Long-distance signals regulating stomatal conductance and leaf growth in tomato (Lycopersicon esculentum) plants subjected to partial root-zone drying

• Published in: Journal of experimental botany Vol. 55; no. 407; pp. 2353 - 2363
• Main Authors: Sobeih, Wagdy Y., Dodd, Ian C., Bacon, Mark A., Grierson, Donald, Davies, William J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Oxford University Press 01-11-2004; Oxford Publishing Limited (England)
• Subjects: Abscisic acid; Abscisic Acid - metabolism; ACO1AS; Agronomy. Soil science and plant productions; Arid soils; Biological and medical sciences; Drying; Economic plant physiology; ethylene; Ethylene production; Ethylenes - metabolism; Fundamental and applied biological sciences. Psychology; Genotype; Hydrogen-Ion Concentration; leaf growth; Leaves; long-distance signalling; Lycopersicon esculentum; Lycopersicon esculentum - genetics; Lycopersicon esculentum - growth & development; Lycopersicon esculentum - metabolism; partial root-zone drying; Physiology of Plants Exposed to Drought Stress; Plant growth; Plant growth regulators; Plant Growth Regulators - metabolism; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant roots; Plant Shoots - metabolism; Plants; Signal Transduction; Soil; Soil water; stomatal conductance; Time Factors; tomato; Water - metabolism; Water relations, transpiration, stomata; Xylem; xylem pH; Xylem; Root; Growth; Stomatal conductance; Ethylene; ACO1AS; leaf growth; long-distance signalling; Plant leaf; tomato; Water potential; Stress; xylem pH; Dicotyledones; Angiospermae; Lycopersicon esculentum; Water content; Abscisic acid; partial root-zone drying; Spermatophyta; Solanaceae
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jxb/erh204

Tomato (Lycopersicon esculentum Mill. cv. Ailsa Craig) plants were grown with roots split between two soil columns. After plant establishment, water was applied daily to one (partial root-zone drying—PRD) or both (well-watered control—WW) columns. Water was withheld from the other column in the PRD treatment, to expose some roots to drying soil. Soil and plant water status were monitored daily and throughout diurnal courses. Over 8 d, there were no treatment differences in leaf water potential (ψleaf) even though soil moisture content of the upper 6 cm (θ) of the dry column in the PRD treatment decreased by up to 70%. Stomatal conductance (gs) of PRD plants decreased (relative to WW plants) when θ of the dry column decreased by 45%. Such closure coincided with increased xylem sap pH and did not require increased xylem sap abscisic acid (ABA) concentration ([X-ABA]). Detached leaflet ethylene evolution of PRD plants increased when θ of the dry column decreased by 55%, concurrent with decreased leaf elongation. The physiological significance of enhanced ethylene evolution of PRD plants was examined using a transgenic tomato (ACO1AS) with low stress-induced ethylene production. In response to PRD, ACO1AS and wild-type plants showed similar xylem sap pH, [X-ABA] and gs, but ACO1AS plants showed neither enhanced ethylene evolution nor significant reductions in leaf elongation. Combined use of genetic technologies to reduce ethylene production and agronomic technologies to sustain water status (such as PRD) may sustain plant growth under conditions where yield would otherwise be significantly reduced.