Interactive ion-mediated sap flow regulation in olive and laurel stems: physicochemical characteristics of water transport via the pit structure

• Published in: PloS one Vol. 9; no. 5; p. e98484
• Main Authors: Ryu, Jeongeun, Ahn, Sungsook, Kim, Seung-Gon, Kim, TaeJoo, Lee, Sang Joon
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22-05-2014; Public Library of Science (PLoS)
• Subjects: Biology and Life Sciences; Calcium; Calcium - metabolism; Calcium ions; Cavitation; Embolisms; Engineering and Technology; Environmental changes; Environmental effects; Environmental regulations; Flow control; Flow velocity; Flowers & plants; Hydraulics; Hydrogels; Imaging techniques; Laurus - physiology; Mechanical engineering; Medical imaging; Olea - physiology; Physical Sciences; Pipe and tube industry; Plant Stems - physiology; Plants; Potassium; Potassium - metabolism; Radiography; Science; Stems; Transport; Water; Water transport; Xylem; New York; United States > US; South Korea
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0098484

Sap water is distributed and utilized through xylem conduits, which are vascular networks of inert pipes important for plant survival. Interestingly, plants can actively regulate water transport using ion-mediated responses and adapt to environmental changes. However, ionic effects on active water transport in vascular plants remain unclear. In this report, the interactive ionic effects on sap transport were systematically investigated for the first time by visualizing the uptake process of ionic solutions of different ion compositions (K+/Ca2+) using synchrotron X-ray and neutron imaging techniques. Ionic solutions with lower K+/Ca2+ ratios induced an increased sap flow rate in stems of Olea europaea L. and Laurus nobilis L. The different ascent rates of ionic solutions depending on K+/Ca2+ ratios at a fixed total concentration increases our understanding of ion-responsiveness in plants from a physicochemical standpoint. Based on these results, effective structural changes in the pit membrane were observed using varying ionic ratios of K+/Ca2+. The formation of electrostatically induced hydrodynamic layers and the ion-responsiveness of hydrogel structures based on Hofmeister series increase our understanding of the mechanism of ion-mediated sap flow control in plants.