The effect of root cooling on hormone content, leaf conductance and root hydraulic conductivity of durum wheat seedlings ( Triticum durum L.)

• Published in: Journal of plant physiology Vol. 162; no. 1; pp. 21 - 26
• Main Authors: Veselova, Svetlana V., Farhutdinov, Rashit G., Veselov, Stanislav Yu, Kudoyarova, Guzel R., Veselov, Dmitry S., Hartung, Wolfram
• Format: Journal Article
• Language: English
• Published: Jena Elsevier GmbH 01.01.2005; Elsevier; Elsevier Science Ltd
• Subjects: Aba; abscisic acid; Abscisic Acid - physiology; Cold Temperature; Cytokinins; Cytokinins - physiology; durum wheat; IAA; indole acetic acid; Indoleacetic Acids - metabolism; leaf conductance; Leaf extension growth; Plant Growth Regulators - metabolism; Plant Growth Regulators - physiology; plant hormones; Plant Leaves - physiology; Plant Roots - physiology; Plant Transpiration - physiology; Root cooling; root hydraulic conductivity; root zone temperature; roots; Seedlings - physiology; stomatal conductance; Time Factors; transpiration; Triticum - physiology; Triticum turgidum subsp. durum; Water - metabolism; water content; Water relations; Aba; Cytokinins; Leaf extension growth; IAA; Root cooling; Ipa; Water relations; Ba; RWC
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2004.06.001

Root cooling of 7-day-old wheat seedlings decreased root hydraulic conductivity causing a gradual loss of relative water content during 45 min (RWC). Subsequently (in 60 min), RWC became partially restored due to a decrease in transpiration linked to lower stomatal conductivity. The decrease in stomatal conductivity cannot be attributed to ABA-induced stomatal closure, since no increase in ABA content in the leaves or in the concentration in xylem sap or delivery of ABA from roots was found. However, decreased stomatal conductance was associated with a sharp decline in the content of cytokinins in shoots that was registered shortly after the start of root cooling and linked to increases in the activity of cytokinin-oxidase. This decrease in shoot cytokinin content may have been responsible for closing stomata, since this hormone is known to maintain stomatal opening when applied to plants. In support of this, pre-treatment with synthetic cytokinin benzyladenine was found to increase transpiration of wheat seedlings with cooled roots and bring about visible loss of turgor and wilting.