Annual review of plant physiology and plant molecular biology.

[17]  T. H. Honert,et al.  Water transport in plants as a catenary process , 1948 .

[18]  F. Tardieu,et al.  Does engineering abscisic acid biosynthesis in Nicotiana plumbaginifolia modify stomatal response to drought , 2001 .

[19]  Stomatal Water Relations and the Control of Hydraulic Supply and Demand , 2002 .

[20]  M. Tyree,et al.  Plant hydraulic conductance measured by the high pressure flow meter in crop plants. , 2000, Journal of experimental botany.

[21]  Maurizio Mencuccini,et al.  Stomatal responsiveness to leaf water status in common bean (Phaseolus vulgaris L.) is a function of time of day , 2000 .

[22]  W. J. Davies,et al.  Xylem Sap pH Increase: A Drought Signal Received at the Apoplastic Face of the Guard Cell That Involves the Suppression of Saturable Abscisic Acid Uptake by the Epidermal Symplast , 1997, Plant physiology.

[23]  E. Schulze,et al.  The concentration of xylem sap constituents in root exudate, and in sap from intact, transpiring castor bean plants (Ricinus communis L.) , 1995 .

[24]  S. Zhang,et al.  The guard‐cell apoplast as a site of abscisic acid accumulation in Vicia faba L. , 2001 .

[25]  J. Comstock,et al.  The temperature dependence of shoot hydraulic resistance: implications for stomatal behaviour and hydraulic limitation , 2001 .

[26]  Jianhua Zhang,et al.  The relations of stomatal closure and reopening to xylem ABA concentration and leaf water potential during soil drying and rewatering , 1999, Plant Growth Regulation.

[27]  François Tardieu,et al.  Variability among species of stomatal control under fluctuating soil water status and evaporative demand: modelling isohydric and anisohydric behaviours , 1998 .

[28]  R. Oren,et al.  Water deficits and hydraulic limits to leaf water supply. , 2002, Plant, cell & environment.

[29]  William J. Davies,et al.  Integration of hydraulic and chemical signalling in the control of stomatal conductance and water status of droughted plants , 1993 .

[30]  L. Popova,et al.  Abscisic acid – an intraleaf water-stress signal , 2000 .

[31]  J. Passioura.  The Transport of Water from Soil to Shoot in Wheat Seedlings , 1980 .

[32]  J. Schroeder,et al.  GUARD CELL SIGNAL TRANSDUCTION. , 2003, Annual review of plant physiology and plant molecular biology.

[33]  P. Melcher,et al.  Hydrogel Control of Xylem Hydraulic Resistance in Plants , 2001, Science.

[34]  E. Schulze,et al.  Effects of drought on nutrient and ABA transport in Ricinus communis , 1996 .