金边卫矛冷驯化期间SOD和POD同工酶及蛋白的研究

采用凝胶电泳技术比较观察了金边卫矛冷驯化期间叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）同工酶谱及总蛋白的动态变化，就其变化规律与抗寒性的关系作了探讨,并首次鉴定了叶片中SOD的类型.结果表明:冷驯化期间叶片SOD同工酶未发生谱带数目的变化，但有谱带的增强表达，其中Cu-ZnSOD的变化较FeSOD明显.POD同工酶不仅有酶带的增强表达，而且有一条新的弱酶带出现.SOD、POD同工酶谱带随着冷驯化时间的延长而增强表达，但到达一个高峰后逐渐回落到接近对照水平.这表明植株在冷驯化期间随着SOD、POD同工酶变化而形成的低温适应机制可能是提高植株抗寒力的一个重要原因.金边卫矛在冷驯化期间诱导出4种分子量分别为18.7、19.5、15.7和18 kD的酸性蛋白，脱锻炼后仍然存在，表达量基本维持在低温处理时的水平，推测它们可能是抗冻蛋白，与冷驯化后金边卫矛在冰冻温度下的抗冻性相关.同时发现，叶片中多种蛋白质的含量与未驯化苗相比都有所增加，其中分子量分别为17.7、15.8 kD的碱性蛋白B和C及分子量为15.5 kD的酸性蛋白D的增强表达趋势较为明显，这3种蛋白在脱锻炼后含量均下降到接近对照水平，推测与植物在低温条件下代谢途径的改变有关. 

SOD and POD isozymes and proteins in the leaves of Euonymus radicans ‘Emorald & Gold’ during the cold acclimation

A comparative observation was carried out on the changes of superoxide dismutase(SOD),peroxidase(POD) isozyme bands and total proteins in the leaves of Euonymus radicans 'Emorald & Gold' during the cold acclimation,and the relationship between their variations and the plant cold resistance was discussed.The types of SOD in the seedling leaves were first distinguished.Results showed that the SOD isozyme did not increase or decrease in band number,but the intensities of some bands increased,among which Cu-ZnSOD changed more obviously than FeSOD.POD isozyme had not only the enhancement of band intensity but also the appearance of a new weak isozyme band.The intensities of SOD and POD isozyme bands increased continuously with the prolongation of cold acclimation duration and culminated then declined to the control levels. So it was suggested that the adaptability to low temperatures caused by changes of isozymes during the cold acclimation might be one of the major reasons for enhancing the cold-resistance of plants.Four new acid proteins,A,E,F and G,with molecular weights of 18.7,19.5,15.7 and 18 kD caused by the cold acclimation still existed in the leaves of de-acclimated seedlings,whose contents decreased little,and they were considered to be antifreeze-proteins correlative to the antifreeze ability of acclimated seedlings under a series of freezing temperatures.It was also found that the contents of most proteins in the leaves of acclimated seedlings increased compared with unacclimated seedlings,among which the contents of alkaline proteins B(17.7 kD) and C(15.8 kD) as well as acid protein(15.5 kD) increased obviously.The contents of these 3 proteins in the leaves of de-acclimated seedlings all dropped to near the control levels and it was also suggested that the changes of proteins B,C and D might be correlated to the changes in the metabolic pathways of plants at low temperatures.