Chilling stress leads to increased cell membrane rigidity in roots of coffee (Coffea arabica L) seedlings
Chilling stress leads to increased cell membrane rigidity in roots of coffee (Coffea arabica L) seedlings
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DOI：
10.1016/s0005-2736(96)00177-0
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发表时间：
1997-01-14
影响因子：
3.4
通讯作者：
Magalhaes, AC
中科院分区：
文献类型：
--
作者：
Alonso, A;Queiroz, CS;Magalhaes, AC
热带和亚热带高等植物在低温下表现出明显的生长抑制作用。在咖啡幼苗的根尖段，其中进行了6天的温度为10，15，20和25摄氏度，在黑暗中，我们已经检测到增加的量的丙二醛形成在10摄氏度的治疗，伴随着更高的电解质渗漏。电子顺磁共振（EPR）技术和脂肪酸自旋探针5-，12-和16-doxylstearic acid被用来评估细胞膜流动性。在烷基链的第5和第16个碳原子的深度处，与15和25 ℃相比，在10 ℃下的幼苗中，氮氧自由基检测到更坚硬的膜。在C-12位置的链的探针表现出非常有限的运动，是不敏感的冷冻诱导的膜的变化。完整的组织和微粒体制剂根尖的EPR参数表明，流动性基本上是相同的，当在C-5和C-16位置的链进行评价，并大大流体微粒体膜的C-12位置的双层的区域。氮氧自由基在C-16位的旋转运动在约15 ℃时发生相变。探针16-doxylstearic酸的重定向运动的计算的能量势垒在5-15摄氏度的温度下比在15-25摄氏度的区间中更高，这表明在相变之下膜脂质假定更有序和紧凑的阵列。膜刚度引起的冷却被解释为由于脂质过氧化反应，可能已经促进了膜相变以下的过氧化链的密度较高。
Tropical and sub-tropical higher plant species show marked growth inhibition when exposed to chilling temperatures. In root tip segments of coffee seedlings which were subjected for 6 days to temperatures of 10, 15, 20 and 25 degrees C, in darkness, we have detected an increased amount of malondialdehyde formed in the 10 degrees C treatment, accompanied by higher electrolyte leakage. The electron paramagnetic resonance (EPR) technique and the fatty acid spin probes 5-, 12- and 16-doxylstearic acid were used to assess cellular membrane fluidity. At the depth of the 5th and 16th carbon atom of the alkyI chains the nitroxide radical detected more rigid membranes in seedlings subjected to 10 degrees C compared with 15 and 25 degrees C. At the C-12 position of the chains the probe showed very restricted motion and was insensitive to chilling induced membrane alterations. EPR parameters for intact tissues and microsome preparations from root tips showed that the fluidity was essentially the same when evaluated at C-5 and C-16 positions of the chains, and was considerably more fluid for microsomal membranes in the region of the C-12 position of the bilayers. The rotational motion of the nitroxide at C-16 position of the chains experienced a phase transition at about 15 degrees C. The calculated energy barriers for reorientational motion of the probe 16-doxylstearic acid were higher at temperatures of 5-15 degrees C than in the interval of 15-25 degrees C, suggesting that below the phase transition the membrane lipids assume a more ordered and compacted array. Membrane rigidity induced by chilling was interpreted as due to lipid peroxidation that could have been facilitated by higher density of peroxidizable chains below the membrane phase transition.