盐胁迫对黄瓜幼苗根系生长和多胺代谢的影响

以两个不同抗盐性黄瓜品种为试材,采用营养液水培法,研究了NaCl胁迫对幼苗根系生长和多胺代谢的影响.结果表明:盐胁迫下黄瓜幼苗根系生长受抑制,膜脂过氧化和电解质渗漏升高,而弱抗盐品种‘津春2号'的变化幅度大于抗盐品种‘长春密刺';盐胁迫下‘长春密刺'根系精氨酸脱羧酶、鸟氨酸脱羧酶和S-腺苷蛋氨酸脱羧酶活性升高幅度均大于‘津春2号',其最高值分别比对照增加了149.3%、60.1%、69.4%和118.6%、56.2%、50.6%;'长春密刺'多胺氧化酶活性升高幅度小于‘津春2号',而二胺氧化酶活性仅在‘长春密刺'中增加.'长春密刺'根系游离态亚精胺和精胺、结合态和束缚态多胺含量均显著增加,而‘津春2号'根系游离态腐胺含量显著增加.表明黄瓜根系中较高的游离态亚精胺和精胺、结合态和束缚态多胺以及较低的游离态腐胺含量有利于提高幼苗对盐胁迫逆境的适应能力.

Effects of salt stress on cucumber seedlings root growth and polyamine metabolism

By the method of water culture, this paper studied the effects of NaCl stress on the seedlings root growth and polyamine metabolism of two cucumber cultivars 'Changchun mici' and 'Jin-chun No. 2'. The results showed that under NaCl stress, root growth was inhibited, and lipid peroxidation and electrolyte leakage increased. These changes were more obvious in salt-sensitive 'Jin-chun No. 2' than in salt-tolerant 'Changchun mici'. NaCl stress caused an increase of agrinine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) activities in cucumber roots, which was much greater in 'Changchun mici' than in 'Jinchun No. 2'. At the highest value, ADC, ODC and SAMDC activities increased by 149.3%, 60.1% and 69.4% in 'Changchun mici' and 118.6%, 56.2% and 50.6% in 'Jinchun No. 2', respectively, in comparison with the control. Diamine oxidase activity increased in 'Changchun mici' but not in 'Jinchun No. 2', and the increment of polyamine oxidase activity in 'Changchun mici' was smaller than that in 'Jinchun No. 2'. As a result, the contents of free spermidine and spermine and of conjugated and bound polyamines in 'Changchun mici' increased significantly, while that of free putrescine had a significant increase in 'Jinchun No. 2'. It could be concluded that higher levels of free spermidine and spermine and of conjugated and bound polyamines and lower level of free putrescine in roots could improve the adaptability of cucumber seedlings to salt stress.