Visualization of freezing behaviors in leaf and flower buds of full-moon maple by nuclear magnetic resonance microscopy
Visualization of freezing behaviors in leaf and flower buds of full-moon maple by nuclear magnetic resonance microscopy
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DOI：
10.1104/pp.115.4.1515
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发表时间：
1997-12-01
期刊：
影响因子：
7.4
通讯作者：
Arata, Y
中科院分区：
文献类型：
--
作者：
Ishikawa, M;Price, WS;Arata, Y
利用H-1核磁共振（NMR）显微镜研究了圆月槭越冬芽的冻结行为。所获得的图像主要反映了来自未冻水的移动的（即非冰）质子的密度。在不同的冰点以下温度下拍摄的核磁共振图像的比较揭示了在差热分析中哪些组织产生了高温和低温辐射。在A.在-7 ℃时，鳞片和茎皮组织已被冻结，但原始花序和顶生原始枝在-14 ℃时仍保持过冷，侧生原始枝在-21 ℃时仍不冻结。这些过冷组织的冷冻与其活力的丧失有关。随着温度的降低，过冷的原始芽和花序的大小逐渐减小，表明这些组织中的器官外冷冻。在此过程中，原基下的黑暗区域的形成和随后的逐渐变暗的过冷原基的基部是可见的。随着侧枝原基的冷却，未冻区大大减少。由于外侧原基在零下40摄氏度的温度下仍然存活，没有可检测到的低温冷冻，它们可能经历了I型器官外冷冻。木质部的深度过冷被清楚地成像。核磁共振显微镜是一个强大的工具，非侵入性可视化协调冻结行为在复杂的植物器官。
H-1-Nuclear magnetic resonance (NMR) microscopy was used to study the freezing behavior of wintering buds of full-moon maple (Acer japonicum Thunb.). The images obtained predominantly reflected the density of mobile (i.e. non-ice) protons from unfrozen water. A comparison of NMR images taken at different subfreezing temperatures revealed which tissues produced high-and low-temperature exotherms in differential thermal analyses. In leaf and flower buds of A. japonicum, the scales and stem bark tissues were already frozen by -7 degrees C, but the primordial inflorescence and terminal primordial shoots remained supercooled at -14 degrees C, and the lateral primordial shoots were unfrozen even at -21 degrees C. The freezing of these supercooled tissues was associated with their loss of viability. The size of the supercooled primordial shoots and inflorescences was gradually reduced with decreasing temperature, indicating extraorgan freezing in these tissues. During this process the formation of dark regions beneath the primordia and subsequent gradual darkening in the basal part of supercooled primordia were visible. As the lateral shoot primordia were cooled, the unfrozen area was considerably reduced. Since the lateral primordia remained viable down to -40 degrees C, with no detectable low-temperature exotherms, they probably underwent type I extraorgan freezing. Deep supercooling in the xylem was clearly imaged. NMR microscopy is a powerful tool for noninvasively visualizing harmonized freezing behaviors in complex plant organs.