北方樹木の寒冷環境適応機構の解明

抄録

In order to survive severe winters without snow cover, boreal tree species have evolved superior freezing adaptation mechanisms. The freezing resistance of living cells in their aerial parts is well-controlled seasonally and exceeds -30°C in mid-winter. Although freeze–thawing can cause functional failure of their water transport system, boreal tree species have abilities to solve the problem and resume growth in spring. In this review, I introduce two topics on freezing responses of boreal tree species: (1) freezing adaptation mechanisms of xylem parenchyma cells which avoid intracellular freezing by deep supercooling, and (2) winter embolism formation mechanisms by which hydraulic architectures, vessels and tracheids, lose their function. In addition, possible relationship between freezing behavior of xylem parenchyma and their roles in embolism repair in early-spring is discussed.