低温下抗氧化酶活性与冬油菜根细胞结冰关系的初步研究

Preliminary Study on the Relation of Antioxidant Enzyme Activities at Low Temperature and the Ice Formation in Root Cells of Winter Rapeseed

以4个抗寒性不同的油菜品种的根为材料,于低温试验箱内连续降温处理(4℃/24h,0℃/24h,-3℃/24h,-6℃/24h,-9℃/24h,-15℃/24h,-21℃/24h),检测其抗氧化酶(POD、CAT)活性,并结合POD同工酶电泳和冷冻前后幼苗的形态变化特征,探讨油菜根部抗氧化酶活性变化与细胞冰冻状态间的相关性以及油菜根的抗冻机理。结果显示:(1)弱抗寒性油菜品种(‘临油7号’和Vision)在低温冷冻后,叶面出现大量水渍,之后叶片萎缩直至焦枯,根部出现水渍后软化直至干枯死亡;强抗寒性品种(‘陇油6号’和‘陇油8号’)在冷冻后不产生水渍或水渍极少,其根在冻后损伤也较轻微。(2)在连续冷冻条件下,弱抗寒性油菜根部POD和CAT活性在降温初期有较大幅度的变化,之后就保持恒定,说明根部细胞已完全结冰;而强抗寒性油菜根部POD和CAT活性在降温初期变化较小,后期持续大幅增加,表明根部细胞仍保持溶液状态;POD同工酶分析也反映出类似的变化规律。研究表明,低温下冬油菜根部抗氧化酶活性变化和细胞冰冻状态之间存在相关性;细胞结冰通常会给植物造成致死性伤害,强抗寒油菜品种能安全越冬的关键就是能通过某种机制避免细胞内结冰,其结冰温度越低,抗寒性越强。

With rapeseed roots of four different cold hardiness under continuously cool treatment（4 ℃ 24 h,0 ℃ 24 h,-3 ℃ 24 h,-6 ℃ 24 h,-9 ℃ 24 h,-15 ℃ 24 h,-21 ℃ 24 h） in the low temperature test boxes,testing the antioxidant enzymes activities（POD and CAT） and the POD isozymes electrophoresis and morphological variation characteristics of rape seedlings before and after the frozen treatments.To explore the correlation for changes of antioxidant enzyme activities at low temperatures and the ice formation in root cells of winter rapeseed and antifreeze mechanism of the winter rapeseed root.The result showed that：（1）The varieties of weak frost resistance rapeseed（＇Longyou 7＇ and Vision） in the low temperature appeared a large number of water damage was on the surface of leaves,then the leaf blade atrophied until withered,root appeared water softening until dry death;strong frost resistance varieties（＇Longyou 6＇ and ＇Longyou 8＇） in the frozen did not produce water damage,or water damage was less,and the damage of its root was slighter.（2）Under continuously cool treatment,POD and CAT activities of the weak frost resistance rapeseed roots in early cooling had large changes,and then kept constant,indicating that the cells of roots had completely froze;POD and CAT activities of strong frost resistance rapeseed root in early cooling had small changes,which greatly increased in later period,indicating that the cells of roots remained solution state;The analysis of POD isozyme also reflected a similar change.Research showed that there were some correlations between changes of antioxidant enzyme activities of winter rapeseed root and the frozen stage of root cells in low temperature.Cell ice usually caused plant fatal damage,which stated that the key that strong cold hardiness rapeseed can winter safely was that avoiding intracellular ice formation,and the lower freezing temperature of its cells is,the stronger the cold hardiness of them is.