用自旋标记ESR波谱法研究杨树抗寒性

STUDY ON COLD RESISTANCE OF POPLAR BY ESR SPIN LABEL

以自旋标记物Ｔｅｍｐｏ（２，２，６，６－四甲基哌啶－１－氮氧基）标记杨树叶膜磷脂酰甘油（ＰＧ），通过电子自旋共振波谱法（ＥＳＲ）测定了杨树不同抗寒品种及其杂种后代ＰＧ的相变温度。同时用气相色谱法对ＰＧ脂肪酸组成进行了分析。结果表明，不耐寒的美洲黑杨（Ｐｏｐｕｌｕｓｄｅｌｔｏｉｄｅｓｃｖ＇Ｌｕｘ＇Ｉ６９／５５母本）的ＰＧ在４℃左右发生相变，抗寒的欧美杨（ＰｏｐｕｌｕｓｅｕｒａｍｅｒｉｃａｎａｃｖＩ－４５／５１，父本）的ＰＧ则在－１２℃发生相变，６个杂种后代均在－２℃－１１℃范围内发生相变。而且磷脂的脂肪酸组成分析表明，不同抗寒品种叶内ＰＧ的饱和脂肪酸水与ＰＧ的热致相变行为相关。抗寒品种的ＰＧ饱和脂肪酸水平低于不抗寒品种，以致前者的ＰＧ相变温度低于后者从而表现为抗寒。

Phosphatidyl glycerol (PG) was isolated from leaves of different cold resistant varie- ties of poplar and their hybrids, and phase - transition temperatures were determined by electronic spin resonance spectroscopy (ESR) method using Tempo [ 2 , 2, 6, 6 - tetram - ethylpiperidine - I - oxy 1 (structure) ] as the spin label. The fatty acid composition of their PG was analyzed by gas - chromato - graphy method. The results showed that PG from the cold - sensitive plant Cottonwood (Populus deltoides cv.' Lux' I - 69 / 55, female parent) underwent a thermotropic phase -separation at about 4 ℃. In contract, PG from the cold - resistant poplar Populus euramericana cv. I-45/5l (male parent) went into the phase-separation state at about -12℃. . PG from the six hybrids entered the phase - separation state at the temperature ranging from -2℃ to ll ℃. The analyzation of fatty acids compositions in phosphatide suggest that saturated fatty acids level (the sum of palmiate plus hexadeca - trans - 3 - enoate plus stearate) as a proportion of total phosphatidyl glycerol fatty acids was closely related to the thermotropic phase - transition behavior of phosphatidyl glycerol from different cold - resistance varieties. The saturated fatty acid level of PG from cold - resistance plant was lower than that from cold - sensitive plant so that the phase - transition temperature of PG from the former was lower than that of the latter and displayed the cold resistance.