Glucose‐induced activation of rubidium transport and water flux in sunflower root systems

• Published in: Journal of experimental botany Vol. 52; no. 354; pp. 99 - 104
• Main Authors: Quintero, José M., Molina, Raúl, Fournier, José M., Benlloch, Manuel, Ramos, José
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.01.2001; OXFORD UNIVERSITY PRESS
• Subjects: Absorption. Translocation of ions and substances. Permeability; Agronomy. Soil science and plant productions; Biological and medical sciences; Carbon Radioisotopes; Deoxyglucose - analogs & derivatives; Deoxyglucose - pharmacology; Economic plant physiology; Exudation; Exudation rate; Fructose - pharmacology; Fundamental and applied biological sciences. Psychology; glucose; Glucose - analogs & derivatives; Glucose - pharmacology; Helianthus - metabolism; Helianthus - physiology; Helianthus annuus; Nutrition. Photosynthesis. Respiration. Metabolism; Phosphorylation; Plant physiology and development; Plant roots; Plant Roots - physiology; Plants; Regulation of Growth, Development and Whole Organism Physiology; Root systems; Rubidium; Rubidium - pharmacokinetics; rubidium transport; Sorbitol - pharmacology; Spectrophotometry, Atomic; Sugars; sunflower; Sunflowers; Water - physiology; Water and solutes. Absorption, translocation and permeability; Xylem; Yeasts; Translocation; Xylem; Root; Induction; Biological transport; Glucose; Compositae; Rubidium; Oil plant(vegetal); Fructose; Signal transduction; Regulation(control); Absorption; Helianthus annuus; Analog; Dicotyledones; Angiospermae; Carbohydrate; Spermatophyta; Potassium
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jexbot/52.354.99

Excised 20‐d‐old sunflower roots (Helianthus annuus L. cv. Sun‐Gro 393) were used to study the effect of different sugars on rubidium and water fluxes. The roots sensed and absorbed glucose from the external medium inducing the activation of rubidium accumulated in the root (Rb+ root), the flux of exuded rubidium (JRb) and, to a lesser degree, the exudation rate (Jv). These effects were also triggered by fructose, but not by 6‐deoxyglucose (6‐dG), a glucose analogue which is not a substrate for hexokinase (HXK). The effect of 2‐deoxyglucose (2‐dG), an analogue that is phosphorylated but not further metabolized, was complex, suggesting an inhibitory effect on solute transport to the xylem. The amounts of glucose required to activate rubidium and water fluxes were similar to those previously reported to regulate different processes in other plants (0.5–10 mM). When sorbitol was used instead of glucose, neither rubidium uptake (Rb+ root plus JRb) nor Jv was activated. It is proposed that glucose present in the root plays an important signalling role in the regulation of Rb+ (K+) and water transport in plant roots.