Satoshi Nakaba1, Asami Hirai1, Kayo Kudo2, Yusuke Yamagishi3, Kenichi Yamane4, Katsushi Kuroda5, Widyanto Dwi Nugroho6, Peter Kitin7, Ryo Funada8. 1. Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan. 2. Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan, Institute of Wood Technology, Akita Prefectural University, 11-1 Kaieisaka, Noshiro, Akita 016-0876, Japan. 3. Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan, Graduate School of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan. 4. Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan. 5. Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan. 6. Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan, Faculty of Forestry, Universitas Gadjah Mada, Jalan Agro No. 1 Bulaksumur, Yogyakarta 55281, Indonesia and. 7. Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison WI 53706, USA. 8. Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan, funada@cc.tuat.ac.jp.
Abstract
BACKGROUND AND AIMS: When the orientation of the stems of conifers departs from the vertical as a result of environmental influences, conifers form compression wood that results in restoration of verticality. It is well known that intercellular spaces are formed between tracheids in compression wood, but the function of these spaces remains to be clarified. In the present study, we evaluated the impact of these spaces in artificially induced compression wood in Chamaecyparis obtusa seedlings. METHODS: We monitored the presence or absence of liquid in the intercellular spaces of differentiating xylem by cryo-scanning electron microscopy. In addition, we analysed the relationship between intercellular spaces and the hydraulic properties of the compression wood. KEY RESULTS: Initially, we detected small intercellular spaces with liquid in regions in which the profiles of tracheids were not rounded in transverse surfaces, indicating that the intercellular spaces had originally contained no gases. In the regions where tracheids had formed secondary walls, we found that some intercellular spaces had lost their liquid. Cavitation of intercellular spaces would affect hydraulic conductivity as a consequence of the induction of cavitation in neighbouring tracheids. CONCLUSIONS: Our observations suggest that cavitation of intercellular spaces is the critical event that affects not only the functions of intercellular spaces but also the hydraulic properties of compression wood.
BACKGROUND AND AIMS: When the orientation of the stems of conifers departs from the vertical as a result of environmental influences, conifers form compression wood that results in restoration of verticality. It is well known that intercellular spaces are formed between tracheids in compression wood, but the function of these spaces remains to be clarified. In the present study, we evaluated the impact of these spaces in artificially induced compression wood in Chamaecyparis obtusa seedlings. METHODS: We monitored the presence or absence of liquid in the intercellular spaces of differentiating xylem by cryo-scanning electron microscopy. In addition, we analysed the relationship between intercellular spaces and the hydraulic properties of the compression wood. KEY RESULTS: Initially, we detected small intercellular spaces with liquid in regions in which the profiles of tracheids were not rounded in transverse surfaces, indicating that the intercellular spaces had originally contained no gases. In the regions where tracheids had formed secondary walls, we found that some intercellular spaces had lost their liquid. Cavitation of intercellular spaces would affect hydraulic conductivity as a consequence of the induction of cavitation in neighbouring tracheids. CONCLUSIONS: Our observations suggest that cavitation of intercellular spaces is the critical event that affects not only the functions of intercellular spaces but also the hydraulic properties of compression wood.