抄録
Most of the leaf tissues of bamboos employ deep supercooling as the mechanisms of cold hardiness. Their mechanisms of deep supercooling and freezing injury still remain unknown. Here, we analyzed precise freezing behaviors in leaf tissues of Sasa kurilensis. Differential thermal analyses (DTA) of both leaf blades and leaf sheath revealed that a large low temperature exotherm (LTE) initiated around -20C. We observed acoustic emission (AE) during the course of DTA using three sensors of pocket AE or AE tester. Detected number of AE events differed considerably depending on the sensor. But they showed clear distribution patterns compared to control: AE in leaf blades occurred mainly in the later half of the LTE while those in leaf sheath occurred mainly in the first half of the LTE. AE has been observed in association with cavitation bubble formation in xylem vessels caused by desiccation or freezing. Cryomicroscopy detected freeze-induced cavitation in the later half of LTE only in leaf blades. But the number of cavitation events was much less than AE events. AE events were most probably resulted from freezing of deep-surpercooled cells in this species.
