Roles of cell walls and intracellular contents in supercooling capability of xylem parenchyma cells of boreal trees

• Published in: Physiologia plantarum Vol. 148; no. 1; pp. 25 - 35
• Main Authors: Kasuga, Jun, Endoh, Keita, Yoshiba, Megumi, Taido, Ippei, Arakawa, Keita, Uemura, Matsuo, Fujikawa, Seizo
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-05-2013; Blackwell; Wiley Subscription Services, Inc
• Subjects: Acclimatization; Biological and medical sciences; Cell Wall - physiology; Cold Temperature; Fagus - physiology; Fagus - ultrastructure; Fundamental and applied biological sciences. Psychology; Intracellular Fluid - physiology; Microbiology; Morus - physiology; Morus - ultrastructure; Plant physiology and development; Trees - physiology; Trees - ultrastructure; Xylem - physiology; Xylem - ultrastructure; Xylem; Plant physiology; Content; Parenchyma; Supercooling; Intracellular; Cell; Cell wall
• ISSN: 0031-9317; 1399-3054
• DOI: 10.1111/j.1399-3054.2012.01678.x

The supercooling capability of xylem parenchyma cells (XPCs) in boreal hardwood species differs depending not only on species, but also season. In this study, the roles of cell walls and intracellular contents in supercooling capability of XPCs were examined in three boreal hardwood species, Japanese beech, katsura tree and mulberry, whose supercooling capability differs largely depending on species and season. XPCs in these species harvested in winter and summer were treated by rapid freezing and thawing (RFT samples) or by RFT with further washing (RFTW samples) to remove intracellular contents from XPCs in order to examine the roles of cell walls in supercooling. RFT samples were also treated with glucose solution (RFTG samples) to examine roles of intracellular contents in supercooling. The supercooling capabilities of these samples were examined by differential thermal analysis after ultrastructural observation of XPCs by a cryo‐scanning electron microscope to confirm effects of the above treatments. XPCs in RFTW samples showed a large reduction in supercooling capability to similar temperatures regardless of species or season. On the other hand, XPCs in RFTG samples showed a large increase in supercooling capability to similar temperatures regardless of species or season. These results indicate that although cell walls have an important role in maintenance of supercooling, change in supercooling capability of XPCs is induced by change in intracellular contents, but not by change in cell wall properties.