静电场对苜蓿愈伤组织抗寒能力的影响

用正负高压静电场 (HVEF)处理苜蓿叶片来源的愈伤组织后 ,在4℃下暗培养。我们发现静电场处理可不同程度地提高愈伤组织的淀粉酶 ,过氧化物酶 ,和超氧化物岐化酶的活性和可溶性蛋白的含量 ,促进愈伤组织对冷害的防御能力。在冷处理过程中 ,细胞膜中饱和脂肪酸 (棕榈梭和硬脂酸 )和不饱和脂肪梭含量先升高然后降低 ,而高压静电场处理组的不饱和脂肪酸 (油酸、亚油酸、α -亚麻酸、β-亚麻酸 )含量高于对照组 ,脂肪酸不饱和指数 (UIFA)也高于对照组 ,这说明静电场处理可促进愈伤组织细胞抗寒能力提高。此外 ,丙二醛 (MDA)含量在静电场处理组低于对照组的测定结果也验证了前面的结果。

EFFECTS OF HIGH VOLTAGE ELECTROSTATIC FIELD ON COLD-ACCLIMATING ABILITY OF ALFALFA (M edicago sativa L) LEAF CALLUS

Positive( )and negative(-)high voltage electrostatic field(HVEF)with 1kV/cm,-1kV/cm and -2kV/cm intensity were used to treat alfalfa leaf callus at 4 dark culture in vitro to study the cold acclimation of callus.The results showed that during 16 days cold treating,the activities of amylase(AMY),catalase(CAT),peroxidase(POD)and superoxide dismutase(SOD)of callus decrease early,then increase and then decrease to a different extent,Malondeadehyde(MDA)levels of cold-acclimated callus increases continuously meanwhile soluble protein contents of callus waves irregularly,the vigor of callus decreases with delay of treatment time.Callus of groups treated with HVEF of defferent intensities and directions show higher enzyme activities of AMY,POD,CAT and SOD than those of the control throughout cold culture,so dose the soluble protein content in callus. MDA level in treated group callus,on thr contrary,are lower markedly than that of the control.Viability rate of callustested by TTC in treatment groups is also greatly higher than that of the control at 16th day. Among treatment groups,the HVEF of -2kv/cm has the most significant enhancement of cold-acclimation in callus.Components of membrane fatty acids of callus at 3rd, 8th,16th day cold-acclimated culture were also analysed.The result shows that total contents of saturated fatty acids, mainly palmitic acid(16:0)and stearic acid(18:0),rose at early during the cold treatment then drop meanwhile the unsaturated fatty acids includinglionleic acid(18:2),oleic acid(18:1)and a,y-linolenic acid(18:3)increase firstly decrease slowy,so does index of unsaturated fatty acids(IUFA). Callus in HVEF treatment groups have higher contents of unsaturated fatty acids and lower contents of saturated fatty acids as well as higher IUFA than that of the control at corresponding cold treatment stages. The result corresponds to the above conclusion, especialy MDA accumulation in cells. Since higher OUFA of membrane often contributes much to cold-acclimation of plant tissue, HVEF treatment keeps membrane in moew adaptable structure and function to the cold, therefore raise the cold-resistance of callus. By affecting components and properties of membrane, including membrane-binding proteins,lipids and their polarities and phases, HVEF also promotes many other metabolic level to adapt plant tissue to adversity.