外源亚精胺对盐胁迫下黄瓜根系多胺含量和抗氧化系统的影响

Effects of Exogenous Spermidine on Polyamine Content and Antioxidant System in Roots of Cucumber Under Salinity Stress

采用营养液栽培,研究了外源亚精胺(Spd)对盐胁迫下抗盐能力不同的2个黄瓜品种"长春密刺"和"津春2号"幼苗根系生长以及根系中多胺(PAs)含量和抗氧化系统的影响。结果表明,外源Spd提高了盐胁迫下黄瓜根系游离态Spd和精胺(Spm)、酸可溶性结合态和酸不溶性结合态腐胺(Put)、Spd和Spm含量,降低了游离态Put含量;同时提高了超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,降低了超氧阴离子(O2-.)产生速率、过氧化氢(H2O2)和丙二醛(MDA)含量及电解质渗透率,明显促进了幼苗根系生长;根系中酸不溶性结合态Spd含量与抗氧化酶活性间呈正相关性。表明黄瓜幼苗根系中较高的游离态Spd和Spm、酸可溶性结合态和酸不溶性结合态PAs尤其是酸不溶性结合态Spd含量有利于提高植株抗氧化酶活性,降低O2-.产生速率和膜脂伤害,增强植株抗盐性。

A hydroponic experiment was carried out about cucumber seedlings of two different cultivars in salinity tolermace to explore the effects of exogenous spermidine on polyamine content and antioxidant system in roots of the seedlings under salinity stress. Results showed that under salinity stress, exogenous spermidine increased the contents of free spermidine and spermine, perchloric acid soluble conjugated （PS-conjugated） and perchloric acid insoluble conjugated （PIS-conjugated） putreseine,spermidine and spermine, and decreased the content of free putrescine in roots of cucumber. Besides, it also increased SOD, POD and CAT activities, decreased O2^- production rate, H2O2 and MDA contents and electrolyte leakage, thus significantly promoting root growth. Furthermore, positive correlation was observed of the content of PIS-conjugated spermidine in seedlings roots with antioxidmat enzyme activity. The findings suggest that high levels of free spermidine and spermine, PS-conjugated and PIS-conjugated polyamines, particularly PIS-conjugated spermidine, may enhance antioxidant enzyme activity, decrease O2^- production rate and membrane damage, thus strengthening salinity tolerance of the plant.